A third-generation rotary closed loop drilling system (RCLS) has been introduced in the Norwegian and UK sectors of the North Sea. The initial deployments during May were successful in the Norwegian sector. The new AutoTrak G3 system by Baker Hughes Inteq drilled over 6,000 ft in a single run to TD in 65 drilling hours. The first UK deployment provided the operator with significant financial savings based on previous drilling performance in the field.
The system is a fully modular, automated bottom hole assembly consisting of a steering unit, formation evaluation sub, and a two-way communications module. As with previous-generation tools, this integrated system combines pad steering technology with formation evaluation and drilling optimization sensors. All the system components were extensively re-engineered to improve sensor integration and accuracy, higher levels of 3D steering precision, reservoir navigation capabilities, and enhanced reliability.
Since its commercial introduction in 1997, the RCLS has been used in more than 1,000 wells - drilling 5 million ft and accumulating more than 100,000 operating hours. This third-generation system underwent extensive field trials, logging a total of 6,000 operating hours between October 1999 and April 2002.
New drilling record
A new drilling footage record at Unocal's North Pailin A platform in the Gulf of Thailand was set recently. From spud to completion, Halliburton drilled a record 111,713 ft in 34 days. A total of 12 wells were drilled at an average measured depth of 9,309 ft and an average bottomhole temperature of 284° F; total operating time was 572 hours. Each well was drilled highly deviated with a 3D design in three sections, 11 3/4 in., 8 1/2 in., and 6 1/8 in., using Sperry-Sun's adjustable gauge stabilizer AGS technology in the 6 1/8-in. section. Three of the 8 1/2-in. sections also resulted in individual world records of 831 ft/hr, 850 ft/hr, and 933 ft/hr, plus daily footage records of 5,223 ft and 6,007 ft.
The first three wells were logged using the HEAT Suite quad combo with an operating efficiency of 100% and average logging time of four hours. Logging-while-drilling (LWD) services obtained triple combo data for the remaining nine wells. A total of 41,260 ft of LWD data were obtained. The total time in hole for the LWD tools was 295.75 hours, saving approximately 36 rig-hours. For the 6 1/8-in. sections, a 4 3/4-in. LWD triple combo was used, obtaining an average rate of penetration of more than 400 ft per hour.
The Gulf of Thailand is a highly faulted area, with various pockets of gas and oil found throughout the Thailand-controlled southern portion. Most wells are highly deviated with as many as 12 individual pockets of production in a single well. Unocal produces more than 30% of the total gas in Thailand, with 75% of the gas used for electricity generation.
World record completion
Weatherford International Inc. has achieved a world record 15,100-ft horizontal open hole completion and sand screen deployment in the North Sea Captain field, block 13/22a, while working for ChevronTexaco.
The well's aspect ratio was gauged at 15,100 ft, 4,000 ft longer than prior completions in the area, with a TVD of 2,800 ft. This resulted in an aspect ratio of 4.4, the largest ever achieved drilling for a subsea development from a semisubmersible rig.
Engineers worked closely from conceptual design of the production casing string through the deployment of the open-hole sand screen completion. Additionally, specialized centralizers, completion running string tools and subs were applied to reduce friction and extend the reach of the high angle well and contributed to the achievement.
Plans are underway to use this package on 16 additional wells being drilled by the semisubmersible Sedco 704. The sand screens in well 13/22a-B10y were landed with 65,000 lb remaining above block weight, offering the possibility to extend the reach farther on subsequent wells.
Solid expandable application
A record-length solid expandable tubular (SET) system by Enventure Global Technology has been installed in a Malaysian well. The cooperative effort of Sarawak Shell Berhad and Petronas Carigali resulted in the installation of a record 4,504-ft length of 7 5/8-in. expandable cased-hole liner (CHL) inside 9 5/8-in. casing, which was then expanded to 8.54 in. outside diameter (OD) to replace the existing tubing with a larger production conduit.
Production gains result from large-bore conduits.
The project resulted in four other important "firsts" for the SET system - the first application used to increase production in tubing constrained gas wells, the first technology application in the Asia region, the first application to utilize a wireline retrievable plug, and Shell's first cased-hole liner.
Smedvig's West Pelaut rig was used to run 4,504 ft of 7 5/8-in. by 9 5/8-in. expandable CHL in an E11 offshore gas well located off the coast of Sarawak, Malaysia. The expandable liner was set in a 9 5/8-in., 43.5-ppf casing to a setting depth of approximately 5,000 ft. The system was then expanded using propagation pressures of about 2,100 psi, and pressure tested at 1,600 psi for 15 minutes per regulatory requirements. Post-expansion inside diameter (ID) of the 7 5/8-in. expandable liner was 7.8 in. (compared to a pre-expansion ID of 6.2 in.), while post-expansion yield and collapse are estimated at 5,850 psi and 2,560 psi, respectively. The 7 5/8-in., 29.7 ppf liner expanded 13.9% into the 9 5/8-in., 43.5 ppf base casing, exhibiting a 4.36% reduction in overall length.
In addition to establishing a record expandable length, this project is the first application of this technology used to increase the production capacity of a tubing constrained gas well. By increasing the internal diameter of the tubing from 6.2 in. to 7.8 in, total deliverability of this reservoir will increase.
The installation is also the first to use a wireline retrievable plug to pressure against expansion rather than have to drill out a shoe. In a standard system the plugging device is on the bottom of the liner, has to be drilled out, and is non-retrievable.
To date, 60 solid expandable tubular installations have been completed resulting in expanding a total of 47,139 ft of tubulars and 1,215 proprietary expandable connections.