Extended-Reach Drilling Techniques Find Application in Liu Hua Oil Field

Liuhua 11-1 oilfield is one of the assets of CNOOC, developed in 1995. In 8 years of production, the water cut has increased significantly (average water cut of 90%) with oil production rate continuing to decline, at the production declining rate, the economic life of Liu Hua 11-1 oilfield was expected to end in year 2002. Steps were taken in order to extend the economic life of the field. These include some infill sidetrack wells from the old wellbore to new target reservoir, but the result was not significant. In 2001, an infill ERD project was initiated to use the existing old wellbore to sidetrack to the East Wing structure of the oil field; the structure is about 4.5km from the existing main facilities. 6 ER wells have been drilled so far and the result was excellent. The ERD technique has created a few records in Chinese oil and gas industry. With respect to a VS/TVD ratio B3 ERW4 has created the largest in China (4.58), ranks within the top 25 worldwide extended reach wells but significantly from a floating production system this well ranks within the top 10 wells, in terms of this ratio. This infill ERD project has been proven to be very efficient and economical to Liu Hua 11-1 oilfield to develop the shallow satellite oilfields surrounding the main structure. The successful of these extended reach wells has increased the production and extended the economic life of the Liu Hua oilfield, at the same time, this has been a first experience and technical breakthrough for a Chinese oil company in extended reach well drilling. This paper highlights the drilling challenges in Liuhua 11-1 Extended Reach Well infill drilling campaign, and the application of drilling optimization, well placement process that has been successfully executed for the project.