Thin oil columns horizontal wells optimization through advance well placement application in west China

Lu Liang is an oil field that has been producing for nearly 10 years. Thus, bottom water level has increased and accumulates remaining unproduced bypass thin oil columns reservoirs within the field. Horizontal well is recognized in rejuvenating these thin oil columns and since the oil column is thin at the top of reservoir with bottom water drive, the placement of the horizontal section near top of the reservoir is the key in avoiding early water break through, minimizing attic oil and optimizing reserve recovery. The team recognized the existing conventionally-steered horizontal wells with standard technology cannot guarantee the optimum placement near reservoir top due to existence of great subsurface challenges. The short-comings to be overcome are: 1. Exiting from the reservoir resulting in low reservoir contact, low drainage area and low recovery factor; 2. Inability to maintain distance to reservoir top resulting in bypassed oil, early water break through and low recovery factor. In this paper, technical assessment and filtration by the team enrooting to the successful selection and implementation of advance Well Placement Distance-to-Boundary technology to overcome the challenges will be highlighted. Subsequently total of 25 and 19 horizontal wells had been completed in 2008 and 2009 successfully and placed within 0.5 m below the verge of reservoir top without exit, keeping the well away from OWC. The success is registered with better Productivity Index based on well performance test done and the wells have been producing more than 90% oil whilst five times increase in production observed since put into production. This application had put the horizontal well in the optimal position possible for draining. Hence, oil incremental and longer production sustainability can be achieved and it has enabled horizontal wells to be economically developed in a thin oil-bearing zone in Lu Liang field and other similar fields in China. Copyright 2010, Society of Petroleum Engineers.