10033 Perforating Techniques For Maximizig Productivity

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Perforating Techniques for Maximiz ng Well Productivity

by W,T, Bell, * Schlumberger

Well Services

●MemberSPE.AIME Copyright 1982,Society of Pelrolm!rn Engineers This paper was presented al the International Petroleum Exhibition and Technical Symposium of the Society of Petroleum Engineers held in Bejing. China, 1826 March, 1982.The material is subject 10correction by the author. Permission 10copY is restricted to an abstract of not more than 300 words, Write SPE,6200 North Central Expressway, Dallas, Tex: .75206 USA.Telex 730989 —

ABSTRACT

wellbore fluid type, pressure, formation characteristics, and damage conditions.

any well objective of A major to attain maximum completion is production. The perforating equipment and techniques that are used have a very determining the important bearing on production that results.

is to In general, the ot~ective perforate in a way that produces minimum to at the flow resistance interface. reservoir/perforated-system This can be done by:

the nature of According to the reservoir, wells may be completed either nt:turally, with sand-control measures, or with formation stimulation by acidization The welland/or hydraulic fracturing. bore-to-formation pressure relationship at be perforating may the time of overbalanced, balanced, or underbalanced. be retrievable, Perforating guns may semi-expendable, or expendable; designed for operation through tubing or in open casing; run on wireline or on tubing.

- estab~ishing well conditions enhance cleanup of perforations, and

that the

- choosing perforators and techniques for best flow performance. The intent of this paper is to describe the nature of the choices to be made, to discuss some of the factors that these choices, and where bear on justified, to make recommendations and draw conclusions as to the appropriate action.

various the This paper describes combinations of guns and techniques that are in commorr use, with the ~dvantages and The four basic disadvantages of each. shot performance parameters, i.e., density, perforation diameter, penetration depth, and gun phasing, are ranked in order of relative importance for natural, sand-control, and stimulated completions. makes Where justified, the author recommendations and draws conclusions.

NATURAL COMPLETIONS natural completion involves The formations that do not require artificial worthwhile to permit alteration hydrocarbon production. This definition excludes completions requiring thus fracturing or massive stimulation by acitlization, as well as those requiring sand-consol idation gravel-packing or Not excluded, however, are treatment. with “mud wells that are lightly treated acid” to cope with wellbore damage.

INTRODUCTION Perforating techniques to get best well productivity depend on the type of well completion; i.e., natural flow, sand control, or hydraulically fractured.

Ideally, the well is perforated placed directly on production.

Even within a particular completion method, choices of technique and equipment are constrained by the well configuration,

and

Factors Influencing Perforated-System Flow 5!!+W2!iJrec?icts that productivity of the perforated system is governed by those

Referencesand illustrations at end of paper 143

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PERFORATING TECHNIQUES FOR MAXIMIZING WELL PRODUCTIVITY

✟

which introduce “skin”, or factors resistance to flow I . These skin factors can be considered in three categories . (Ficj. la): meaning flow - Convergent (s1)? caused by the directi~n losses changes of reservoir fluid as it enters the perforations.

?.08 k. hf (Ap) Q~ = ------ ------- ----ST + p (ln re/rw ) where:

Q~ = flow rate corrected for skin factors, and ST = s,

“ Wellbore damage (sz), the region of reduced permeability (ks) around the wellbore, caused by invasion of incompatible fluid. - Crushed zone (S3), a region of permeability surrounding reduced the perforation. This zone results from the compressive action of the Lab results jet. perforating indicate that the ~rushed zone is about half an inch (13 mm) in thickness, with permeability (kc) reduced to about 0.1 to 0.2 times that of the undisturbed rocks.

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+ s, . + S3

ST is reduced to a practical mini~~m value, productivity ratio (Q~/Qr) value of unity. approaches its maxin,um Importance Relative Parameters

—of

Geometrical

the minimizing In terms of ST, importance of the controllable geometrical f,lctorscan be ranked as follows 3: 1) Shot density. Figure 2 2) Penetration depth.

Effects of these factors are dependent system. on the geometry of the perforated Fig. lb illustrates the variables: - Depth of penetration? ap. - Shot density, h (shots per ft). - Gun phasing, @ (angular displacement of successive shots).

zero-degree phasing 3) Gun phasing; results in 10 to 15 percent loss in productivity ratio compared with 90, 120, and 180-degree phasing. 4) Perforated hole diameter tively insignificant).

(rela-

Positive- — %s Reverse-Pressure Perforating

- Diameter of perforation, dp.

ht = total interval

(overbalanced) Positive-pressure perforating in the natural completion can and/or damaged plugged result in Shooting in drilling mud, perforations 4. for example, usually results in plugging. reversed by when Then pressure is swabbing, onl;na few perforations become system. Swabbing functional the reverses pressure in small, incremental steps, encouraging the perforations in better portions of the zone to break down and begin producing. This in turn reduces across the the differential pressure remaining ones, leaving them unproductive. shot density Thus, a low effective seriously which reduces results, even though the productivity ratio, penetration depth may be large.

All= pressure differential from formation to wellbore

Subsequent acidizing in such instances seldom fully corrects the problem.

To see how these factors interact with flow, consider first the open wellbore, where flow rate is predicted in one manner by: 7.08 k. ht (Ap) Q, = --------------p(ln re/rw ) where:

}

Qr = flow rate k. = permeability to oil

P

= fluid viscosity

re = radius of the drainage area rw = radius of the wellbore

Incorporating the effects of factors, flow rate now becomes 2:

skin

clean, compatible Perforating in fluids is less damaging, although lab and field results indicate that perforations positive pressure are often made under difficult to clean up by swabbing, even when compatible completion fluid is used. can, however, be Such perforations violent by cleaned effectively backsurging, as is descri~~d in a later section.

W.

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Whatever the fluid in the wellbore, perforation cleanup is greatly enhanced by perforating under conditions of reverse For best effectiveness, such pressure. “underbalancerl” pressure conditions should be adjusted to just above a certain system assures that threshold value [Fig. 3). Operating at too low cleanup flow in reduced resu~t can a AP operc~ting at AD’s above the efficiency; threshold level usually will not improve cleanup and subsequer,t production rate.

recovered. In cases where more gun runs needed, the procedure is the same except that successive guns are positioned and the well drawn down to re-establish differential before ham; pressure (Balanced-pressure perforating used, not as desirable as but is course, reverse-pressure shooting.) Of provisions must be made to handle any p;oduced fluid at the s>rface. are

In the case of long zones, it is preferable to perforate low-permeability intervals first, followed by the other Eigber intervals of permeability. Otherwise, the back gressure caused by flow from the higher-permeability sections might prevent clea;l~p of the lowerpermeability perforations. Lower-permeability zones often require higher differential pressure to effect cleanup.

Ap The threshold level of reverse fo~~tion type am varies Wm requ=cl characteristics, Particularly PorositY and ~ound mustbe permeabili”]. Values higherTypically, “ empirically. permeability zones, 200 to ~~rlpsi (1.38 to 3.45 MPa) is a good range for liquid producers, and 1000 to 2000 psi (6.9 to In producers. MPa) for gas 13.8 low-permeability zones, the values roughly double; some gas wells in stubborn sands such as the Morrow of New Mexico have been completed successfully with differential pressures as high as 5000 psi (34.5 MPa).

Alternatively, flowing of the well is often omitted, particularly in the case of hi~her-permeabil ity liquid producers. The tuGing is simply allowed to fill, the gun withdrawn, and then the well produced for final cleanup. results are Typical productivity aenerallv. observed t.obe satisfactory, and ;uperior to those obtained - ‘with positive-pressure perforating. The margin of improvement increases with decreasing permeability, and in gas wells.

NETHODS —OF REVERSE-PRESSURE PERFORATING Three rather different techniques in use: 1)

the common method,

wireline

BELL

are

through-tubing

production improved Frequently, results are reported where wells initially completed positive-ptessure under through are conditions reperforated tubinq, using reverse pressure.

7) the tubing-conveyed technique, and ~) a hybrid positive-pressure/reversesurge technique.

Through-Tubing Equipment Types WIRELINE THROUGH-TUBING —— TECHNIQUE .THE .—

Shaped-charge perforators are of three types, as shown In Fiq. 5: steel hollowc~~rier retrievable, =emi-expendable, and gun Common expendable guns. fully diameters range from 1 31”8to 2 7/8 inches the size of (35 to 73 mm) to accommodate used in the field. production tubing

Fig. 4 compares the through-tubing method with “conventional” wireline positive-pressure perforating. AS implied, small-diameter guns are run through the tubing, located as to depth (by means of gamma-ray or neutron tools and magnetic casing-collar locators) , and fired under conditions of reverse pressure. Note that equipment is surface pressure-control required, along with small-diameter cables (0.18 to 0.22 inch: 4.6 to S.6 mm), to allow equipment to be run in and out of the well with pressure at the surface.

and characteristics Perforator ~erformance features vary with gun type 5. The steel refi~’.~~e ~uns, most commonly used, offer pressure~temperature ratings to 25,000 psi and 500°F (172 MPa and 260° c) wi th some special explosive packages available which will go to 600°F (316° C). and reliable, are rugged, They no debris-free. As the guns produce casing deformation, they are well suited for ‘~se in older wells where casing may be weak corrosion. Generally, due to penetrating capability is from 0.7 to O.R that of the expendable types. Guns are usually designed for in-line firing for clearance control, and are equipped with positioning devices of the magnetic or mechanical types to assure most favorable casing wall. positioning against the

The technique involves running tubing and packer, installing wellhead equipment, reverse presadjusting the differential the gun assembly and sure, running locator, (weights, positioners, collar etc.]. The well is perforated and permitted (15 - 30 a brief period to flow for minutes) prior to recovering the gun, to that the perforated system is assure gun assembly is up. The cleaned

145

3

PERFORATING TECHNIQUES FOR MAXIMIZING WELL PRODUCTIVITY

4

Positioning improves the performance (Fig. 6) .

consistency of

Two principal operational characterize these guns: 1)

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In short, for deep wells or in c~ses of high wellhead p~essure, the steel retrievable guns arc usually to be Fr.eferred. Likewise, where the well is to be flowed prier to gun retrieval, the debris-free feature of the retrievable guns reduces the likelihood of sticking the gun in the with risk tubing. Sticking is a expendable guns unless the well is shut in long enough after firing to allow debris to fall back into casing.

limitations

A minimum hydrostatic pressure must be maintained on the gun during excessive preclude firing, to swelling could Such swelling. result in sticking the gun in the tubing. In liquid, from (1to 500 psi (3.5 MPa) is required; in gas, the figure may range from 500 to MPa) , 31.0 4500 psi (3.5 to depending on the gas type.

Operational precautions to be observed include: - to avoid a fishing operation, you determine that the level of reverse differential pressure is not so high as to blow the gun/cable up the tubing when flow bsgins after A computer program iS firing. available to the facilitate calculation,

2) Gun length is limited to about 20 m) , although longer (6.1 feet be The can run. assemblies principal limitation is imposed by the gun that the requirement assembly be no longer than the practical height of the lubricator. Well pressure dictates the number of gun weights necessary for the assembly to descend, and the length of these weights must take away from the effective gun length.

“ to avoid loss of control well, you insure that:

of

the

a) appropriate wireline pressurecontrol gea~ has been selected. b) pressure gear has been recently pressure testsd.

perforators are The semi-expendable generally rated from POOO to 15,000 psi (5s.1 to 103.4 MPa) and 300 to 350*F (150 As explosive components are to 177* c). expossd to the wellbore environment and gun frames are less sturdy, these guns are generally considered somewhat less rugged and reliable than the steel retrievable charges, from the Debris models. fragmented by charge detonation, remains in the well. It is usually not considered unless firing is above a objectionable packer. Casing deformation is produced 6, although the modern front-mounted strip or bar carrier guns produce only about half guns as o~her expendable much as Penetration as compared with the steel retrievable types varies from 1.25 to 1.35 times as deep.

c) pressure tests are conducted after mounting on the wellhead. TUBING-CONVEYED PERFORATING TECHNIQUE An alternate, non-wireline method of reverse-pressure7 ~rforating is illustra. A large-diameter, ted in Fig. multiphased casing gun is typically run into the well below the packer on a tubing string. Tubing is run dry or partially filled, to establish the desired level of reverse differential pressure. The assembly is positioned as to depth by means of wireline collar-locator and gamma-ray or neutron tools, and the packer set. Just before firing, a vent is opened below the packer to equalize pressure and allow passage of fluids between casing bore and tubing.

Fully expendable guns offer essentsame and ially the features semi-expendable as characteristics versions, except that more debris is left in the well, and more casing deformation is produced. Many of the models available are phased at angles other than zero de~rees, nonpositioned, thus resulting in entrance-hole vauiable penetration and size due to the gun clearance problem 6) Consequently, productivity (Fig. could be adversely affected (even though phasing itself is desirable in general). Both expendable and semi-expendable guns are usually made up to the length desired and salvo-fired.

;.hegun is typically equipped with a percussion-type firing device located in the top of the perforator. It is fired by dropping a bar, or ‘go-devil”, down the tubing. On firing, fluid rushes into tubing through the vent. The gun may be subsequently dropped to bottom to permit future wireline operations through the tubing.

●

Guns usuall y -eng %%nO;n ;~~ larg~ameter cas general same The guns have the 8. characteristics as those steel retrievable that except guns discussed previously? they are larger, and therefore offer

for a particular Selection of ~ depe=s on wellbore conditions operation of fluid type, pressure, temperature, casing condition, and wellhead pressure. 146

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W.

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Then the tubing and packer are run in the hole, with a seal disk installed as shown in Fig. 9. The seal disk permits the tubing to be run dry, or with any desired water cushion. The packer is set, and differential pressure adjusted to the desired reverse value. Then a sinker bar This is dropped to shear the disk. results in a sudden imposition of large the at levels reverse-pressure perforations, which terds to surge the perforations clean.

Productivity results, based on field indications, are equal to or better than wireline those of the through-tubing method . The margin of improvement appears more to increase under conditions of extensive wellbore damage. compared

performance; - Higher gun penetration and multiphasing.

5

WpAcTll Completion Action (Positive The involves Technique) . method perforating the well conventionally with positive pressure, using large-diameter casing guns such as those shown in Fig. 8. To keep formation damage to a minimum, guns are preferably fired in the presence of a compatible completion fluid.

advantages of greater penetration and 90or I?O-degree multiphasing. The commoner in the casing guns offer penetrations range of 11 to 15 inches (280 to 406 mm) , and entry holes from 0.38 to 0.46 inches (9.7 to 11.7 mm). (See API RP-43, Sec. II data for more details.) The comparable through-tubing guns produce penetrations about 4(Ito 55 percent as deep, and entry holes 60 to 75 percent as large in diameter.

Principal features as the wireline method are:

BELL

with

Productivity results are reported as favorable, roughly equal to those of the tubing-conveyed method.

i.e.,

- Higher differential pressures may be used without risking blowing the gun/cable assembly up the hole. (However, some completion specialists hold that reverse differential pressures in excess of the estab1ished threshold levels are not beneficial, and si]ould be avoided. can These excessive flow rates actually impair permeability, due to migration of fine particles.)

Operational features as compared wi th the wireline through-tubing method are: i.e., performance; - Higher gun penetration and multiphasing. - Higher differential pressures may be used without risk of blowing the gun/cable assembly up the hole. “ Rig time is equivalent or less.

- Operational rig time is equal to or less than that for wireline. - Cost is normally about greater.

25

- Cost is slightly less.

percent

- The method is simple. OPERATIONAL. —PRECAUTIONS:

- Tc check the gun for malfunctions such as partial detonations, it is necessary to withdraw the assembly from the well.

- proper selection of the shear disk important consideration. is an Different disks are used, depending on hydrostatic pressure.

- Gun misfires are time consuming and expensive.

- As an added precaution, the running of a tubing plug immediately above the disk is recommended, to protect against premature shearing. Once the packer is set, you recover the plug by slick line and proceed with the operation.

SPECIA~ PRECAUTIONS: - The tubing should be clean, free of scale, debris, etc.; otherwise the sinker bar will not detonate the S>ch a misfire requires gun. the sinker bar and retrieving the tubing before out cleaning making another firing attempt.

PERFORATING .— FOR SAND CONTROL are formations Unconsolidated gravel-packing completed mostly plastic less com!&ly by techniques; are The latter consolidation methods. usually confined to short zones and upper zones of dual completions.

flowline should be - The surface securely tied down, to preclude accidents caused by whipping action at high-pressure flows. THE HYBRID — SURGE TECHNIQUE —— another Yet perforated-system

method response

to is

Gravel-pack adder skin factorqti:;ffe;~;o;;~ w the perforated efficiency of Gravel occupies the perforations,

improve called 147

fl% system 9. as shown

6

PERFORATING TECHNIQUES FOR MAXIMIZING WELL PRODUCTIVITY in the schematic of Fig. 10, introducing another resistance to flow. AS formation fluid enters the perforation “tunnel”, linear, resulting in a flow becomes substantial pressure drop. This pressure drop is governed by the area of the tunnel It can be kept to a cross section. larger-diameter using by minimum perforations and more of them. In the (lO-mm) holes are example, three 0.4-in. equivalent to one of 0.7 in. (18 mm).

1) Shot density (most important). 7) Perforation diameter. (Total perforated area is the key.] 3) Gun phasing. 4) Depth of penetration. perforating consolidation Plastic tech~ essentially follow the same guidelines as for natural completions, using conventional casing guns of the type shown in Fig. 8, or through-tubing types as in Fig. 5. Perforations should be cleaned by flowing, as by back surging before trying to inject plastic. Thi~ practice has proved its importance toward obtaining a uniform treatment over the Successful treatment entire interval . reduces the number of well failures caused by partial treatment of a zone where only a few perforations take the plastic. Perforations made with positive pressure perform well under unlikely to are injection, since they may be filled with debris before back-flowing.

ravel-pack compl ePerforating for toward both more tions 1s thus ~nd?ng ~igger holes -- typically 8 shots P@r foot (26 per meter), but going to 12 shots per foot or more, with hole diameters of 0.6 to 0.8 inrh (15 to 20 mm). Guns usually used are of two general 7 to 9 S/P-inch For the~mmon types. (]7g to 744 mm) casing completion, the wireline-operated 5-inch (l?7-mm) carrier gun (Fig. 8) is usually run. Four shots per foot (13 shots per meter) are placed salvo, gun in the casing with each C.l lowed by additional salvos in the same 1.”.. interval to achieve the desired total shot density. Maximum gun length per trip into (i2 meters). the well is about 40 feet Selective firing techniques are normally shot densities used to achieve high without additional trips in the hole.

PERFORATING FOR HYDRAULIC FRACTURING too Formations having permeabilities low to produce naturally are rOutinelY fractured and/or acidized.

“slick-bodied” (15?-mm) The 6-inch retrievable gun (Fig. 11) fires 12 shots per foot (39 per meter) at once, phased at The entry-hole 60 or 90 degrees. (15 t:ft:; diameters age 0.6 to 0.8 in. The rigure shows the gun mm) . firing. Lengths up to 40 feet (12 meters) are practical for wireline operation. If greater lengths are desired, these guns can be run, fired, and retrieved on tubing to save rig time; a useful option where rig costs are exceptionally high, such as offshore. Guns are depth-positioned and fired as in the tubing-conveyed technique in such cases.

The associated perforating technique the typically selected to control is hydraulics of the treatment, and at the same time to provide good formation communication for subsequent production. Generally, the entry-hole sizes and the the distribution of perforations over target interval are the main elements of design. The usual objective is to control pressure drop across the perforations, thus holding down hydraulic horsepower losses.

are Large-diameter expendable guns seldom used for gravel-packing operations, because of their characteristic casin9 damage and debris.

with%%%%%a#%%%$ YzE~~~l~~::G guns (Fig. 8). Perforating is usually at 4 shots per foot (13 per meter), phased at 90 or 120 degrees, with hole diameters of 0.4 to 0.5 in. (10 to 13 mm). The e~:~f~ zone is perforated, often including Positivethe zone. sections within clean fluid, shooting in pressure sometimes acid, is common and effective, since :racturing overrides any damage that perforations might have suffered.

Completion conditions established for include using gravel-pack perforating clean fluids that are compatible with the formations. Pressure in the wellbore is positive. Prior to gravel par~ing, perforations are washed through and behind pipe by means of a ‘wash packer”, using a clean, compatible fluid. Relative Parameters

Importance ——

of —

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Although deeper gun penetration is not a perforating emphasized normally requirement, it is con~~dered desirable well is to be tested before when the treatment to establish design criteria for the operation.

Geometrical

the of preferred ranking The geometrical parameters differs frog the order listed for natural completions :

Perforating at 4 per foot is generally enough to provide desirably low levels of 148

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W.

T.

perforation pressure drop, thus reducing hydraulic horsepower requirements.

Sand-cor,trol completions place very different demands on the perforating job. The overriding requirement in gravel-pack completions is for large perforation area, meaning big holes and lot~ of them. Completions using plastic consolidation are less common. They call for clean, uniform perforations, making limited backsurging attractive.

of other means Ball sealers or isolation are sometimes used to assure vertical fracture extension throughout the Perforating in this way assures zone. after communication perforation good fracturing with any higher-permeability channels that might exist within the zone.

completions Fracturing/acidizing perforations which will keep require hydraulic horsepower losses to a minimum. Uni form hole sizes and 90-degree shot selective-firing phasing are desirable; offer advantages for systems gun limited-entry frac jobs.

fracturing, fewer For limited-entry They are are used . perforations the throughout distributed usually of higher the interval(s) “ permeability, ~~th diamet~~~e~ontrolled at 0.375, 0.5, or 0.7 in. (9.5, 13, or 18 mm) . Since the perforations are often widely scattered, selective-firing guns of usually 1? are the type shown in Fig. used to reduce rig tire.

ACKNOWLEDGMENT The author thanks C. R. Fast for his assistance in reviewing current perforating techniques for hydraulic fracturing.

by controlled diameter is Hole positioning the guns against the wall of zero perforating at the casing for clearance with zero-degree phasing. Some of these devices are designed to provide enhance burr-free perforations to ball-sealer operation. Ball sealers are more commonly used than in single-zone fracturing, since the objective is usually to create fractures in more than one zone.

REFERENCES

fracturing operations Through-tubing use the retrievable steel guns shown in fired Fig. !5, but assembled to be or Expendable selectively. semi-expendable guns are not usually used on selective firing operations.

The preferred follows:

of —

ranking

1.

Locke, S.: WAn Advanced Method for Predicting the Productivity Ratio of a Perforated Well”, SPE R804 , SPE 4th Symposium on Formdtion Damage, 1980.

2.

“Productivity of Hong, K. C.: a in Completions Perforated Pet. Homogeneous Reservoir”, —. Jour. Tech., Aug., 1975. ——

3.

“The Bell, W. T. and Bell, R. M.: Paradox of Gun Power vs. Completion the Efficiency” , Transactions of Explosives Conference of the IADC , Ju~e 9-11, 1981.

4.

C.: and Worzel, H. Allen, T. 0. “Productivity Methods of Evaluating and Drilling Gun Perforating”, Production Practice API, 1956, m 112-125.

5.

Buzarde, L. E., Kastor, R. L., Bell, L. : T and DePriester, C. w. Well -“Produc~~on Operations I Completions”, SPE Continuing Education Series, 1972.

6.

and Shore, J. B.: Bell, W. T. “Preliminary Studies of Casing Damage and * Drilling from Gun Perforatorsw Production Practice, 1964, pp. 7-lT

Geometrical here

is

7

equal . TWO basic methods are used: through-tubing perforating by wireline, and tubing-conveyed perforating. A third hybrid method perforates under positive pressure in the presence of a compatible completion fluid, but uses a sheared-disk hacksurge to technique clean the The advantages and perforations. drawbacks of each method arc discussed.

particularly at 90 Multiphasing, minimize desirable to degrees, is perforations breakdown pressure, since will be more likely to align with the preferred azimuth of formation fracture. This means that perforation communication with the fracture will be less tortuous than, for example, when shots are fired at right angles to the plane of a vertical fracture.

Relative Importance Parameters

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as

(consistency 1) Perforation diameter as well as size)l along with specific numbers of shots. 2) Phasing. 3) Depth of penetration.

CONCLUSIONS Natural com letions w en per orating done under are is ‘l””’s ‘ore productive +---f-being other factors reverse pressure, 149

8

PERFORATING TECHNIQUES FOR MAXIMIZING WELL PRODUCTIVITY 7.

R.: Garcia, D. J. and Paslay, P. t~prediction of Gun-Cable Behavior When High Under Perforating Gas Zones Reverse Pressures” , Transactions of the Explosives Conference of the IA~C, June 9-11, 1981.

R.

“A A* Cone, E. for &ercoming Technique l?amage”, SPE 7009.

9.

Suman, G. 0., Jr.: “Perforations -A Prime Source of Well Performance Pet. Tech. , April, Problems”, Jour. —— 1972, pp. 399-411.

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Completion Formation

and Rasmussen, J. 10. Lagrone, K. W. in Completion “A New Development w.: Limited Entry Methods -The Pet. Tech., July, Technique”, Jour. —— 1963, pp. 695-702. 11. Webster, K. R., Goins, W. C., Jr., “A Continuous and Berry, S. C.: Technique”, Fracturing Multi-Staqe Pit. Tech. , .Tune, 1965, pp. Jour. —. 619-625.

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(.8.,..:,;

.*

Diameter

Fig. 9- The “PACT” hybrid technique

1s4

Casing

Gun

J

40 MESH (.016” DIA.) GRAVEL- PERMEABILITY 27,500 md PERFORATION / sCREEN LINER

. ..

“-----/

FLIJID FLOW3 BBL.S PER DAY ‘0.8 CP OIL

“TIJ~NEL”-2“ LONG

cASING CEMENT ‘ TUNNEL

PRESSURE

DIAMETER o.4’’. o.7’’.

–—— ——— —.———— —---

__-14.79 4.84

DROP Psi Psl

Fig. 10- Pressl)re drop through perforation tunnel.

CROSS SECTIONALVIEW OF PERFORATIONS

Fig. 11- 6.inch diameter slick-bodied relievable gun.

155

CCL> CONTROLLER ASSEMBLY>

(


NO. 2

SWITCHING

SYSTEM GUN NO, 2 <

INTERMEDIATE ADAPTER < GUN NO. 1 GUN NO. 1 <

(A)

(B)

Fig.

12-

Selective firing perforators.

(c)