THE MULTIPLE COMPLETION CHOKE ASSEMBLY - A NEW PROFIT MAKING TOOL by J. W. Hodges Sun Oil Company Beaumont, Texas __0— For presentation at the 15th Annual Technical Meeting PETROLEUM & NATURAL GAS DIVISION, C. I. M. May 6-8, 1964 Calgary, Alberta
THE MULTIPLE COMPLETION CHOKE ASSEMBLY - A NEW PROFIT MAKING TOOL
by
J. W. Hodges Sun Oil Company Beaumont, Texas
__0—
For presentation at the 15th Annual Technical Meeting
PETROLEUM & NATURAL GAS DIVISION, C. I . M.
May 6-8, 1964 Calgary, Alberta
The Multiple Completion Choke Assembly -
A New Profit-Making Tool
Abstract
This paper describes the construction, method of operation,
and f i e l d performance of the Sun Oil Company-developed Multiple
Completion Choke Assembly.
This down-hole commingling tool has been i n operation since
March, I960. I t has been used i n approximately 75 wells located i n
Louisiana, Texas, Mississippi, Oklahoma, Mexico, Kuwait, and India.
Sun O i l Company's Gulf Coast Division, through the use of
this tool during the past four years, has saved approximately
$289,000 i n tubular goods, and produced approximately $282,750 worth
of hydrocarbons not otherwise recoverable.
The paper reports the results of Sun O i l Company's i n s t a l l a
tions and discusses the various applications and li m i t a t i o n s of the
t o o l .
The method of allocating production to each zone is
explained„
Advantages and disadvantages i n simultaneous production of
two separate reservoirs through a single tubing s t r i n g are enumerated.
Construction and Operation
Fig. 1 shows a well equipped to receive a multiple completion
choke assembly. A retainer type packer separates the two producing
zones. The upper packer is optional. A side-door choke landing
nipple hookup is located i n the tubing s t r i n g above the lower packer.
The multiple completion choke assembly w i l l be locked i n t h i s landing
- 1 -
nipple. Normally located a j o i n t or two above the upper zone, the
position of the landing nipple hookup can be varied to sui t well
conditions. For example, where the two zones are widely separated,
i t might be placed just above the lower packer to f a c i l i t a t e bottom
hole pressure tests of the lower zone.
The tool consists of two separate assemblies, as shown in
Fig. 2. The outer assembly, which is run on a wire l i n e and locked
in the landing nipple, contains the check valves and packing seals
which prevent flow from one zone to the other.
The orifice-head assembly, which carries the tungsten-carbide
choke beans, is run separately and is seated and locked i n the outer
assembly. The method of running each section is i l l u s t r a t e d i n Fig. 3.
Fig. 4 is a schematic drawing which shows how the device
works. Production from the lower zone enters the assembly through
a slotted section, flows through a sleeve-type check valve, enters
and flows through the tube of the orifice-head assembly, is choked
and - now regulated - flows into the tubing. Produced f l u i d s from
the upper zone enter the casing opposite a blast j o i n t on the tubing,
flow through the ported collar of the side-door choke landing-nipple
hookup, through the upper slotted section, through the upper check
valve, into the annulus surrounding the tube, and through the upper-
zone choke bean into the tubing. Here the two controlled flow
streams, which have been segregated to t h i s point, combine and flow
to the surface.
Allocation of Production
Detailed instructions for testing and allocation of pro
duction are available i n the manufacturer's "Service Manual fo r
-2-
Otis Type 'S' Multiple Completion Choke Assembly—Dual Flow"; i n
general, however, allocation i s based on the results of a stabilized
test of one of the zones while the other zone is blanked o f f . The
established rate from t h i s zone is then subtracted from the commingled
rate to calculate production from the second zone.
Test procedure w i l l depend on whether or not one of the
zones i s i n c r i t i c a l flow. A stream is i n c r i t i c a l flow when
alterations i n pressure downstream from an o r i f i c e do not affect the
rate of flow. The c r i t i c a l point i n a gas stream flowing through
an o r i f i c e occurs when the pressure downstream from the o r i f i c e i s
53$ of the upstream pressure; for gas-liquid mixtures, the c r i t i c a l
r a t i o is higher but should not exceed approximately 0.58.
I f one of the zones is i n c r i t i c a l flow, alterations i n
the tubing i n l e t pressure (the pressure immediately downstream from
the multiple completion tool) w i l l not change the predetermined
rate from that zone, and the allocation process i s si m p l i f i e d .
I f neither zone is i n c r i t i c a l flow, the zone with the
higher pressure is tested i n d i v i d u a l l y at several rates i n a range
of tubing i n l e t pressures expected to occur during commingled flow.
By p l o t t i n g the rate versus tubing i n l e t pressure, a graph i s
obtained from which the production from the zone can be determined
during commingled flow. Fig. 5 shows the results of such a test
i n the Kinder Field, Louisiana. This graph can be used to determine
the rate from the lower zone during commingled flow. I f the zone
is out of c r i t i c a l flow, i t s rate is a function of the tubing i n l e t
pressure.
The method of allocating production with the multiple
completion tool is basically the same as that used i n conventional
-3-
practice; i.e., determining the rate from each zone by testing,
commingling the production downstream from the choke beans, and
allocating the interim production between test periods on the
basis of the individual tests. In either case, accurate allocation
depends upon the consistency with which each zone continues to
produce at i t s tested rate, and t h i s i s i n large measure dependent
upon accurate flow rate control. The tungsten carbide choke beans
in the multiple completion choke assembly, being highly resistant
to erosion and located below the zone of p a r a f f i n deposition
(precluding plugged chokes) w i l l provide better flow rate control
than w i l l conventional surface chokes. In Sun's wells, the o r i f i c e
head has been pulled approximately 450 times, and i n each instance
the chokes have remained true to gauge.
Applications
The multiple completion choke assembly is not a specialty
t o o l . I t is applicable i n almost any type of multiple completion.
Sun Oil Company has made nineteen i n s t a l l a t i o n s i n wells ranging
i n depth from 3790' to 15,576' and i n bottom hole pressure from
814 psi to 8173 p s i .
I t is applicable i n multiple o i l , multiple gas, and
combination oil-gas wells.
I t can be run on i n i t i a l completion, or i n the conversion
of a concentric or twin s t r i n g dual completion. In the l a t t e r case,
when either zone becomes defi c i e n t , the tool can be i n s t a l l e d with
wire-line tools, preferably i n a Type nS M side-door choke landing
nipple; a hook-wall tool i s available, however, i f a side-door
nipple has not been run.
-4-
A l i s t of i t s applications follows.
1. In wells where one or "both zones require a r t i f i c i a l
l i f t , one set of gas l i f t valves can be used to produce the two
zones through the tool at reduced cost and greater efficiency than
is possible i n other types of dual completions.
2. As a means of using gas-cap gas to l i f t liquids from
the lower part of the same sand.
3. Two multiple completion tools can be used with dual
strings of tubing to produce either three, four, or f i v e zones
simultaneously.
4. The tool Is compatible with slim hole multiple com
pletions .
5. Applicable to tubingless completions and permanent
type completions.
6. Can be used to produce selective completions dually.
7. Can be modified and used to i n j e c t salt water or
gas into separate reservoirs with reasonably accurate allocation
to each reservoir.
There are two limi t a t i o n s to the use of the t o o l : l )
where there is excessive sand production and 2) where there is
i n s u f f i c i e n t reservoir energy for required production and external
gas is not available for gas l i f t .
Table No. 1 describes the wells i n which Sun has used
the multiple completion choke assembly.
Advantages
The advantages i n using the multiple completion choke
assembly are as follows:
-5-
lo Reduction in well equipment costs. In Sun Oi l
Company's Belle Is l e Unit #1-56, Belle Is l e Field, Louisiana,
approximately $42,000 was saved on equipment alone as compared
to a twin st r i n g dual.
2. Increased ultimate recovery. The economy of the
method has resulted i n production from reservoirs which would not
have been tested otherwise. For example, i n Sun's Belle I s l e Unit
#3-5, over $97,000 worth of hydrocarbons were produced i n the f i r s t
year of operation from a questionable zone that would have been
writ t e n o f f i f t h i s tool had not been available.
3. Increased daily production. The income from Sun's
Vicksburg Unit #3, Kinder Field, Louisiana (the lower zone i n a
dual completion), has increased from $2770 per month to $8500/month
since i n s t a l l a t i o n of the tool i n March, I960. The gas-oil r a t i o
has decreased from 54,000 c.f. per bbl to 19,600 c.f. per bbl. See
Fig. 6.
4. Reduction i n workover costs (compared to multiple-
s t r i n g completions.)
5. Reduction i n surface equipment costs. This includes
heaters, separators, compressors, high pressure g a s - l i f t l i n e s ,
meters, etc.
6. Maximum use of reservoir gas. By bottom hole choking
and commingling production immediately above the tool, gas breaking
out of solution at this point results in the lowest possible
gradient in tbe tubing. When a strong well i s combined with a
weak well in this way, the weak well can be produced at i t s
maximum potential. This not only prevents waste; i t Is also quite
economical to the operator, as i t postpones or eliminates the need
-6-
to provide a r t i f i c i a l l i f t f or the weaker zone. Conventional
completions, by maintaining separation of production to the surface,
i n t h i s respect act contrary to the principles of conservation.
The multiple completion choke assembly i s i n effect a
single-point i n j e c t i o n , retrievable flow valve, u t i l i z i n g gas
supplied d i r e c t l y from the formation at maximum efficiency. To
i l l u s t r a t e the degree of efficiency, i n Sun Oil Company's Dishman-
Lucas #1, Sour Lake Field, Texas, a comparison was made between
this method and a conventional gas l i f t system. This study showed
that the multiple completion tool used one-sixteenth as much gas
and produced twice as much l i q u i d .
7. Reduction i n corrosion i n h i b i t o r and p a r a f f i n t r e a t
ment costs.
Disadvantages
1. Cost of testing. The periodic testing required
results i n wire-line costs otherwise not incurred; however, there
are two important considerations that should not be overlooked:
(a) the future value of the money saved by virtue of using the
t o o l . In Belle I s l e Unit #1-56, the $42,000 saved i n i n i t i a l cost
is worth $44,520 at 6$ compound interest after one year, $56,205
afte r f i v e years, and $75,215 at the end of ten years. Obviously,
th i s gain in value w i l l absorb wire-line costs (which have run
from $50 per month to $150 per month i n Sun's nineteen wells);
(b) the use of the tool w i l l result i n an increase i n production i n
most wells. The income from just one additional barrel of o i l per
day w i l l i n most instances pay the wire-line costs.
2. Somewhat more complicated (technical) method of
-7-
production accounting. The engineer i n charge must practice more
of his production technology than is normally required i n routine
production accounting. This may or may not be a disadvantage, and
the bulk of the work can s t i l l be handled by the production clerk.
Attitude of the Conservation Agencies
Co-operation of the various State agencies has come about
through recognition that l ) commingling down hole with the choke
assembly is no d i f f e r e n t from commingling at the surface; 2) the
tool i s mechanically sound; 3) the tool w i l l prevent waste and
increase ultimate recovery; and 4) most of the people i n the o i l
industry are honest. Those that aren't w i l l f i n d a cheaper way
to produce multiple completions dishonestly.
Conclusions
Simultaneous production of two reservoirs through a single
s t r i n g of tubing w i l l i n many wells result i n a si g n i f i c a n t reduc
t i o n i n completion and l i f t i n g costs and increase i n current income
and ultimate recovery. The Multiple Completion Choke Assembly w i l l
maintain separation of reservoirs and control the rate of production
from each. Test procedures have been developed which provide an
acceptable method of determining the production from each zone. A l l
requirements imposed by the State regulatory agencies can be
s a t i s f i e d .
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CASING
TUBING
UPPER PACKER (OPTIONAL)
FLOW COUPLING
LANDING NIPPLE
PORTED COLLAR
- POLISH NIPPLE
UPPER ZONE
X x--BLAST JOINT
PACKER
PERFORATED NIPPLE (OPTIONAL)
LOWER ZONE
, t , k « < , d a « .
Fig. 1—Well Properly Equipped for Multiple Completion Choke Assembly
11 ll
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Fig. 2—Multiple Completion Assembly for 2-3/8-in. Tubing. Check valves and choke beans are shown opposite position occupied within t o o l .
UPPER-ZONE CHOKE BEAN
UPPER-ZONE FLOW PATH -
LOWER-ZONE FLOW PATH
FLUIDS COMBINED HERE LOWER-ZONE CHOKE BEAN
ORIFICE-HEAO ASSEMBLY
OUTER ASSEMBLY
UPPER CHECH VALVE PORTED COLLAR
UPPER PERFORATIONS
LOWER CHECK VALVE
EQUALIZING DISC
PRODUCTION PACKER
LOWER PERFORATIONS
Fig. ^--Schematic Drawing Showing Operation of Multiple Completion Choke Assembly
GAS PRODUCTION mcf/day (Ji tk (J\
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R A Y C. JONES Chai rman
H A R O L D F R E E M A N V i c e - c h a i r m a n
W I L B U R N C A R T W R I G H T Member
C A R L B. M I T C H E L L Secretary
OKLAHOMA
Corporation Commission
DAN R. D U N N E T T D i rec to r Of Conse rva t i on
F E R R I L L H. ROGERS Conse rva t i on A t t o rney
O K L A H O M A CITY O K L A H O M A
D. L . JONES A s s i s t a n t D i rec to r
S T A N L E Y ROGERS A s s i s t a n t D i rec to r
W. J . M A R S H A L L A s s i s t a n t D i rec to r
W. H. S O L L E R S Trial Examiner
R A L P H L . W A M P L E R A s s t . Conse rva t i on A t t y .
N E L L RHODES F ISHER A s s t . Conse rva t i on A t t y .
O I L A N O GAS C O N S E R V A T I O N
DEPARTMENT
4, 1963
Mr. Russell Thompson Attorney at Law 1719 First National Building Oklahoma City 2, Oklahoma
Miehaal B. Sllva, Attorney Phillip* Patrol am Company Oklahoma Mortgaga Building Oklahoma City 2, Oklahc
Mr. Joa A. Owens Sun Oil Coopany P. 0. Box 2831 Beaumont, Texas
Mr. William a. Dow Citlas Service Oil company Box 4577 Oklahoma City 2, Oklahoma
Mr. Jamas R. Marty Amarada Petroleum Corp ora tl< Liberty Bank Building Oklahoma City 2. Oklahoma
Hr. Karl Tunscell Otis Engineering Corp. 301 S. S. 29 Oklahoma City. Oklahoma
Mr. A. J. McCraady Socony Mobil Oil Company 120 Northwest 2 Oklahoma City 2, Oklahoma
Centl Rat Cauaa CD No. 19034
Enclosed find copy of Report of Trial Examiner in tha above canoe, which will ba filed on tha 9th day of Decenber, 1363, and you have until Decembar 12v 1963, ia which to file exceptions thereto* i f you so desire.
Yours vary truly.
CORPORATION COMMISSION OF QKLAHOKA
Raloh L. Wamnler I Ralph I*. Wampler Trial Bxamiaer
RLW/b 1.