May 2001 Vol. 222 No. 5  Drilling

Robert E. Snyder,  Editor

Offshore rig deliveries, new drilling technologies

As reported in the Offshore International Newsletter, 2001 will see essentially the final year of the new offshore rig construction surge that started in 1996, with contractors taking delivery of 15 – 16 new offshore rigs, many originally slated for delivery in 2000 or earlier. Several of these deliveries have been beset with operator contract cancellations or construction disagreements that have required special negotiations.

TransoceanSedcoForex inherited three under-construction semis in its acquisition of Sedco Forex – Sedco Express, Cajun Express and Sedco Energy. The three, which will be delivered in the first and second quarter, had contracts, but the Sedco Express deal was cancelled by TotalFinaElf, and negotiations are continuing.

Transocean also took delivery of its Discoverer Deep Seas drillship earlier this year – it is working for Chevron. And semi Deepwater Horizon is mobilizing to the GOM. Ocean Rig and Friede Goldman have been struggling with construction of semis Eirik Raude and Leiv Eiriksson. A new agreement should see the two out of the yard this year.

Four more-or-less identical semis are due to be delivered to Pride International and Petrodrill Construction this year. Pride will take delivery of the Pride Carlos Walter and Pride Brazil, to drill for Petrobrás in May and June, respectively. Petrodrill expects to take delivery of semis Amethyst 4 and Amethyst 5 in September and December, respectively, with both rigs committed to Petrobrás. And around mid-year, Stena Drilling will take delivery of semi Stena Don, for a five-year contract with Statoil.

For other rig types, Smedvig will take delivery of a new semi tender rig, and Rowan and Ensco International each will take delivery of a newbuild jackup. Smedvig’s West Alliance is scheduled for October delivery; jackups Ensco 102 and Rowan Gorilla VII both have year-end delivery dates. None of these three units yet has a contract.

Drilling up in Texas. The Railroad Commission of Texas says it issued a total of 1,082 original drilling permits in February 2001, compared to 884 in February 2000.

Drilling permits for 2001 to date, total 2,223, up from 1,614 during the same period in 2000. The February total included 817 permits to drill new oil and gas wells, 36 to re-enter wellbores and 229 for recompletions. Permits issued in February included 313 oil, 301 gas, 439 oil/gas, 23 injection and six other permits.

In one example hot Texas area, Anadarko Petroleum announced that it plans to spend $535 million during 2001 to expand its operations in the East Texas Bossier gas play. This year’s planned Bossier spending for the operator is up 32% over last year. About $420 million will go toward drilling / completing 36 exploratory and 186 development wells in the play. Also included is more than $100 million for lease acquisition, expansion and upgrades of gathering lines and treating facilities.

Anadarko currently has 27 rigs drilling for the Bossier sands in East Texas, and six drilling a similar type play in Jackson Parish, Louisiana. In January, Anadarko drilled its 300th well in the Bossier.

New drill fluid application in North Sea. Cabot Corp. has announced a major milestone in development of its new Cesium Formate drilling and completion fluid. The high-density fluid was successfully used to drill and complete a reservoir section of a well in Huldra field in the Norwegian North Sea. The field, operated by Statoil, is considered one of the most challenging HP/HT developments yet undertaken in the Norwegian North Sea.

The well utilized the 16.28-ppg, CF-based fluid to drill, and then complete, the reservoir section with sand screens, where reservoir pressure / temperature exceeds 9,700 psi and 285°F. An 8-1/2-in. hole was drilled through the reservoir at 45°. During drilling, mud properties were stable, with little or no maintenance required. Drilled cuttings integrity and hole conditions were good, with no indications of instability in the exposed shale sections above the reservoir.

After logging, the fluid was screened over 400-mesh screens to remove coarse solids, and the wire-wrapped screens were run "smoothly." This successful new application in the Norwegian North Sea follows the fluid’s extensive use during completion operations in the UK sector for Shell, Total and Elf.

Wireline ram design. The UK’s Elmar Services Ltd. has introduced a new proprietary design of wireline BOP ram. The Q-Guide is a new design, capable of shutting off well pressure by reliably guiding and sealing wireline typically entering the BOP at a non-parallel angle. The design is also capable of employing Elmar’s new Multiline Inner Seal to allow switching between slickline, electric-line and fishing operations without having to change rams.

Recent reports have pointed to difficulties in traditional ram designs when wireline enters at certain angles to the BOP bore axis, which can often occur in deviated wells. If the rams close before the wireline is positioned in the line groove, the cable can be trapped and damaged, thus reducing safety and integrity of the operation. This problem has occurred in the field, and it has been confirmed in trials conducted by Elmar. It is found to be more likely to happen with large-bore BOPs, e.g., 4-in. ID and larger.

The new ram, on closure, provides a positive alignment for the wireline. Special guides on either side of the inner seal restrict the wireline so that the section of line contacting the seal is always centered and parallel to the BOP axis. These rams will be supplied as standard for all future Elmar wireline BOP orders. The new inner seals can be used with the guide to create a universal "multiline" ram. Although the line groove in the inner seal is sized for 5/16-in. line, the seal is able to seal around any line from 0.092 to 0.312-in. OD.

The new guide demonstrated excellent reliability in field trials conducted in late 2000. The seal has already been used with success in the North Sea, Gulf of Mexico and Asia Pacific, for a number of major service companies.