TX 75083-3836, U.S.A., fax 01-972-952-9435. AbstractComposite bridge plugs (CBPs) save operator time and money by enabling quick and easy installation and removal. CBPs can be installed under pressure in multi-zone, commingled gas wells without using expensive formation kill weight fluids. Kill weight fluids can reduce production from the well, and in some cases have damaged newly fractured zones to the extent that production has been cut in half. After remedial operations, CBPs can be removed using coiledtubing-conveyed milling equipment in one fourth of the time required to mill traditional cast iron bridge plugs. Formation damage can be substantially reduced using low viscosity milling fluids that easily remove composite cuttings from the wellbore. This is especially important because of the low annular velocities characteristic of coiled tubing operations. The wellbore is left cleaner than those using cast iron bridge plugs in similar operations. CBPs can withstand high pressures for up to 10 days without compromising their pressure integrity and without the need for a cement barrier on top of the CBP. Initial field runs have demonstrated that the CBPs can be milled as quickly as 30 minutes compared to 2 hours for milling conventional cast iron bridge plugs. Multi-zone, commingled gas wells using as many as 7 CBPs have been brought back on production after taking only 12 hours to remove all CBPs, including rig-up and rigdown of the coiled tubing unit. Field runs also indicate CBPs can be milled quickly when set at depths exceeding 19,000 feet.
fax 01-972-952-9435. AbstractMetal-to-metal sealing technology is an innovative type of medium to high expansion seal that uses compliant metal as a pressure barrier and incorporates an extraordinary seal performance envelope that cannot be achieved by conventional elastomeric seals. Zonal isolation tools, including bridge plugs and straddle systems, using metal-to-metal sealing technology in place of conventional elastomers may radically challenge existing engineering philosophies by providing a pressure sealing system capable of exceeding the limitations of other existing sealing technologies and eliminating many traditional elastomeric failure modes.The metal-to-metal seal has the potential to change the way downhole equipment provides pressure integrity during pressure pumping operations by utilizing a controlled application of load to expand the metal seal to achieve a fully formed pressure barrier which allows for the metal-to-metal seal in bores of up to 160% of the original seal diameter.In the well servicing market, recent applications of the metal-to-metal seal and the latest lab testing have suggested the prospective of the technology for products for not only the conventional markets but also in the hostile HPHT arena. Metal-to-metal sealing technology could make well suspensions and intervention possible in hostile HPHT wells that were previously deemed inoperable by the complete removal of elastomers from the design. Demonstrating versatility in applications on land to deepwater locations, metal-to-metal sealing devices can be easily deployed on slickline, electric wireline, coiled tubing, or drill pipe to save operator rig time in areas where cost savings are critical.Case studies of the high performance characteristics of the metal-to-metal sealing technology in terms of design, testing, and implementation will recognize its alignment in regards to conventional elastomeric sealing technologies as well as high-expansion inflatable technology.
In 2008, ConocoPhillips completed the plug and abandonment (P&A) of two of eight water injection wells at the 2/4 W Platform in the Norwegian sector of the North Sea. The average performance was 65 days per well. One of the most challenging aspects of the 2008 P&A campaign was deep section milling of the casing to install the secondary reservoir barrier where multiple section mill runs were necessary. In mid-2009 ConocoPhillips resumed operations to P&A the remaining 6 wells. The scope to P&A the remaining 6 wells was increased to include a second barrier across the Miocene which called for more section milling than the first campaign. ConocoPhillips management challenged the rig team to significantly improve performance on the second campaign. Performance on the final six wells improved dramatically to an average of 46 days. P&A requirements called for section milling 165 feet of 9 7/8" casing at depths ranging from 8,585 ft to 10,896 ft. A joint ConocoPhillips and Baker Hughes team was formed to seek a method to significantly reduce the time required to mill the casing for the second campaign. The team set an aggressive goal of milling the section in one run. In addition a plan would be needed for additional section milling to achieve the second Miocene plug as well as potential for 13-3/8" milling to achieve adequate isolation.Two new technologies were implemented to improve the performance of section milling operations during the P&A campaign. A new cutter technology that had shown significant impact resistance and longer life than previous cutter technology was installed on the section mill blades which demonstrated increased resistance to wear and improved chip breaking ability. In addition, a new downhole optimization sub was included in the BHA that gathered information at the section mill and sent the data back to surface in real-time for on-site evaluation by engineers.These two technologies significantly reduced rig time due to the longer lasting cutters as well as the real-time data transmitted back to surface from the downhole optimization sub. The information from the optimization sub was evaluated onshore during the entire P&A campaign and operational improvements were made as each successive well was completed.
fax 01-972-952-9435. AbstractMetal-to-metal sealing technology is an innovative type of medium to high expansion seal that uses compliant metal as a pressure barrier and incorporates an extraordinary seal performance envelope that cannot be achieved by conventional elastomeric seals. Zonal isolation tools, including bridge plugs and straddle systems, using metal-to-metal sealing technology in place of conventional elastomers may radically challenge existing engineering philosophies by providing a pressure sealing system capable of exceeding the limitations of other existing sealing technologies and eliminating many traditional elastomeric failure modes.The metal-to-metal seal has the potential to change the way downhole equipment provides pressure integrity during pressure pumping operations by utilizing a controlled application of load to expand the metal seal to achieve a fully formed pressure barrier which allows for the metal-to-metal seal in bores of up to 160% of the original seal diameter.In the well servicing market, recent applications of the metal-to-metal seal and the latest lab testing have suggested the prospective of the technology for products for not only the conventional markets but also in the hostile HPHT arena. Metal-to-metal sealing technology could make well suspensions and intervention possible in hostile HPHT wells that were previously deemed inoperable by the complete removal of elastomers from the design. Demonstrating versatility in applications on land to deepwater locations, metal-to-metal sealing devices can be easily deployed on slickline, electric wireline, coiled tubing, or drill pipe to save operator rig time in areas where cost savings are critical.Case studies of the high performance characteristics of the metal-to-metal sealing technology in terms of design, testing, and implementation will recognize its alignment in regards to conventional elastomeric sealing technologies as well as high-expansion inflatable technology.
This paper will focus on a project to redevelop a wireline deployable metal-to-metal seal, ISO 14310 VO qualified, retrievable bridge plug system to allow it to be conveyed successfully in a high rate gas well for acid stimulation zonal isolation operations. Functionality of the original system including the plug and hydrostatic setting assembly had previously been tested in a fluid environment yet envisioned for a gas well application. Initial well installations gave results that led to a reconsideration of the forces being generated by the running and pulling tools due to the differences between a gas and a fluid environment and their impact on system reliability and functionality. The paper will discuss some of the problems discovered with the system for this particular application and the system redesign over a one-year period, which included a number of qualification tests performed at near to real well conditions. This discussion will include information on the complexities of performing such tests and the solutions used to develop a successfully qualified "fit-for-purpose" redesign. The paper will conclude with a high-level overview of the system's first deployment in an actual field well application. Introduction In mid 2006, the operator ran a specifically developed high expansion, retrievable, metal-to-metal (MTM) bridge plug on three 7-in. monobore wells to provide mechanical zonal isolation for high rate, multi-stage acid treatments. The acid stimulation objectives in these three wells were fully met and the MTM seal performed to expectations; however, there were significant operational problems related to the plug system. The MTM bridge plug had been selected due to previous operational problems with conventional elastomeric element type retrievable bridge plugs as well as a number of advantages that the technology presented over these conventional types of plugs for the operator's specific application. Over the course of a year, the system was redesigned to address specific findings from those initial operations. The redesign involved modifications to the plug and the inclusion of additional components and functionality in the running and pulling tools to ensure repeatable system reliability and operability. Final system qualification was extensive and more comprehensive than normally performed for such a system. The redevelopment program and qualification testing demonstrated the importance of testing complete systems at conditions representative of those that would be encountered in actual well operations. Repeat testing was important to establishing system reliability. It also highlighted the need for a project-based approach with clear communication on a regular basis between multi-disciplinary, cross-functional teams. Completion and Reservoir Overview The operator has implemented two different types of big bore wells to deliver high flow rates. The well types are a 7-in. tubing monobore and a 9" x 7"-in. tubing optimized big bore (OBB). They are shown in Fig. 1. The reservoir formations are cased and cemented behind a 7-in. production liner in both types of well. Typical well deviations are approximately 55º. The reservoir formations have significant vertical extent and are initially over-pressured but at moderate temperature. Reservoir pressures may vary between zones and this causes cross flow between completed reservoirs. To produce at the design rates for an extended period, high volume matrix-rate-multi-stage (MRMS) acid stimulations are required. The substantial reservoir heterogeneities combined with the significant vertical extent of the productive zones present extreme challenges for acid treatments for all zones.
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