To address the unfavorable thermal recovery factor of abundant ultra-viscous oil resources using vertical and horizontal wells in Xinjiang's Fengcheng Oilfield, Steam-Assisted Gravity Drainage (SAGD) parallel horizontal wells were experimentally drilled in block A in 2008, which delivered on 100% encountering rate of oil formations and controlled the wellbore trajectories within the design. However, the production witnessed difficulties in setting oil well pumps and insufficient submergence depth. To tackle this issue, a drilling test to connect one of the SAGD parallel horizontal wells and the vertical well was performed. With several pioneering technologies in China, the test succeeded and created a new technological approach for the development of ultra-viscous oil in Xinjiang Oilfield.

This paper describes the principle, process, and equipment of the drilling technology in the test, analyzes the field results of the section milling of large size casing, under-reaming of the intersection interval, intersection between a horizontal well and a vertical well, and down-hole gravel packing, and presents comments on the field application and future development of the technology.

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