BP Installs First Dual ESP System at Wytch Farm
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Reprinted from: May 2005 issue, pgs 27-29. Used with permission. INTELLIGENT WELL COMPLETIONS SPECIAL FOCUS BP installs first dual ESP system at Wytch Farm Environmentally sensitive location gets downhole backup pump to reduce workover requirement. P. Duffy, D. Cooke, BP; and R. Mackay, D. Whitelock and E. Jamieson, Schlumberger BP has recently installed a is usually charged as an oper- REDA dual electrical submers- ating expense to the well, plat- ible pump (ESP) system from form or field. Consequently, Schlumberger at Wytch Farm cost and frequency of work- oil field, Dorset, England. The overs, when combined with system, designed for redun- lost revenue from deferred oil dant operation, will enable BP production while scheduling a to reduce workover frequency workover, can significantly im- by increasing ESP system run- pact operating costs. This espe- life. Wytch Farm is a mature cially affects the economic vi- field in an environmentally ability of mature fields or other sensitive area. Any reduction marginal developments. in workover frequency is seen The redundant-pump strat- as a big win within BP. egy is intended to reduce the ESPs installed in simi- number of workovers over the lar Wytch Farm wells have life of a well, and, thus, cost. achieved run-lives in excess The Wytch Farm well needing of 1,500 days. Therefore, the a new ESP presented a further new ESP assemblies were de- powerful motive to minimize signed to account for changing workovers—it is located on a reservoir conditions over this small island off the southern period and feature two differ- Fig. 1. Looking east over Poole Harbour, Round Island is in coast of England in Poole Har- ent pump configurations, with the foreground and Furzey Island (oil derrick indicates Wytch bour, Dorset, England, Fig. 1. plans to switch operation be- Farm location) lies beyond. (Photo courtesy J. P. Allen, Images This region has been described tween the two systems in the of Dorset). as, “nationally important . future. Gauges that allow the one of the richest in lowland use of a 24-hr surveillance, Britain for diversity of natural monitoring and optimization companies have been involved in the in- habitats and many important service also were installed. stallation of more than 30 oil well com- nature reserves,” by the Poole Harbour Described here are: the background pletions equipped with two ESPs. The Study Group. Exposure to a potential of dual ESPs to reduce workover costs; second pump is intended as a backup (or HSE (Health, Safety and Environment) need for the dual system in Wytch Farm’s redundant) device to be used should the incident can be directly related to the environmentally sensitive Well L-12; de- first pump fail. amount of well intervention activity un- sign features of the system; and delivery Most of these 30 wells are located off- dertaken by the operator. BP is thus dili- and installation in September 2004. shore, where interventions to replace a gent about minimizing interventions. failed pump involve using a mobile off- BACKGROUND shore drilling unit or an existing platform WYTCH FARM, WELL L12 Over the past eight years, Schlumberger drilling rig. The cost of such an operation Wytch Farm is the largest onshore MAY 2005 World Oil SPECIAL FOCUS INTELLIGENT WELL COMPLETIONS Fig. 2. Today, Wytch Farm oil fi eld comprises eight mainland sites in the southern UK and two on Furzey Island. oil field in Western Europe. The devel- the well and install a new ESP. opment comprises eight mainland well A maximum run-life for the new in- sites, plus two on nearby Furzey Island, stallation was obviously desired. Famil- Fig. 2. The field has 57 wells actively iar with backup ESP systems, BP had producing, plus 26 injectors; it has an es- already considered using this technology timated 500 MM bbl of recoverable oil. to minimize workover costs and prolong First oil was produced in 1960. the economic life of other wells in the Wytch Farm encompasses three pri- Wytch Farm development. Well L12 of- mary reservoirs: Frome at 800 m (2,625 fered both the opportunity to implement ft), Bridport at 924 m (3,032 ft), and a backup system and install two different Sherwood at 1,585 m (5,200 ft). The pump sets in the same well to cope with Wareham and Kimmeridge formations changing reservoir conditions over time. are also oil productive in the area. Well L12, situated on Furzey Island, SYSTEM DESIGN produces from the Sherwood formation. The redundant system used compris- Following a lateral sidetrack in 2003, L12 es two complete ESPs, each deployed on was completed with a single ESP system. a bypass system, Fig. 3. A pump-support After initially producing 5,000 bopd with sub, from which the lower ESP/bypass low water cut, the well declined substan- system is hung, is included at the base of tially to 2,000 bopd and the ESP suffered the upper ESP bypass. premature failure from low flow. To operate the lower ESP, a blanking When considering next steps, uncer- plug is set in a nipple profile below the tainty arose about what rate of future lower Y-tool to prevent recirculation. An Fig. 3. Two complete ESP systems are production to expect. A subsequent ESP isolation tool straddles two other nipple installed in Well L12, each a different workover could result in an oversized profiles, above and below the upper Y- pump confi guration. The lower unit is pump if the well continued to decline, tool. This serves to isolate the upper ESP producing 2,450 bopd with a 38% water cut. BP expects to switch to the upper or an undersized pump should produc- while the lower is operating, and creates unit in about 2.5 years. tion stabilize. Both scenarios had poten- the production flow path, Fig. 4. tial for further workovers in the future, Production can be switched to the up- which would require rig moves at signifi- per ESP by removing the isolation tool cant cost and environmental risk. and installing a second blanking plug The dual-bypass system had to fit In an attempt to avoid such a rig in the nipple profile below the upper Y- within the 9⅝ -in., 40.0-ppf casing and move to Furzey Island, a jet pump was tool. The second blanking plug prevents accommodate the selected 5.40-in. OD installed in a sliding sleeve above L12’s recirculation of the upper ESP during ESP set. To optimize the lower ESP siz- existing ESP assembly. It was thought operation. ing, the largest size of bypass tubing pos- that the jet pump might achieve an ac- The existing lower completion in Well sible was used for the upper ESP bypass ceptable production rate and help char- L12 includes a sliding sleeve. Access to assembly. This was 2⅞ -in. VAM FJL acterize future well performance. The the sleeve was a design requirement for flush-joint tubing. jet pump produced around 600 bopd, any new artificial lift completion. The The nipple sizes in the dual-bypass as- but it also provided time to gather well dual-bypass system was the ideal solu- sembly were dictated by the bypass tub- performance data and hence determine a tion to maintain the intervention path, ing size, and the need to maintain access more accurate rate prediction for an ESP. while enabling a backup ESP system to to the sliding sleeve in the lower comple- A decision was then made to workover be deployed. tion. It was possible to use the standard MAY 2005 World Oil With this in mind, the upper and lower stalled without incident in September ESP assemblies were configured differ- 2004. In accordance with the planned ently. The lower assembly, which will be operating strategy, the blanking plug was used first, includes a 125-hp motor. The set in the lower system telescopic swivel upper assembly includes a 150-hp mo- nipple, and the isolation tool was set tor and additional pump stages so that across the top nipple and upper telescop- the target flow rate can be maintained ic swivel nipple, isolating the upper ESP when water cut increases. An advanced and creating the flow path for the lower gas handler will accommodate the pre- ESP. The lower ESP was started and is dicted rise in gas-to-oil ratio over time. producing 2,450 bopd with a water cut BP expects to switch production to the of 38%. WO upper ESP system after about 2.5 years to maintain optimal performance as con- ACKNOWLEDGMENT ditions change. The authors thank the managements of BP and Included with each of the ESP as- Schlumberger for permission to publish this article. semblies is a Phoenix MultiSensor, Type 1 gauge, which measures pump intake THE AUTHORS pressure, pump discharge pressure, in- P. Duffy, well operations lead for BP in Wytch take temperature, motor winding tem- Farm, holds a bachelor’s degree in engineering perature, vibration and current leakage. from the University of Liverpool, England. He has worked in a variety of petroleum and well engineering positions within BP for 15 years. SYSTEM DELIVERY He is a chartered engineer, and member of the To coincide with planned rig move- Institution of Mechanical Engineers. ments, and avoid additional rig moves, D. Cooke, senior completions engineer for BP BP wanted the workover to occur just in Wytch Farm, holds a bachelor’s degree in six weeks after placing the order for the mining engineering from the Camborne School dual-ESP system. With this in mind, the of Mines, England. He has worked in a variety system was designed to use standard 9⅝ - of completion engineering positions with ser- in.