The paper describes the world's first use of expandable solid tubing to close off perforations. The development and testing of the system leading up to the two field installations is described with the execution and validation process. The fundamental concept of solid tubular expansion had been proven to be sound, but four main development hurdles needed to be overcome. Extensive innovation in design and material selection culminated in two main applications being fulfilled, with subsequent testing proving the absolute success of the technology. These first few steps pave the way to a number of existing commercial applications and our ultimate goal of mono-diameter wells. Introduction Solid tubular expansion technology is the downhole process of expanding the diameter of pipe in situ by means of pumping or pulling a mandrel through it. There are a number of applications for the technology1,2,3,4. One such application is to repair casing and shut-off unwanted fluid entry. The main advantage of using this technology as opposed to conventional means is that it can restore the casing to its original integrity without a significant loss in internal diameter. Methods used previously, such as casing patches or packer straddles, result in severe inside diameter restrictions and have suffered from leaks in the packer or the patches. Expandables were thus seen as a potential innovative breakthrough. Shell U.K. Exploration and Production (Shell Expro), operating in the U.K. sector of the North Sea on behalf of Shell UK Limited and Esso Exploration and Production UK Limited, has been actively involved with the development of solid tubular expansion from the start, and has been working closely with e2 TECH. This was to maximize the learning value and to obtain early experience with the technology prior to its use in their high cost offshore environment. A structured, step-wise approach to technology implementation was followed. Testing the system in test wells was included, both vertical and horizontal, up to a depth of 2,400 ft to fully prove the system in a lower cost land operation prior to the high cost offshore environment of Shell Expro. The fundamental concept of solid tubular expansion had been proven to be sound, but besides the actual expansion process, there were a number of hurdles that needed to be overcome. Among these were (a) to source a suitable pipe material and (b) design connections that are able to withstand the expansion ratios and meet the requirements such as burst and collapse, (c) an anchor and (d) sealing system. Concepts were conceived, developed and tested and many challenges overcome which led to the successful installation of four systems in producing wells. Using a work-over hoist, perforations in both oil and gas wells were sealed off and a clad was installed to act as a shroud for an ESP. Not only did the solutions solve the operators’ problems and increased production, but due to the characteristics of some of the wells, allowed the systems to be tested much more rigorously than would normally have been carried out. Methodology Overview Due to the technology being in its infancy a number of core technologies had to be demonstrated. These were developed with the upcoming application in mind. The design process can be split into two separate design areas. Firstly, the liner system; this is the part that completes the well, consisting of the expandable liner and sealing / holding mechanisms, cone launcher and connections. Secondly, the ‘deployment system’ area; considered the more traditional set of tools, e.g. temporary anchor, disconnect mechanisms, load sub and the expansion mandrel.
A detailed test program was performed with an eccentric tool at the Baker Hughes Experimental Test Area (BETA) field research facility to evaluate the feasibility of its use in an Expandable Tubular Technology application in the North Sea. The testing used a 9–7/8" Drill Out Steerable Ream While Drilling (DOSRWD) tool in conjunction with 6–1/2" pilot bits (both PDC and roller cone). Motor bent housing settings included 1.0°, 1.5°, 1.75° and 2.0° bends to evaluate directional and stability response. Surface speeds were varied from 0, 35, 50 and 75 rpm at each motor housing setting. Caliper logs including four and six-arm and ultrasonic borehole imaging (UBI) tools were used to characterize the borehole under all conditions. The analysis included directional tendencies, down hole vibration monitoring and borehole diameter, quality and degradation over time. The test results show the 9–7/8" DOSRWD system is capable of providing the high quality wellbore required for expandable tubular technology, ensuring the casing can be run, expanded and isolated across the formation. Introduction Expandable tubular technology has the potential to significantly reduce well construction costs. Conventional well construction results in telescoping of the well size from the wellhead down to the reservoir. Apart from resulting in large expensive surface casing, wellheads, trees and operating equipment, the method can result in an unworkable small hole size at the required depth. This could then lead to compromises in well operability or in worst case failure to reach the final objective. Expandable tubulars can help solve difficult drilling challenges posed by high-pressure zones, deepwater environments and troublesome sub-salt plays.1,2,3,4,5 Its innovative characteristics allow operators to explore in remote geologic regions and exploit reserves once considered unprofitable if drilled with conventional technology. Instead of using progressively smaller diameter pipe as drilling progresses deeper, Expandable Tubular Technology allows tubular diameters to be expanded with specially designed "pigs," or mandrels. This reduces well tapering while preserving borehole size. Expandable technology can also extend the profitable life of mature fields by internally cladding existing wellbores to isolate troublesome zones. This developing technology has created a need for improved understanding of the directional tendencies of eccentric drilling tools run on steerable assemblies and the wellbore geometry and quality that can be achieved with these tools. Consistent wellbore diameter is of particular concern for expandable tubulars. If the wellbore diameter is too small, expansion of the pipe with a fixed diameter cone might not proceed properly across sections of firm formation. Worse yet, the expansion cone could become stuck requiring remediation or sidetrack of the well. A wellbore that is too large could affect the sealing effectiveness depending on the sealing system used. For example, a closer diameter tolerance would be required if the seal mechanism is an integral part of the casing (elastomer bonded to the outside of the casing).
Gas wells completed in prolific reservoirs before the advent of bigbore completions do not produce to full potential due to tubing constraints. This phenomenon was observed in several mature, carbonate gas fields offshore Malaysia developed back in the early 1980s. At that time, tubing configuration was limited to 7" completion run in 9 5/8" production casing. Given the size of the production casing, any workover option to enhance outflow performance was limited to recompletion with 7 5/8" tubulars which would result in a 10% gain in well capacity through improved outflow performance.The advent of solid expandable tubular technology in the new millenium has opened up a revolutionary possibility for transforming a conventional well with 7" tubing to a bigbore producer. The concept involves installing and expanding extended lengths of 7 5/8" solid tubulars inside 9 5/8" casing. This will yield a production conduit with a larger internal diameter than conventional 7 5/8" tubulars. Thereafter, gas production occurs through the solid expandables based on a philosophy similar to long casing flow monobores.A field trial to test this novel re-completion concept was carried out in a gas field offshore Sarawak in December 2001. Expected benefit of a re-completion to solid expandable tubulars is a 40-50% increase in well deliverability from prolific reservoirs previously tubing constrained.If proven successful, this novel recompletion design will be extended to other tubing constrained gas wells in the area.The paper will present the results of this field trial, which is the first of its kind in the world. Details encompassing the conceptual solid expandable completion design, modifications and improvisation required for a SET gas well workover, the SET installation sequence and results from the trial will be presented.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
customersupport@researchsolutions.com
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.