Unique Aspects Encountered Drilling a Record Setting Extended Reach Well in China

Abstract

Abstract In 1997 Phillips, with its partners China National Offshore Oil Corporation and Pecten Orient Company, drilled the Xijiang 24–3-A 14 extended reach well from its XJ 24–3 platform in the South China Sea, offshore China. This well set a world record with a horizontal displacement of 26446 ft. Measured depth at TD is 30308 ft. This well was needed to gain access to reserves in a satellite field some 5 miles from the platform. The reservoir is a series of stacked sands. An S-shaped well with an 80° tangent to near the top of the first reservoir dropping to a 54° inclination by TD was required to hit each of these sands within the closure. In addition to difficulties such as target tolerance, torque and drag, hole cleaning, and wellbore stability, normally expected in extended reach wells, this well presented a number of unique problems. Among the unique problems were the relatively small size of the platform and the platform drilling rig, the lack of extended reach wells in the area, the limited oilfield infrastructure resulting in long lead times, and the near exploratory nature of the well. This paper will discuss the drilling and completion of the well and how Phillips addressed each of these problems. A comparison will be made between the experiences of this well and Phillips experiences on extended reach wells in the UK North Sea. Introduction Phillips drilled the 24–1–1x exploratory well in South China Sea block 1511 1 in 1985. This well found oil in II different sands within the Hanjiang formation. The pay thickness totalled 141 ft. Testing showed the sands to be normally pressured with a high flow capacity. The reservoir fluid was a waxy crude oil with API gravity ranging from about 34° to 38° and no associated gas. Pour point of the oil was 90° - 110°F. Additional drilling in the area discovered the 24–3 and 30–2 fields. Plans for developing these two fields were formally approved in January 1992. The fields are located some 80 miles southeast of Hong Kong in 330 ft of water (Fig I). Two platforms were installed and development drilling began in 1994. A total of 26 development wells, including 2 horizontal wells were drilled and completed by the summer of 1996. During the design phase in 1991, attempts were made to include the accumulation found by the 24–1–1x in the development plan, however the small reserve size would not justify a separate platform. At the time drilling an extended reach drilling well from the 24–3 platform some 5 miles away was considered unachievable. By the fall of 1995 the envelope for extended reach wells had been expanded by several operators in the North Sea. Phillips was among the group of operators developing confidence and experience in extended reach drilling techniques. The improvements in extended reach capabilities led Phillips and its partners to rethink the potential of drilling an extended reach well. A team was formed to study the feasibility of drilling the extended reach well. The team included representatives from Phillips, its partners China National Offshore Oil Corporation and Pecten Orient Company, and several service companies.