1. Subzone Redevelopment of the
Long Beach Unit, Wilmington Oil
Field: A Case Study
Jack A. Robertson, * SPE, City of Long Beach
Jeffery A. Blesener, SPE, City of Long Beach
Samuel Soo Hoo, SPE, City of Long Beach
Summary. A major program of irifill subzone redevelopment to improve vertical waterflood conformance has
been successful in materially improving oil recovery performance in the Long Beach Unit of the Wilmington oil
field, CA. The well completions in individual subzones or layers will result in greatly improved future reservoir
management opportunities through individual subzone or layer monitoring and control.
Introduction
The Wilmington oil field constitutes the largest oil-
producing feature of the Redondo Beach/Wilmington
trend, one of numerous such fault-oriented oilfield trends
in the Los Angeles basin of southern California (Fig. 1). I
Although production began as early as the late 1930's in
the western portion of the field, the majority ofthe eastern
portion, which now includes the Long Beach Unit (Fig.
1), was left undeveloped because it underlay both the
recreational offshore harbor area and the downtown area
of the City of Long Beach, CA. An earlier pronounced
surface-subsidence problem in the western portion of the
field was a major factor in the environmental concern. 2
In the early 1960's, legislative and other legal actions
cleared the way for unitization and development of the
eastern area under highly controlled conditions designed
to protect the surface environment. These conditions in-
cluded requirements for unitization of the entire area, re-
striction of major development to no more than four
environmentally enhanced manmade offshore islands, and
replacement of all reservoir fluid withdrawals and main-
tenance of original reservoir pressures through water in-
jection. Other features of these actions resulted in unique
administrative and operational responsibilities. In sum-
mary, the City of Long Beach, CA, functions as unit oper-
ator through its Dept. of Oil Properties and is the majority
unit participant through its trusteeship for the state-owned
tidelands tract. The California State Lands Commission
and its staff must approve the plan of operations and budg-
et, the bottomhole location of all new wells and redrills,
and certain other specific well details. The state also
receives the major portion of the net profit revenue from
the unit through its ownership of the tidelands tract and
as a result of the highly competitive net-profits-retention-
type bidding on the agreements with the several contrac-
tors. The THUMS Long Beach Co. became the field con-
tractor for the unit operator as a result of this bidding.
•Now a consultant.
Copyright t 987 Society of Petroleum Engineers
Journal of Petroleum Technology, October 1987
Initial Development
Initial development of the Long Beach Unit began in 1965
and continued into mid-1970. Some 590 wells were com-
pleted, roughly one-fourth of those being injectors. The
restriction to five drilling sites commonly required highly
deviated wells with kickoff depths as shallow as 100 to
200 ft [30 to 61 m] and maximum hole angles of 70 to
75° [1.22 to 1.31 rad]. Figs. 2 and 3 illustrate the resultant
individual well plan view that was used to develop the
area and a sectional view of typical well courses. Because
of the necessity for sand control in all but the deepest two
reservoirs, gravel-packed, slotted liners were the common
completion method. With the environmental and space
limitations on surface pumping equipment and the ultimate
expectation of large fluid-lifting requirements as a result
of waterflooding, electric submersible pumping was
selected as the major lift method.
Reservoir Characteristics
The maximum oil-productive intervals in the Long Beach
Unit comprise almost 6,000 ft [1,830 m] of interbedded
sands and shales between subsea depths of 2,250 and
8,200 ft [686 and 2500 m]. A fractured shale reservoir
overlying the basement schist also has been oil-productive
in limited areas. The original completion plan developed
the oil-productive section in six zones: Tar, Ranger, Up-
per Terminal, Terminal, Union Pacific-Ford, and 237
Basement. With the exception of the 237 Basement zone,
each of these completions included long sections of al-
ternating heterogeneous sands, with interbedded, compe-
tent shales serving in most cases as a barrier to vertical
permeability. In the major Ranger zone, completions typi-
cally included up to 1,100 ft [335 m] of interval, with
even longer intervals in some of the other zones. Typical
original full-zone completions in the Ranger and Terminal
zones are shown in Figs. 4 and 5.
Structurally, the Wilmington field is a long anticlinal
feature with extensive cross-faulting, creating some six
major reservoir blocks within the Long Beach Unit portion
of the field. The areal extent of the Ranger zone required
some type of in-zone injection plan, and a staggered line
drive on about lO-acre [4-ha] spacing was selected with
1229

2. IITNS"
r SAN lOSE RILLS(
" SANTA 1I0NICA )
C( ).....,.;....../-' LOS ANGELES
i"'- """ • ...,:
"~"~-'.._f" ),MONTEBELLO
./
-INGLEWOOD ""''''~''' (--......
~ .. (,) ~ '1
SANTA FE SPRINGS ,,"~ (~INO
" '-',.-~.s. ~ILLS
WEST COYOTE , - ~"':AS; C~OT.!J
r .....'~'-·"
r). SANTA ANA
'-, WTNS.
'-,
HUNTINGTON BEACH
'-,.,/",,,,,,--
EAST WILMINGTON o ,
OIL FIELD ..........MILES
Fig. 1-Location of Long Beach Unit in the Los Angeles
basin.
three producing rows between the injection rows. Other
zones were flooded by use of peripheral injection support.
Reservoir sand characteristics exhibit the heterogeneous
character typical of most California oil provinces with
poor grain sorting and a wide range of clay content.
Porosities typically range from 17 to 30%, with permea-
bilities ranging widely up to several darcies. Oil gravities
vary from as low as 11 to 30°API [1.07 to 0.88 g/cm3],
depending on the zone, and with variation within the major
Ranger zone dependent on structural depth. Mobility ra-
tios average 30 in the Ranger zone and range as high as
65 in the lower-gravity areas or zones. As previously men-
tioned, statutory requirements for voidage replacement
resulted in the initiation of water injection simultaneously
with initial oil production.
Waterflood Performance of
Original Development
As could be expected under the reservoir and completion
conditions outlined above, waterflood breakthrough oc-
curred early in the major linedrive waterflood areas. The
presence of higher-permeability sand layers in the upper
portion of most "zones" resulted in preferential produc-
tion and waterflooding of the upper sand members, with
little recovery from the lower subzones. This was height-
ened by reluctance to set the large submersible pumps into
the liners, resulting in high fluid heads over the lower
Fig. 2-Well courses necessary to develop Unit from island sites.
1230 Journal of Petroleum Technology, October 1987

3. -2000 t:
g
-3000 0
"4000 ji
-5000
--~-~~-~--~,--------,-J
1000 2000 3000 4000 5000 8000 7000 8000
DRIFT DISTANCE. FT.
Fig. 3-Typical directional well sections, Long Beach Unit
wells.
sands, as well as the common presence of fill in the lower
portion of the long liners. Whereas most original zone
completions were provided with several segregation points
by use of external liner packers, these did not generally
prove effective for practical waterflood control because
of the high deviation angles and other factors. Attempts
to change injection profiles or water entry materially by
other means were also largely unsuccessful in altering the
poor vertical waterflood conformance. This condition is
illustrated by a typical Ranger zone injection profile and
producing water entry survey (Fig. 6). The water-cut es-
calation in most pools and its obvious effect on ultimate
oil recovery became a major concern at this time (Fig. 7).
Field Redevelopment
The dramatic improvement in oil production economics
in the late 1970's provided increased interest in infill drill-
ing throughout the industry.3 In the Long Beach Unit,
certain minor pools or subzone flank areas had not been
fully developed originally because of low oil gravities and
the questionable nature of their floodability, and/or be-
cause of high drilling costs and mechanical completion
problems inherent in long directional drift distances from
the drilling islands. Development resumed in several of
these areas on a limited basis beginning in 1978. At this
time, unit entities had considerable interest in infill drill-
ing possibilities within the major in-zone areas under ac-
tive waterflood.
Subzoning Pilot Project
In late 1979, and at the initiative of the State Lands Com-
mission staff, a pilot area within the Ranger zone line-
drive waterflood area was selected for a test designed to
improve vertical waterflood conformance by "twinning" .
existing full-zone injectors with new subzone wells, com-
pleted only in the lower portion or subzone of the Ranger
zone. Three new lower subzone injectors were completed,
which demonstrated that this interval did have acceptable
injectivity when completed in this manner. After the es-
tablishment of appreciable Lower Ranger subzone injec-
tion rates, however, observation of production response,
through production monitoring and fluid entry surveys,
indicated little increase in production rates from the low-
er intervals in the full-zone offsetting producing wells.
Journal of Petroleum Technology, October 1987
ORIGINAL
FULL ZONE
COMPLETIONS
1I
I
I
I
I
I
I
L
TYPICAL SUBZONE
REDEVELOPMENT
COMPLETIONS
- Fo- 1UPPER RANGER
SUBZONE
COMPLETIONS
- F -
i~- ..- I
- H -
l~- .-
LOWER RANGER
SUBZONE
COMPLETIONS
- G -
-G4 -
-GS -
-G6 -
~I
I
~
-HX 1-
...... C>-
"HX" SAND I
SUBZONE I
COMPLETIONS :
Fig. 4-Ranger zone section showing typical original full-
zone completion and new subzone completion intervals.
This was attributed to a combination of permeability dif-
ferential between the Upper and Lower Ranger subzones,
high producing fluid heads over the Lower Ranger, liner
fill, and formation and/or gravel-pack plugging resulting
from a long no-flow condition. At this time, these full-
zone wells were producing large volumes of high water-
cut production from the Upper Ranger subzone. To mon-
itor the project adequately, several lower subzone produc-
ing wells were also completed, which yielded excellent
producibility at water cuts significantly lower than the ex-
isting full-zone completions. Completion of wells in the
lower subzone with casing and pump settings at the top
of this interval allowed for the relief of the fluid column
backpressure and a fresh completion. Ultimately, the
Lower Ranger subzone development in this pilot test area
1231

4. ORIGINAL TYPICAL SUBZONE
FULL ZONE REDEVELOPMENT
COMPLETIONS COMPLETIONS
: I
I
I
I
-K-
- l -
-w-
- .-
-A8-
-AC-
-AD-
-AE-
'Y'TO' AA'
SUBZONE
COMPLETIONS
I
1
'AA'TO'AC'
SUBZONE
COMPLETIONS
• AC'TO' AE'
SUBZONE
COMPLETIONS I
Fig. 5-Terminal zone section showing typical original full-
zone completion and new subzone completion intervals.
largely twinned the original full-zone development pattern.
The performance of the Lower Ranger subzone in this
area demonstrated several conclusions.
1. Well injectivity and reservoir transmissibility in the
Lower Ranger subzone were adequate to the center row
of the staggered line drive.
2. No significant production interference occurred with
the original full-zone wells, which were producing almost
exclusively from the upper subzone.
3. Low producing water/oil ratios (WOR's) in new,
lower-subzone completions, particularly in the center or
cleanup row, verified the poor vertical zonal conformance
with low waterflood throughput and high remaining oil
saturations in the lower subzone.
1232
SPINNER SURVEY FLUID ENTRY SURVEY
INJECTION RATE ,BID PRODUCTION RATE ,BID
o 2000 4000 6000
I
I
_..J
11225 BID
Iso BID
Iso BID
Fig. 6-Typical water injection and producing profiles in
original wells.
80
f-
:::J
0
DC
W
~
;:
f-
Z
W
0
DC
W
a.
YEARS
Fig. 7~Poor unit water-cut performance resulting from in-
efficient vertical conformance.
The positive effect of subzoning on water injection dis-
tribution, production rates, and waterflood efficiency in
the pilot area can be seen in Figs. 8 through 10.
Interim Subzone Program
In the period from late 1980 through 1982, subzone
redevelopment was expanded to the Upper Terminal and
Terminal zones and to other blocks and areas of the
Ranger zone. This program largely involved completing
one or several lower subzone wells in each distinct
drainage area to verify or to evaluate subzone oil satura-
tions, WOR's, production capacity, subzone reservoir
pressures, injectivity, etc. An additional value to this new
well drilling program was the knowledge gained by log
analysis on remaining oil saturation and flood perform-
ance in the upper subzones after 15 years of waterflood-
ing. As an example, water injection "underride" was
found to be common in the massive Upper Ranger Fo
sands. Injection profile surveys had failed to indicate this.
Journal of Petroleum Technology, October 1987

5. '~'OOOI
I
lO,OOO~
I
I
H'OI)I)~
I
""oj
i
TOTAL
~,OOOOWER RANGER SUBZONE
~ -1
n ~ ~ W ~ ~ " ~ ~ "
YEARS
Fig. 8-lmproved waterflood distribution in Lower Ranger
zone pilot area.
In the eastern portion of the field, the HX1 to J Upper
Terminal subzone had been included in full-zone com-
pletions below the Upper and Lower Ranger, resulting
in some 1,100 ft [335 m] of completion interval. The ini-
tial well completed in 1981 in only the HX to J subzone
had an initial production rate of 328 BID [52 m3Id] oil
with less than 50% water cut. WeIfs originally completed
in the full Ranger zone interval in this area were producing
an average rate of 175 BID [28 m3Id] oir' with 75 % water
cut at that time. The typical "Terminal zone east" com-
pletion had included some 1,200 ft [366 m] of total inter-
val, and throughput analysis indicated virtually no
recovery of the major oil reserves in the lowermost AC
to AE subzones. The original full-zone Terminal zone
wells, including these subzones, were typically producing
some 110 BID [17 m3
Id] oil at water cuts in the range
of 81.0%. Initial lowermost AC to AE subzone comple-
tions, however, had typical initial oil rates of 340 BID
[54 m3Id] with water cuts in the range of 3.0%.
YEARS
Fig. 9-lncremental oil rate from subzoning in Lower
Ranger zone pilot area, Ranger zone Block 6.
40 ~-----~--~---~-----"
30
'"::1
~0
ti 0
'!l i!'
'"
i ~ z
0 20 :"""~
~?:
10
o ------r- -.----------r-" +-~ .,-- -.- t .- ~
o 0.5 1
PORE VOLUMe
,
1.5
1
Fig. 10-lmprovement in WOR vs. waterflood throughput
relationship in pilot area, Ranger zone Block 6.
TABLE 1-WATERFLOOD THROUGHPUT ANALYSIS
Ranger 6 Voidage Blocks Ranger 7 Voidage Blocks
Subzones 2 3 4 5 6 2 through 6 7 8 9 10 11 12 13 14~- ~-
Number of PV's Throughput
Fo 1.07 1.12 1.17 1.13 1.19 1.19 0.37 1.22 0.93 0.67 1.34 1.14 0.93 0.63
F and H 0.42 0.93 1.11 0.86 0.32 0.69 0.23 0.60 0.82 0.72 0.95 0.71 0.55 0.14
X 0.25 0.58 0.71 0.57 0.27 0.46 0.60 0.50 0.52 0.87 0.86 0.69 0.32 1.05
G to G6 0.13 0.27 0.34 0.30 1.03 0.29 2.70 0.19 0.33 0.24 0.32 0.39 0.31 0.32
Total 0.45 0.71 0.83 0.78 0.65 0.71 0.31 0.72 0.80 0.62 0.99 0.83 0.64 0.43
Calculated Instantaneous Water Cuts by Subzones, %
Fo 97.4 96.5 95.4 95.3 97.2 96.5 86.9 95.1 89.1 91.0 94.4 96.1 93.9 98.2
F and H 90.0 95.4 95.0 93.1 81.6 92.4 68.9 87.1 87.0 91.8 91.2 92.4 87.6 41.5
X 75.6 91.1 90.7 88.0 75.3 86.9 93.6 83.7 77.5 93.7 89.8 92.1 73.6 99.2
G to G6 16.0 72.1 74.9 70.8 96.6 73.8 99.1 33.3 61.2 59.8 64.4 82.8 72.3 94.4
Total 88.4 92.1 91.1 91.1 92.4 91.2 78.7 90.3 87.4 92.4 91.3 93.8 90.0 89.2
Calculated "Conformance" of Current Composite Throughput
Total 0.57 0.72 0.90 0.88 0.64 0.76 0.68 0.97 1.33 0.83 1.18 0.79 0.87 0.32
Number of Years to 2 PV's at March 1981 Rates
Fo 15 11 10 14 9 11 37 9 23 24 7 9 18 27
F and H 30 12 11 13 55 19 63 18 14 19 10 24 20 43
X 59 26 17 27 121 31 57 59 187 19 19 33 135 127
G to G6 210 61 45 69 15 58 419 952 44 417 39 310 52
Journal of Petroleum Technology, October 1987 1233

6. a::
Fig. 11-Example of 2-PV waterflood sweep map.
20 -------~---_o_-­
15 - '"z
=====...~ ..............i........
","z,;;
~~
""Z'"
.....j ...........
Z:"O~' .......................•...•..
~g
~ 10
~~ : :
i rl ...
o 'f--.-~~~if-------c-~~~-~----.-+-~~
o u u u ~
PORE VOLUME
Fig. 12-Typical improvement in individual pool waterflood
efficiency from subzone redevelopment, Ranger 90 south.
Reservoir Modeling
In 1981, a small area in the Ranger zone was selected
for three-dimensional black-oil simulation to determine
whether this would be useful as a guide for locating areas
and subzones of remaining high oil saturation. The simu-
lation did not prove to be useful, largely because of the
layering complexity, lack of layer information, lack of
true boundaries with the staggered linedrive configura-
tion, and other faCtors. A similar simulation, previously
performcd as part of a caustic flood project, also was not
helpful as a guide to subzone conditions.
A simplified modeling technique was developed by the
staff of the State Lands Commission and expanded upon
1234
20
15
'"o 10
3:
o
0.0
~ik:L1 i
0.1 0.2 0.3 0.4 O.S
PORE VOLUME
I
0.6
i
0.7
. __...i
I
I0.8
Fig. 13-lmprovement in total unit waterflood efficiency
from subzone redevelopment.
by the the City of Long Beach staff on the basis of water-
flood throughput concepts. This involved allocating total
well fluid production within aselected grid to the individu-
al sand layers on the basis of historical water-injection
profiles. The relationship between the resultant fluid
throughput and instantaneous fractional flow character-
istics for any layer were then based on curves developed
for that layer from laboratory coreflood tests and histori-
cal waterflood performance in the western portion of the
Wilmington field. An analysis of individual reservoir sub-
blocks by use of this model (Table 1) proved reasonably
accurate and useful as a guide in predicting individual sand
and subzone saturation conditions. The Long Beach city
staff has expanded this concept for operational subzone
waterflood monitoring. Examples of this are subzone
waterflood sweep mapping (Fig. 11) and computer graph-
ics showing historical WOR vs. PV throughput history
for reservoir areas or layers (Figs. 10, 12, and 13).
5·Year Development Plan
On the basis of information and results derived from the
interim redevelopment period, in late 1982 the staff of
the City of Long Beach developed a formal plan for sub-
zone redevelopment in all zones. This resulted in 10
separate subzone development programs with subzone
well density and injection well requirements generally
based on the subzone reservoir fluid throughput modeling
concept discussed. Because the transmissibility and oil
saturations in some portions of the large staggered-line-
drive Ranger zone areas were still uncertain, lower sub-
zone locations were generally planned only in the center
or "cleanup" producing rows, until the need for such
redevelopment in the rows offsetting injection could be
evaluated. Typical subzone divisions of the Ranger and
Terminal zones are shown in Figs. 4 and 5.
This plan had several basic objectives: (1) to increase
reservoir fluid throughput in lower subzone layers (within
the previously developed in-zone waterflooded areas) that
had low cumulative and low current waterflood throughput
rates and resultant higher remaining oil saturations; (2) to
develop subzones on the flanks or in other areas that were
not fully developed originally and to place them under
active waterflood; and (3) to use subzone completions to
Journal of Petroleum Technology, October 1987

7. YEARS
Fig. 14-Estimated Incremental oil rate from subzone
redevelopment program.
provide for future subzone waterflood performance mon-
itoring and improved waterflood management.
With the establishment of a formal plan, it was possible
to establish certain guidelines for mechanical decisions
that proved to be very effective.
1. New well completions were to be committed gener-
ally to completions in the lower subzones. This would pro-
vide for large-diameter casing and pump settings at the
top of the subzone to minimize the producing fluid head.
The commitment of development investment dollars to
lower subzones, with oil reserves currently not fully in-
volved in waterflood conformance, maximized the pos-
sibilities for investment payout by developing "new" oil
production.
2. Production from the more mature floods in the up-
per subzones would be maintained by workovers or short
casing shoe redrills of the full-zone wells completed in
the original development. When sand control became a
major problem, the lower subzones in these wells could
be plugged and sand control re-established with short inner
liners over the upper subzones. Redrills that became nec-
essary would need to penetrate only the upper subzone,
resulting in a significant cost saving.
3. Log analysis through the upper subzones, penetrated
in the new lower subzone wells, would provide informa-
tion for tests of selective completion methods attempting
to complete only the intervals of high oil saturation inter-
spersed within the highly flooded upper subzones.
5·Year Plan Results
In the period between Jan. 1983 and June 1986, more than
300 wells were drilled or redrilled from this plan. During
the interim subzone development period, the previous
precipitous decline in oil production rate was arrested and
the oil rate was held relatively constant. The 5-year-plan
programs were even more effective and resulted in a 17 %
increase in oil rate by the end of 1984 (Fig. 14). Conven-
tional economic analysis resulted in individual well pay-
outs ranging from 4 to 8 months. Oil production from each
of the fiscal year's new subzone well development pro-
grams in the 5-year plan has been at significantly lower
WaR's than current unit averages (Fig. 15). The effect
of this on the unit's water cut has been positive in arresting
Journal of Petroleum Technology, October 1987
f-
::J
U
100 -
80
'" 60w
'<i:
3
f-
Z
t3 40
'"~
20
UNIT AVE.
---:e-o- --------&-----
'3 YEARS
-••
Fig. 15-Comparison of average water cuts from each fis-
cal year redevelopment program with total unit cut.
YEARS
Fig. 16-Effect of subzone redevelopment on unit water-
cut trend.
the prior increasing trend and virtually stabilized it for
several years (Fig. 16). The improved waterflood effi-
ciency is demonstrated by the changes in WaR vs. water-
flood throughput trends, examples of which are typified
by the performance of the Ranger 90 south pool (Fig. 12).
The total Long Beach unit response to the redevelopment
program is illustrated in Figs. 13 and 14. Cumulative oil
recovery from the unit is currently more than 650 million
bbl [103 x 106 m3].
During the subzone development program, and partic-
ularly during the 5-year-plan period, numerous secondary
benefits or well completion improvements resulted from
the ability to observe individual subzone well per-
formance.
1. Shorter well completion intervals and a planned de-
velopment program significantly reduced drilling and
completion costs and improved operational development
efficiency.
2. Drainage patterns could be implemented on the basis
of an individual subzone requirement rather than an aver-
age for all layers, which was necessary in the original full-
zone wells with long, deviated completions from widely
separated drilling sites.
1235

8. 3. The early mechanical failure of completions in the
Lower Ranger subzone made it evident that original full-
zone wells had been completed with gravel pack and liner
slot sizes too large for this subzone.
4. Completion damage problems, which became obvi-
ous in certain subzones, occasioned the development of
an inhibited polymer drilling and completion fluid, which
resulted in materially improved completions in those
subzones.
Subsequent Planning
By mid-1986, some 3V2 years had passed since the for-
mal 5-year-plan redevelopment was initiated. During that
period, more than 300 wells were completed, which in-
cluded a significant portion of the important redevelop-
ment originally contemplated in each subzone program.
Subsequent planning involved slowing the current lev-
el of drilling activity, starting in mid-1986, and placing
increased priority on monitoring and analysis of the sub-
zone performance data now available. This information
would be used to re-evaluate future subzone well require-
ments and to formulate future unit planning. As a first
step in this process, an extensive pattern of new subzone
reservoir pressure monitor wells was selected to improve
the future knowledge of layer pressure in each zone.
Conclusions
1. Redevelopment of the major zones in the Long Beach
Unit, using shorter subzone completions in intervals of
higher remaining oil saturation, has been successful in
materially improving vertical waterflood conformance, oil
production rate, and resultant oil revenues.
2. Areas not originally fully developed have been suc-
cessfully developed on a subzone basis and initiation of
waterfloods in these areas has been successful.
3. The program was successful because it recognized
the major recovery problem-poor vertical waterflood
conformance-and concentrated its efforts on sweeping
the unswept subzones. *
·Sarem. A.M.: "Does Infill Drilling Increase Ultimate Recovery." Distinguished Lec-
turer speech presented at forum meeting. Long Beach, CA (March 1984).
1236
4. Redevelopment of each subzone layer will provide
a basis for improving future waterflood efficiency and
reservoir management and for maximizing ultimate eco-
nomical oil recovery.
Acknowledgments
We thank the management of the Dept. of Oil Properties,
City of Long Beach for permission to publish this paper.
We also recognize the contributions of the staffs of the
Extractive Development Program, State Lands Commis-
sion, State of California, and the THUMS Long Beach
Co. in carrying oui the 5-year development plan.
Special acknowledgment is given to the efforts ofW.M.
Thompson, manager, State Lands Commission staff, in
initially implementing the subzone concept in the Long
Beach Unit and for his contributions and support in the
subsequent programs.
References
I. Mayuga, M.N.: "Geology of California's Giant Wilmington Oil
Field," paper presented at the 1968 AAPG Annual Meeting, April
22.
2. Huey, W.F.: "Subsidence and Repressuring in Wilmington Oil
Field," Summnry ofOperations, California State Div. of Oil & Gas
(1965).
3. Barber, A.H. Jr. et al.: "Infill Drilling To Increase Reserves-
Actual Experience in Nine Fields in Texas, Oklahoma, and Illinois,"
JPT (Aug. 1983) 1530-38.
General Reference
Ruble, D.B.: "Case Study of a Multiple Sand Waterflood, Hewitt Unit,
OK," JPT (March 1982) 621-27.
SI Metric Conversion Factors
bbl x 1.589873 E-Ol
ft x 3.048* E-Ol
mile x 1.609 344* E+OO
*Conversion factor is exact. JPT
Original manuscript received in the Society of Petroleum Engineers office April 2, 1986.
Paper accepted for publication April 7, 1987. Revised manuscript received June 4,
1987. Paper (SPE 15101) first presented at the 1986 SPE California Regional Meeting
held in Oakland, April 2-4.
Journal of Petroleum Technology, October 1987