Steam Displacement - Kern River Field.pdf

8/17/2019 Steam Displacement - Kern River Field.pdf

1/7

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.


2/7

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-


3/7

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.


4/7

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


5/7

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


6/7

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.

JQ~J~NAL OF PETROLEUM TE HNOLOGY


7/7

,

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.

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Steam Displacement - Kern River Field.pdf