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Relations of Borehole Resistivity to the Horizontal Hydraulic Conductivity and Dissolved-Solids Concentration in Water of Clastic Coastal Plain Aquifers in the Southeastern United States

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Relations of Borehole Resistivity to the Horizontal Hydraulic Conductivity and Dissolved-Solids Concentration in Water of Clastic Coastal Plain Aquifers in the Southeastern United States

By ROBERT E. FAYE and WINSTON G. SMITH

U.S. GEOLOGICAL SURVEY WATER-SUPPLY PAPER 2414

U.S. DEPARTMENT OF THE INTERIOR

BRUCE BABBITT, Secretary

U.S. GEOLOGICAL SURVEY

GORDON P. EATON, Director

Any use of trade, product, or firm namesin this publication is for descriptive purposes onlyand does not imply endorsement by the U.S. Government.

UNITED STATES GOVERNMENT PRINTING OFFICE: 1994

For sale byU.S. Geological Survey, Map Distribution Box 25286, MS 306, Federal Center Denver, CO 80225

Library of Congress Cataloging in Pubiication Data

Faye, Robert E.Relations of borehole resistivity to the horizontal hydraulic conductivity and

dissolved-solids concentration in water of clastic coastal plain aquifers in the southeastern United States / by Robert E. Faye and Winston G. Smith, p. cm. (U.S. Geological Survey water-supply paper; 2414)

Includes bibliographical references.1. Groundwater flow Southern States Measurement. 2. Geophysical well

logging Southern States. 3. Aquifers Southern States. 4. Water qual ity Southern States. I. Smith, Winston G. II. Title. III. Series.

GB1197.7.F38 1994551.49'0975-dc20 93-13587

CIP

CONTENTS

Abstract....................................................................................................................................... 1Introduction................................................................................................................................... 1Theory and Concepts ....................................................................................................................... 2

Summation Model................................................................................................................... 3Product Model........................................................................................................................ 11

Relations of Borehole Resistivity to Aquifer Hydraulic Characteristics and Water Quality.................................... 18Applications and Testing of Regression Models ....................................................................................... 25Summary and Conclusions................................................................................................................. 30References .................................................................................................................................... 31

FIGURES

1. Map showing study area and county and site locations of wells ............................................................. 42-9. Graphs showing:

2. Resistivity borehole log at site CH-186 showing short- and long-normal curves and the screened andestimated contributing intervals................................................................................................ 15

3. Relation of horizontal hydraulic conductivity to grain-surface resistivity as defined by the summationmodel...............................................................................................................................20

4. Relation of horizontal hydraulic conductivity to apparent formation factor as defined by the productmodel............................................................................................................................... 21

5. Relation of horizontal hydraulic conductivity to aquifer bulk resistivity............................................... 226. Relation of horizontal hydraulic conductivity to aquifer water resistivity.............................................. 237. Relation of dissolved-solids concentration in aquifer water to aquifer water resistivity............................. 248. Relation of aquifer water resistivity to aquifer bulk resistivity .......................................................... 259. Relation of dissolved-solids concentration in aquifer water to aquifer bulk resistivity .............................. 26

TABLES

1. Summary of well location and construction data.................................................................................. 62. Generalized correlation of geologic units and aquifer units..................................................................... 113. Summary of borehole geoelectrical properties and aquifer water-quality characteristics at well sites ................... 124. Summary of borehole geoelectrical properties and aquifer hydraulic characteristics at well sites........................ 165. Summary of results of regression analyses......................................................................................... 196. Summary of regression model estimates of aquifer water-quality characteristics ........................................... 277. Summary of regression model estimates of horizontal hydraulic conductivity............................................... 288. Summary of error analyses of regression model estimates of aquifer water-quality characteristics...................... 309. Summary of error analyses of regression model estimates of horizontal hydraulic conductivity ......................... 30

Contents III

CONVERSION FACTORS

Multiply

inch (in.)foot (ft)

mile (mi)square mile (mi2)

square foot per day (ft2/d)cubic foot per second (ft3/s)

cubic foot per secondper square mile (m3/s/km2)

million gallons per day (Mgal/d)

By25.40.30481.6092.5900.092900.028320.01093

0.04381

To obtain

millimeter (mm)meter (m)kilometer (km)square kilometer (km2)square meter per day (m2/d)cubic meter per second (m3/s)cubic meter per secondper square kilometer [(ft3/s)/mi2]cubic meters per second (m3/s)

Temperature in degrees Celsius (°C) can be converted to degrees Fahrenheit (°F) as follows:

°F=1.8(°C)+32

Transmissivity is reported in the standard unit cubic foot per day per square foot times foot of aquifer thickness [(ft3/d)/ft2] ft. For convenience, the mathematically reduced form ft2/d is used in this report.

IV Contents

Relations of Borehole Resistivity to the Horizontal Hydraulic Conductivity and Dissolved-Solids Concentration in Water of Clastic Coastal Plain Aquifers in the Southeastern United StatesBy Robert E. Faye and Winston G. Smith

Abstract

Aquifer bulk resistivity and grain-surface resistivity (inverse of grain-surface conductance) were tested as geoelectrical analogs to the hori zontal hydraulic conductivity of clastic, fresh water aquifers in the Southeastern United States. Bulk resistivity was also tested as a geo electrical analog for dissolved-solids concentra tions in aquifer water. Bulk resistivity was defined as the average resistivity across a con tributing interval measured by the long-normal (64-inch) or induction log. Grain-surface resist ivity was empirically defined as the difference between aquifer bulk resistivity and aquifer water resistivity (computed from specific con ductance). Sources of data were borehole geo physical logs and results of water-quality and aquifer-test analyses related to unconsolidated sands and clayey sands at more than a hundred sites in seven Southeastern States. Water bearing units were composed of sediments rang ing from the Late Cretaceous to middle Eocene.

All bivariate data were related using the logarithmic regression model Y=AXB . Aquifer bulk resistivity and grain-surface resistivity were moderately correlated to horizontal hydraulic conductivity (70 and 72 percent correlation coefficients, respectively). Apparent formation factor, defined as the ratio of aquifer bulk resistivity to aquifer water resistivity, was shown to be poorly correlated with horizontal hydraulic conductivity (38 percent correlation

coefficient). Aquifer bulk resistivity was shown to be highly correlated with dissolved-solids concentration and aquifer water resistivity (88 and 93 percent correlation coefficients, respec tively).

Regression models using bulk resistivity and aquifer water resistivity as independent variables were applied at four locations in South Carolina and Louisiana to predict dissolved- solids concentrations in aquifer water. Absolute mean error of prediction was 20 and 6 percent, respectively. A regression model using bulk resistivity to predict horizontal hydraulic con ductivity was applied at 27 sites in 6 Southeast ern States, resulting in an absolute error ranging from 4 to 95 percent with a corresponding mean error of 43 percent.

INTRODUCTION

This report describes the development and application of several regression models that relate borehole geoelectrical properties to horizontal hydraulic conductivity and the dissolved-solids con centration in water of clastic, unconsolidated aqui fers in the Southeastern United States. The regres sion models are applicable to regional as well as to local aquifer systems composed of unconsolidated sands and clayey sands. The area of investigation extends from the Coastal Plain of North Carolina, across the Atlantic and Gulf Coastal Plains of South Carolina, Georgia, Alabama, Mississippi, and Loui-

Introduction

siana, and north into the Mississippi embayment to the vicinity of Memphis, Tenn. (fig. 1, table 1).

Borehole and well data were obtained from more than a hundred sites related to several Coastal Plain rock-stratigraphic units (tables 1, 2). To sim plify the designation of aquifers for a regional inves tigation, a nomenclature based on chronostratigraphy was used. Aquifers were grouped into three general ized categories: Late Cretaceous, Paleocene and early Eocene, and middle Eocene (table 2). Where the Meridian Sand Formation of middle Eocene age is used for water supply, it generally is developed in combination with sands of the upper Wilcox Group. Accordingly, for this study, data related to the Meridian Sand were grouped with aquifers of Paleo cene and early Eocene age.

The general lithology of Coastal Plain clastic aquifers does not vary substantially throughout the study area and is characterized by unconsolidated sand and clayey sand commonly thinly interbedded with clay. Quartz sand is ubiquitous to aquifers of the study area and ranges in size from coarse- to fine-grained. Clay is seldom entirely absent from water-bearing sands and commonly constitutes a substantial part of the aquifer matrix. Much of this clay is probably authigenic (Lee and Strickland, 1988; Chapelle and McMahon, 1991; McMahon and Chapelle, 1991) and occurs within the intergranular spaces of the aquifer matrix. The thickness of sand units in which wells are commonly screened is rarely less than 10 ft and seldom exceeds 200 ft (table 1). Regionally, the thickness of discrete water-bearing sand units decreases a%d the clay con tent increases downgradient from outcrops. The dissolved-solids concentration of aquifer waters also generally increases seaward or downgradient from outcrops (Clarke and others, 1983, 1985; Lee, 1988; Pettijohn, 1988).

Hydraulic and water-quality characteristics are highly variable throughout the study area. The dissolved-solids concentration in water samples col lected from freshwater aquifers ranges from about 20 to 2,000 milligrams per liter (mg/L) (tables 3, 6). The observed horizontal hydraulic conductivity (Kh) of Coastal Plain aquifers ranges from about 4 to greater than 500 feet per day (ft/d) (tables 4, 7). Porosity of water-bearing sands regionally varies between 20 and 4Q percent but variations within aquifers at a single well or locally between wells appear to be minor (Jones and Buford, 1951; Hos- man and others, 1968; Zack, 1977; Cahill, 1982;

Clarke and others, 1985; and Faye and McFadden, 1986). The observed temperature of aquifer water at the point of well discharge ranges from about 16 to 43°C(61 to 110°F)(table3).

Borehole resistivity across intervals of water bearing sands is highly variable locally (fig. 2) and areally (tables 3, 4). Average bulk resistivity (R0) across contributing water-bearing intervals varies from less than 10 to about 600 ohm-meters (ohm-m) throughout the study area. Bulk resistivity represents the total electrical resistance contributed from all sources (grains, matrix material, and water) within the aquifer.

Most transmissivity data (table 4) were obtained from the files of the U.S. Geological Sur vey. Some transmissivity data were obtained from reports that summarize the results of aquifer-test analyses. These include, primarily, results described by Zack (1977), Aucott and Newcome (1986), Faye and McFadden (1986), and Slack and Darden (1991). Borehole geophysical logs, water-quality data, and well-construction data were, for the most part, obtained from the files of the U.S. Geological Survey (tables 1, 3).

THEORY AND CONCEPTS

In a clastic, porous media saturated with freshwater (dissolved-solids concentration less than 5,000 mg/L), both fluid flow and electrical current move in a tortuous path through the interstices of the media. Accordingly, electrical conductance of the clastic porous media may be substantially influ enced by those properties of the media that enhance the ionic content and volume of interstitial water. Such properties can be characterized or measured by determining the specific conductance and dissolved- solids concentrations of the water, the degree of mineralization of the porous media (particularly the percentage of clay), the particle-size distribution of the clay, silt, and sand grain solids, and the media porosity. Other media properties that probably mini mally affect electrical conductance are the sand grain shape and the nature of sand grain packing. Media hydraulic characteristics also vary according to changes in many of these same properties.

Consider that the bulk resistivity of a freshwa ter aquifer is, for the most part, a function of elec trolyte resistivity (Re) and matrix solids resistivity (Rm); therefore,

2 Relations of Borehole Resistivity In the Southeastern United States

R0=f(Re,Rm}. (1)

Electrolyte resistivity is largely a function of the ionic strength of the aquifer water and ion exchange between the water and the surfaces of clays and other fine-grained aquifer solids. This latter process is termed surface conductance (Alger, 1966; Pfannkuch, 1969), the resistance equivalent for which is designated grain-surface resistivity (Rs) in this report; accordingly,

Re =f(Rw'Rs)> (2)

where Rw is the resistivity of aquifer water. The magnitude of grain-surface resistivity decreases with increasing ionic exchange capacity between the aquifer water and the fine-grained aquifer solids exposed to this water (Alger, 1966). Thus, the greater the percentage of clays and sands of small grain size that comprise the aquifer and the greater the ionic content of the aquifer water, the smaller is the related grain-surf ace resistivity.

Grain-surface resistivity cannot be directly measured. In addition, the geophysical and electro chemical relations of grain-surface resistivity to other borehole geophysical and hydraulic properties are poorly understood and only empirical relations have been developed (Pfannkuch, 1969; Worthing- ton, 1976, 1977; Urish, 1981; Huntley, 1986). A consistent, measurable relation that includes the bulk resistivity and water resistivity components of equa tions 1 and 2 has been observed, however, such that bulk resistivity always exceeds water resistivity for a saturated porous media (Keys and MacCary, 1971; Engineering Enterprises, Inc., written commun., August 23-24, 1983). Data reported for this study (tables 3, 4) and by Jones and Buford (1951), Tur- can (1962), and Brown (1971) indicate that bulk resistivity in Southeastern Coastal Plain clastic, freshwater aquifers is consistently greater than aqui fer water resistivity, and that water resistivity com prises a major percentage of bulk resistivity for any contributing interval.

Matrix solids resistivity is the result of elec tron conductance through the grain-to-grain contacts of contiguous sand grains of the aquifer. Quartz sand is virtually a nonconducting material and matrix solids resistivity is considered infinitely large.

Dimensional analyses by Muskat (1937) and De Wiest (1965) determined that horizontal hydrau lic conductivity is directly proportional to the square

of the diameter of aquifer pore openings. Therefore, increasing percentages of clay, silt, and fine-grained sand in a clastic aquifer tend to decrease both the average pore diameter and the average horizontal hydraulic conductivity. Such increases in clay and fine-grained sand in freshwater-saturated aquifers also tend to decrease grain-surface resistivity. Accordingly, grain-surface resistivity might be an appropriate geoelectrical analog for the horizontal hydraulic conductivity (Kh) of unconsolidated, clas tic porous media; that is

Kh =f(Rs). (3)

Alternatively, the variation of bulk resistivity across water-bearing sands and clayey sands (fig. 2) largely could be the result of changes in clay con tent, manifest as variations in grain-surface resistiv ity. Thus, bulk resistivity could also be a suitable geoelectrical analog for horizontal hydraulic conduc tivity.

To investigate the relations of aquifer bulk resistivity and grain-surf ace resistivity to horizontal hydraulic conductivity, grain-surface resistivity must first be defined in terms of geoelectrical properties that can be measured in the field. A parallel resist ance model, similar to that used by Pfannkuch (1969), is used to relate aquifer bulk resistivity to electrolyte resistivity and matrix solids resistivity,

1 1 1o e m

(4)

Because matrix solids resistivity is considered to be infinite, equation 4 reduces to

jr=-rT > and" o "~e

(5)

Rs). (6)

Because the exact, deterministic form of equation 2 is unknown, elementary hypothetical relations are used and substituted into equation 6 to evaluate grain-surface resistivity in terms of bulk resistivity and aquifer water resistivity. The hypothetical mod els applied in this study are a summation model (Re =Rw +Rs) and a product model (Re =Rw xRs).

Summation Model

The summation model explains grain-surface resistivity as the difference between bulk resistivity

Theory and Concepts

94° 90°

34°

30°

Base modified from U.S. Geological Survey, National Atlas digital data, 1:2,000,000,1970Albers Equal-Area Conic projectionStandard parallels 29°30' and 45°30', central meridian -96°00'

Figure 1. Study area and county and site locations of wells.

4 Relations of Borehole Resistivity in the Southeastern United States

82° 78°

NORTH CAROLINA

SOUTH CAROLINA

EXPLANATION

COUNTY LOCATION OF WELL SITES

WELL SITE LOCATION Data used for regression models

WELL SITE LOCATION Data used for application and testing

- APPROXIMATE LOCATION OFPHYSIOGRAPHIC BOUNDARY

o 50 100 150 200 MILES

100 150 200 KILOMETERS

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ce C

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unity

Wat

er S

yste

m T

est

#2W

alla

ce C

omm

unity

Wat

er S

yste

m T

est

#3

Wal

lace

Com

mun

ity W

ater

Sys

tem

Tes

t #

3G

rand

Can

e Te

st #

1N

. D

esot

o W

ater

Sys

tem

Tes

t #

3N

. D

esot

o W

ater

Sys

tem

Wel

l #3

Man

sfie

ld T

est

Wel

l #2

N.

Des

oto

Test

Wel

l #

2K

eatc

hie

Wat

er S

yste

mK

eatc

hie

Test

Wel

l #

2

Girl

Sco

ut C

amp

Test

Wel

lR

iser

Roa

d C

omm

unity

Wat

er D

istri

ct W

ell

Bea

r C

reek

#2

Pum

kin

Cen

ter

Test

#1

Rus

ton

Sta

te S

choo

l #1

S.D

. B

eard

Pro

perty

Wat

er W

ell T

est

Hic

o W

ater

Tes

t #

2W

esle

y C

hape

l Wat

er W

ell

Rus

ton

Test

Wel

lR

usto

n W

ater

Wel

l #1

Cla

renc

e W

ater

Wel

lR

obel

ine

Test

Wel

l #

2

Edg

efie

ld T

est

Rot

e #1

Edg

efie

ld #

2C

hous

hatta

Ind

ustri

al T

est

Par

k #2

Cho

usha

tta T

est

#1E

dgef

ield

Obs

erva

tion

Wel

lH

alfw

ay-C

arro

ll Te

st #

3

Man

y Te

st H

ole

#3M

any

Test

Hol

e #

3To

ledo

Ben

d Te

st S

ite #

4

Ber

nice

Tes

t W

ell

Roc

ky B

ranc

h W

ater

Tes

t #2

32 32 31 31 31 31 31 31 31 32 32 32 31 32 32 32 32 32 32 32 32 32 32 32 32 32 31 31 32 32 32 32 32 32 31 31 31 32 32

11 11 54 57 54 53 54 51 51 04 15 13 59 17 09 06 12 28 17 19 42 36 43 29 29 31 50 41 02 03 01 02 03 03 34 34 46 48 40

15 15 05

28 56 57 56 25 25 54 07 37 55 44 58 50 49 08 51 04 02 58 25 00 47 30 52 41 46

05 25

07 06 10 41 41 00 33 03

93 93 93 93 93 93 93 93 93 93 93 93 93 93 93 93 92 92 92 92 92 92 92 92 92 92 93 93 93 93 93 93 93 93 93 93 93 92 92

54 54 53 55 27 27 34 32 32 48 48 46 46

48 59 56 19 37 44 42 32 41 45 40 38 39 01 19 19 20 20 21 20 21 28 28 46 39 12

26 26 40 39 46 03 18 16 16 45 37 18 29 54 24 41 04 17 42 03 26 18 02 40 25 51 02 21 35 14 39 09 07 47 55 55 56 11 09

Wilc

ox G

roup

Wilc

ox G

roup

Wilc

ox G

roup

Wilc

ox G

roup

Wilc

ox G

roup

Wilc

ox G

roup

Wilc

ox G

roup

Wilc

ox G

roup

Wilc

ox G

roup

Wilc

ox G

roup

Wilc

ox G

roup

Wilc

ox G

roup

Wilc

ox G

roup

Wilc

ox G

roup

Wilc

ox G

roup

Wilc

ox G

roup

Spa

rta S

and

Spa

rta S

and

Spa

rta S

and

Spa

rta S

and

Spa

rta S

and

Spa

rta S

and

Spa

rta S

and

Spa

rta S

and

Spa

rta S

and

Spa

rta S

and

Wilc

ox G

roup

Wilc

ox G

roup

Wilc

ox G

roup

Wilc

ox G

roup

Wilc

ox G

roup

Wilc

ox G

roup

Wilc

ox G

roup

Wilc

ox G

roup

Wilc

ox G

roup

Wilc

ox G

roup

Wilc

ox G

roup

Spa

rta S

and

Spa

rta S

and

10 10 10 10 10 10 10 10 10 10 10 10 10 22 10 20 20 20 10 10 15 10 10 10 20 60 10 10 10 10 10 10 10 10 20 20 10 10 20

24 30 44 10 24 54 10 24 44 32 46 10 22 22 18 20 78 63 78 11 32 66 52 62 132

104

46 32 10 30 14 22 42 20 32 20 22 36 42

3 3 4 3 2 4 4 4 3 2 3 2 3 14 3 3 2.75

3 2 2 2 3 3 3 4 10 4 2 14 2 2 3 4 3 14 14 4 3 2

30 30 65 14 30 18 40 24 23 50 43 50 40 34 40 42 43 38 28 28 33 30 25 25 33 800 35 75 20 33 20 43 50 38 26 30 62 56 36

Tabl

e 1.

S

umm

ary

of w

ell

loca

tion

and

cons

truct

ion

data

Con

tinue

d

Cou

nty

Sta

te

wel

l nu

mbe

rLo

cal w

ell

nam

eLa

titud

e Lo

ngitu

de

Deg

Min

Sec

Deg

Min

Sec

Rep

orte

d w

ater

be

arin

g un

it(s)

Tota

l sc

reen

le

ngth

(ft

)

Est

imat

ed

cont

ribut

ing

inte

rval

(ft

)

Ope

ning

s di

amet

er

(in.)

Tes

t di

scha

rge

(gal

/min

)

Lo

uis

ian

a C

ontin

ued

Web

ster

Web

ster

Web

ster

Web

ster

Web

ster

Web

ster

Web

ster

Web

ster

Web

ster

Web

ster

Win

nW

inn

Win

nW

inn

Win

nW

inn

Cal

houn

Cia

rke

Hin

dsH

inds

Hin

dsH

inds

Hin

dsLa

uder

dale

Laud

erda

leLo

wnd

esLo

wnd

es

Mad

ison

Ran

kin

Was

hing

ton

Yaz

oo

WE

-139

WE

-265

WE

-268

WE

-270

WE

-281

WE

-291

WE

-292

BW

E-3

08W

E-3

21A

WE

-321

B

WI-

113

WI-

114

WI-

120

WI-

127

WI-

140

WI-

143

K10

1R

31

G84

H14

6H

149

H18

8M

99C

53C

54P

20P2

1

W74

K11

9L7

0G

81

Loui

sian

a O

rdna

nce

Pla

ntJe

nkin

s W

ater

Tes

t Wel

l #1

Old

Sho

ngal

oo W

ater

Wel

l Tes

t #

2Je

nkin

s W

ater

Tes

t Wel

l #

2C

entra

l Tes

t Wel

l #1

Pal

met

to B

each

Com

mun

ity #

1N

orth

Sho

ngal

oo C

omm

unity

Wat

er W

ell

Thom

asvi

lle T

est W

ell

#1G

erm

anto

wn

Wat

er T

est

Wel

l #1

Ger

man

tow

n W

ater

Tes

t W

ell

#1

Hur

rican

e C

reek

#2

Gum

Spr

ings

Wat

er W

ell T

est

Win

nfie

ld T

est #3

Cal

vin

Test

#1

Gan

sviH

e Te

st W

ell

Cal

vin

Test

Wel

l

Cal

houn

City

Wel

l #1

Hiw

anee

Wat

er A

ssn.

#1

City

Of J

acks

on "

W-D

"C

ity O

f Jac

kson

"N

-B"

City

Of J

acks

onJa

ckso

n Zo

o W

ell

#1C

ity O

f Jac

kson

"W

-B"

Nav

al A

ir S

tatio

n #

4N

aval

Air

Sta

tion

#1W

eyer

haeu

ser

#2

Wey

erha

euse

r #

3

Tow

n O

f M

adis

onTo

wn

Of

Pea

rlA

rcol

a W

ell #3

Mis

siss

ippi

Che

mic

al C

orp.

Tes

t Wel

l

32 32 32 32 32 32 33 32 32 32 32 31 31 31 32 31 33 31 32 32 32 32 32 32 32 33 33 32 32 33 32

32 31 59 31 28 25 00 52 42 42 01 53 55 58 08 57 51 51 18 22 23 19 16 33 33 21 21 27 15 16 54

44

9336

93

35

9337

93

53

9353

93

33

9339

93

05

9305

93

18

9253

92

06

9202

92

34

9256

92

Mis

siss

ippi

18

8903

88

45

9020

90

06

9009

90

48

9015

88

14

8846

88

46

88

02

9018

90

19

9021

90

26 23 18 22 14 23 21 25 13 13 41 47 37 46 44 46 17 41 16 14 09 13 17 37 36 28 27 08 07 52 22

23 35 00 31 09 35 52 52 46 46 41 00 43 41 10 35 59 02 58 00 42 22 00 23 59 02 10 23 11 22 43

Wilc

ox G

roup

Car

rizo

Form

atio

nS

parta

San

dC

arriz

o Fo

rmat

ion

Car

rizo

Form

atio

nW

ilcox

Gro

upS

parta

San

dS

parta

San

dS

parta

San

dS

parta

San

d

Spa

rta S

and

Spa

rta S

and

Spa

rta S

and

Spa

rta S

and

Spa

rta S

and

Spa

rta S

and

Gor

do F

orm

atio

nLo

wer

Wilc

ox G

roup

Spa

rta S

and

Spa

rta S

and

Spa

rta S

and

Spa

rta S

and

Spa

rta S

and

Low

er W

ilcox

Gro

upLo

wer

Wilc

ox G

roup

Cok

er F

orm

atio

nC

oker

For

mat

ion

Spa

rta S

and

Spa

rta S

and

Spa

rta S

and

Mer

idia

n S

and

Wilc

ox G

roup

70 10 10 10 10 10 10 10 10 10 10 20 10 10 20 10 57 70 60 60 60 32 65 61 47 156

156 50 60 50 260

66 34 24 26 28 22 64 29 62 34 70 88 40 44 54 48 38 129

166

110

243 70 95 104 74 148

180

102

210

202

108

8 3 4 3 4 4 3 3 3 3 3 3 2 4 2 3 12 8 8 8 8 6 8 8 8 10 6 8 8 6 6

260 50 41 40 38 35 43 20 43 50 25 25 35 33 30 30 240

450

610

610

600

170

610

700

610

2,00

075

4

560

610

250

900

Jone

sT2

7U1

Wey

erha

user

Wel

l #

235

Nor

th C

arol

ina

00

51

77

3509

Pe

edee

For

mati

on30

5280

Tabl

e 1.

S

umm

ary

of w

ell

loca

tion

and

cons

truct

ion

data

Con

tinue

d

Cou

nty

Bar

nwel

lB

arnw

ell

Bea

ufor

t

Dor

ches

ter

Hor

ryH

orry

Laud

erda

le

She

lby

She

lby

She

lby

She

lby

She

lby

She

lby

Sta

te

wel

l nu

mbe

r

BW

-79

SR

P 9

05-1

20p

BF

M5

4

DO

R-2

21H

O-3

36H

O-4

16

LD-.H

-6

SH

J-10

4S

H-.K

-73

SH

:L-6

9S

H:L

-8S

HP

-25

SH

:U-1

8

Loca

l wel

l na

me

Tow

n O

f W

illis

ton

Sav

anna

h R

iver

Pla

ntH

ilton

Hea

d D

eep

Wel

l

Oak

broo

k W

ell #

3N

orth

Myr

tle B

each

#2

Oce

an L

akes

#6

City

Of

Rip

ley

#2

Mem

phis

Lig

ht,

Gas

, an

d W

ater

Mem

phis

Lig

ht,

Gas

, an

d W

ater

Tes

t #6

Mem

phis

Lig

ht,

Gas

, an

d W

ater

Ger

man

tow

n W

ell #

2B

ucke

ye #

10D

upon

t W

ell #5

Latit

ude

Long

itude

Deg

33 33 32 32 33 33 35 35 35 35 35 35 35

Min

S

ec

Deg

Sou

th C

arol

ina

23

48

8113

40

81

14

46

80

57

32

8050

16

78

38

15

78

Ten

ness

ee

44

44

89

05

38

9005

15

89

02

59

8905

04

89

09

14

8916

00

89

Min

24 34 44 09 40 57 31 01 55 52 48 57 58

Sec

07 31 40 46 24 42 42 45 36 13 32 41 43

Rep

orte

d w

ater

be

arin

g un

it(s)

Mid

dend

orf

Form

atio

nM

idde

ndor

f Fo

rmat

ion

Cap

e Fe

ar F

orm

atio

nM

idde

ndor

f Fo

rmat

ion.

Bla

ck C

reek

For

mat

ion

Bla

ck C

reek

For

mat

ion

Bla

ck C

reek

For

mat

ion

Mem

phis

San

d

Mem

phis

San

dM

emph

is S

and

Mem

phis

San

dM

emph

is S

and

Wilc

ox G

roup

Mem

phis

San

d

Tota

l sc

reen

le

ngth

(ft

)

100 50 82 69 150

120 -

167 80

Est

imat

ed

cont

ribut

ing

inte

rval

(ft

)

330 70 184 64 320

384 90 70 130

110

102

195

102

Ope

ning

s Te

st

diam

eter

di

scha

rge

(in.)

(gal

/min

)

10 6 6 8 8 12 6 _ 12 10

1,40

075

0

600

500

400

590

1,68

01,

700

820

300

1,20

01,

570

App

licat

ion

and

Tes

t S

ites

Hou

ston

Des

oto

Win

n

Bol

ivar

Cla

rkC

lark

Leak

eLe

eM

adis

on

Mad

ison

Mon

tgom

ery

New

ton

Ran

kin

DS

-411

WI-

115B

T131

K8

L51

O34

F31

O46

W69

M12

A34

G42

_ -

31 31 31 33 32 32 32 34 32 32 33 32 32

Ala

bam

a

12

30

85

Loui

sian

a

52

37

9351

15

92

Mis

siss

ippi

36

35

9005

26

88

02

39

8837

52

89

21

09

8838

02

89

25

14

90

21

09

8933

41

89

20

32

89

25 53 52 46 29 52 37 35 54 08 33 19 58

00 38 39 05 58 54 35 04 15 09 23 11 02

Tusc

ahom

a Fo

rmat

ion

Nan

afal

ia F

orm

atio

nC

layt

on F

orm

atio

n.

Wilc

ox G

roup

Spa

rta S

and

Spa

rta S

and

Low

er W

ilcox

Gro

upS

parta

San

dLo

wer

Wilc

oxM

cSha

n Fo

rmat

ion

Mer

idia

n S

and

Upp

er W

ilcox

Gro

up.

Spa

rta S

and

Low

er W

ilcox

Gro

upM

iddl

e W

ilcox

Gro

up

Spa

rta S

and

_ 20 10 81 40 40 60 60 71 81 51 31 40

3240 56 12 84 82 12

6 72 114 96 202 88 80 134

_ 4 2 8 8 6 6 6 6 10 6 8 6

2620 25 12

270

280

280

340

160

410

940

170

470

330

Tabl

e 1.

S

umm

ary

of w

ell

loca

tion

and

cons

truct

ion

data

Con

tinue

d

o CO a 00 o I . I I (D

I?

Cou

nty

Stat

e w

ell

Loca

l w<

num

ber

sll n

ame

Deg

Latit

ude

Min

Long

itude

Sec

Deg

M

in

Sec

Rep

orte

d w

ater

be

arin

g un

it(s)

Tota

l sc

reen

le

ngth

(ft

)

Estim

ated

co

ntrib

utin

g in

terv

al

(ft)

Ope

ning

s di

amet

er

(in.)

Test

di

scha

rge

(gal

/min

)

Mis

siss

ippi

C

ontin

ued

Ran

kin

Ran

kin

Ran

kin

Ran

kin

Scot

tSc

ott

Smith

Yaz

oo

Ons

low

Cha

rlest

onD

orch

este

r

Hor

ryH

orry

Hor

ry

Mar

ion

Mar

ion

G51

-

K120

-

K17

5 -

K18

6 -

J35

-L4

5 -

L26

-

O30

-

V25

P4

-

CH

-186

-

DO

R-2

11

-

HO

-309

-

HO

-335

-

HO

-353

-

MR

N-6

7 -

MR

N-7

8 -

32 32 32 32 32 32 32 32 34 32 33 33 33 33 34 31

20 16 17 17 20 21 00 48 51 36 09 45 49 37 11 12

34 40 36 10 51 57 46 26 31 00 25 43 34 15 56 30

89 90 90 90 89 89 89 90 77 80 80 78 78 78 79 85

58

2007

08

08

4102

38

40

1927

19

23

20

03

52

Nor

th C

arol

ina

29

16

Sou

th C

arol

ina

06

2231

18

57

4241

15

57

42

14

0425

00

Spar

ta S

and

Spa

rta S

and

Spar

ta S

and

Spar

ta S

and

Spa

rta S

and

Mer

idia

n Sa

ndSp

arta

San

d

Mer

idia

n Sa

ndU

pper

Wilc

ox G

roup

.

Blac

k C

reek

For

mat

ion

Mid

dend

orf F

orm

atio

nEl

lent

on F

orm

atio

nBl

ack

Cre

ek F

orm

atio

nC

ape

Fear

For

mat

ion.

Blac

k C

reek

For

mat

ion

Bla

ck C

reek

For

mat

ion

Bla

ck C

reek

For

mat

ion

Bla

ck C

reek

For

mat

ion

Blac

k C

reek

For

mat

ion

Mid

dend

orf

Form

atio

nC

ape

Fear

For

mat

ion.

70 50 80 100

122

110 61 60 55 116 60 15 195 70 50 90

105 65 146

114

190

144

142 84 66

260 84 70 420

110

208 90

8 8 8 8 8 8 6 6 6 8 4 8 6 8

300

600

750

770

680

1,00

032

0

230

750

450 32

500

300

570

Rep

orte

d ca

sing

dia

met

er.

2 A

quif

er-t

est

disc

harg

e at

City

of

Dot

han

wel

l #9

.3

Est

imat

e ba

sed

on e

lect

ric

log

data

at

near

by S

elm

a St

reet

wel

l.

Table 2. Generalized correlation of geologic units and aquifer units

System

Tertiary

Cretaceous

Series

Eocene

Paleocene

Upper Cretaceous

Group

Claiborne

Wilcox

Midway

Selma

Tuscaloosa

Geologic units West East

T-J f Sparta Sand| | on | Tallahatta Formation

11g ' Camzo Formations IMeridian Sand member of the Tallahatta Formation

Tuscahoma Formation

Nanafalia Formation

Clayton Formation

Providence Sand

Ripley Formation

Cusseta Sand2

Blufftown Formation

Eutaw Formation

McShan Formation

Gordo Formation

Coker Formation

Ellenton1 Formation

Peedee2 Formation

Black Creek2 Formation

Middendorf3 Formation

Cape Fear4 Formation

Aquifer unit

middle Eocene

Paleocene and

early Eocene

Late Cretaceous

1 Not part of Midway Group.2 Not part of Selma Group.3 Part of Lumbee Group.4 Not part of Tuscaloosa Group.

and aquifer water resistivity. Because horizontal hydraulic conductivity is also explained as a func tion of grain-surface resistivity,

Kh=f(Rs}=f(R0-Rw). (7)

Product Model

The relation of grain-surface resistivity to bulk resistivity and water resistivity explained by the product model is expressed by the following equa tion,

Kh=(f(Rs)=f(R0/Rw). (8)

The right-hand side of equation 8 generally corre sponds to the definition of apparent formation factor (Fa) described by Pfannkuch (1969) and Worthing- ton (1977). Apparent formation factor is the ratio of bulk resistivity to water resistivity in freshwater-

saturated porous media containing clays or other conductive solids and previously has been used to estimate horizontal hydraulic conductivity (Alger, 1966; Croft, 1971; Urish, 1981; Biella and others, 1983; Alger and Harrison, 1989). Intrinsic formation factor (F) is similarly defined but applies only to porous media saturated with highly conductive elec trolytes, such as brines (Archie, 1942). Where porous media are saturated with brine, geoelectrical conductance is almost entirely through the electro lyte (pore spaces); grain-surface conductance is min imal. All subsequent references to formation factor are to apparent formation factor.

Application of equations 7 and 8 at well sites requires a data base that includes aquifer-test results or laboratory determinations of hydraulic character istics, borehole lithologic and well construction logs, calibrated borehole resistivity logs, and chemi cal analyses of water samples from the completed wells.

Theory and Concepts 11

Table 3. Summary of borehole geoelectrical properties and aquifer water-quality characteristics at well sites[ohm-m, ohm-meter; |xS/cm, microsiemens per centimeter; mg/L, milligrams per liter; , no data]

County

ChoctawDale

BurkeDoughertyDoughertyDougherty

HoustonJohnston

LaurensPulaski

Richmond

Richmond

Twiggs

CaddoCaddoCaddoCaddo

Caddo

CaldwellClaiborne

ClaiborneClaiborne

DesotoDesotoDesotoDesotoDesotoDesotoDesotoDesotoDesotoDesoto

DesotoDesoto

Desoto

Desoto

DesotoDesotoDesoto

State well number

CHO-1-

31Z00212L02113L02113L022

16T00224V001

21U00418T001

30AA13

30AA15

17V004

CD-435CD-447CD-460CD-492

CD-498A

CA-98CL-135A

CL-140ACL-140B

DS-372ADS-372BDS-372CDS-376DS-377DS-381ADS-381BDS-386DS-391DS-396

DS-397DS-403

DS-404A

DS-404B

DS-406DS-409DS-414B

AvbeuTk9e WaterLocal well name resistivity ^^

(Ho) (Oft

(ohm-m) { o;

Choctaw County #1Fort Rucker #9 (TW-3)

Bechtel Corp. #1 (TW-1)Albany TW-10Miller Brewing Company PW2Miller Brewing Company PW3

Pabst Brewing Co. #4Wrightsville Firetower (USGS

TW-1).Laurens TW-3 (1-16 Rest Stop)Arrowhead (USGS TW-1)

Kimberly-Clark ObservationWell #1.

Kimberly-Clark ObservationWell #3.

J.M. Huber HP5

Blanchard Test Hole #1Vivian #3.Rodessa Water Test #1Town Of Belcher Water System

Well #2.Ida Test Well #2

Cotton Plant Test #2Claiborne Parish Police Jury

Well#l.Homer Test Well #2Homer Test Well #2

Stanley Water Test Well #1Stanley Water Test Well #1Stanley Water Test Well #1S. Mansfield #1Longstreet Water Test Well #1Keatchie Water Test Well #1Keatchie Water Test Well #1Toledo Bend Site #2Stanley Water SystemRambin- Wallace Community Test

Well #1.Rambin- Wallace Test #2Wallace Community Water System

Test #2.Wallace Community Water System

Test #3.Wallace Community Water System

Test #3.Grand Cane Test #1N. Desoto Water System Test #3N. Desoto Water System Well #3

31120

20030

10066

580110

120280

170

200

430

21323315

45

18160

140150

100232933272730272990

3040

27

27

302720

Alabama

33.023.5

Georgia

_24.020.020.0

19.030.0

24.924.5

25.0

25.0

-

Louisiana

20.6

-

_

-

21.621.621.721.923.322.821.121.720.5

21.521.1

21.5

22.5

21.023.9

Specific conductance of well discharge

((iS/cm)

900320

2 180

560321321

35145

11579

120

107

46

916697916

1,550

273

1,360139

190200

1891,1601,310

607112765885

1,5101,800

384

;,030403

772

768

5701,6201,660

Water Water resistivity resistivity at discharge

at 25°C (flj temperature (Rwx) (ohm-m) (ohm- m)

11.131.3

55.617.931.231.2

28669

87127

83.3

93.5

217

10.914.310.96.5

36.6

7.471.9

52.650.0

52.98.67.6

16.513.013.111.36.65.6

26.0

9.724.8

13.0

13.0

17.56.26.0

9.532.3

55.618.334.934.9

32862.3

87.2128

83.3

93.5

217

12.014.310.96.5

36.6

7.471.9

52.650.0

52.99.38.2

17.813.913.611.97.26.0

28.8

10.527.1

14.1

13.7

19.16.36.0

Dissolved-solids concentration of well discharge

(mg/L)

'535

3242

192192431

4112

475426

88

91

547

517419204902

151

836170

137169

162738805379463458526889

1,070260

681267

481

469

341921940


Table 3. Summary of borehole geoelectrical properties and aquifer water-quality characteristics at well sites Continued

County State well number

AvbeuTk9e WaterLocal well name resistivity ££%*.

' °> (°C,\(ohm-m) { ^>

Specific conductance of well discharge

(ixS/cm)


at 25°C (fl J temperature (Rwx) (ohm-m) (ohm- m)


(mg/L)

Louisiana Continued

DesotoDesotoDesotoDesotoJacksonJackson

JacksonJacksonLincolnLincoln

LincolnLincolnLincolnLincoln

NatchitochesNatchitoches

Red RiverRed RiverRed River

Red RiverRed RiverRed River

SabineSabineSabine

UnionUnion

WebsterWebsterWebster

WebsterWebsterWebsterWebster

WebsterWebsterWebster

WinnWinnWinnWinnWinnWinn

CalhounClarke

DS-417DS-423DS-458DS-459JA-101BJA-136

JA-140JA-150LN-117LN-131B

LN-135ALN-140LN-151LN-48

NA-362NA-413

RR-181RR-182RR-241

RR-247RR-249RR-251

SA-407ASA-407BSA-431

UN-57UN-71B

WE- 139WE-265WE-268

WE-270WE-281WE-291WE-292B

WE-308WE-321AWE-321B

WI-113WI-114WI-120WI-127WI-140WI-143

K101R31

Mansfield Test Well #2N. Desoto Test Well #2Keatchie Water SystemKeatchie Test Well #2Girl Scout Camp Test WellRiser Road Community Water

District Well.Bear Creek #2Pumkin Center Test #1Ruston State School #1S.D. Beard Property Water

Well Test.Hico Water Test #2Wesley Chapel Water WellRuston Test WellRuston Water Well #1

Clarence Water WellRobeline Test Well #2

Edgefield Test Hole #1Edgefield #2Choushatta Industrial Park

Test #2.Choushatta Test #1Edgefield Observation WellHalfway-Carroll Test #3

Many Test Hole #3Many Test Hole #3Toledo Bend Test Site #4

Bernice Test WellRocky Branch Water Test #2

Louisiana Ordnance PlantJenkins Water Test Well #1Old Shongaloo Water Well

Test #2.Jenkins Water Test Well #2Central Test Well #1Palmetto Beach Community #1North Shongaloo Community

Water Well.Thomasville Test Well #1Germantown Water Test Well #1Germantown Water Test Well #1

Hurricane Creek #2Gum Springs Water Well TestWinnfield Test #3Calvin Test #1Gansville Test WellCalvin Test Well

Calhoun City Well #3Hiwanee Water Assn. #1

274025243745

120302795

604560

150

5325

468826

325522

235525

15027

322640

34383854

80160160

343030323727

4135

_22.222.022.022.525.6

21.924.422.822.8

22.223.626.025.0

20.623.1

25.8 21.1

19.418.320.0

21.920.822.2

24.725.0

21.721.122.2

21.723.919.420.6

21.122.8-

20.624.4 21.722.222.2

Mississippi

33.338.5

953539562779

1,090536

243402870277

316409408252

6361,240

345308783

706265773

1,280591817

4101,140

6761,790

472

1,060689421611

322168201

1,250897840979851

1,080

1,135800

10.518.617.812.89.2

18.7

41.224.911.536.1

31.624.424.539.7

15.78.1

29.032.512.8

14.237.712.9

7.816.912.2

24.48.8

14.85.6

21.2

9.414.523.816.4

31.159.549.8

8.011.111.910.211.89.3

8.812.5

10.519.819.013.79.7

18.5

44.125.212.137.9

33.625.224.039.7

17.38.4

28.532.514.0

16.144.014.4

8.418.613.0

24.68.8

15.96.1

22.6

10.114.927.018.1

33.962.449.8

8.811.211.911.012.69.9

7.59.7

568331330457681331

191258486192

231283274187

403789

217206464

396188450

800357480

290650

412974290

603434265365

200150179

699501494566528603

605


Table 3. Summary of borehole geoelectrical properties and aquifer water-quality characteristics at well sites Continued

County State well number Local well name

Av®ra9e Water Specific . u . . discharge conductance of

resistivity temperature we|| discharge

(ohm-m) <°C> <^S/cm>


at 25°C (Rw) temperature (Rwx) (ohm-m) (ohm- m)


(mg/L)

Mississippi Continued

Hinds Hinds Hinds HindsHinds

LauderdaleLauderdaleLowndes Lowndes

MadisonRankinWashington Yazoo

Jones

BarnwellBarnwellBeaufort

Dorchester

Horry Horry

Lauderdale

Shelby

Shelby

Shelby

Shelby Shelby Shelby

G84 H146 H149 H188M99

C53C54P20 P21

W74K119L70 G81

T27U1

BW-79SRP905-120PBFT-454

DOR-221

HO-336 HO-416

LD:H-6

SH:J-104

SH:K-73

SH:L-69

SH:L-8 SH:P-25 SH:U-18

City Of Jackson "W-D" City Of Jackson "N-B" City Of Jackson Jackson Zoo Well #1City Of Jackson "W-B"

Naval Air Station #4Naval Air Station #1Weyerhaeuser #2 Weyerhaeuser #3

Town Of MadisonTown Of PearlArcola Well #3 Mississippi Chemical Corp.

Test Well.

Weyerhauser Well #2

Town Of WillistonSavannah River PlantHilton Head Deep Well

Oakbrook Well #3

North Myrtle Beach #2 Ocean Lakes #6

City Of Ripley #2

Memphis Light, Gas, and Water.

Memphis Light, Gas, and Water Test #6.

Memphis Light, Gas, and Water.

Germantown Well #2 Buckeye #10 Dupont Well #5

55 78 66 2660

400400150 150

404040 70

150

270610

6.

11

7. 17

200

300

380

400

550 190 160

29.0 28.0 28.0 26.030.6

_

33.031.027.0 35.0

North Carolina

-

South Carolina

20.0

,2 43.5

31.1

,8 26.5 24.0

Tennessee

18.3

17.2

16.1

16.7

17.2 21.7 19.4

420 390 340 449420

616893

117

387370610 670

280

5646

1,900

980

1,850 1,080

187

143

148

88

63 174 180

23.8 25.6 29.422.323.8

16414710785.5

25.827.016.4 14.9

35.7

179217

5.3

10.2

5.4 9.3

53.5

69.9

67.6

114

159 57.5 55.6

21.9 24.1 27.6 21.821.3

164147107 85.5

22.023.915.7 12.3

35.7

200217

3.8

9.0

5.2 9.5

62.5

83.9

83.5

138

190 61.9 63.2

362267

275337

66541622

231217479 408

184

3638

1,310

-

1,150 670

104

80

89

54

47 125 180

1 Davis and others (1983).2 Water-quality data from makeup well #2 (K.R. Davis, Georgia Geologic Survey, written commun., 1989).3 Lee (1984).4 Water-quality data from Clarke and others, 1985.5 Water-quality data from well HP-6 (K.R. Davis, Georgia Geologic Survey, written commun., October 4, 1989).


SCREENED CONTRIBUTING INTERVAL INTERVAL

SHORT AND LONG NORMAL RESISTIVITY

1,975 i

2,000

2,025

2,050

LU

< 2,075u_DCZ> CO

Q-z.< 2,100

LU DO

LU U_

z

X H Q_ LU Q

2,125

2,175

2,200

2,225

2,250

<:-~~. ^ Probable mud invasion

I___I I___I

8 10 12 14 16 18 20 22

OHM-METERS

Figure 2. Resistivity borehole log at site CH-186 showing short- and long-normal curves and the screened and estimated contributing intervals.


Table 4. Summary of borehole geoelectrical properties and aquifer hydraulic characteristics at well sites[ft2/d, feet squared per day; ft/d, feet per day; ohm-m, ohm meters; , no data]

County

ChoctawDale

Burke

DoughertyDougherty

Houston

RichmondRichmond

Twiggs

State well number

CHO-l

31Z002

13L02113L022

16T002

30AA1330AA15

17V004

Local well name

Choctaw County # 1Fort Rucker #9 (TW3)

Bechtel Corp. #1 (TW-1)

Miller Brewing Company PW2Miller Brewing Company PW3

Pabst Brewing Co. #4

Kimberly-Clark Observation Well #1Kimberly-Clark Observation Well #3

J.M. Huber HP5

Average Transmissivity horizontal

(7) hydraulic (ft/d) conductivity

(K,)(ft/d)

Alabama

'4,00027,800

Georgia

321,100

35,32033,790

332,300

34,95036,550

38,710

3327

66

2112

51

2024

56

Average bulk

resistivity

(ohm-m)

31120

200

10066

580

170200

430

Surface resistivity (Rs)

(ohm-m)

2089

140

7035

290

90110

210

(ohm-m)

2288

140

6631

250

90110

210

Louisiana

CaddoCaddoCaddoCaddoCaddo

CaldwellClaiborneClaiborneClaiborne

DesotoDesotoDesotoDesotoDesotoDesotoDesotoDesotoDesotoDesotoDesotoDesotoDesotoDesotoDesotoDesotoDesotoDesotoDesotoDesotoDesoto

JacksonJacksonJacksonJackson

LincolnLincolnLincolnLincoln

CD-435CD-447CD-460CD-492CD-498A

CA-98CL-135ACL-140ACL-140B

DS-372ADS-372BDS-372CDS-376DS-377DS-381ADS-381BDS-386DS-391DS-396DS-397DS-403DS-404ADS-404BDS-406DS-409DS-414BDS-417DS-423DS-458DS-459

JA-101BJA-136JA-140JA-150

LN-117LN-131BLN-135ALN-140

Blanchard Test Hole #1Vivian #3Rodessa Water Test #1Town Of Belcher Water System Well #2Ida Test Well #2

Cotton Plant Test #2Claiborne Parish Police Jury Well #1Homer Test Well #2Homer Test Well #2

Stanley Water Test #1Stanley Water Test Well #1Stanley Water Test Well #1S. Mansfield #1Longstreet Water Test Well #1Keatchie Water Test Well #1Keatchie Water Test Well #1Toledo Bend Park Site #2Stanley Water SystemRambin- Wallace Community Test Well #1Rambin- Wallace Test #2Wallace Community Water System Test #2Wallace Community Water System Test #3Wallace Community Water System Test #3Grand Cane Test #1N. Desoto Water System Test #3N. Desoto Water System Well #3Mansfield Test Well #2N. Desoto Test Well #2Keatchie Water SystemKeatchie Test Well #2

Girl Scout Camp Test WellRiser Road Community Water District WellBear Creek #2Pumkin Center Test #1

Ruston State School #1S.D. Beard Property Water Well TestHico Water Test #2Wesley Chapel Water Well

100240270160580

62011,4005,4806,020

31080

640330

90130670

1,870200820

1,040190

1,200900620750110620440230180

4,5503,8809,890

500

9404,8001,3402,670

6.3167.55.3

39

31120120140

318

11339.05.4

22432034191950211916112820139.0

5862

13046

29732643

2132331545

18160140150

1002329332727302729903040272730272027402524

3745

12030

27956045

101822

8.58.4

119287

100

47142117141419202364201514141321141721

7.211

282681

5.1

16592821

91822

8.58.4

119287

100

471421151313182023612013131311211417206.0

10

2727784.8

15572620


Table 4. Summary of borehole geoelectrical properties and aquifer hydraulic characteristics at well sites Continued

County State well number Local well name

Transmissivity

(ff/d)

Average horizontal hydraulic

conductivity (Kh)(Wd)

Average bulk

resistivity

(ohm-m)


(ohm-m) (ohm-m)

Louisiana continued

LincolnLincoln

NatchitochesNatchitoches

Red RiverRed RiverRed RiverRed RiverRed RiverRed River

SabineSabineSabine

UnionUnion

WebsterWebsterWebsterWebsterWebsterWebsterWebsterWebsterWebsterWebster

WinnWinnWinnWinnWinnWinn

CalhounClarke

HindsHindsHindsHindsHinds

LauderdaleLauderdale

LowndesLowndes

MadisonRankinWashingtonYazoo

Jones

LN-151LN-48

NA-362NA-413

RR-181RR-182RR-241RR-247RR-249RR-251

SA-407ASA-407BSA-431

UN-57UN-7 IB

WE- 139WE-265WE-268WE-270WE-281WE-291WE-292BWE-308WE-321AWE-321B

WI-113WI-114WI-120WI-127WI-140WI-143

K101R31

G84H146H149H188M99

C53C54

P20P21

W74K119L70G81

T27U1

Ruston Test WellRuston Water Well #1

Clarence Water WellRobeline Test Well #2

Edgefield Test Hole #1Edgefield #2Choushatta Industrial Park Test #2Choushatta Test #1Edgefield Observation WellHalfway-Carroll Test #3

Many Test Hole #3Many Test Hole #3Toledo Bend Test Site #4

Bernice Test WellRocky Branch Water Test #2

Louisiana Ordnance PlantJenkins Water Test Well #1Old Shongaloo Water Well Test #2Jenkins Water Test Well #2Central Test Well #1Palmetto Beach Community #1

5,88013,400

1,600590

1901,230

100440

1,420320

310930230

5,1302,270

1,260800880630

1,120320

North Shongaloo Community Water Well 5,080Thomasville Test Well #1Germantown Water Test Well #1Germantown Water Test Well # 1

Hurricane Creek #2Gum Springs Water Well TestWinnfield Test #3Calvin Test #1Gansville Test WellCalvin Test Well

Calhoun City Well #3Hiwanee Water Assn. #1

City Of Jackson "W-D"City Of Jackson "N-B"City Of JacksonJackson Zoo Well #1City Of Jackson W-B

Naval Air Station #4Naval Air Station #1

Weyerhaeuser #2Weyerhaeuser #3

Town Of MadisonTown Of PearlArcola Well #3Mississippi Chemical Corp. Test Well

Weyerhauser Well #2

1,0207,6203,080

3,6104,4102,1402,5401,7402,670

Mississippi

42,8004 1 1,500

46,00043,300

4 13,0004 1,80044,700

420,300421,700

48,70045,900

44,10049,800

428,7004 18,200

North Carolina

2,200

45130

3518

1941

7.1203416

9.74711

14054

1924372440157935

12091

525054583256

7489

3630542650

200290

5933

4047

140170

42

60150

5325

468826325522

235525

15027

3226403438385480

160160

343030323727

4135

5578662660

400400

150150

40404070

150

36110

3717

17561318179.1

153813

12018

1720192524143849

100110

261918222518

3223

3152373.7

36

240250

4365

14132455

110

36110

3617

18561216117.6

153612

12018

1620172423113646

100110

251918212417

3425

3354384.2

39

240250

4365

18162458

110


Table 4. Summary of borehole geoelectrical properties and aquifer hydraulic characteristics at well sites Continued

County

BarnwellDorchester

HorryHorry

Lauderdale

ShelbyShelbyShelbyShelbyShelbyShelby

State well number

BW-79DOR-221

HO-336HO-416

LD:H-6

SH:J-104SH:K-73SH:L-69SH:L-8SH:P-25SH:U-18

Local well name

Town Of WillistonOakbrook Well #3

North Myrtle BeachOcean Lakes #6

City Of Ripley #2

Memphis Light, GasMemphis Light, GasMemphis Light, Gas

Average Transmissivity horizontal

(7) hydraulic (fr/d) conductivity

(K»)(ft/d)

South Carolina

5 13,000590

#2 52,00052,700

Tennessee

22,300

, and Water 19,800, and Water Test #6 21,100, and Water 26,700

Germantown Well #2 21,200Buckeye #10Dupont Well #5

14,10056,800

399.2

6.37.0

250

280160240210

72560

Average bulk

resistivity

(ohnvm)

27011

7.817

200

300380400550190160


(ohm-m)

860.8

2.47.7

150

230310290390130100

p re o i"e l"o nwx\

(ohm-m)

652.0

2.67.5

140

22029026036013097

1 Davis and others (1983).2 Scott and others (1984).3 Faye and McFadden (1986).4 Slack and Darden (1991).5 Aucott and Newcome (1986).

RELATIONS OF BOREHOLE RESISTIVITY TO AQUIFER HYDRAULIC CHARACTERISTICS AND WATER QUALITY

Relations of geoelectrical properties to hydrau lic and water-quality characteristics were developed using the general logarithmic regression model

Y=AXB , (9)

where Y and X are dependent and independent vari ables, respectively, and A and B are regression coef ficients. This model has previously been used by investigators to evaluate the relations of aquifer characteristics to geoelectrical properties (Alger, 1966; Mazac and others, 1985; Huntley, 1986; and Yao An Guo, 1986).

Measurements of bulk resistivity and horizon tal hydraulic conductivity require an evaluation of the aquifer interval contributing water to a well (table 1). Contributing intervals were determined by comparing reported screened intervals to the thick ness of juxtaposed sands and clayey sands identified on lithologic and corresponding borehole geophysi cal logs. Contributing intervals were commonly bounded above and below by clays of considerable thickness (fig. 2). In general, the estimated contrib-

uting interval for large-capacity wells (discharge greater than 500 gallons per minute (gal/min)) was somewhat to substantially larger than the screened interval. Where screened intervals were small com pared to the total thickness of a water-bearing unit and well discharges were also comparatively small (ranging from 20 to 50 gal/min), contributing inter vals and screened intervals frequently were consid ered coincident or nearly coincident.

Infrequently, large disparities occurred between the total screen length at a well and the total estimated contributing interval. At these sites, short-interval screens commonly were placed oppo site relatively thick water-bearing sands. Because the contribution of each sand interval to total well discharge was unknown, the total sand thickness of partially screened intervals was considered the con tributing interval. Estimates of total contributing interval at wells used in this study ranged from 10 to 630 ft and were considered to be accurate within ±25 percent of reported values (table 1).

Aquifer bulk resistivity for this study was con sidered to approximately equal resistivity measured by the long-normal (64-inch) resistivity log or by the deep induction log. Long-normal logs were unavailable at sites 31Z002, in Burke County, Ga., SH:P-25 in Shelby County, Tenn., and SRP


Table 5. Summary of results of regression analyses[DSC, dissolved-solids concentration; Fa, apparent formation factor; Kh , horizontal hydraulic conductivity; R0 , bulk resistivity; Rwx , water resistivity; LC, Late Cretaceous; PLE, Paleocene-early Eocene; ME, middle Eocene] (General equation Y=AXB)

Dependent variable

Y

KhKHKHKhRWX

DSCDSCKh (LC)Kh (PLE)Kh (ME)Kh (LC)Kh (PLE)Kh (ME)

Independent variable

X

(R0-RWX)FaR»x

R0Ro

Ro

Rwx(R0-RW*)(R0-RWX)(R0-RWX)R0

R0RO

Coefficient A

3.8145.71.8.56

8,5005,110

5.51.58.93.2

.573.8

Exponente

0.661.0.59.74.92

-.85-.92

.43

.88

.54

.481.0

.67

Correlation coefficient (percent)

7238567093

-88-96

807871777871

Standard error of estimate

(log cycle)

0.68.91.82.70.35.44.27.52.56.56.55.56.56

Number of data pairs

105106106105111106106

144744144744

905-120p in Barnwell County, S.C., and resistivity measured by the short-normal (16-inch) log was used to estimate bulk resistivity. Average bulk resistivity for a contributing interval was determined by computing the area between the log trace and the line of zero resistivity and dividing by the respective vertical interval. Resistivity log scales varied throughout the study area. In general, vertical scale resolution was larger than 100 ft per inch and hori zontal scale resolution was larger than 200 ohm-m per inch.

The formation temperature was considered equal to water temperature at the point of well dis charge and was available at most well sites. Water- temperature measurements were considered accurate within ±0.5°C (table 3).

Specific conductance determined by laboratory or field measurements is commonly reported in micromhos or microsiemens per centimeter at a standard temperature of 25°C (77°F); therefore, it is related to aquifer water resistivity at 77°F in ohm-m, by the following expression (Miller and others, 1988),

Rw77= 10,QQQ/specific conductance. (10)

Where water discharge temperatures were known (table 3), aquifer water resistivity (Rw) was con verted from resistivity at the standard temperature of 77°F to the resistivity at the known temperature (Rwx). This conversion was accomplished using the equation described by Jorgensen (1989),

D _ WX 7>f7 (11)

where tL is aquifer water resistivity at the observed

water temperature at the point of well dis charge, in ohm-m;

Rw77 is aquifer water resistivity at the standardtemperature, in ohm-m; and

Tx is water temperature at the point of welldischarge, in degrees Fahrenheit.

Where well discharge temperatures were unknown, aquifer water resistivities were unadjusted and based on the standard temperature of 77°F. Aquifer water resistivity measurements at standard temperature are considered accurate within ±10 per cent of reported values (table 3).

Computed values of horizontal hydraulic con ductivity used in regression analyses (figs. 3-6, table 5) represent average aquifer transmissivity per unit length of contributing interval (table 1). Trans missivity values used to compute horizontal hydrau lic conductivity were derived, for the most part, from analyses of single-well, aquifer-test data using modified nonequilibrium methods (Ferris and others, 1962). A few results of multiple-well, nonequilib rium analyses (Theis, 1935; Hantush and Jacob, 1955) were also used.

Uncertainty related to determinations of con tributing interval, bulk resistivity, water resistivity, and horizontal hydraulic conductivity can be attrib uted to random and systematic errors of measure ment, and to spatial variations of geoelectrical prop-

Relations of Borehole Resistivity to Aquifer Hydraulic Characteristics and Water Quality 19

1,000

-. 100

o

O O O

O Ntr Ox

10

i i i T i i i r

Bivariate data points

O Late Cretaceous

A Paleocene-lower Eocene

n Middle Eocene

D

OO

95-percent prediction interval band for a single observation

/(^horizontal hydraulic conductivity

A?o=bulk resistivity

A?wx=aquifer water resisitivity

10 100

GRAIN SURFACE RESISTIVITY (RO-RWX), IN OHM-METERS

1,000

Figure 3. Relation of horizontal hydraulic conductivity to grain-surface resistivity as defined by the summation model.

erties and hydraulic characteristics. Measurement errors relate largely to inaccuracies caused by field and laboratory instruments or observations and could only be indirectly evaluated for this study. For example, site data were eliminated from further analyses where aquifer water resistivity exceeded average bulk resistivity. Such anomalies were reported infrequently and were attributed to instru ment error.

Uncertainties related to transmissivity evalua tions are probably the result of errors introduced by the spatial variation of aquifer hydraulic character istics. Standard methods of analysis for transmissiv ity are generally based on assumptions that aquifer properties are spatially constant. Such assumptions are seldom, if ever, completely satisfied by water bearing units. Regardless, standard methodologies of

aquifer-test analysis have consistently been applied in the study area with apparently successful results (Hosman and others, 1968; Zack, 1977; Davis and others, 1983; Faye and McFadden, 1986; Slack and Darden, 1991) and transmissivity values reported here are considered equally valid (table 4). To account for uncertainty, computed transmissivity values are considered accurate within ±25 percent of reported values (table 4).

Differences in aquifer volume represented by borehole resistivity measurements and aquifer-test results may be substantial at large-capacity wells. Lateral variation in the hydraulic characteristics and geoelectrical properties of local water-bearing units is, however, probably small within the radius of influence of a pumping well. Thus, geoelectrical properties and hydraulic characteristics determined


1,000

CCLLJ Q.

~ 100 -C

O

O O O

O NQC O X

O

° n ° n OO

o oo o o

o


fto=bulk resistivity

resisitivity

O Bivariate data point

j__i__i i10

APPARENT FORMATION FACTOR

Figure 4. Relation of horizontal hydraulic conductivity to apparent formation factor as defined by the product model.

from substantially different aquifer volumes are con sidered representative of the entire aquifer volume contributing water to the well. To ensure that aver age hydraulic conductivity values were based on a representative aquifer volume, data from aquifer tests of short duration (less than 2 hours) were not used. Aquifer-test duration related to transmissivity data cited in this report exceeded 4 hours at most sites (table 4; Aucott and Newcome, 1986; Faye and McFadden, 1986; Slack and Darden, 1991).

Mud invasion of permeable zones during drill ing also can substantially affect borehole resistivity and aquifer-test results. Where substantial invasion of drilling mud has occurred, resistivity measure ments will reflect the geoelectrical properties of the drilling mud, rather than of the aquifer. In addition, analyses of aquifer-test data collected by pumping

from mud-invaded sands generally result in com puted transrnissivities that are lower than corre sponding values for contiguous noninvaded sands. Mud-invaded zones were identified by comparing the divergence between short- and long-normal resistivity measurements (fig. 2). Where invasion occurred across a substantial part of the contributing interval and well development appeared limited or ineffective, site data were rejected for further analyses.

Regression analyses using equation 9 were completed for various combinations of geoelectrical, hydraulic, and water-quality data listed in tables 3 and 4. Results of these analyses are summarized below (eqs. 12-17), in table 5, and in figures 3-9. Discharge temperature data were unavailable at 22 sites (table 3). Accordingly, water resistivity at


1,000

-. 100

uD Qz o u

oN DC OX

Bivariate data points

O Late Cretaceous

A Paleocene-lower Eocene

n Middle Eocene

D

D

D

OO


OO

K.,-1.8/?,0.74


/?0=bulk resistivity

10 100

BULK RESISTIVITY (RQ), IN OHM-METERS

1,000

Figure 5. Relation of horizontal hydraulic conductivity to aquifer bulk resistivity.

these sites used in regression analyses (eqs. 13, 16) were standard (Rw77) rather than adjusted (Rwx). Correlation coefficients for all analyses range from about 70 to 96 percent, except for the product model relation of horizontal hydraulic conductivity to apparent formation factor, which is 38 percent (table 5). These results, when compared to the results of regression analyses based on the summa tion model (eq. 12) and aquifer bulk resistivity (eq. 17), indicate that the apparent formation factor (eq. 8) is not a useful geoelectrical analog for the hori zontal hydraulic conductivity of clastic aquifers con sidered in this study. Accordingly, references in this report to relations of horizontal hydraulic conductiv ity to grain-surface resistivity refer only to the rela tion explained by the summation model (eq. 7).

Following are the regression equations that relate horizontal hydraulic conductivity (Kh), dissolved-solids concentrations (DSC) in aquifer water, and aquifer water resistivity (Rwx) to the borehole geoelectrical properties of bulk resistivity (R0) and grain-surface resistivity (defined by the summation model (R0 RWX)):

K^l.^Re-R^?-66 , (12)

DSC=5llOR, -0.92

-0.85

RWX =Q.56R0 ' ,

Kh =5.1Rwx°- 5 and

(13)

(14)

(15)

(16)

(17)


1,000

O

O O O

QC Q 10

O

0.59


ffwx=aquifer water resisitivity


i i i i J___I I

10 100 1,000

AQUIFER WATER RESISTIVITY (Rwx), IN OHM-METERS

Figure 6. Relation of horizontal hydraulic conductivity to aquifer water resistivity.

Regression statistics for equations 12 and 17 (table 5) indicate that grain-surface resistivity as defined by the summation model (eq. 7) and bulk resistivity (R0) are equally significant geoelectrical analogs for horizontal hydraulic conductivity (Kh).

Quasi-validation of the use of grain-surface resistivity as a geoelectrical analog for horizontal hydraulic conductivity is indicated by the regression analysis relating horizontal hydraulic conductivity (Kh) to aquifer water resistivity (Rwx, table 5, fig. 6). Consider that the grain-surface resistivity of a freshwater-saturated, unconsolidated, clastic porous media decreases as the percentage (and surface area) of fine-grained sediments increases. Such increases might be indicated by corresponding increases in the ionic strength of the aquifer water and in the ion exchange between the water and fine-grained sedi ments, particularly clays (Alger, 1966). Accord

ingly, a positive trend should be evident between horizontal hydraulic conductivity and the resistivity of aquifer water. Although regression statistics are not strongly conclusive (table 5), increasing values of aquifer water resistivity are shown to generally relate to increasing values of horizontal hydraulic conductivity.

Evaluation of figures 3 and 5 indicates that a general grouping of hydraulic conductivity data occurs based on the age of aquifer sediments; the lowest values generally relate to aquifers composed of sediments of Cretaceous age and the highest val ues generally correspond to aquifers composed of sediments of middle Eocene age. Thus, horizontal hydraulic conductivity and estimated values of grain-surface resistivity paired according to site and age were related using the logarithmic regression model (eq. 9). Data were grouped into three major


10,000

Q_

CO

OzOoCOQ _l O co

O CO COQ

1,000

100

i i n r n i i TT

95-percent prediction interval band fora single observation

O

DSC=5110ff,

water resistivity


-0.92

DSC=dissolved-solids concentration

O

I I I I I I I J____I I I I I I

10 100

AQUIFER WATER RESISTIVITY (Ftwx), IN OHM-METERS

1,000

Figure 7. Relation of dissolved-solids concentration in aquifer water to aquifer water resistivity.

chronostratigraphic groups corresponding to aquifers composed of sediments of Late Cretaceous, Paleo- cene and early Eocene, and middle Eocene age. Regression equations describing these relations using surface resistivity (R0 RWX) as the independent vari able are

0 Rwx)0.43Late Cretaceous

Paleocene and early Eocene

Kh =l.5(R0-Rwxf-**, and

middle EoceneTf - Q QfD _ D \0.54 ^OO^

Corresponding equations using bulk resistivity (R0) as the independent variable are

(18)

(19)

Late Cretaceous0.48

Paleocene and early Eocene

middle Eocene

and

Kh =3.8R0°-67

(22)

(23)

(21)

Regression statistics for these equations indi cate a moderate degree of correlation between the independent and dependent variables. Correlation coefficients range from 71 to 80 percent and stand ard errors of estimate range from 0.52 to 0.56 log cycles (table 5). Data pairs related to 14 sites were used to develop equations 18 and 21. These data were obtained from South Carolina, Georgia, and Mississippi. The number of site data pairs used to develop equations 19 and 22, and 20 and 23 are, respectively, 47 and 44 (table 5). Data related to equations 20 and 23 are the most widespread in the study area, ranging from Georgia to western Tennessee.


1,000

xO 100

Z) O

10

i i i T i ir

0.92RWX=0.56RQ

Rwx=aqu\fer water resisitivity

ffo=bulk resistivity


O


O

J___I I I I I I I J____I I I I I I I

10 100

BULK RESISTIVITY (RQ), IN OHM-METERS

1,000

Figure 8. Relation of aquifer water resistivity to aquifer bulk resistivity.

APPLICATIONS AND TESTING OF REGRESSION MODELS

Equations 12-15 and 17-23 can be used to provide estimates of the vertical distribution of aqui fer horizontal hydraulic conductivity (£/,), aquifer water resistivity (Rwx), and dissolved-solids concen tration (DSC) of aquifer water at borehole sites in the study area. Applications should be limited to aquifers in the Southeastern United States consisting of unconsolidated sands and clayey sands ranging in age from Late Cretaceous to middle Eocene. Equa tions relating horizontal hydraulic conductivity to geoelectrical properties may not be valid for sand thicknesses less than 10 ft or for sands containing saline water. Specifically, the regression equations should not be applied to water-bearing sands where

hydraulic and water-quality characteristics are sub stantially different from those used to develop the regression relations. In the absence of water-quality data, equations 15, 12, and 14 can be applied sequentially to provide estimates of aquifer water resistivity, horizontal hydraulic conductivity, and dissolved-solids concentration. All applications, with the exception of equation 13, require the use of rea sonable surrogates of aquifer bulk resistivity, such as long-normal (64-inch) resistivity.

Regression equations 13-15 and 18-23 (tables 6-9) were applied to bivariate data from selected well sites in the Southeastern United States. Equa tions 13-15 were applied at several borehole sites, largely in South Carolina, where measurements of the specific conductance and dissolved-solids con centrations of aquifer water are reported at several depths (Lee, 1984).

Applications and Testing of Regression Models 25

10,000

0 C/) Q

zLUoz o o

O C/) c/)Q

100

\ i i i i i i r i iii T i i r


DSC=8,500fl,-0.85

DSC=dissolved-solids concentration

R Q=bulk resistivity


__i___i i i i i i i i i i i i i i i i i i i10 100

BULK RESISTIVITY (/? ), IN OHM-METERS

1,000

Figure 9. Relation of dissolved-solids concentration in aquifer water to aquifer bulk resistivity.

Equations 18, 19, 21, and 22 were applied at site CH-186, near Charleston, S.C. (table 1), where borehole geophysical logs, well construction infor mation, aquifer hydraulics data, and water-quality data permit the computation of horizontal hydraulic conductivity using estimates of both grain-surface resistivity and bulk resistivity. Horizontal hydraulic conductivity values computed using regression mod els were compared to corresponding values deter mined from a single aquifer test using the completed well, and from laboratory permeameter analyses of core samples. Equations 21-23 were used to esti mate horizontal hydraulic conductivity at 26 other sites where water resistivity data were unavailable.

The application of regression equations 12-15 and 17-23 indicates that aquifer water resistivity,

dissolved-solids concentration, and horizontal hydraulic conductivity can be estimated with reason able accuracy using appropriate geoelectrical analogs and regression-based models. Observed dissolved- solids concentrations at a total of four sites in South Carolina and Louisiana ranged from about 300 to 1,300 mg/L and were compared to estimates com puted using bulk resistivity and aquifer water resist ivity as independent variables (table 6). Estimates of dissolved-solids concentration based on aquifer water resistivity (eq. 13) were generally more accu rate (particularly at high concentrations of dissolved solids) than estimates based on bulk resistivity (eq. 14), with mean absolute errors of 6.2 and 20 per cent, respectively (table 8). Estimates of aquifer water resistivity based on bulk resistivity (eq. 15)


Tabl

e 6.

S

umm

ary

of r

egre

ssio

n m

odel

est

imat

es o

f aq

uife

r w

ater

-qua

lity

char

acte

ristic

s[o

hm-m

, oh

m m

eter

s; m

g/L

, m

illig

ram

s pe

r lit

er;

°C,

degr

ees

Cel

sius

; , n

o da

ta]

> ? I o 3 CO 0) i. 8co i' a 3J <§ i Co CO o 3

Rep

orte

d_

. W

ell

sam

ple

Cou

nty

. .

Ku

num

ber

dept

h(ft

)

Cha

rles

ton

1 C

H-1

86

2,03

02,

120

2,15

02,

250

Dor

ches

ter2

D

OR

-211

58

0-60

01,

326-

1,34

61,

828-

1,84

8

Mar

ion2

M

RN

-78

345-

355

517-

537

748-

768

811-

831

1,01

0-1,

030

Des

oto3

D

S-35

5 25

2-26

2

Wat

er

resi

stiv

ity

at 2

5°C

(ohm

-m)

3.2

5.9

5.8

4.1

36.0 5.5

7.3

18.2

11.8

13.0 3.9

3.5

10.4

1 Dat

a ob

tain

ed f

rom

the

files

of

the

U.S

.2

Lee

(198

4).

3 Tu

rcan

(19

62).

Tem

pera

ture

of

dis

char

ge

wat

er(C

)

30.0

31.0

32.0

32.0

24.0

26.6

31.7

20.4

21.4

23.2

23.7

23.0

20.5

Wat

er

resis

tivity

at

dis

char

ge

tem

pera

ture

(ohm

-m)

2.9

5.2

5.0

3.6

36.7 5.3

6.4

20.2

12.8

13.6 4.0

3.7

11.5

Dis

solv

ed-s

olid

s co

ncen

tratio

n (D

SC)

re!(m

g/L)

(Q

Sout

h C

arol

ina

2,06

01,

070

1,09

01,

510

180

1,16

078

8

313

496

450

1,54

01,

700

Lou

isia

na

586

/era

ge

sistiv

ity

hm-m

)

10 7.2

11 8.8

78 11 16 73 36 36 15 10 23

Com

pute

d w

ater

re

sist

ivity

(R

wx, e

q. 1

5)(o

hm-m

)

4.7

3.4

5.1

4.1

31 5.1

7.2

29 15 15 6.8

4.7

10

Com

pute

d di

ssol

ved-

solid

s co

ncen

tratio

n (D

SC, e

q. 1

3)(m

g/L)

1,92

01,

120

1,16

01,

570

186

1,10

092

6

322

489

463

1,43

01,

530

540

Com

pute

d di

ssol

ved-

solid

s co

ncen

tratio

n (D

SC,

eq.

14)

(mg/

L)

1,20

01,

600

1,10

01,

300

210

1,10

080

0

220

400

400

850

1,20

0

590

Rep

orte

d w

ater

-bea

ring

unit(

s)

Mid

dend

orf

Form

atio

nD

o.D

o.D

o.

Elle

nton

For

mat

ion

Bla

ck C

reek

For

mat

ion

Cap

e Fe

ar F

orm

atio

n

Bla

ck C

reek

For

mat

ion

Do.

Mid

dend

orf

Form

atio

nD

o.C

ape

Fear

For

mat

ion

Wilc

ox G

roup

Geo

logi

cal

Surv

ey.

Tabl

e 7.

S

umm

ary

of r

egre

ssio

n m

odel

est

imat

es o

f ho

rizon

tal h

ydra

ulic

con

duct

ivity

[ft/d

, fe

et p

er d

ay;

ohm

-m,

ohm

met

ers;

,

no d

ata]

Delations of

Borel 3" O

(D* 8en a 3 5" (D W O (D Q> cn (D 5 c 3 I

CL S 1

Rep

orte

d sa

mpl

e W

ater

...

U

dept

h re

sist

ivity

Te

mpe

ratu

re

Cou

nty

. or

est

imat

ed

at 2

5°C

of d

isch

arge

nu

moe

r co

ntrib

utin

g (f

lj

wat

er(°

C)

inte

rval

(o

hm-m

) (ft

)

Cha

rles

ton

CH

-186

'6

06

1.0

-'6

40

.9

-'2

,030

3.

2 30

.0'2

,120

5.

9 31

.0'2

,150

5.

8 32

.0C

harl

esto

n C

H-1

86

1,98

0-2,

240

34.5

33

1.0

Hou

ston

575-

815

Des

oto

DS

^ll

56

-112

-

-W

inn

WI-

115B

17

4-18

6 -

-

Wat

er

Ave

raae

C

ompu

ted

resis

tivity

h

Ik

Hyd

raul

ic

hydr

aulic

at

dis

char

ge

. f.

.. co

nduc

tivity

co

nduc

tivity

te

mpe

ratu

re

,_ .

(Kh)

(K

h)

(Rwx

) h

W**

) (e

qs.

18,

19, o

r 20

) (o

hm-m

) (ft

/d)

Sout

h C

arol

ina

-

4.5

-

9.5

2.9

115.

2 7.

25.

0 11

4.2

*7.0

Ala

bam

a'°4

2

Lou

isia

na

-

20-

24

A/fi

fisi<

E<ei

nni

23.6

4.

525

.6

1021

6 14

219

7.4

217

1251

3 8.

6

915 8.

6 -

45

-

Com

pute

dh^

raul

ic

Rep

orte

d co

nduc

tivity

f

^*

r\nn

... ,

wat

er-b

earin

g

(eqs

. 21

, 22

, or

23)

un

it(s)

(ft

/d)

2.6

5.4

10 8.3

10 8.1

24 11 32

Low

er E

ocen

e (u

nnam

ed)

Do.

Mid

dend

orf

Form

atio

nD

o.D

o.D

o.

Tus

caho

ma

Form

atio

nN

anaf

alia

For

mat

ion

Cla

y ton

For

mat

ion.

Wilc

ox G

roup

Spar

ta S

and

Des

oto

Win

n

Bol

ivar

Cla

rke

Cla

rke

Lea

keL

eeM

adis

on

Mad

ison

Mon

tgom

ery

New

ton

Ran

kin

Ran

kin

Ran

kin

Ran

kin

Ran

kin

Scot

tSc

ott

Smith

Yaz

oo

DS

^ll

WI-

1 15

B

T131

K8

LSI

03

4F3

10

46

W69

M12

A34

G42

G51

K12

0K

175

K18

6J3

5L4

5L

2603

0

1,38

8-1,

472

1,27

0-1,

352

346-

472

1,18

6-1,

258

1,480-1,576

998-

1,20

0 86

8-95

6 48

0-56

01,228-1,362

1,25

2-1,

357

800-

865

436-

582

1,20

0-1,

314

710-

900

1,24

6-1,

390

876-

1,01

81,

424-

1,50

8

20 24

Mis

siss

ippi

13 67 110 45 8.

065 65 41 48 75 54 60 99 55 37 46 64 49

8.6

45 617

631

6160 640 «7

.461

9

635 64

.562

165

468

063

464

764

263

661

765

461

6

21 38 89 26 8.7

37 62 23 27 69 55 59 83 56 43 26 62 28

Spar

ta S

and

Low

er W

ilcox

Gro

upSp

arta

San

dL

ower

Wilc

ox G

roup

McS

han

Form

atio

nM

erid

ian

Sand

, U

pper

Wilc

ox G

roup

.Sp

arta

San

dL

ower

Wilc

ox G

roup

Mid

dle

Wilc

ox G

roup

Spar

ta S

and

Do.

Do.

Do.

Do.

Do.

Mer

idia

n Sa

ndSp

arta

San

d M

erid

ian

Sand

Tabl

e 7.

S

umm

ary

of r

egre

ssio

n m

odel

est

imat

es o

f ho

rizon

tal

hydr

aulic

con

duct

ivity

Con

tinue

d

Tam

Dl?

W

ater

W

ater

C

ompu

ted

deot

h re

sSS

v

Tem

oera

ture

re

sist

ivity

A

quife

r bu

lk

Hyd

raul

ic

hydr

aulic

^

<%

d£s

"? 3

? W

SK

"ft*

-"sr

-sr

-T

IT

«

£i*

W

ater<

C)

,<,«

»),

<*-*

«

(e.,,,8^,0

,,0,

Nor

th C

arol

ina

Ons

low

V

25P4

55

2-61

8 -

55

35

-

Sout

h C

arol

ina

Hor

ry

HO

-309

35

0-42

0

-

24

78.6

-

Hor

ry

HO

-335

29

0-71

0 -

-

-

11

87.4

-

Hor

ry

HO

-353

38

0-49

0 -

-

-

18

87.3

-

Mar

ion

MR

N-6

7 21

6-42

4 -

48

848

Com

pute

dhy

drau

lic

Reo

orte

d co

nduc

tivity

.

(eqs.

2r2

2.o

r23)

^tU

T*

(ft

/d)

22

Bla

ck C

reek

For

mat

ion

15

Bla

ck C

reek

For

mat

ion

10

Do.

13

Do.

21

Do.

1 Rep

orte

d sa

mpl

e de

pth.

Con

trib

utin

g in

terv

al e

stim

ated

at

±5

ft fr

om r

epor

ted

sam

ple

dept

h.2

Hyd

raul

ic c

ondu

ctiv

ity b

ased

on

resu

lts o

f pe

rmea

met

er t

ests

. (W

.A.

Pryo

r, U

nive

rsity

of

Cin

cinn

ati,

wri

tten

com

mun

., D

ecem

ber

4, 1

974)

.3

Ave

rage

of

valu

es r

epor

ted

at d

epth

s of

2,0

30 f

t, 2,

120

ft,

2,15

0 ft

, an

d 2,

250

ft. (

tabl

e 6

and

Park

er L

abor

ator

y, C

harl

esto

n, S

.C.,

wri

tten

com

mun

., D

ecem

ber

27,

1974

).4

Ave

rage

val

ue c

ompu

ted

acro

ss e

stim

ated

con

trib

utin

g in

terv

al.

5 C

ompu

ted

from

res

ults

of

aqui

fer

test

on

fini

shed

wel

l.6

Hyd

raul

ic c

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ctiv

ity b

ased

on

tran

smis

sivi

ty v

alue

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m S

lack

and

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den

(199

1).

7 H

ydra

ulic

con

duct

ivity

bas

ed o

n tr

ansm

issi

vity

val

ue f

rom

Zac

k (1

977)

.8

Hyd

raul

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ased

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tran

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ty v

alue

fro

m A

ucot

t an

d N

ewco

me

(198

6).

9 A

quif

er-t

est

resu

lts f

rom

nea

rby

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ls D

otha

n #1

0 an

d #1

2.10

Est

imat

e ba

sed

on e

lect

ric

log

data

at

near

by S

elm

a St

reet

wel

l.

Table 8. Summary of error analyses of regression model estimates of aquifer water-quality characteristics[DSC, dissolved-solids concentration; Rwx , water resistivity; R0, bulk resistivity]

Dependent variable

DSC DSC Rwx

Independent variable

Rwx

Equation number

13 14 15

Number of

estimates

13 13 13

Range of estimate error

(percent)

1.4-18 .7-50

1.9-70

Mean estimate error

(percent)

6.2 2025

Standard deviation of estimate error

(percent)

4 17 21

Table 9. Summary of error analyses of regression model estimates of horizontal hydraulic conductivity[Kh , horizontal hydraulic conductivity; R0 , bulk resistivity; Rwx , water resistivity]

Dependent Independent variable variable

V D A/I Ko

(CH-186"data)K D

(CH-186 data)V DA-fc l\o

(without statistical outlier)

Equation Number number estimates

21, 22, or 2318 or 19

21 or 22

21, 22, or 23

326

6

31

Range of Mean Standard deviation estimate error estimate error of estimate error

(percent) (percent) (percent)

3.6-41113-79

3.6-56

3.6-95

5540

34

43

6925

18

23

resulted in absolute errors ranging from about 2 to 70 percent, and a mean error of 25 percent (table 8). Horizontal hydraulic conductivity was computed at site CH-186 using grain-surface resistivity and bulk resistivity as independent variables (eqs. 18, 19, and 21, 22). Estimates were compared to values of horizontal conductivity determined from permeameter analyses at five cored intervals and from aquifer-test results for the finished well. At three of the five intervals, errors of estimated horizontal hydraulic conductivity based on grain-surface resist ivity were less than errors for corresponding values computed using bulk resistivity as the independent variable. These errors ranged from 13 to 79 percent and 4 to 56 percent, respectively (table 9). Results related to the finished well test were similar. Hori zontal hydraulic conductivity was also computed at 26 other sites using only bulk resistivity as the inde pendent variable (eqs. 21-23). Absolute error for all sites ranged from about 4 to 400 percent. Mean error was 55 percent (table 9). Absolute error at one site was larger than two standard deviations from the mean absolute error and is considered a statisti cal outlier (site M12, table 7). When the absolute error for this site was removed, the mean absolute error was 43 percent and the error range was 4 to 95 percent.

SUMMARY AND CONCLUSIONS

Aquifer bulk resistivity and grain-surface resistivity (inverse of surface conductance) were the oretically related to the horizontal hydraulic conduc tivity of freshwater aquifers composed of sands and clayey sands. Regression equations were subse quently used to test the theoretical concepts using borehole geophysical, water-quality, and hydraulic characteristics data obtained from more than a hun dred well sites in the Southeastern Coastal Plain of the United States. Data were obtained from aquifers composed of sediments ranging in age from Late Cretaceous through middle Eocene. Bulk resistivity was estimated using long-normal (64-inch) and dual induction borehole resistivity logs. Grain-surface resistivity was empirically defined as the difference between bulk resistivity and aquifer water resistivity (computed from specific conductance). Horizontal hydraulic conductivity, as used in this report, is the average aquifer transmissivity per foot of contribut ing interval and ranged from about 4 to more than 500 ft/d. All paired data were related using the loga rithmic regression model Y=AXB . All paired data used in regression analyses were considered average values across a specified interval contributing water


to a finished well. Estimated thicknesses of the con tributing intervals ranged from 10 to about 600 ft.

Regression analyses indicate a moderate corre lation between bulk and grain-surface resistivities and horizontal hydraulic conductivity. The correla tion coefficients developed by using all hydraulic conductivity data (105 data pairs) were 70 and 72 percent, respectively. The correlation coefficients of similar analyses using data grouped by the age of water-bearing units (Late Cretaceous, 14 data pairs; Paleocene-early Eocene, 47 data pairs; and middle Eocene, 44 data pairs) ranged from 71 to 80 per cent. These results indicate that aquifer bulk resist ivity and grain-surface resistivity are useful geoelectrical analogs for the horizontal hydraulic conductivity of clastic, unconsolidated aquifers in the Southeastern United States.

Separate regressions of the resistivity and dissolved-solids concentrations of aquifer water using aquifer bulk resistivity as the independent variable indicated a high degree of correlation between these variables (correlation coefficients of 93 and 88 percent, respectively). An analysis of the relation of dissolved-solids concentration to aquifer water resistivity resulted in an exceptionally high degree of correlation (correlation coefficient of 96 percent). Dissolved-solids concentrations used in these analyses ranged from about 30 to 1,300 mg/L.

An analysis of the relation between horizontal hydraulic conductivity and apparent formation factor (ratio of aquifer bulk resistivity to aquifer water resistivity) resulted in a correlation coefficient of 38 percent. Although formation factor and apparent formation factor had previously been presented as useful geoelectrical analogs to horizontal hydraulic conductivity at a local scale, results of this study indicate that, at a regional scale, little or no signifi cant correlation exists between apparent formation factor and horizontal hydraulic conductivity.

Regression equations presented in this report were applied and tested at a total of 27 sites in 6 Southeastern States. When used as independent vari ables, aquifer water resistivity and aquifer bulk resistivity were shown to reasonably predict the dissolved-solids concentration of aquifer water (mean absolute errors of about 6 and 20 percent, respectively). Similarly, bulk resistivity was used to estimate aquifer water resistivity (mean error of 25 percent). The absolute error of estimates of horizon tal hydraulic conductivity computed using aquifer bulk resistivity as the independent variable ranged

from about 4 to 400 percent. Mean absolute error was 55 percent. Elimination of one data point con sidered to be a statistical outlier improved the mean estimate error to 43 percent with an error range of 4 to 95 percent.

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