overview to linked in

ENHANCED RESERVOIR

CHARACTERISATION BASED UPON

BOREHOLE

IMAGES

&

DIPMETER

DATA

SAADALLAH GEOCONSULTANT AS

A. SAADALLAH Dr.

Misjonsveien 39, N-4024 Stavanger Norway

Tel. + (47) 51 52 62 65 (office)

Email: [email protected]

website: www.saadgeo.com

mailto:[email protected]

http://www.saadgeo.com/

WARNING !

THIS PRESENTATION WAS

PREPARED IN 2005

IT HAS TO BE UPDATED BY

INCLUDING NEW TOOLS (such as

those of Weatherford) AND OTHER

ELEMENTS OF INTERPRETAION

ENHANCED RESERVOIR

CHARACTERISATION BASED UPON

BOREHOLE IMAGES & DIPMETER

DATA

OVERVIEW

1 Introduction

2 Dipmeter Tools

3 Imaging Tools

4 Borehole Map

5 Stereographic Projections

6 From Raw Data to Geologically Interpretable Outputs

7 Basic Interpretation

8 Clastic Reservoirs

9 In Situ Stress Issue

10 Fractured Reservoirs

11 Key Features to keep in mind

12 Key References

INTRODUCTION

From Logging & Petrophysic

point of view

to

a Geologic Mapping of the

Borehole Wall concept

Curve:

ONE value (Rock Propriety)

vs.

ONE Depth (MD)

From Logging & Petrophysic point of view to a Geologic

Mapping of the Borehole Wall concept

Dip needed very early in

Logging industry (Seismic not

yet performed or/and poor, Oil

goes up!)



Curve: a value (Rock Propriety) vs. Depth (MD)

Dip needs a set of at least 3

measurements of the SAME

FEATURE: Dipmeter tool: 4

curves




Dip needed very early in Logging industry (Seismic not yet

performed or/and poor, Oil goes up!)

Technology improvements: more data,

magnetometers, accelerometers, transmission

of data (pulse within mud) IMAGING

TOOLS: ca 100 000 measurements per Meter

MD: MAPPING OF THE BOREHOLE

WALL.

From Logging & Petrophysic point of view to a Geologic Mapping of

the Borehole Wall concept


Dip needed very early in Logging industry (Seismic not yet

performed or/and poor, Oil goes up!)

Dip needs a set of at least 3 measurements of the SAME FEATURE:

Dipmeter tool: 4 curves

From Logging & Petrophysic point of view to a

Geologic Mapping of the Borehole Wall concept


Dip needed very early in Logging industry (Seismic

not yet performed or/and poor, Oil goes up!)

Dip needs a set of at least 3 measurements of the

SAME FEATURE: Dipmeter tool: 4 curves

Technology improvements: more data,

magnetometers, accelerometers, transmission of

data (pulse within mud) IMAGING TOOLS: 100

000 measurements per Meter MD: MAPPING OF

THE BOREHOLE WALL.

From1 Dip in 1 day (1969

Sidi Ferruch Algiers)

1250 Dips measured (2004) a fractured reservoir

From 1 Dip in 1 day (1969

Sidi Ferruch Algiers)

To

1250 Dips measured (2004

fractured reservoir)

From FEW to

THOUSANDS of

MEASUREMENTS

That’s

DIGITAL GEOLOGY

New ways of thinking,

managing data, processing,

interpreting…and more

and more data…in real

time …new challenges for

geoscientists

Logging History Mile Stones: 1927 Figure 1.The first electric

log was obtained Sept.

27, 1927, on the

Diefenbach 2905 well,

Rig.No. 7,

at Pechelbronn,Alsace,

France.The resistivity

curve

was created by plotting

successive readings.

Logging History Mile Stones: 1947

1941: logging took another major step forward with the

introduction of the Spontaneous-Potential

Dipmeter.

1947: This measurement was improved further with the

Resistivity Dipmeter

1952: Continuous Resistivity Dipmeter

Logging History Mile Stones:

Imaging Tools 1968 BHTV (BoreHole TeleViewer) Mobil Acoustic...

1986: FMS (Formation MicroScanner) Schlumberger Electric...

1991 FMI (Fullbore Formation Microscanner) Schlumberger...

1994 RAB (Resistivity at the Bit) LWD Schlumberger...

2001 OBMI (Oil Base MicroImager) Schlumberger...

NEXT: high resolution imaging LWD tools (technical issue to

transmit data while drilling solved: WO (2007??)

Followed by other logging companies: Baker Hughes, Halliburton

MAIN DIPMETER TOOLS

Tool Name Main Technical

Characteristics Resolution

Logging Company

Name & Mud

Environment

SHDT

(Stratigraphi

c Dipmeter)

8 microresistivity electrodes on

4 pads (2 per pads)

Sampling: 0.1 in

Vertical

resolution: 1-2

cm

Schlumberger’s tool

Water-base mud

HEXDIP

(Hexagonal

Diplog)


6 pads

Baker Hughes’ tool

Water-base mud

SED (Six

Arm

Dipmeter)


6 pads

Halliburton’ tool

Water-base mud

TOOL Example:

SED (Halliburton)

HIGH RESOLUTION IMAGING TOOLS

Electrical and Acoustic

of the main logging companies

in petroleum industry BAKER HUGHES:

- STAR (electrical & acoustic)

- CBIL

SCHLUMBERGER:

- FMI (FMS)

- UBI

HALLIBURTON:

- XRMI (EMI)

- CAST

EMI FMI STAR

Use electrical responses of the formation to create Images.

Pad-based Microresistivity (conduct. mud),

sensitive to poor pad contact. Depth of investigation: 1 in.

Resolution linked with electrical contrast:

Bedding ca. 1 cm; Fracture ca. 1 mm (Resistivity Contrast)

4 Pads & Flaps

2 X 12 Sensors

192

75% of 8.5”

Arm configuration

Sensors

Coverage

Logging Speed 1800/1500 ft/hr

X-, Y-Spacing 0.1-0.2 in.

6 Pads

2 X 12 Sensors

144

56% of 8.5”

1200/2400 ft/hr

0.1 in.

6 Pads, 2 rows

25 Sensors

150

0.2 in.

58% of 8.5”

1800 ft/hr

Main Characteristics of Electrical Imaging Tools

CAST UBI CBIL

Acoustic response of the formation to build up images

Rotating transducer (Transmitter-Receiver)

Ultras. pulse 250-500 kHz. Water- and Oil-based mud,

100% borehole coverage, sensitive to borehole shape,

Depth of investigation: 0, Travel Time and Amplitude Attenuation

Resolve feature down to 1 in.

7.5 Rot /Sec

180 samples /rev

Vertical Sampling

rate & Logg. speed

Image Resolution 0.4 in at 250 kHz

0.2 in at 500 kHz

Main Characteristics of Acoustic Imaging Tools

1 in. 2100 ft/hr

0.4 in 800 ft/hr

0.2 in 400 ft hr

Measurements

0.3 in

1200 ft/hr

200 samples/rev 6 Rot/Sec

12 (STAR)

250 samples/rev

0.2 in

2400 ft/hr

TOOL Example:

FMI (Schlumberger)

BOREHOLE MAP

BoreHoleMap Borehole

Tool

Projection: Boreholemap

Tool within the Borehole: RB

Attitude of a plane in Space

Attitude of an axis in Space

Boreholemap representation: Sinecurve

Tadpole

BoreHoleMap: Orientation Borehole Axis DEVI: Deviation (inclination): Angle 00-90 Deg (from vertical to horizontal axis)

HAZI: Borehole axis azimuth: Angle 000-360 Deg (from N-000- to N -360 clockwise)

MD: Measured Depth

Tool Axis (Sonde Axis) DEVI: Sonde Deviation: Angle 00-90 Deg (from vertical to horizontal axis)

Sonde DEVI = Borehole DEVI

P1AZ: Ref PAD (PAD1): Azimuth PAD1 = Angle 000-360 Deg from North (000) or

from the BOREHOLE HIGH SIDE clockwise

MD: Measured Depth

0 90 180 270 3600

Y-A

xis

: M

D

X-Axis: Azimuthal & Perimeter

ORIENTATION of the BOREHOLE MAP

Y-AXIS:

- Borehole High Side

- Tool Frame

- North

& MD

X- AXIS:

- Borehole Perimeter

& Azimuthal

ORIENTATION of the

TOOL WITHIN the Borehole

Tool ROTATES (around the AXIS) its

EXACT position INSIDE the BOREHOLE

has to be known at EVERY measurement

RB: Relative Bearing:

Angle between the referenced-arm (P1AZ) and a fixed feature

(North, High side of the Borehole) is recorded at

every measured point

AXIS ATTITUDE in SPACE:

Dip/Dip-Azimuth

1. - Projection of core-features

onto a borehole map

2. - Projection of a planar-feature

onto the borehole map (Fault…)

3. - Projection of a linear-feature of a surface

onto the borehole map

(Striation on Fault-Surface)

Core Goniometry

Methodology

Projection of Core: Borehole Map

A reference line parallel

to the core axis

= master calibration line

with the MD

= Y-Axis

Orthogonal projection onto

a cylindrical surface = Borehole Map

Perimeter

= 2 P R

= 3600

= X-Axis (cm & Deg)

Projection of a Planar-feature

DIP-AZIMUTH

900 1800 2700

2P PR PR/2 3PR/2

PR

PR

Sine curve TOP

Sine curve BOTTOM

=DIP-AZIMUTH

Perimeter

=3600

=2PR R-0 cm

360-00

Master Calibration Line

DIP-AZIMUTH (cm or Deg)

relative to the master calibration line

Projection of a Planar-feature

DIP

900 1800 2700

2P PR PR/2 3PR/2 R-0 cm

360-00

Sine Curve

Amplitude

Tang DIP = Core Diameter

DZ

DZ

AXIS On Borehole Map

Fault Surface with Striation (Sandstone clast) in Shale

Projection of a Linear-feature

of a Surface onto the Borehole Map

900 1800 2700

2P

PR PR/2 3PR/2

R-0 cm

360-00

Tang DIP = Diameter of the Core

PR

DZ

DZ

DIP-AZIMUTH of the line relative

to the master calibration line

Projection of a Linear-feature

of a Surface onto the Borehole Map

900 1800 2700

2P

PR PR/2 3PR/2

R-0 cm

360-00

DIP-AZIMUTH of the LINE relative

to the master calibration line

TADPOLE

0 Deg 90 Deg

N (000Deg)

E (090 Deg)

S (180 Deg)

W (270 Deg)

15/225 Deg

10/135 Deg

STEREOGRAPHIC

PROJECTION

We are dealing

with DIP POPULATIONS

NOT with

INDIVIDUAL DIP

Analysing Dip Populations:

Stereographic Projections

SCHMIDT PROJECTION

Upper Hemisphere

Only ORIENTATION Matters

NOT the Spatial POSITION

UPPER HEMISPHERE

Vertical & Horizontal lines

Girdle of Lines

Vertical &

Horizontal

Planes

One Pop. Dipping

increasingly South:

GIRDLE

Lines

Schmidt

Net

Projection of a

Plane: Pole &

Cyclographic

Planes

Schmidt Net

Schmidt Net

Unimodal

Population

Unimodal Population

Bimodal

Population

GIRDLE: Population Related to Fault

GIRDLE: FOLD

Compass Rose 348.75 011.25

033.75

056.25

078.75

101.25

123.75

146.25

168.75

191.25

213.75

236.25

258.75

281.25

303.75

326.25

EE--WW EE--WW

NN--SS

NN--SS

NENE--S

WSW

NE

NE--S

WSWN

WN

W--SESE

N.N

EN

.NE

--S.S

WS

.SW

N.N

EN

.NE

--S.S

WS

.SW

E.NEE.NE--W

.SWW.SW

E.NEE.NE--W

.SWW.SW

N.N

WN

.NW

--S.S

ES.S

E

N.N

WN

.NW

--S.S

ES

.SE

W.NWW.NW--E.SE

E.SE

W.NWW.NW--E.SE

E.SE

NW

NW

--SESE

090270

180

360/0

045

135

225

Dipping Striking

348.75…011.25: N E-W

011.25…033.75: N.NE W.NW-E.SE

033.75…056.25: NE NW-SE

056.25…078.75: E.NE N.NW-S.SE

078.75…101.25: E N-S

101.25…123.75: E.SE N.NE-S.SW

123.75…146.25: SE NE-SW

146.25…168.75: S.SE E.NE-W.SW

168.75…191.25: S E-W

Dipping Striking

168.75…191.25: S E-W

191.25…213.75: S.SW W.NW-E.SE

213.75…236.25: SW NW-SE

236.25…258.75: W.SW N.NW-S.SE

258.75…281.25: W N-S

281.25…303.75: W.NW N.NE-S.SW

303.75…326.25: NW NE-SW

326.25…348.75: N.NW E.NE-W.SW

348.75…011.25: N E-W

315

From RAW Data to

GEOLOGICALLY

Interpretable Outputs

Main Processes

Raw data, microresistivity measurements recorded by electrode tool,

need to be processed:

Speed correction,

Magnetic declination correction,

Depth shift offset (when it is needed)

Generation of image/dip logs.

Main Processes Speed correction, convert data, recorded vs. time into data vs. depth

&

correct depth offset due to oscillations along the axis tool.

Oscillations are caused by irregularities of the borehole or in fact due

to the none-constant speed of the tool while running the logs.

Generally, a sliding window of 10 ft is used for an average cable speed

of 1600 ft/hr.

SPEED CORRECTION: is applied

to correct for erratic tool motion

& convert data recorded in time to depth

T0 T0

T1 T1

T2-7 T2-7

T8

Y A

xis

: M

D

0 90 180 270 3600

T0 T0

T1 T1

T2 T2

T3 T3 0.2 in.

IN THEORY: Tool moves up the

borehole recording measurement-sets

At regular timing (T0 – T3)

IN REALITY: Tool moves ERRATICALLY up

the borehole recording measurement-sets at

regular timing (T0 – T3)

Main Processes

Magnetic declination correction, applied to inclinometry measurements

recorded by the tool (relatively to the

magnetic North) to convert them to

Geographic North.

Main Processes Depth shift offset (when it is needed)

Correlation of GR from another Run (Wireline Log) & GR from FMI

Geological Feature determined from other sources

Main Processes Generation of images Static normalised images (called Static Images):

computation carried out in a window covering all the

logged section.

Dynamically normalised images (called Dynamic Images):

sliding window (5 Ft).

Scale in the range white-yellow-brown-dark :

white-yellow: minimum conductivity

To

brown-dark: maximum conductivity.

QC: Depth Match, Static & Dynamic Images

Geological Features: Bed Boundary, Bedding

Dynamic Image



Dynamic Image Static Image




Calipers




Calipers

GR




Calipers

GR

RHOB




Calipers

GR

RHOB

NPHI



PROCESSING of

DIPMETER

DATA

Measurements

recorded by pads

during the run

Represented by

resistivity curves

specific to each

pad

are correlated

during

the process

(spikes)

Correlation

process will fit a

plane & compute

its dip/dip-

azimuth

Processing Dipmeter Data: -1 m sliding window (1600 ft/hr average cable speed

- Corresponding step: 0.5 m

- Search angle 70 Deg

Window

length (cm)

Step length

(cm)

Max. Search

Angle relative

to borehole

Deg.

Computed log

name Comments

100 50 80 Hex100X50X8

0

Computed log

used for

interpret dips

stored in a new

log named

INTERPR100

60 30 60 Hex60X30X60

20 10 40 Hex20X10X40

Processing Dipmeter Data: -1 m sliding window (1600 ft/hr average cable speed

- Corresponding step: 0.5 m

- Search angle 70 Deg

Dip Log: Computed Dips Only

High & Low Confidence

Noise

Poor Data Intervals

From Atlas of Borehole Imagery Ed L.B. Thompson Aapg 2000

QUALITY CHECK

From LOADING

To

FINAL INTERPRETATION


Calipers

GR

RHOB

NPHI



Other Points:

Repeat Section (200 ft MD)

Tool Rotation (less than one turn per 30 ft)

Slip-Stick Behaviour

Raw data in original format (LIS, DLIS)

Field Print (orientation, Pad#, Magnetic

Declination Value, Correction (Not Done)

IF Orientation Don’t Fit with Previous Field Model ?

Comparison with OTHER RUNS

Geology is the BEST QC

Tool has picked the “wrong” North?

Rotation of the Dip Log, around the borehole axis

(Same Methodology as in Core Goniometry)

Assume the Same Error during all the RUN

ROTATION Vertical Borehole

DIP remains the Same

DIP-Azimuth Changes

ROTATION Deviated Borehole

BASIC

INTERPRETATION

INTERPRETATION:

3 Steps

1: Collecting Geologic Data

2: Analysing Dip Populations

3: Correlating Geologic Features

INTERPRETATION Step 1

Collecting Geologic Data

-1) Diptype Listing

-2) Image Quality

-3) Zonation Based on Image Fabric

Highlighting:

-4) Lithology (Sedimentology) Facies

-5) Deformation Facies

DIPTYPE LISTING:

3 Geologic Surface Types:

-1) Sedimentologic

-2) Structural

-3) In Situ Stress Features

Identification of Geological Features Picked out directly from images &/or inferred

Sedimentological features:

- Bedding planes Structural-Dip, Paleo-Horizontal Dip

- Cross-bedding Paleo-Transport Directions, Deposi-

- Unconformities tional environments

- Image facies Help define reservoir units

Tectonic features:

- Faults: Fault-block rotation, strike-slip component

- Fractures: Fracture analyses of reservoir:

Fracture population characterisation, fracture

densities, Maximum fracturing directions

- In-situ Stress features: Breakout, Tensile Fractures

In Horizontal wells: syncline & anticline structures,

younging direction, Bedding-plane-correlation

to constrain reservoir zonation

SEDIMENTOLOGIC Features Listing PARTICULAR to a RESERVOIR

Related to data from other sources (Cores,

Petrophysics, Seismic, Field Studies) to help

CORRELATE


Calipers

GR

RHOB

NPHI

Bed Boundary



FMI


Calipers

GR

RHOB

NPHI

Bed Boundary

Bedding



FMI

Calipers

GR

RHOB

NPHI

Foreset Boundary

Cross

Bedding

Bed Boundary

Foreset

Foreset, Foreset Boundary & Cross Bedding

FMI

Calipers GR

RHOB

NPHI

SS

Bedding

Heterolithic

Bedding

Shale

Bedding

Shale Bedding, SS Bedding & Heterolithic Bedding

FMI

TECTONIC Features Listing PARTICULAR to a RESERVOIR

Related to data from other sources (Cores,

Petrophysics, Seismic, Field Studies) to help

CORRELATE

Part of a Diptype List (Fractured Reservoir)

Diptype Name,

(Correspondent

Geological Notion),

colour used in plots

and Fig., and

Illustration (Go to Fig

#)

Description & Correlation with Geological

Feature Comments

FAULT

(Fault), Red

GoToFig11

Narrow or large, and discrete resistive or

conductive anomaly displayed along a sub-

planar feature cutting sedimentologic planes.

Also, a clear cut off the bulk resistivity,

highlighting a plane considered as a fault

plane.

Fault is differentiated from

Fracture.

BEDDING

(Bedding),

Green

GoToFig12

Change in the bulk conductivity along a

planar boundary at the lowest scale of the

image, i.e. centimetre scale. Regularly

repeated planar features corresponding to

current bedding planes.

The current bedding planes are

generally parallel to bed boundary

and regularly repeated in the bed or

layer.

Confusion sometimes with Shale

Bedding, Bed Boundary and

Stylolite

Fault, Bedding, BedBoundary m MD, Vertical Well, Scale: V=H FMI processed &

interpreted with

Recall

Reverse Minor Fault

with a ca 15 cm throw

Examples of

Geological Features

Bedding plane

in the Hangingwall Block

The same Bedding plane

in the Footwall Block

Minor Fault

Fault Interpreted as a

probable

Reverse Fault

FMI

HORIZONTAL WELLS

Younging Direction in Horizontal Well Younging Direction

Downward Upward

Cross section

of anticline

drilled by a

Horizontal Well

Younging direction

inferred from

the shape of

the sine curve

TD

Inward direction Outward direction

Bedding Plan Correlation: a methodology to

help define reservoir units

Younging Direction -INTERVAL without fault

picked out

-SHORT interval

- A BEDDING PLANE ,

bounding reservoir units

picked and choosen as

STRATUM GUIDE

- Locations where Stratum

guide is cut

DOWNWARD

or UPWARD

are picked out To be Performed Carefully!

Bull’s eye structure in Borehole Images

of Horizontal Well:

= Anticline structure

= Inflexion of the well-track (concave profile)

Or Outward direction

Inward direction Inward direction

Borehole high side

Wood-Grain structure in Borehole Images

of Horizontal Well:

= Syncline structure

= Inflexion of the well-track (convex profile)

Or Outward direction

Inward direction Inward direction

Borehole high side

From Atlas of Borehole Imagery

Ed L.B. Thompson Aapg 2000

Cross Bedding, Closed Fracture m MD, Vertical Well, Scale: V=H FMI processed &

interpreted with Recall

Discontinuous & Continuous Fractures m MD, Vertical Well, Scale: V=H

FMI processed &

interpreted with

Recall

IN SITU STRESS

CHARACTERISATION

Tensile Fractures (Images)

Borehole Breakout (Images)

Borehole Breakout (Calipers)

Constrain the entire Population

Determination of the SHmax Direction

Borehole Breakout (from Calipers)

Criteria to Constrain

1) Tool Rotation < 30 Deg

2) Caliper Difference > 0.5 in

3) Smaller Cal > BS-1.5 in

4) Bigger Cal > BS

5) Avoid Key Seat ovality (angle

> 15 Deg)

SHmax

Determination :

Plotting All to Get

Global Picture

QUALITY IMAGE ZONATION

Poor Intervals are flagged

IMAGE FABRIC ZONATIONS

Image Fabric might be related to Geological

Features… Interference of tool behaviour (&…)

Zonation Uncertainty…calibrated, correlated…

Zonation Helps define reservoir features:

1)Highlighting Matrix (Sedimentologic, Lithology): Thinly Bedded, Nodular, Vuggy…matrixes

2) Highlighting Deformation Facies (Stylolite

Associated Fractures, Fracture Zone 1…)

LITHOLOGY ZONATION

Highlighting Matrix (Sedimentologic, Lithology): Thinly Bedded, Nodular, Vuggy…matrixes

Example of Image Fabric Zonation

Highlighting Matrix Characteristic

Zonation Name & Colour

used to flag the

corresponding interval,

and Illustration (Fig)

Description & Correlation with

Geological Features and Events Comments

Thinly Bedded

Matrix (Red)

GoToFig11

Interbedded matrix with thinly bed including

cross bedding. It is possible to pick every 5

cm a bedding surface.

This layer might be rich in

clay, shale, fine grain that

might be a horizontal barrier to

fluid displacement.

It can be used to determine the

Paleohorizontal dip if

necessary.

Nodular Matrix

(Green) GoToFig12

Conglomerate-shaped matrix with resistive

nodules. This might be related to

conglomerates or not, it has to be calibrated

with other data sources (cores, mud logs,

field studies…). Resistive nodules might be

related to some anisotropic proprieties of the

matrix or to some tight features.

The resistive spots are

considered as tight or close

therefore not used by fluids as

porosity.

On the contrary, the “matrix”

between the resistive spots is

conductive so it is considered

as actual/potential significant

porosity

Zonation Highlighting Sedimentology

Image Fabrics:

Thin Bedded

&

Bioturbed

m MD, Vertical Well, Scale: V=H FMI processed &

interpreted with Recall

Vuggy Matrix

Important Features:

Isolated

Interconnected

Size (Relatively)

Up Grading

Down Grading

(Correlation

with Flooding

Surfaces)

Intersected by

Deformed Zones

Scale

Rudist Shuaiba (Cr)

Bu Hasa Field (Abu

Dhabi)

DEFORMATION FACIES

ZONATION (Stylolite Associated Fractures, Fracture Zone 1…)

Example of Zonation Highlighting

Deformation Features, Stylolite & Karstic Associations, and Poor Images

Zonation Name &

Colour used to flag

the corresponding

interval, and

Illustration (Fig)

Description & Correlation with

Geological Features and Events Comments

Poor Image

(Red)

GoToFig11

Image is of poor quality, high to moderate

uncertainty in the interpreted features of the

flagged interval.

Poor quality of image correspond

often to washout intervals

Stylolite

Associated

Fractures

(Green)

GoToFig12

Tiny Fractures (up to 20 cm vertical-length)

sub perpendicular to Stylolite surface,

occurring in the lower side, or upper side or

both sides of the stylolite surface. Fractures

are striking in all azimuths (radial) or in

particular azimuths: it is not clear.

Sometimes a couple of stylolite surfaces

with their associated fractures are close

enough to constitute a Stylolite Zone

This zone, subhorizontal might play a

positive role in draining fluids

horizontally.

Such feature is known as used by fluid

paths in some carbonate reservoirs.

It might be considered as “pipe-layer”

parallel to the Stylolite surface.

If crossed by Fracture Zone or

Fractured/Cataclastic zone this might

increase the draining propriety.

The question is about the role

regarding vertical path of fluids:

obstacle or drain?

Stylolite Associated Fractures m MD, Vertical Well, Scale: V=H

FMI (Processed &

Interpreted with Recall)

INFERRED Features

By Analysing Dip Populations

Examples:

Girdle: Inferred faults

Bimodal: Unconformities

Paleohorizontal dip

Structural Dips: Per Units,

Logged Section

Structural Dip & / or Paleo-Horizontal Dip: ?

“...Dips with constant magnitude and azimuth in a low energy environment

can be selected. They correspond to the groups of beds, whose bedding planes have not

undergone any biogenic or tectonic alteration. It can reasonably be assumed that these

beds were deposited on nearly horizontal surfaces and that their present dips are the

result of tectonic stresses” Tire de Serra, O. 1985, “Sedimentary environments from

wireline logs”.

“By Structural dip is intended the “general attitude of beds”. It is the dip that would

be measured at outcrop. It is usually the dip seen on seismic reflectors, themselves a

generalisation. It avoids any sedimentary structures of any size and is generally

considered to represent the depositional surface which also is considered to be

horizontal.” Tire de Rider, M. H. 1996 “The geological interpretation of well logs”

I call it: PALEO-HORIZONTAL DIP

I call it: STRUCTURAL DIP

Paleo-Horizontal Dip, as is suggested by the name, is the dip of bedding planes that

were originally deposited horizontally. Low energy sediments such as shale, planktonic

sediments and coals, in specific conditions, can be assumed to be deposited

horizontally.

Such bedding planes may be used to infer tectonic events such as uplift, tilting or fault

block rotation.

Structural dip is restricted to the mean dip of a lithological formation that can be used

in geological (structural) cross-section, or related to a specific marker that can be

correlated to a seismic one, avoiding detailed sedimentological structures at small

scale. The dip and associated dip-azimuth can be used to infer the geometry of the

units, for structural purposes at rather bigger scale, no matter what its genetic origin,

or what events the unit has previously undergone.

PALEO-HORIZONTAL DIP

STRUCTURAL DIP

The way I see it, and use it in my interpretation:

Paleo-Horizontal Dip: Interval of Low Energy Deposits

Paleo-Horizontal Dip: Whole Dip-type Population

of Low Energy Deposits

Structural Dip: Several Dip-type Populations: Bed

Boundary, ...

PALEOHORIZONTAL DIP Implemented to Rotate Out Dips

After Rotation

Before Rotation

CROSS

BEDDING

(After Gareth, G.; 2000, in PESGB Newsletter)

Terminology used in FMI image interpretation

Foreset Boundary

Cross-Bedding Planes

Foreset Boundary

Foreset Boundaries

&

Cross- Bedding

are Parallel (Planar

Cross Bedding)?

= SS Bedding

Track-tadpole presentation

Cross-section presentation

PALEOCURRENT

DIRECTIONS

Paleocurrent directions: ONE DIRECTION

in

ONE SET

Paleocurrent directions: DIRECTIONS in

ONE SET

PALEOCURRENT DIRECTIONS

GLOBAL

RESULTS

Major Minor

Cross Bedding

Interval Method

Whole Pop.

SS Bedding

Interval Method

Whole Pop.

Heterolithic

Whole Pop.

Paleocurrent directions: Global Results

PALEOCURRENT

DIRECTIONS

Vs

GEOLOGIC TIME

Ex. 1: SAME DIRECTION Paleocurrent directions are stacked up from

bottom to top:

-Bottom (Dark Blue)

-Middle of the unit (Green)

-Top (Yellow)

Ex. 2: CYCLE Re-Considering the previous example (Global

Result)

Major Minor

Cross Bedding

Interval Method

Whole Pop.

SS Bedding

Interval Method

Whole Pop.

Heterolithic

Whole Pop.

Paleocurrent directions: Global Results

Paleocurrent Directions (from O to 360 Deg)

S

N

N

E

W

Geological

Time

Northerly

Paleocurrent

Cycle

N

S

W-SW

S

Final Result: Distinct Stacked Paleocurrent cycles

W

N

PaleoHorizontal Dip Implemented to

Constrain Fault Block Rotation

Unconformity from Bimodal Bedding

Population: whole section


Population: Upper Unit


Population: Lower Unit

Geometry

of the

whole

section

INFERRING

GEOLOGIC

FEATURES:

FAULTS

Fault

Pattern

FAULT: Picked & Constrained (girdle) 1of2

FAULT: Picked & Constrained (girdle) 2 of 2

Constraining a Normal Fault with Roll Over 1of 2

Constraining a Normal Fault with Roll Over 2 of 2

Key References

overview to linked in

Documents

logging industry seismicnot

main logging companies

logging speed1800 fthr

logging history mile

depth mddip

value rock propriety

mud imaging tools

yetperformed orand poor