Exxon Mobil Corp. subsidiary Exxon Neftegas Limited (ENL), has completed drilling of the Z-11 well, the longest measured depth extended-reach drilling (ERD) well in the world. Located on Sakhalin Island offshore Eastern Russia, the record-setting Z-11 achieved a total measured depth of 37,016 ft (11,282 m) or over 7miles.


The multiphase Sakhalin-1 project includes the Chayvo field which is located 5 to 7 miles (8 to 11 km) offshore. The Z-11 was drilled to the Chayvo reservoir from the Yastreb rig, the world's largest land-based drilling rig. Overall, the Chayvo field reached its peak production rate of 250,000 b/d of oil in February 2007 after an on-schedule startup in October 2005. The Z-11 is the 17th ERD producing well to be completed as part of the Sakhalin-1 Project. It was drilled in 61 days, more than 15 days ahead of schedule and below expected cost with no safety or environmental incidents.


Since the first Sakhalin-1 well was drilled in 2003, the time required to drill these world-class wells has been reduced by more than 50%. When compared to industry benchmarks, Sakhalin-1 wells are the world's fastest drilled ERD wells.


"ExxonMobil, through the operatorship of Exxon Neftegas Limited, is pleased that the Sakhalin-1 Consortium achieved this record-setting milestone," said Neil Duffin, president of ExxonMobil Development Company. "Our consortium is committed to the continuing development of the Sakhalin-1 Project which will require significant investment, planning, execution, operating expertise and the employment of leading-edge technology."


The project team applied ExxonMobil proprietary technologies, including Integrated Hole Quality (IHQ) technology and the Fast Drill Process, to deliver the Z-11 well.


"The physics based modeling and experimental validations of our IHQ technology allowed us to successfully design and drill the Z-11," said Steve Cassiani, president of ExxonMobil Upstream Research Company. "With this technology we were able to take into account a broad range of interdependent design variables including rock strengths, stresses, and wellbore hydraulics to successfully drill this well."


Used in conjunction with IHQ technology was an optimization process called Fast Drill, which is a unique energy-based analysis tool and work process that allows rig site and drilling engineering personnel to maximize performance in every foot of hole drilled.


The Sakhalin-1 Project will bring significant economic benefits to Russia including over US $50 billion in direct revenues to the Russian state, major infrastructure improvements, technology transfer and the supply of natural gas to customers in the Khabarovsk Krai in the Russian Far East. Notably, over 80% of the Sakhalin-1 Project drilling rig operators are Russian nationals and project contract awards to Russian companies have reached approximately US $3.8 billion.


Exxon Neftegas Limited (30% interest) is operator for the project, which includes the Japanese company Sakhalin Oil and Gas Development Co. Ltd., (30%); affiliates of Rosneft, the Russian state-owned oil company, RN-Astra (8.5%), Sakhalinmorneftegas-Shelf (11.5%); and the Indian state-owned oil company ONGC Videsh Ltd. (20%).


Source:ExxonMobil


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