Abstract

The Liuhua16-2/20-2/21-2 joint oil field in South China Sea development represents a breaking record to the application of a VSD to dual ESP; in that the cable length between the VSD and the motor is 26km; which is 5 km longer than in any current operational systems; a new world's record.

This paper addresses essential design procedures and key points need special attention when deliver VSD long distance drive power system simulation; analysis results have been given. A new contracting strategy to conduct full-scale physical test; testing program and its results have been discussed. Liuhua 16-2 oilfield was put into production in Q3-2020; demonstrating VSD could successfully drive subsea dual ESP over 26km cables. This This proven record will bring more possibilities to exploit the vast resources of deep-water long distance tieback projects; especially marginal reservoir development.

Introduction

Long-distance tie-back of subsea production system is a common economic development mode in deep-water oil and gas field development. When deep-water oilfields are developed by artificial lift; power supply feasibility of electric submersible pumps or multiphase boosting pump could be one of the limiting factors faced if the distance is long (Harrall; 1998).

Track records of VSD direct drive ESP include Liuhua11-1 (0.5km; 1996); Gannet E (14.5km; first oil 1998); Otter (21km; 2003); Jubarte Phase II (4.1km; 2010); Liuhua4-1 (14km; 2012) etc. (Qiu; 2020). To the best knowledge of author; Otter; an oil field located 21km from the host platform; is the longest subsea tieback with dual ESPs completed to date. With the discovery of Liuhua16-2/20-2/21-2 oil fields; operators in South China Sea are risking more ambitious subsea step-outs. Oil from Liuhua16-2 oil field will be driven 26km to FPSO via downhole electric submersible pumps. This is a significant increase on the previous distance record for subsea ESPs in the North Sea; the 21 km between Otter and the Eider platform.

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