"With the push to maximize production from mature reservoirs where the drilling targets are becoming smaller and smaller, we had to find a way of reducing drilling costs and sidetracking from an existing but obsolete well. TTRD is a good way of doing that," said Todd Franks, well engineer, Technology Team, Shell U.K. Exploration and Production. "Developing a rotary steerable system for drilling slimholes will help us reach targets and achieve drilling performance comparable to conventional hole sizes."
The new system will offer a step-change in the cost of drilling with rotary steerable technology when applied through tubing since there is no need to pull the completion string for redrills. The system is expected to reduce the cost of accessing infill-drilling targets and enable the economic recovery of small pockets of trapped hydrocarbons in tough environments, such as existing fields in the North Sea.
"This is an exciting opportunity for Schlumberger, BP and Shell to jointly develop a piece of leading-edge technology," said Ian Searle, senior drilling engineer, BP Exploration Operating Company Ltd. "The system will play a significant role in unlocking additional recoverable reserves and extending the life of the North Sea oil industry."
Schlumberger plans to develop and build the new system by 2005, using its experience with the PowerDrive Xtra(a) 475 rotary steerable system for 6-inch hole size. This technology is unique in that it offers full rotation of the entire drillstring at uniform speed. There are no stationary components to create friction that reduce efficiency. Effectively there is no physical "anchor" to hold up the bottomhole assembly (BHA) during drilling. Efficient flow of drilled cuttings past the BHA ensures fewer cuttings are reground, maximizing rate of penetration.
Adds Paal Kibsgaard, president, Drilling & Measurements, Schlumberger Oilfield Services. "This collaboration with Shell and BP underscores our focused, global approach in implementing drilling strategies and ensures that development of a special application system will progress rapidly from research to product development. The introduction of such a new technology will enable drilling of previously unattainable targets."
Rotary steering with slimhole, through-tubing rotary steerable technology has major implications in mature areas like the North Sea, where the trend is toward field life extension. Cost discipline is crucial on redrills of existing wellbores designed to drain small pools of hydrocarbons. Drilling 6-in. and smaller hole as the primary size for infill sidetracks removes the cost of preparing the well by cutting and pulling the tubulars in place to accommodate a larger hole tool.
The system will be developed and built at the Schlumberger Global Drilling Technology Center located in Stonehouse, Gloucestershire, U.K.
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