Drilling advances

	Vol. 225 No. 4
ROBERT E. SNYDER, EXECUTIVE ENGINEERING EDITOR

Deepwater exploration expands. A record number of drilling rigs are working in ultra-deepwater in the Gulf of Mexico. For the first time, 12 rigs are drilling for oil and gas in 5,000-ft water or greater in the Gulf – an important milestone which demonstrates how industry continues to focus on new frontiers. The US is now in its ninth year of sustained expansion of domestic oil/gas development in the deepwater US gulf, and it shows no sign of decreasing, MMS says.

Deepwater oil production rose 535% between 1995 and 2002; deepwater gas production rose 620% over those same years. Production from the Gulf now accounts for more than 30% of all US oil production; and 23% of its gas. Industry made several announcements of new oil/gas discoveries over the last three years. Most notably, there were five announced discoveries in 5,000-ft, or greater, water in 2001, three in 2002 and six in 2003.

Of the 12 rigs drilling in waters deeper than 5,000 ft, eight belong to Transocean, including five drillships and three semisubs; GlobalSantaFe has two drillships working; Diamond Offshore has one semisub active; and Pride has a platform rig working on Dominion's Devils Tower Spar in 5,724-ft water.

US Commission on Ocean Policy report. The Commission will release its Preliminary Report (PR) on April 20. Embargoed copies will be available. Release of the PR is part of a two-stage process. First, the report will be available for review/ comment by the nation's governors and interested stakeholders. Notification of availability of the PR will appear in the federal Register, and will include the date by which comments must be received. An electronic copy of the report and detailed instructions for submitting comments will be available on the Commission website, oceancommission.gov, once the report is released.

As mandated by the Oceans Act 2000 (P.L. 106-256), the US Commission on Ocean Policy will establish findings and make final recommendations to the President and Congress for a coordinated/ comprehensive national ocean policy. The new policy will address a broad range of issues, from ocean governance, to marine resources stewardship and pollution prevention, to enhancing/ supporting marine science, commerce and transportation.

Although the PR will be a work in progress, its findings/ policy recommendations will reflect a consensus of Commission members and put forward what they believe to be a balanced approach.

Powered rotary steerable drilling. Schlumberger Oilfield Services announced the launch of its PowerDrive vorteX rotary  steerable system (RSS) at the recent IADC/SPE Conference in Dallas. The system is the newest addition to the company's PowerDrive family of rotary steerable tools. Unique attributes include a fully integrated, high-torque power section that converts mud hydraulic power to additional mechanical power. Benefits are fast drilling and a reduction in nonproductive rig time.

According to Schlumberger, the power of the rig surface equipment, combined with the downhole high-torque power section of the system, significantly increases available torque, rotation speed, and downhole power at the bit. All available energy is used to drill the hole efficiently and maximize ROP. The system includes an optional inclination hold function which allows a tangent or horizontal section to be drilled automatically, without intervention from the directional driller.

This automatic downhole control makes it possible to drill a hole section at a higher ROP and with greater accuracy than can be achieved with a conventional, surface-operated control setup. In addition to performance drilling in hard rock, the new system is suitable for rigs that lack power to rotate the drillstring during conventional directional drilling. The system takes advantage of the unique full-rotation capability inherent in the PowerDrive product family that offers a number of benefits, the most important being high rates of penetration and good hole cleaning. The integrated power section increases bit rpm and can reduce drillstring rotation speed, reducing downhole vibrations.

Versatile MWD tool. Weatherford has developed a reliable, durable, modular measurement while drilling system that can meet challenges of harsh drilling conditions in underbalanced environments, or the more basic requirements of overbalanced applications. The company set out to develop a system that provides a magnitude improvement in reliability. The result was TrendSET, an electromagnetic measurement-while-drilling (EM/MWD) system that was to be commercially available in 1st quarter 2004.

Providing a reliable system that could work with Weatherford's other underbalanced offerings was a key business driver in initially developing the technology. The UB drilling environment is harsh, characterized by extreme shock and vibration. So the new system's electronics were specifically designed to withstand these conditions. Another requirement was developing a system that could transmit signals through compressible fluids, since conventional mudpulse systems used for MWD have been limited in their ability to perform this function. TrendSET solves this problem with two means of data transmission: E-WAVE electromagnetic data transmission and DuraPulse mud-pulse telemetry. The first serves as the wireless guidance for the UB system, transmitting directional/ formation data from downhole.

Weatherford says the new system is not just for UB and that it contains the full complement of MWD sensors, including directional, pressure, gamma and resistivity, allowing components to be combined for the precise application needed. For instance, in conventional applications, it provides higher reliability and faster data rates than conventional MWD tools. With no moving parts, the sub is more reliable than a mudpulser. The telemetry also allows for higher data rates than a pulser-based MWD system. Additionally, the surface detection software can recognize and filter smaller signals, allowing for greater depth capability. It will work in areas above highly resistive formations, anhydrates or salt zones.

Tool components have undergone more than 500 hr of testing with no failures. Testing showed that the tool was transmitting information at about 10,800 ft, and data compared favorably and accurately to traditional MWD and single-shot data. The integrated system was field tested in mid-December.