OPERATING EXPERIENCE WITH ESP AND PERMANENT DOWNHOLE FLOWMETERS IN WYTCH-FARM EXTENDED-REACH WELLS

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 fie ld. These reserves, which have been undeveloped until recently, are no w being exploited with electric submersible pumps (ESP's) in extended- reach wells drilled from onshore wellsites. The relatively high produc tivities achieved as a result of successful horizontal completions hav e pushed ESP technology to the limits in terms of capacity and power r equirements. This paper presents a case history of the unique set of p roblems encountered during and subsequent to startup of the ESP's in t he first three wells. The problems, in particular pump-suction-blockag e problems, were directly attributable to the position of the ESP's in the near-horizontal section (82 to 85 degrees) of the wells. The pape r also describes the innovative permanent downhole flowmeter system in corporated in the completion. The system measures and logs flow-rate d ata, pump-suction and -discharge pressures, and temperature. Examples are presented that clearly demonstrate how these data have been invalu able in understanding the problems encountered in the initial extended -reach wells and the role the system has played in extending ESP run l ives. Finally, completion-equipment modifications and operating-proced ure changes, successfully introduced to resolve the problems encounter ed in the first two wells and to avoid them in subsequent wells, are d escribed.