Captain Field Electric Submersible Pump, Condition Monitoring And Completion Systems
Authors: Cohen D.J. 
Published: October 2008

The Captain Field has been developed with high volume ESP systems, designed for maximum reliability. The process involved integration of new technologies and production practices to the development of high horsepower systems for viscous oil wells and aquifer lift.

This paper describes the key aspects of the design and implementation of the artificial lift systems employed in the development of this offshore field using horizontal wells in unconsolidated sand Appraisal well testing results were used to develop key facility and well functionality, and development of a performance based incentive pump supply contract. Electrical testing demonstrated suitability of electrical penetrator systems for high amperage service. System selection and sizing integrated specially designed full scale multiphase loop performance testing with viscous crude. Completion equipment selection targeted systems to add flexibility for extending pump run times.

New downhole monitoring systems were developed integrating ESP condition monitoring with downhole flow and reservoir performance evaluation. Surface control systems integrated downhole and surface parameters to optimize performance and protection of equipment. Special operating guidelines were developed and utilized during the early production phase for troubleshooting, optimization ofwell performance and reservoir evaluation.

Introduction

The Captain Field is approximately 90 miles north-east of Aberdeen, Scotland in the UK Continental Shelf Block 13/22a. The field was discovered in 1977 and it was clear that economical extraction of the low density (19 API), viscous (88 centipoise), low gas oil ratio crude oil, from a shallow field (3000 ft depth) with a large area extent (7.3 miles × 3.3 miles) would not be easy. The permeable, unconsolidated, thin sands (100 ft) were underlain by water in portions of the field

Not until appraisal testing conducted in 1990 and 1993 using electrical submersible pumps and long horizontal wells with prepack screens, was it clear that these technical challenges could be overcome. During 1993, a ten well appraisal program, including an extended well test of a field development prototype well, water coning test, field delineation drilling, and topsides definition engineering was successfully completed.

Conclusions from this program indicated that successful field development would require horizontal wells up to 6,000 ft long, artificial lift systems to deliver 15,000 BPD from each oil well producer. It would require sand control well completions, the capability of performing production logging and coiled tubing intervention of the horizontal completions. It would require high temperature and high retention time fluid separation equipment to treat 60,000 BOPD and 200,000 BWPD, and a single aquifer lift well to deliver 60,000 BWPD make up water for waterflooding at full voidage replacement. The field would be developed in two stages, with the main western section developed first with a Wellhead Protection Platform (WPP), producing via subsea pipelines to a Floating Production, Separation and Offloading (FPSO) vessel.