February 2000 Vol. 221 No. 2  Drilling

Robert E. Snyder,  Editor

Big merger completed, new offshore technology

The world’s largest offshore drilling contractor and the third largest oilfield service company was officially created on December 31, when Transocean Offshore completed its merger with Sedco Forex, and the latter was spun off from its parent, Schlumberger. In the merger, about 109.6 million ordinary shares of Transocean Offshore are being issued to Schlumberger stockholders, who will hold about 52% of Transocean Sedco Forex; but Schlumberger has no ownership interest in the new company.

Victor Grijalva, appointed chairman of the board said, "Transocean Sedco Forex possesses critical mass in all seven major operating regions of the world, allowing it to create additional offshore drilling efficiencies, including the industry’s largest fleet of deepwater drilling vessels." J. Michael Talbert, appointed president and CEO, added, "Customers will benefit from the modern, versatile and geographically diverse fleet, totaling 74 mobile offshore drilling units." Other appointments include: Jean P. Cahuzac, executive VP and president of Europe, Middle East and Africa operating regions; and W. Dennis Heagney, executive VP and president of Asia and the Americas operating regions.

New drilling / completion fluid. In December, Cabot Corp. announced major applications of Cabot Specialty Fluids’ new cesium formate drilling / completion fluid. The high-density, solids-free fluid was successfuly used in a record well completion operation for Total Oil Marine in the UK North Sea, conducted on TotalFina’s Dunbar platform. The field is operated by Total Oil Marine, with partner Elf Exploration UK.

The D22 well utilized 15.9-ppg cesium / potassium formate in a completion operation on an extended-reach well drilled from the platform. Engineers turned to the new mixture after initial attempts to complete met with sustained and costly difficulties. The well was initially drilled to 24,124 ft MD, and a horizontal displacement of 18,553 ft. The new fluid provided the required density and a solids-free environment; it was easy for crews to handle and featured a low coefficient of friction, which aided the completion, and running of CT strings into the long, highly deviated well.

Another major application for Elf Exploration UK was conducted on Elf’s Elgin / Franklin development in the Central North Sea. The field is considered the most challenging high-pressure, high-temperature development yet undertaken in the North Sea. The 22/30c-G3 well utilized 18.3-ppg cesium formate. The well had a measured depth of 21,143 ft MD, a TVD of 18,050 ft, with a maximum deviation of 45°.

The well was originally suspended with low-toxicity oil-mud which, upon re-entry, was displaced to synthetic oil-based mud. This subsequently exhibited severe barite sag, a problem difficult to manage in solids-laden fluids at high temperature and high deviation. Concerned with the temperature effect on solids-laden fluids, Elf turned to the new fluid earlier than originally planned. The fluid was shown to be compatible with all major elements of completion equipment.

Alwyn North drilling program. Aberdeen-based KCA Drilling, a UK subsidiary of Abbot Group, has completed the handover program for the TotalFina-operated Alwyn North platform. KCA crews have taken over responsibility for the operation and maintenance of the rigs and are now an integral part of the platform team. One crew of 43 is in place and operating one rig. Following modifications, additional KCA personnel will join the crew, allowing both rigs to operate simultaneously.

Initial operations have involved completion of a perforation program on Well N39 and a workover on Well N10 as part of the Alwyn miscible gas project. The workover program will continue on three additional wells, followed by a shutdown in March to complete rig modifications. Following the shutdown, one rig will be involved in the miscible gas injection workover program, or coiled tubing drilling; the other will commence the field’s ambitious Triassic ERD program, planned to extend into 2003.

New offshore publication. In December, Simmons & Company International and Bassoe Offshore consultants published the inaugural issue of The Offshore Driller. The publication, in slick-cover format is intended to appear monthly, arriving before the 10th. The first issue features some 12 pages of useful statistics, including summarys of offshore drilling stocks, rig supply / demand, dayrates and a rig fleet summary.

The following 33 pages review selected drilling contractors (10 in the first issue), including fleet listings with rig types, work areas, contract endings and current net asset valuations. Also included are a newbuild rig summary table and recent rig purchases / sales. For more information, contact Jennifer Hu at: 713 223 7840. The Offshore Driller is also available on the two companies’ web sites: www.simmonsco-intl.com or www.bassoe.com.

Openhole sidetrack. BJ Services has successfully completed a contract for Total Oil Marine (operator) and partner Elf Exploration UK for the provision of coiled tubing, pumping and engineering services to a CT sidetrack on Alwyn North platform Well 3/9A-N30 in the North Sea. The CT team for the project comprised Total as operator and project leader; BJ providing CT services, engineering services, fluids and solids control; Baker Hughes INTEQ providing directional services and drilling assemblies; and Baker Oil Tools providing window-milling equipment and fishing services.

According to BJ, it is one of the deepest sidetracking operations ever carried out in the North Sea, at depths of up to 4,000 m (13,120 ft). The operation was technically very challenging because of the depths and the well architecture, which was complicated by reservoir location with respect to the exit from the motherbore. The well trajectory was required to turn in azimuth through 180° and build angle to horizontal.

The well was completed using the actual coil used to drill the well. This was perforated and used as a liner for the newly drilled open hole. The well was then put on production.

Copyright © 2000 World Oil
Copyright © 2000 Gulf Publishing Company