(e) Downhole pump system
5. WELL COMPLETION DESIGNS
5.1 Land or Platform Based Completions
31/2 in Otis 'X' Landing Nipple Baker Anchor Seal Assembly Baker 'DB' Packer Millout Extension Crossover 51/2 in x 31/2 in 31/2 Hydril EU Tubing 31/2 in Otis 'X' Nipple 31/2 in Otis 'X' Nipple
Perforated Flow Tube Wireline Entry Guide
Wireline Operated Sliding Side Door 7" Casing
Sub Surface Safety Valve with Flow Couplings
3 1/2" Tubing
COMPLETION NO. 1 (Figure 17)
This completion type features the use of VAM tubing with an anchor seal assembly latched into a permanent packer. The VAM tubing is required due to the production or injection of gas with relatively high closed in surface tubing pressures. The permanent packer would be made up with its tailpipe and run in and set on drillpipe or with electric wireline cable. The absence of a moving seal assembly infers that little expansion/contraction will occur, or that the need for good differential pressure sealing integrity is paramount.
Figure 17
Single Zone Completion with no Provision forTubing Movement
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4
Wellbore Completion Concepts
Casing
Nipple
Nipple
No Go Nipple Locator Seal Assembly Permanent Packer Seal Bore Protector Sub Surface Safety Valve
Tubing
Wireline Operated S.S.D.
Millout Extension
Perforated Flow Tube
Liner W.E.G
COMPLETION NO. 2 (Figure 18)
This design provides for production through a tubing string utilising a moving seal assembly located inside a permanent packer. Additional features include 2 nipples located in the tailpipe, the upper one for pressure isolation if the tubing string is retrieved and the lower for landing bottom hole pressure survey gauges.
Figure 18
Single Zone Completion Utilising a Locator Seal Assembly
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9 5/8" Casing
7" Hydril Production Tubing S.S.S.V. Nipple with Flow Coupling
Mill-out Extension
4 in VAM/Hydril Tailpipe Wireline Operated Sliding Side Door
Perforated Tube
Extra Long Tubing Seal Receptacle with Nipple and Anchor Seals on the Slick Joint
Permanent Packer Wireline Set
Nipple
Landing Nipple
7" Liner
COMPLETION NO. 3 (Figure 19)
This design has been frequently used in high production rate areas, where its large bore tubing minimises pressure drop in the tubing. The packer and tailpipe can be set on electric cable or coiled tubing and the tubing string subsequently latched into the packer with an anchor seal assembly at the base of an extra long tubing seal receptacle ELTSR. The range of tubing movement is typically anticipated to be 5 -15 ft but depends on the range of operational temperatures. Rates of 20,000 - 30,000 bbl/d can be typical for this type of completion.
Figure 19
SingleHigh Flowrate Zone Completion Utilising an Extra Long Tubing Seal Receptacle for Tubing Movement
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Wellbore Completion Concepts
9 5/8" Casing 7" Production Tubing S.S.S.V. Nipple with Flow Coupling Nipple
Polished Bore Receptacle
7" Liner
Liner Packer and Hanger Assembly
Side Pocket Mandrel for Chemical Injection or with Shear Valve to Permit Circulation
COMPLETION NO. 4 (Figure 20)
This design again is specifically for high flowrate production/injection and is an alternative to Fig 19. It is referred to as a Monobore as it has a large, relatively constant diameter from surface through the reservoir and this facilitates concentric access and intervention. It utilises a polished bore receptacle at the top of the 7" liner which accepts a seal assembly at the base of the tubing string. The seal assembly provides a moving seal area to accommodate expansion and/or contraction of the tubing. This design thus offers a continuous 7" O.D. conduit for flow from the wellhead to the perforations. As shown here, there is no facility for isolating below the PBR but this can be achieved if the well is completed below the PBR with a packer and small tailpipe containing a wireline nipple to accept a plug or more reliably by running a thru-tubing bridge plug. Circulation to kill the well is preferred using a shear valve in a side pocket mandrel instead of a sliding side door.
Figure 20
Single Zone High Flowrate Injection/Production Completion Utilising a Polished Bore Receptacle
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9 5/8" Casing
7" VAM/Hydril Production Tubing S.S.S.V. Nipple with Flow Coupling Nipple Landing Nipple Nipple Nipple 7" Liner
Side Pocket Mandrels for Subsequent Gas Lift
Perforated flow Tube Retrievable Packer
COMPLETION NO. 5 (Figure 21)
This illustrates a completion which utilises gas lift to allow production to occur or to increase production rates. The string comprises several side pocket mandrels containing injection valves at various depths which are designed to open and allow gas to enter the tubing from the annulus. The design utilises a retrievable packer which is preferable if it is suspected that a completion will require mechanical repair at frequent intervals, e.g. to replace non-operating gas lift valves.
Figure 21
Single Zone Completion Utilising a Gas Lift Facility
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Wellbore Completion Concepts
Junction Box Surface Power Cable Wellhead Incorporating Boll Weevil Hanger
Retrievable Hydraulic Set Packer
Downhole Cable Tubing Production Annulus Production Production Tubing (3 1/2") Selective Nipple Bypass Tubing (2 3/8") Pothead Connection Y-Tool Block
Motor Lead Extension
Pump (5.44" OD)
ESP / Bypass Tubing Clamps Motor (5.44" OD)
Pressure Sensors
Bypass Tubing (3 1/2")
9 5/8" Casing
COMPLETION NO. 6 (Figure 22)
Here the reservoir may have insufficient pressure to lift the crude to surface or the crude may be too viscous or possess a low pour point and thus assisted flow is required. The design features a downhole electrically operated pump in a side leg tailpipe. The advantage of locating the pump in the side leg is to allow access to the producing zone below the tailpipe, say for production logging surveys, etc. Note that a retrievable hydraulic set packer is used which reduces the difficulties in pulling the string should the pump need replacing regularly – typical run life for a large capacity ESP is currently 1-3 years, but this depends upon installation efficiency and the actual operating environment.
Figure 22
Single Zone Completion Utilising an lectriccaly Powered Submersile Pump
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9 5/8" Casing 3 1/2" EU Tubing Crossover 3 1/2" x 2 7/8" 2 7/8" EU Tubing 3 1/2" Otis 'XO' SSD 3 1/2" Otis Flow Coupling 2 7/8" Otis 'XO' SSD Collet Latch Otis RDH Packer 2 7/8" Otis 'XO' SSD 2 7/8" Otis Flow Coupling 2 7/8" Otis 'XN' Landing Nipple 2 7/8" Perforated Tube 2 7/8" Baker 'R' Nipple 2 7/8" Mule Shoe3 1/2" Otis Blast Joint
3 1/2" Baker Locator Tubing Seal Assembly Baker 'D' Packer
Crossover 3 1/2" x 2 7/8" 2 7/8" Otis 'XO' SSD 2 7/8" EU Tubing
2 7/8" Otis 'XN' Landing Nipple 2 x S.S.S.V. with Flow Couplings
COMPLETION NO. 7 (Figure 23)
This completion utilises two tubing strings allowing separated production from each zone with a significant degree or reservoir management. The lower packer is a permanent packer and the longer tubing string is connected to it using a seal assembly. The upper packer is a retrievable dual packer. All equipment is duplicated, e.g. 2 sub- surface safety valves, 2 circulating devices, etc. To combat erosion on the longer string at the point of entry of fluid from the upper zone into the wellbore, thick walled joints known as “Blast Joints” are used. This design can be extended to 3 strings with 3 packers allowing for production from 3 zones or, if production occurs up the annulus, from 4 zones. However such a well is not overly common because of its high degree of mechanical complexity.
Figure 23
Dual Completion allowing Segregated Production
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Wellbore Completion Concepts
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4 1/2" VAM Production Tubing
31/2" VAM Production Tubing S.S.S.V (x2)
Hydraulic Set Retrievable Dual Packer
Nipple
Nipple
Gas Lift Mandrels
Travel Joint
Locator Seal Assembly Wireline Set Permanent Packer
Wireline Set Permanent Packer Wireline Operated S.S.D
Wireline Entry Guide
9 5/8" Casing
COMPLETION NO. 8 (Figure 24)
This complex design introduces flexibility into the completion since it allows for selective production from either or both of the zones with continuous gas lift using gas injected down a separate string or for concurrent production of both zones using the two tubing strings. In this design, the gas is injected using the tubing to avoid excessive gas pressures being exerted on the production casing, which can be especially serious at surface with the possibility of casing burst if the casing has deteriorated.
Figure 24
Selective Dual Zone Producer with optional Gas Lift Facility
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Casing
Wireline Isolating Nipple
Wireline Isolating Nipple Borehole Wall
Direct Controled S.S.S.V
Direct Controled S.S.S.V Perforations on Upper Zone
Perforations Cement Sheath
COMPLETION NO. 9 ( Figure 25)
Although the title of this type of completion is somewhat of a misnomer, it offers advantages in both cost and simplicity over the previous completions but potentially suffers from some basic limitations as discussed earlier. However, this type of completion has been applied in some areas, for example, the Middle East and the USA. It can either take the form of a single, dual or a triple completion.