steam displacement - kern river field.pdf
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Steam Displacement- Kern River Fieici
C.oBuraell, SPBAIME, Getty Oil Co.
Introduction
The Kern River field is a few miles northeast of
Bakersllekf in the southeastern part of the San
Joaquin Valley, It is one of the largest in California
in terms of its original oil in place and cumulative
production, The latter, as of Jan. 1, 1969, was ap-
proximately 476 million bbl. On the 12,100 produc-
tive acres there are more than 5,100 active producing
wells, ranging in depth from 500 to 1,300 ft.
The reservoir and fluid characteristics of the Kern
River field are considered favorable for secondary
recovery by steam displacement. The gravity of the
produced oil ranges from 12° to as high as 16.5°
API, and averagesabout 13.5°. The oil has an average
viscosity
4,000 cp at the reservoir temperature of
90”F. At 250”F, this viscosity is reduced to 15 cp.
The structure of the Kern River field is a simple
homocline on the east flank of the San Joaquin Geo-
syncline, dipping toward the southwest at 4°. The
productive zone is an unconsolidated sand with con-
siderable dispersed silt interbedded in blue-green
clays. Average permeability of the oil sand is approxi-
mately 4,000 md. The Kern River formation repre-
sents a continental-alluvial fan deposit derived largely
from the westward-flowingKern River.
History of Development
The application of heat to the Kern River sands dates
from Lbe tid 1W()’s. when bottom-hole heaters
-----,
were installed to assist in the recovery of the heavy
crude by improving the mobfity of the oil, reducing
plugging of the perforations, and improving pump
perfornmllce.
Based on the successful program of bottom-hole
heaters in the field, further investigationswere under-
taken to utilize the heat more effectivelyin producing
the viscous oil, Theoretical performance predictions
made a hot waterflood attractive, and in 1961 it was
considered necessary to conduct some fundamental
displacement experiments to verify the predictions.
The results of the laboratory experiments were cii-
caraging, and in Aug., 1962, a 234-acre normal
five-spot pattern was drilled and a pilot hot water-
floodwas begun.
Hot Waterflood Pilot Performance
A total of 2,231,000 bbl of hot water was injected
into the four injection wellsfrom Aug., 1962, to Feb.,
1964. Results from the hot-water injection project
showed that viscous oil displacement by hot water-
floodingwas mechanically feasible,However, because
of inherent reservoir conditions that caused excessive
bypassing and channeling at the required high injec-
tion rates, themethod wasnot economicallyattractive.
It was concluded that to develop an economicprocess,
the sweep efficiencyof the displacingphase had to be
increased substantially either by eliminating the ob-
served channeling or by increasing the heat utilization
efficiency.
steam Di@acement
Steam as a heat earner and displacing fluidwas con-
sidered potentially capable of producing the necessary
improvement in heat utilization. In June, 1964, the
hot waterflood project was converted to a steam dis-
1
~ The heat has been on in Kern River since the mid fifties. First it came from
I
bottom-hole heaters then it came jrom inj=ted hot water. In 1964 a steam drive
was started so that currently the field is sweating out 6,700 barrels a day as a result
of a daily injection of
30,000
barrels of steam.
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TABLE l+ATUS OF ACTWE STEAM DfSmCEMENT PROJECTS,
Single
Dual
Totel Totel
Totel
Oisplt
Swte:p
In&e/y I n&cJ$n
ln&cti~ ln eep
Prodd,yg
Kern
June, 1964
-z——
15
47
62
S3
San Joaquin
juiie, i%%
~—
8 8
19
Ken ,’ASD
March, 196S
9— 9
9
17
G and W “A” DaC., 1968
9— 9
9
16
Read Apri:, I*W9
~~ —
12
12
22
— .
Total
70 15 85
. -- . --
placement drive. This project
is
presently known as
the Kern Project and has been expanded fmm the
original four injection wells to 47 injection wells.
Since 1964, four other steam displacement projects
have been started in various areas in the field; the
San Joaquin Project (8 injection wells), Kern “A”
Project (9 injection wells), G and W “A” Project (9
injection wells) and the Reed Project (12 injection
wells). Table 1 shows the start-up date for each
project along with the number of injection wells and
producing wells. TMs table also shows the number of
generators used in each displacement project. Pres-
ently 85 injection wells are being used in steam dis-
placement operations, with steam being generated by
six 18.5 million Btu/hour, four 20 million Btu/hour
and fourteen 22 million Btu/hour steam generators.
Injection System
Steam is split from a steam generator into individual
injection wells through a header system employing
chokes in critical fiow. TM
pi~du~ T ~ tths
the steam velocity achieve sonic velocity, which for
our conditions calls for a pressure drop of about 55
percent across the choke. The chokes are sized in
relationship to each other to give the desired flow
rate into each injection well. As long as the pressure
drop is greater than 55 percent, the flow rate will be
independent of the actual wellhead injection pressure,
The steam is transmitted through insulated surface
limesto the injection wellhead and in most cases is
injected down casing in the injection wells. However,
dual displacement requires that the steam be split
and injected down tubing through a thermal packer
and down the tubing-casingannuhm Originality,steam
flow was split with an adjustable bean and an orifice
meter to measure the flow rate, which, of course, re-
quired a great deal more surveillance than the critical-
flowchoke system.
During 1970, a central steam boiler plant is to be
installed. This plant will have a heat capacity output
of 240 million Btu/hour. The use of a central plant
is ideal since displacement is a continuous operation,
and a large concentration of steam is mquimd in a
small area. An advantage of these large units over
the smaller steam generators is their improved thermal
efficiency.
Well Completion Techniques
The general plan for steam displacement at Kern
River is to confine the displacement interval to about
50 or 60 ft and to start in the lower portion of the
Kern River formation. Injection wells have generally
been completed with 5 -in. casing cemented to sur-
lW
15/
face and selectively
mRN RIVER FIELD ‘
Number of
Generetore
1s.5
MM Btu Mt%tu Ml%tu 1%’i%
4 4
7
K
— —
2
K
2——
R
— —
2 R
— —
3
R
— — .
6
4 i4
let-perforated.
Five basic types of producing-well completion are
used in these steam displacement operations. They
include punched line= slotted liners, selectivelyper-
forated cemented casing, inner liner completions and
gravel packed liners. Wells with punched liners were
drilled in the early 1900’s.From 1940 through 1966,
the normal producing-well completion method was to
cement an 8Ys-in.water string and then run a 6 6-in.
slotted liner. Slot sizes range from 60 mesh to as
high as 180 mesh. Since 1966, producing wells have
been completed by cementing casing through the oil
zone amf “= ective yjet-perforating 50 to 60 ft of
interval near the bottom of the zone. This limited-
entry, jet-perforated completion has made possible
the injection of steaminto a prescribed interval. Where
sand production becomes a problem, it has become
necessmy to mn inner liners. Although this has helped
to limit the sand production, in many cases it has also
caused pluggingof the wellbore, which interferes with
the flowof fluids.
Water Source
Water is provided for the steam displacement opera-
tions by a central water plant that treats produced
water. This central plant also serves as a source of
water for the steam stimulation operations that are
currently being conducted in the field. It was realized
early in the history of thermal operations that very
large volumes of water would be required if the field
wastobe flooded onafullscale. Theprocess usedin
treating the produced water is to gather it in settlii
sumps to allow the oil and water to separate. The
water is then passed through a flotation cdl, where
its oil content is reduced so it can be filtered. For this,
diatomaceous-earth pressure leaf Inters are used. The
water is deaerated by a vacuum system and by an
oxygen-scavengingchemical and is then softened by
passing through ZeOliteresin water softeners. The
present capacity of the plant is 150,000 B/D, with
design capacity to handle as high as 300,000 B/D by
expanding various pieces of satellite equipment.
Laboratory
Investigation
Laboratory investigations in linear tubes were con-
ducted to provide data on residual oil saturations
from steatnflooding. Table 2 shows the residwd oil
saturation result&g from steamflooding Kern River
crude at vmious injection temperatures. Also shown
on th~ table are the residual oil saturations resulting
from injecting hot water and hot nitrogen at the same
tempature and cumulative heat. Apparently, some
other influencebesides the temperature levelis respon-
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TABLE 2-REsIDUAL OIL sATURATION FOR VARIOUS
THERMAL DISPLACEMENT METHODS
Residual Oil
Tem~eture
Saturation
Type of Displacement
(fraction)
Steam 287
0.137
--—
Steam
338
0.109
Steam
365
0.094
Hot N,
304 0.151
Hot watar
280
0.320
sible for the reduced residual oil saturations when
injecting steam or hot nitrogen. It appears that the
lower residual oil saturation experienced with steam
or nitrogen injection isa result of the formation’sbeing
fiooded by many pore volumes of gas. Shutler,’ in his
work with a mathematical model of the steamdrive
process, has also reached this concision.
Further studies wereconducted in a fiv-spot model
to investigate the effect of injection rate on oil re-
covery. At low injection rates, steam breakthrough is
delayed, but because of higher heat losses, it takes
more injected steam to realize the ultimate recovery.
At higher steam injection rates, steam breaks through
early in the production history. However, this is offset
by the advantage of lower heat losses in obtaining the
ultimate recovery with less steam. As injection rate
is again increased, the trend reverses— probably as
a result of a fingering effect at the higher injection
rate — and the sweep efficiencydrops.
Field Performance
Fig. 1 shows production performance and injection
history for the fiveactive steam displacement projects.
Associatedwith these 85 injection wells (including 15
dual injection wells), on 2 -acre five-spot pattern
spacing, are 157 displacement producing wells. The
present injection rate is 30,400 B/D. Gross produc-
tion from the five projects equals the total injection
rate, which indicates a good capture efficiency.The oil
production rate of 6,740 B/D gives a production per
nattem of 67 B/D.
_.--–—
Kern Displacement Project Performance
Thisproject was begun in Aug., 1962, as a hot water-
flood, utilizing four injectors in a 2 -acre normal
five-spot pattern. In June, 1964, steam injection was
started “intothe four injection wells at a rate of 300
B/D/well. Fig. 2 shows the production performance
from the central producing well, Kern No. 64. An
immediate increase in oil production was obsmved
in this well. After 2 months of continuous injection,
Kern No. 64 production peaked at 155 BOPD.
Although there was no evidence of steam break-
through in Kern No. 64, the wellhead producing tem-
perature was approximately 200°F. By the end of
May, 1966, a total of 629,000 bbl of steam had been
injected into the four input wells.During this period,
injection was interrupted twice to stimulate the wells
immediately outside the pilot pattern. The normal
practice now is to continue injection and to steam-
stimulate the producing wells with a steam generator
used soiely for the purpose. As producing wells be-
come hot from the steam displacement drive, stimula-
tion is no longer required. As shown on Fig. 2,
production from Kern No. 64 responded rapidly to
changes in injection conditions during 1964 and 1965.
Full scale Expansion
The
displacementproject was expanded inMay, 1966,
from four injection wells to 16 injection wells, cover-
ing 40 acres. The project was further expanded to 33
patterns covering90 acres, inOct., 1967; and in Sept.,
1968, it was expanded again, this time to 47 injection
weUscovering 130 acres. Fig. 3 shows the locations
of these expansions.
Fig. 4 is a structure section through the Kern Dis-
placement Project showing the interval being dis-
placed —
the “K” interval of the Kern River forma-
tion. As can be seen, t.hk interval actually breaks into
two to three individual sand stringers. Injection pro-
files showed that in several of the wells steam was
entering only the top sand stringer. During the last
expansion, 15 wells were converted to dual injection
to provide steam injection into the lower stringers.
1
8
Fig. l—Production and injection history for active
Fig. 2—ProducXon history for Kern Well 64,
steam displacement projects. Karn Steam Dkplacement Project.
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TABLE 3-COMPARISON OF PRODUCTION FROM
DIFFERENT WELL COMPLETIONS, KERN
STEAM DISPLACEMENT PROJECT
Y-
of Well Complatlon
Soll~ st ring — jet per forat ed
Sl ot ted l in er
Qmval pack — slotted liner
inner iinar
Lsst6
month’ womgo
Numbw of W*IIS
;
5
011Produotlon
Rato&r l”
i
( CORDES I
~ ~lsesu?AN610N
( OMAR) ,
Iii
.: W? EXMON
...----.-ti_J~ --z::.
>
I
1
t .
I
f
h (REED CRUOE’A” I
1
Fig. 3-Locations of Kern steam displacement
pattarn expansions.
M
*208
126
EL.649’
EL. 670’
Reqmnee from DMerent Well Completions ‘
Various well completion methods were used in the
producing wells in the Kern Displacement Project.
Table 3 shows the average oil response from the dif-
ferent methods, As shown in Fig. 5, the wells with
the various completions are scattered. (Sand character
in the individual wells was determined to be com-
parable and results of comparing completion methods
should be representative,) It was found that tbe jet-
perforated completions were the best welle in the
steam drive, with production during the last 6 monthe
averaging 64 B/D. The wells with slotted liner eom-
pletioru were almost as good, with en average p-
duction of 54 B/D. However, a group of wells with
gravel-pack completions averaged only 38 B/D, and
a few wellswith inner liners averaged only 33 B/D.
Based on this, two gravel-packed wells were recom-
pleted with cemented casingand jet-perforat~ which
resulted in increased oil production. These two wells
are presently making 50 B/D each, mmpared with a
previous production of 25 B/D. The improvement in
all cases was a result of higher total fluid production
rata.
CMRecovery
Table 4 shows oil recoveries for nine confined five-
spot patterns within the Kern Displacement Projeet.
Cumulative oil shown on this table is the total oil
OM
EL. 732’
I
/
‘
n
9
64
EL. 74S’
I
/ ‘
Ii?
4
.
m DISPLACEMENT INTERVAL
10 11?s’
Fig. 4-Structure aeetirm thrwh the Kern Steam Displacement Proiect.
JOURNAL OF PETROLEUM TECHNOLOGY
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produced since the well was placed on hot-water or
steam displacement. In some cases, cumulative gross
production (oil and water) has exceeded the cumu-
lative steam injected, and in other cases it has been
much less than the steam injected. The latter, espe-
cially, is true for those wells that have been com-
pieteciwith either gravci packs or inner liners. Tkse
completion methods have caused an ineffectiveness
in the well’sacting as a sink within the displacement
drive (see Table 3).
Large
Pumpinghits
Since
some of the wells, owing to the way in which
they were compkted, were not capable of producing
their share of the injection fluid, it became necessmy
in early 1969, to install some large pumping units on
those that could produce more than their share.
Thirteen API 114 pumping units and three API 228
pumping units were installed on selectedwells, which
resulted in a favorable production increase. F . 6 is
a production graph for one of these wells. Steam
h~akth~lluh nrzwwerl in ~em No, Z04 dlM@ ~C.,
.. ——..- .— ---- — - --— - -
1968, making it very difKcultto maintain the previous
oil production rate. Since the installation of an API
228 pumping unit with a 144-in. stroke, productkm
has been maintained at a level higher than before
steam breakthrough; and there have been very few
pumping problems. This generally has been the case
with allthe largepumping units that wereinstalled.
The alower speed and longer stroke of these large
mp~g tits appears to be very advantageous in
producing wells with large-volume steam
break-
through, Obtaining accurate fluid levelsin wellsblow-
ing large volumes o f st m h s been very &fEcuIt.It
has been found, also, that to assume that wells are
pumped offwhen they are pounding fluid isnot always
sound. In many cases this is the result, instes@ of a
steam lock in the pump. For one particular producing
well blowing large volumes of ste~ it was decided
to decrease the steam injection rate in the nearby
() INNER UNER
A
ORAVEL
ACKED‘SLOTTCO LINER
U $LOTTEO LINER
O ~0 STRIN6 JET PERF
I
I
I
( COROSS)
i
IOMAR)
---
“A”)
Fig. S-Looations of wells with different weli
completions, Kern Steam Displacement Project.
1s0
1
1
1 1
I
1
1
i
I
.
100
1 1 1 1
11 \
1
,
1
1 IT
In
1 1
1 1
1
[
1
1 ,
I
1 , 1
Iw
1 1
1 ,
1
n I
I
1
,
1 1
1
I
Imm
[
I I
Iwo
q
s
I
on - S?w a?lw d
PJl
I I
I I
Ill
I / I
I
lo, \ ~lmjl~
I
u I
I
ISO,
low
Inol
met
Fig. Qrcduotion history for Kom Wel l 2C
Kern Steam Displacement Proj ect.
TABLE 4-OIL RECOVERIES OF CONFINED PAITERNS
WITH SUFFICIENT HISTORY, KERN STEAM
DISPLACEMENT PROJECT
.$
,J
1 , [
1
1
t
Wdl
Liner compiotion
K No.39
K No. 64*
K
No. 65
K No. 66”
K No.
92””
KNo.84**
KNo.95
K No. 206”
Ostaon
Confined
Dlspiscsment
Msy, 1962
Msy, 1862
May, 1966
Msy, 1866
May,
1866
May, 1966
May,1966
Sept,1967
%pt., 1967
Cumulativeproduction pm-
Gross 011
011Rsts
(BID)
bbl) (bbl)
736,700
635,300
396,600
520,800
S%200
82,600
128,200
26LOO0
142,700
121,700
154,700
102,s00
112,5W
26,400
32,7LM
51,700
76j400
47,4(M
Pmduclng Intetwl l imited to displacement zone
Rwently recompleted
e jet.perfomted 00mpletbn
OCTOBER, 1970
35
40
49
50
52
52
27
66
120
,
, ,
; ~
1 1 r I I
1 1
[ ,
1 1 ,
1 w
r
PI ‘:~,
I
1 ,
r
1 , 1
1
a
“
/;-+ -
1
mT WATZ
I
I I
I 1
1
aeseo
wutumznr-+-lmn SwLAcznrn
1
. .
w
I I
I I
1
;’
100
A(.JI
I I I I
I I
1 ,1
Iws I I W
1s, 1
mu
1s07 I
mu
I
VU,
I
fig. 7—Production and injection hietoty for the
Kern Steem Dlsplecament Proj ect.
1229
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injection well; after this proved unsuccessfd, a large,
long-stroke pumping unit wasinstalled, which resulted
in a twofold increase in gross production and a five-
fold increase in the oil production.
Fig. 7 shows production and injection history for
the total Kern Steam Displacement Project Since in-
stalling the large pumping units, gross production has
increased until it now exceeds the total steam injec-
tion rate of approximately 18,500 B/D. To determine
if the proje as a whole, is following expected trends
a predicted oil rate was calculated. Calculations of
surface, weUbore, and formation heat loss (derived
by published methods”’) werecombinedwith produc-
tion histories and laboratorydetermked sweep effi-
ciencies to develop the predktive model. There is
good agreement between the predicted and actual oil
rates, as shown on Fig. 7.
Kern “A” Dkplacement Project
This project was started in March, 1968. There are 9
injection wells, and 17 producing wells, and steam is
provi&d by two 18.5 million Btu/hour steam gen-
erators. The displacement zone is the “R’ zone in the
Kern River formation. Fig. 8 is a structure section
through the Kern “A” Project, showing the displace-
ment zone. The producing wells were initially steam
stimulated with good results; however, production
declined quite rapidly. After several months, produ-
tion rose sharply as producing wells responded to the
steam drive. Fig. 9 shows the production and injec-
.- .,-,
al
EL. S20’
47===1
/’
I
( TOTAL F&O
/
I
1
1000.
(PREOICTED Pam.
1“ r- L/-
mom
1~
.
1
I
‘oot--kk-i
Fig. 9-Produ&lon and injetilon history for the Kern
“ A” Steam Displacement Project.
$
7-r+-
.
B’
TD 1020’
+ ‘ r= PLACEMENTNTE;;y’
TD997’
Pig. 8-Structure -Ion ttrrough the Kern “ A” Steam D splecement project.
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,
I
~ ~ ‘EXISTING PATTERNS
1
1
I
i
;-
1
,0000.
I
I
I
.
6
i ii33
I
I
I
~
IO O
d“
I
I
p
I
I
“edd @
1°0
;*
1.
*
*
I
I
(KERN ‘~)
------- +:---: ----:--
w
Fig. 10-Map of Kam “A” Steam Displacement Project.
tion history. The rapid displacement response appears
to arise from the new producing wells that are capable
of producing the displaced fluids. Fig. 10 shows the
location of the nine patterns.
For the Kern “A” Displacement Project a dtierent
technique for completing the injection wells was used.
The total thickness of the displacement zone is 80 ft.
This zone consists of a very permeable section on top,
a shaly sand section in the middle, and a fairly perme-
=h e ~=tinn no
~ttnm.. If the entire
sand inteNsI had
“.. “ v ... ..
been perforated, the steam would probably have gone
entirely out the top member and not atlected the lower
part of the Sand. To preverx t , m y the bottom 30
ft of be zone was @orated. In addition, to improve
the steam profile Whin this 30-ft interval, the zone
was perforated with one shot every 2 ft for a total
of 15 shots, as compared with the earlier practice of
perforating with two shots every foot. This reduction
in the number ofperforations has not resulted in exces-
sive weUhead pressure. Spinner surveys show the
average injection profile coverage to be 70 percent
with this methm compared with 40 percent on the
Kern Displacement Project where two holes were
used for eve~ foot.
E4 onosnfcs
Operating costs, capital expenditures, profits, volumes
of steam injected and oil recoveries are not included
in this report. Such data are unique to selected areas
of tlds field and would be misleading if extrapolated
to other fieldsor to all areas of the KernRiver field.
Conclusions
Following am some conclusions derived from the
study under discussion.
1. Under current Conditions, steam displacement
in the Kern River field is an engineering success.
2. Pumping wellswith long-stroke (84-to 144-in.)
pumping units at slow speeds has been successful in
producing wells with large steam breakthroughs.
3. The method of completing a well is a major
factor in the capture of displaced fluids.
Acknowledgment
1 wish to thank J. L. Grolemund, Exploration and
Production Research, Getty Oil Co., for the laboratory
investigations.
References
1.
Shutler, N. D.:
“Numerical, Thrse-Phase Simulation of
the Linear Steam Flood Process”, Sot.
Pet. Eng. J.
(June,
1969) 232-246.
.
2. Ramey, H. J., Jr.: “Wellbore Heat Transmission”, J.
Per.
Tech. (APril,
1962) 427435.
*
-“,
._A T -
“
j k-*—X,
J. W. JSIIU dgcuh=., ?.. ~.:
“I&cr@r Heating
by
Hot Fluid In~lon’*,
Trans.
AIME (1959) 216, 312-
3i5. ?’E’
Original manuscript received in Sociaty of PsWoleum Enginasre
office Nov. 12. 1%9. Revised manuscript reoaived June 1S, 1970.
Paper (SPE 27SS) wcs pme.nted
t SPE 40th Annual California
Regional Fall Msetins, held in San Francisco, NOV. S-7, 1969.
@ Copyright 1970 American Institute of Minin$, Metallurgical, and
Petroleum Enginsere, Inc.