off-bottom cementing process used successfully with conventional liner-hanger systems with newly designed selective-release-plug assemblies
reservoir present, the intended production operations, and many other factors. Dyson et al. (1999) described several sand-control and nonsand-control completion methods, focusing mostly on single-string completions. The following are examples of standard industry methods currently being applied. 2009 NATIONAL TECHNICAL CONFERENCE & EXHIBITION, NEW ORLEANS, LOUISIANA The most simple and cost-effectiveAADE 2009NTCE-11-01: completion method available is the openhole or “barefoot” completion. This method isOFF-BOTTOM CEMENTING used in hard formations where the oil- producing zone is consolidated and not loose.PROCESS USED SUCCESSFULLY The oil-producing zone is completely open,WITH CONVENTIONAL LINER- and no liner or perforated casing is used toHANGER SYSTEMS WITH NEWLY case the hole (Fig. 1) (Helmy, et al. 2006).DESIGNED SELECTIVE-RELEASE- A second completion method involves the usePLUG ASSEMBLIES of a slotted liner or gravel-pack liner. Typically, the liner is suspended or hung fromAUTHOR(S) & AFFILIATIONS: the bottom of an intermediate string and doesHANK ROGERS, HALLIBURTON not reach surface. These types of liners prevent the entry of sands and solids into the liner ID using either a series of slots orEARL WEBB, HALLIBURTON screens, or using gravel (Fig. 2). One of the most common methods ofSTEVEN FIPKE, HALLIBURTON completion is cementing production casing in place through the producing formation, and then perforating the casing. Because the liner or casing must remain in place for the life ofAbstract the well and its replacement would be veryOperators and drilling contractors are continually costly, another string of pipe called tubing issearching for better drilling, cementing, and run into the well to act as the flow stringcompletion techniques to improve well-construction (Fig. 3).operations. In many cases, combining proventechnologies from cementing and completion With the ever-increasing drive to improve theoperations can provide economical advantages to productivity of the well-construction process,both the operator and/or turnkey drilling contractor. conventional construction plans are being challenged. Specifically, one configuration that is gaining inDuring the well-construction phase, when production popularity is a combination of cemented andliners are being installed, a newly designed selective- noncemented sections of the production casing.release-plug system allows stage cementing Typically, this type of cementing technique dates backprocedures to be used with both conventional and to the mid 1940s, when the diverter-valve (DV) stage-expandable liner hangers. This paper documents the cementing tool was first introduced. The DV stage-successful application of selective-release stage- cementing tool allowed casing to be cemented atcementing equipment and completion techniques several levels throughout the length of the casingtogether to provide improved well-construction string by dividing the cement into stages or batches.operations. Each batch is then introduced at the needed level or depth through ports in the DV tool that was run intoBackground the well as an integral component of the casing. This process allowed for critical isolation to be achievedNumerous completion methods are available for while not requiring slurry to be displaced from TD toproducing oil wells and injection wells. The type of the surface.completion method used is governed by the type ofPage 1 of 9, 2009ntce-11-01techpaper-110223211712-phpapp02.doc
When in the well-construction-planning phase, zones, as the flapper prevents the migration ofsome operators consider nontraditional completion formation gas into the column of cement duringmethods to either reduce construction cost, reduce transition.completion cost, or to improve production capacityby reducing formation damage. The use of DV stage- When compared to surface-launch applications,cementing type tools, external casing packers, swell subsurface-launch equipment have functionalpackers, etc. have provided a host of possible limitations that are not common to surface launchconfigurations to well planners. By providing so many jobs and therefore increase their complexity,options, casing-equipment suppliers must design their limitations such as dual-plug/plug-launch equipmenttools to “plug and play” to provide the versatility that set up where plug/plug means DV tool operatingis demanded. plugs are suspended below the running tool and launched when drillpipe wiper plugs launched from The use of DV (or similar) tools above the surface are displaced from the surface to the DVnoncemented sections of casing over producing operating plugs. Once the two plugs join together, theintervals allows an upper hole section to be cemented combined plug/plug assembly is then displaced downwithout contaminating production intervals with the liner or casing to perform their intended function.cement, thus eliminating contact between the cementand cement-sensitive zones where damage to the Multilateral (MLT) junctions present a uniquezone can occur when contact with cement is made. In opportunity to address the challenges of off-bottomsome cases, cement solids that contact sensitive zones cementing. Many types or classifications of MLT arecan plug pores, vugs, or fractures; thereby reducing commonly used in well-construction. In 1998,production potential. Additionally, spacers or flushes Technology Advancement for Multi-Lateral Inc.used to clean filter cake from the wellbore can alter (TAML) formed a JIP to create the TAMLsome formation clays, further affecting production Classification System (Fig. 6), a detailed multilateralpotential. Therefore, performing second-stage technical guide and manual. The original TAMLcementing only has become a very popular isolation membership included 18 companies, which were laterpackage. The practice of cementing an upper section reduced to 14 by mergers in the industry (seeof casing while not cementing a lower section is www.TAML-INTL.org). TAML Level 4 (Fig. 7)commonly referred to as “off-bottom” cementing. cemented-wellbore junction often uses DV stageOne type of off-bottom cementing application is cementers to achieve the cemented junction with therepresented in Fig. 4. This practice is typically main bore where the main body of the lateral is eitherperformed with some type of DV stage-cementing cemented or uncemented. Experience with differenttool and in many cases can be performed on surface multilateral-well plans has led to the common use oflaunch or subsurface-launch applications such as several terms: pitchfork (two parallel laterals), stackedliners, multilaterals or subsea applications. A modified lateral (one lateral directly above the other), gull wingDV stage-cementing tool that incorporates a (dual-opposing laterals), crow’s foot trilateral (threemechanical set packer element (stage packer collar or laterals at ninety degrees to one other, as shown inSPC) to seal below the cementing ports between the Fig. 8), and combinations of designs. Fishbonecasing and the wellbore is also represented in Fig. 4. designs are commonly drilled off to the side of eachTwo common SPCs are used extensively in the main lateral because of the sand-shale laminationsdomestic US market. Flapper-type and poppet-type that are characteristic of some reservoirs.are commonly used to perform second-stagecementing above openhole sections where the Application-Specific Subsurface Plug Typesmechanical set packer element provides low-pressureannular isolation just before cementing. The poppet- A single or dual-stage subsurface (Type H selectivestyle SPC incorporates a back-pressure valve to retain release or SR) plug assembly (Fig. 9) can be usedthe cement in place once displacement is complete with hydraulic DV stage tools to perform stageand allows a conventional cementing plug to be used. cementing in operations where the casing beingThe flapper-type SPC (Fig. 5) requires a latch-down cemented does not come to the surface. This type ofcementing plug to be used in conjunction with a latch plug assembly can be used in vertical or horizontaldown seat or baffle to retain the cement in place once applications below a host of running-tool types andcementing is complete. The flapper valve is can be used with inflatable-type annular casingspecifically designed to be used above gas-producing packers (ACP). A single or dual-stage subsurface plug
assembly typically includes the following features and to prevent sand influx through the exposed area ofadvantages: the casing-window. The plug set allows two-stage cementing of Since the mid-1990s, off-bottom stage-cementing liners or casing strings suspended from a techniques have been used to pump a limited volume casing hanger. of cement around the multilateral junction. Typically The plug set is compatible with both less than 50 bbl of cement are required cover the hydraulic-set and mechanical-set hanger junction +/- 300 ft of the lateral liner. The cement is systems. The setting ball for hydraulic-set displaced through a hydraulically opened stage tool to hangers must be small enough to pass bring the cement top up into the parent wellbore through the plug set and first-stage shutoff casing. An external casing packer is used to keep the baffle adapter. cement above the slotted liner that was used in the The selective-release feature helps prevent the horizontal section, to not damage the completion. A closing plug from releasing prematurely drillpipe dart displaces the drillpipe and engages a before the first-stage latch-down shutoff plug subsurface-release closing plug to displace the liner has been released. and close the cementer. The liner is released by way It can be used to cement a slotted liner of a special adaptation of the subsurface release plug suspended below a hydraulic DV stage set that holds the multilateral liner running tool in the cementing combo tool or below an ACP locked position until the closing plug has been below a hydraulic DV stage-cementing tool. displaced. This prevents premature release of the liner string and allows for a simple mechanical release The second stage-only or off-bottom cementing mechanism that can be activated without turning or(Type S selective release or SR) plug assembly (Fig. moving the lateral liner.10) is designed to be used with plug operated DVstage cementers where no first-stage cementing is The excess cement is allowed to harden and isperformed. This application is primarily used above then cleaned out of the inside of the lateral liner via aopenhole completions where slotted pipe, screens, or 3½-in. x 4½-in. combo string, which also drills outother noncemented lower sections are employed the plugs and stage tools. In some applications, the(Fig. 11). In most cases, this plug assembly is string is run all the way to the shoe of the liner to bedesigned for near vertical wells. However, many jobs sure the slotted liner is clear of obstructions.have been performed successfully where the deviationat the stage tool has reached horizontal. After the lateral liner has been cemented, the Level 4 junction is completed, which recovers the Either of these two plug sets or combinations drilling whipstock and restores full ID access throughbetween the two can be used to perform various the wellbore junction. Lateral reentry can betypes of well configurations where multiple-stage accomplished by the use of a special Completioncementing operations are performed in a subsurface whipstock, which can be latched into position relativeapplication. Though a host of well-specific equipment to the original casing window.must be employed while using the selective-release-plug sets above, this paper will not attempt to Full-Opening Stage-Cementing Toolelaborate on the complex combinations available to Full-opening stage tools (Fig. 12) enabledrilling engineers performing such cementing operators to run casing, cement, and upper-holeoperations. Rather, only a general overview of the sections without the need for drilling operationsoptions available will be covered. before stimulation or production operations. The full-Successful Off-Bottom Cementing Applications opening multiple-stage cementer or FO cementer (FOC) is used to place any number of stages of Multilateral-well designs have seen extensive use cement or other fluids outside a casing string atin the Latin heavy oil fields to enable cold production different selected points along the casing. The FOC isof some very high viscosity fluids. In these wells, operated manually and requires the use of a drill orreservoir exposure must be maximized to achieve tubing string and the sleeve positioner operating toolseconomic production, but adding branches to these (Fig. 13 and 14). After cementing operations arewells requires an economical way to seal the junction complete, the work string and casing can be circulated
clean before the work string is POOH, thereby “More than 200 Multilateral Wells Drilled in theeliminating subsequent drillout that is required for Faja Del Orinoco Extra-Heavy Oil Reservoir”.conventional plug-operated stage tools and saving the STEVEN R. FIPKE, Halliburton. World Heavyoperator costly rig-time and eliminating debris from Oil Congress 2008falling into the noncemented section. IADC/SPE 112302. “New Equipment Designs Enable Swellable Technology in CementlessConclusion Completions” Hank Rogers, Dave Allison, and Earl Webb, Halliburton The acceptance of off-bottom cementing methods Helmy, et al. 2006. Applications of Newcomplement a host of downhole tools designed Technology in the Completion of ERD Wells,specifically for noncemented applications. Cementing Sakhalin-1 Development. Paper SPE 103587annular sections up hole provides long-term annular presented at the 2006 SPE Russian Oil and Gasisolation that can easily be performed with the tools Technical Conference and Exhibition, Moscow,mentioned in the paper. The use of swell packers, Russia, 3–6 October.sleeve collars, screens, or openhole completion Hinkie, et al. 2007. Multizone Completion Withtechniques offer ideal versatility in the noncemented Accurately Placed Stimulation Through Casinghole section. Through combining these discrete Wall. Paper SPE 106705 presented at the 2007technologies, operators are given a host of well- SPE Production and Operations Symposium heldconstruction options in their toolbox. Though this in Oklahoma City, Oklahoma, 31 March-3 Aprilpaper has covered several unique tool configurations 2007.that can be used to perform surface and sub-service “Cementing above screens and slotted liners”,off bottom cementing, it should not be implied that Ray Vincent, Baker Oil Tool, World Oil, Mayall possible configurations have been covered. Rather, 2000this paper is meant to serve as an introduction to off- IADC/SPE 39345. “Development of a One-Tripbottom cement and related equipment. ECP Cement Inflation and Stage Cementing System for Open Hole Completions” Martin P.References Coronado, Mark J Knebel. 1998 IADC/SPE Drilling Conference held in Dallas, Texas 3-6 March 1996.Fig. 1—Conventional openhole or barefoot completion. Fig. 2—Slotted-liner or gravel-pack completion method.
Fig. 4—Conventional off-bottom cementing application where the slurry never contacts the producing or injection interval.Fig. 3—Conventional cemented casing, perforatedproducing interval and production tubing.
Fig. 5—Flapper-type SPC used in off bottom cementing. Fig. 6—TAML MLT classification chartFig. 7—TAML Level 4 junction. Fig. 8—Triple crows foot with fishbones. Approximately 60,000 ft of 8 ½-in. hole drilled in reservoir to maximize wellbore exposure and production efficiency in heavy-oil formations. Fig. 10—Typical SR Type H plug set used with a hydraulic DV tool above a noncemented section with or without conventional ACP/ECP or swell packers. Fig. 9—Selective release (SR) plug set for use with hydraulic DV tools or SPC assemblies in sub-service application.
Fig. 12—Full-opening or work-string-operable stage tools can be supplied withor without integral inflatable packer orused in conjunction with conventionalACP/ECP. The above figure is shown inthe open position. Fig. 11—Typical SR Type H plug set used with a hydraulic DV tool above a noncemented section.
Fig. 13—Operating tools for FO or work-string-operable stage tool. Isolation packers are used to control and direct the flow of fluids from the work string through the circulation ports in the FO stage tool. The above figure shows a FO stage tool with integral inflation packer (combo tool). Tandem tools can also be used with the same type of isolation packers.Fig. 14—Full-opening stage cementer used above an openhole completion that incorporates swell packers for annular stimulation/completioncommunication paths with sleeve type stimulation collars. This equipment set up allows for pinpoint stimulation and life-of-the-well isolation whereneeded.