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The interface between the wellbore and reservoir (bottom hole completion techniques): open hole completions; uncemented liner completions; perforated completion… Production method: pumping; flowing… => selection of flow conduit between reservoir and surface Number of zones to be completed: single or multiple
Designed & Presented by Mr ĐỖ QUANG KHÁNH, HCMUT 12/2010 Đỗ Quang Khánh – HoChiMinh City University of Technology Email: dqkhanh@hcmut.edu.vn or doquangkhanh@yahoo.com The interface between the wellbore and reservoir (bottom hole completion techniques): open hole completions; uncemented liner completions; perforated completion… Production method: pumping; flowing… => selection of flow conduit between reservoir and surface Number of zones to be completed: single or multiple 12/2013 Đỗ Quang Khánh – HoChiMinh City University of Technology Email: dqkhanh@hcmut.edu.vn or doquangkhanh@yahoo.com Bottom Hole Completion Techniquess (a) openhole completion; (b) uncemented liner completion; (c) perforated completion) Openhole Completions o In an openhole or barefoot completion, the production casing is set in the caprock above or just into the top of the pay zone, while the bottom of the hole is left uncased o o Advantages: Exposure of entire pay zone to the wellbore; No perforating expense; reduced casing cost less critical need for precise log interpretation; Reduced drawdown because of the large inflow area; Slightly reduced casing cost; Ease of deepening the well; relative ease of converting the well to a liner completion; no risk of formation damage resulting from cementing casing Disadvantages: inability to control excessive gas-oil and/or water-oil ratios (except in the case of bottom water); need to set casing before drilling or logging the pay; difficulty of controlling the well during completion operations; unsuitability for producing layered formations consisting of separate reservoirs with incompatible fluid properties; inability to selectively stimulate separate zones within the completion interval ; need for frequent clean-outs if the producing sands are not completely competent or if the shoulder of the caprock between the shoe and top of the pay is not stable Uncemented Liner Completions o To overcome the problems of collapsing sands plugging the production system, the early oil producers placed slotted pipe or screens across the openhole section as a downhole sand filter o o Advantages: No formation damage due to completion work no perforation required log interpretation is not critical; Easy to control sand production Adaptable to other special techniques to control sand Cleanout problem can be avoided Deepening of the well can be accomplished easily Not recommended for the following reasons: Sand movement into the wellbore tends to cause permeability impairment by the intermixing of sand sizes, and of sand and shale particles Fine formation sands tend to plug the slots or the screen At high rates, the screen often erodes as formation sand moves into the wellbore Poor support of the formation can cause shale layers to collapse and plug the slots or screen Formation failure can cause the liner itself to collapse Cemented and Perforated Completions By far the most common type of completion today involves cementing the production casing (or liner) through the pay zone, and subsequently providing communication with the formation by perforating holes through the casing and cement Safer operations More informed selection of the zones to be completed Reduced sensitivity to drilling damage Facilitation of selective stimulation Possibility of multizone completions Easier planning of completion operations Selection of flow conduit between reservoir and surface In the selection of the method, a range of considerations may influence the choice including: cost, flow stability, ability to control flow and ensure well safety or isolation; ensuring that the integrity of the well will not be compromised by corrosion or erosion In the case of multizone reservoir, the zonal characteristics will determine to a large extent the flow system selected However, for a single zone completion, the following alternatives exist: Tubingless casing flow Casing and tubing flow Tubing flow without annular isolation Tubing flow with annular isolation Single-String Completions (Single Zone) (a) temporary; (b) tubingless gas well; (c) simple low cost; (d) high pressure; (e) high-rate liner completion) Multiple-String Completions (Multiple Zone) (a) tubingless; (b) low rate, single string; (c) high rate, single string; (d) dual string (parallel gas lift); (e) concentric Commingled Completion Oilfield Glossary Definition: A wellbore completed in two or more reservoir zones that are not in hydraulic communication in the reservoir Backflow (often incorrectly referred to as crossflow) is common during rate cutbacks and buildup tests on these types of completions Packer: a tool to provide a seal between the tubing & the casing of a well to prevent movement of fluids past this sealing point The pack-off is accomplished by expanding or extending the elastomer element outwards from the packer body until it contacts the casing wall Main Applications are: Improve safety by providing a barrier to flow through the annulus Keep well fluids and pressures isolated from the casing Improve flow stability conditions and prevent heading Separate zones in the same wellbore Place kill fluids/ treating fluids in the casing annulus Keep gas lift or hydraulic power fluid injection pressure isolated from formation Anchor the tubing Isolate a casing leak or leaking liner lap Facilitate temporary well service operations 12/2013 Đỗ Quang Khánh – HoChiMinh City University of Technology Email: dqkhanh@hcmut.edu.vn or doquangkhanh@yahoo.com 24 Four Main characteristics classifying packer types are: Setting Mechanism Mechanical-set (weight-set; compression or tension-set; rotational-set) Hydraulic-set Electrical packer Retrievability Retrievable packer Permanent packer (wireline setting or tubing setting) Ability to withstand differential pressure Packer Bore 12/2013 Đỗ Quang Khánh – HoChiMinh City University of Technology Email: dqkhanh@hcmut.edu.vn or doquangkhanh@yahoo.com 25 Weighted-set packers: Employ mainly a slip-&-cone arrangement Slips are attached to a friction device/blocks assisting the setting operation Tubing weight is used to compress & expand the sealing element Packer is released for retrieving by simple upstrain pull Suited for use in straight, relatively shallow, low-pressure wells 12/2013 Đỗ Quang Khánh – HoChiMinh City University of Technology Email: dqkhanh@hcmut.edu.vn or doquangkhanh@yahoo.com 26 Tension-set packers: Set by pulling tension on the tubing Released by simple slacking off on the tubing (most models have some form ‘emergency release’ mechanism) Suitable for use in reasonably shallow wells where moderate differential pressures from below are anticipated Often used in water injection wells and in wells where stimulation work is planned Used in shallow wells where available tubing weight is not sufficient to compress the packing element 12/2013 Đỗ Quang Khánh – HoChiMinh City University of Technology Email: dqkhanh@hcmut.edu.vn or doquangkhanh@yahoo.com 27 Rotational-set packers: 12/2013 Tubing rotation obviously plays a major role in setting and retrieving rotational-set packers Once set, compression and pack-off are mechanically ‘locked-in’ Upward or downward movement is prevented regardless of application of weight or tension via tubing Right-hand rotation is required to retrieve the packer Use to isolate bad order casing in a pumping well Used in shallow to medium depth straight hole where high differential pressures are not expected Disadvantage: need rotation for release Solids setting on top of the packer can make it impossible to work any tubing rotation down the hole Đỗ Quang Khánh – HoChiMinh City University of Technology Email: dqkhanh@hcmut.edu.vn or doquangkhanh@yahoo.com 28 Hydraulic-set packers: use induced fluid pressure to drive the cone behind the slips Once set, they remain set by use of either entrapped pressure or a mechanical lock Single hydraulic-set packer & multi-string hydraulic-set packers Release by picking up on the tubing, some are released by rotation Production tubing string can be run in the well & the tree installed before the packer is set Excellent for use in deviated or crooked holes, where tubing movement is restricted or undersirable Permits the tubing to be in neutral tension, which results in a straight tubing string, assisting the performance of future wireline/concentric work Multiple completion strings may be run and landed simultaneously 12/2013 Đỗ Quang Khánh – HoChiMinh City University of Technology Email: dqkhanh@hcmut.edu.vn or doquangkhanh@yahoo.com 29 Permanent packers: can be run and set on electric Single hydraulic-set packer & multi-string hydraulic-set packers Release by picking up on the tubing, some are released by rotation Production tubing string can be run in the well & the tree installed before the packer is set Excellent for use in deviated or crooked holes, where tubing movement is restricted or undersirable Permits the tubing to be in neutral tension, which results in a straight tubing string, assisting the performance of future wireline/concentric work Multiple completion strings may be run and landed simultaneously 12/2013 Đỗ Quang Khánh – HoChiMinh City University of Technology Email: dqkhanh@hcmut.edu.vn or doquangkhanh@yahoo.com 30 When a retrievable packer is run or run into the internal packer bore and establish a pressure seal Schematic Views of Various Tubing Seal Assemblies, which can be classified according to whether they allow tubular movement or not: Static Seal Assembly (a) Dynamic Seal Assembly 12/2013 Locator Seal Assembly (b,c) Extra Long Tubing Seal Receptacle (d) Travel Joint (e) Polished Bore Receptacle PBR (f) Đỗ Quang Khánh – HoChiMinh City University of Technology Email: dqkhanh@hcmut.edu.vn or doquangkhanh@yahoo.com 31 provide remote sub-surface isolation in the event of a catastrophic failure of the Xmas tree or as a failsafe shutdown system; can be sub-divided into remotely controlled and Directly controlled systems Remotely Controlled SSSV 12/2013 This is the more widely employed and more reliable method The valves normally rely on hydraulic pressure, supplied to the downhole valve by a small /4" monel control line run in the annulus and strapped to the tubing, to keep the valve open The valve itself is normally either a ball type valve or a flapper device As an alternative an electricially operated valve can be used Đỗ Quang Khánh – HoChiMinh City University of Technology Email: dqkhanh@hcmut.edu.vn or doquangkhanh@yahoo.com 32 the method of deploying & retrieving the valve (1) Tubing retrievable where the valve is run as an integral part of the tubing string and can only be retrieved by pulling the tubing (2) Wireline retrievable where the valve nipple is run as an integral part of the tubing and the internal valve assembly can be subsequently run and retrieved on wireline cable The valves normally open due to the hydraulic pressure acting on a piston which moves a flow tube against the ball or through the flapper On bleeding off pressure, a spring ensures reverse movement of the piston and the flow tube, and this allows valve closure Direct Controlled Sub Surface Safety Valves 12/2013 designed to remain open provided either a preset differential pressure occurring through a fixed size orifice in the valve is not exceeded or the flowing bottomhole pressure is maintained above a preset value Any increase in the differential pressure causes a spring to close the valve These valves have fewer limitations on setting depth and are typically set deeper than the remotely controlled valves, e.g in the tailpipe Đỗ Quang Khánh – HoChiMinh City University of Technology Email: dqkhanh@hcmut.edu.vn or doquangkhanh@yahoo.com 33 contains an offcentre pocket with ports into the annulus Using wireline or coiled tubing, a valve can be installed in the packer which allows fluid flow between tubing and annulus, e.g.: (a) Gas Lift Valves This type of valve when landed in the SPM responds to the pressure of gas injected into the annulus, or tubing pressure at the valve depth, to open the valve and allow gas injection into the tubing (b) Chemical Injection Valves These valves allow the injection of chemicals such as corrosion inhibitors, pour point depressants, etc The valve is again opened by annular pressure (c) Circulation To allow circulation of kill fluids or the placement of a lower density fluid cushion, a valve can be installed which can be sheared by pressure allowing communication The port can then only be reclosed by replacing the shear valve by wireline or coiled tubing 12/2013 Đỗ Quang Khánh – HoChiMinh City University of Technology Email: dqkhanh@hcmut.edu.vn or doquangkhanh@yahoo.com 34 permits communication between tubing and annulus consists of two concentric sleeves with elastomeric seals between them and each with slots or holes Using wireline or coiled tubing, the inner sleeve can be moved upwards or downwards to align the openings on both sleeves Its application is for well killing and placement of fluids in the tubing or annulus by circulation 12/2013 Đỗ Quang Khánh – HoChiMinh City University of Technology Email: dqkhanh@hcmut.edu.vn or doquangkhanh@yahoo.com 35 A landing nipple is a short tubular device which has an internally machined profile, capable of accommodating and securing a mandrel run into its bore on wireline or coiled tubing The nipple provides a recess to mechanically lock the mandrel in place using a set of expandible keys a pressure seal against the internal bore of the nippleand the outer surface of the mandrel Some typical nipples and mandrels: 12/2013 Đỗ Quang Khánh – HoChiMinh City University of Technology Email: dqkhanh@hcmut.edu.vn or doquangkhanh@yahoo.com 36 Nipples are installed at various points in the string to facilitate one or more of the following operations: (a) Plugging the tubing for: (i) pressure testing (ii) setting hydraulic set packers (iii) zonal isolation (b) Installing flow control equipment such as: (i) downhole chokes, regulators, SSVs, etc (ii) landing off bottom hole pressure recorders Nipples can be classified into three basic designs: (1) (2) Top No-go where the No-go shoulder is located above the seal bore Bottom No-go where the No-go shoulder is located below the seal bore In this design the No-go shoulder obviously restricts the diameter of the seal bore (3) Selective Nipples In the above two types, the nipple sizes must progressively diminish with the depth of the string Then it is possible to run only one of each size and type in the string With selective nipples as required can be installed since the locking mechanism is selective and has to be specifically actuated by the wireline tool 12/2013 Đỗ Quang Khánh – HoChiMinh City University of Technology Email: dqkhanh@hcmut.edu.vn or doquangkhanh@yahoo.com 37 Nipple profiles consist of the following: i) Lock mandrel recess profile ii) Seal bore (below lock profile) iii) No-go shoulder which is optional but has a minimum through bore and provides positive positioning of the lock mandrel Perforated Joint 12/2013 This allows for flow to enter the string even if the base of the tubing string is plugged by, say, pressure gauges Đỗ Quang Khánh – HoChiMinh City University of Technology Email: dqkhanh@hcmut.edu.vn or doquangkhanh@yahoo.com 38 ... doquangkhanh@yahoo.com Bottom Hole Completion Techniquess (a) openhole completion; (b) uncemented liner completion; (c) perforated completion) Openhole Completions o In an openhole or barefoot completion, the production... The interface between the wellbore and reservoir (bottom hole completion techniques): open hole completions; uncemented liner completions; perforated completion Production method: pumping;... the wellbore Poor support of the formation can cause shale layers to collapse and plug the slots or screen Formation failure can cause the liner itself to collapse Cemented and Perforated Completions