Operating Experience With ESP's and Permanent Downhole Flowmeters in Wytch Farm Extended-Reach Wells

Abstract

Summary One-third of the recoverable reserves in British Petroleum CO.'s U.K. onshore oil field, Wytch Farm, lie in an offshore extension of the field. These reserves, which have been undeveloped until recently, are now being exploited with electric submersible pumps (ESP's) in extended-reach wells drilled from onshore wellsites. The relatively high productivities achieved as a result of successful horizontal completions have pushed ESP technology to the limits in terms of capacity and power requirements. This paper presents a case history of the unique set of problems encountered during and subsequent to startup of the ESP's in the first three wells. The problems, in particular pump-suction-blockage problems, were directly attributable to the position of the ESP's in the near-horizontal section (82 to 85°) of the wells. The paper also describes the innovative permanent downhole flowmeter system incorporated in the completion. The system measures and logs flow-rate data, pump-suction and -discharge pressures, and temperature. Examples are presented that clearly demonstrate how these data have been invaluable in understanding the problems encountered in the initial extended-reach wells and the role the system has played in extending ESP run lives. Finally, completion-equipment modifications and operating-procedure changes, successfully introduced to resolve the problems encountered in the first two wells and to avoid them in subsequent wells, are described. Introduction Wytch Farm, on the southern coast of England ˜100 miles southwest of London (Fig. 1), is the largest onshore oil field in western Europe. The main reservoir lies under Poole Harbor and extends offshore under Poole Bay. Poole Harbor has been designated as an area of outstanding natural beauty, with sites of special scientific interest and special protection areas, and is noted for its landscape, ecology, and amenity value.