This paper presents the performance of Electrical Submersible Pumps (ESPs) in the Wafra field within the Divided Zone Kuwait-Saudi Arabia and covers the period of 4 years started in 1998 - December 2001. Included are the historical failures of ESPs, analysis of failures and some solutions that have helped to reduce the number of failures and that in-turn increased ESP run lives/reduced deferred oil production/saved rig cost/time.
Main reservoirs in the DZ area producing with ESPs include Wara/Burgan sands and Ratawi carbonates. Some ESPs are also operating in heavy oil carbonate Eocene wells, Ratawi limestone in south Fuwaris and Marrat carbonate in Humma field. As these reservoirs are of different lithologies, depths and flow rates vary from 1,000 to 9,000 bfpd, thus all series/types of ESPs have been run.
Tables and plots demonstrate/analyze total number of ESP failures by each reservoir / equipment / components types, mean time to failure (Average Run Life), ESP listings. In summary, it is shown that ‘Mean time to failures’ (Average Run Life) significantly increased from 157 to 370 days within this 4 year period.
ESP completions in Wara sands presented the biggest challenge to reduce ESP failures due to high sand volume erosion. New material design for ESP defined as ARM-COMP "Abrasion Resistance Material- Compression" was utilized successfully. In other reservoirs, new designs of ‘Slim Hole’ ESPs, ‘Shrouded Motors’, ‘Pump Optimizations’, ‘Stimulation jobs to increase intake pressure’ have been used to overcome frequent burnt motor, pump plugging etc., problems. Also, ESP XGC Gas Handler for high GOR wells was successful.
Divided Zone Group (DZG) pursue exploration and optimum development of hydrocarbon resources of the Divided Zone (On-Shore) through Joint Operations (JO). The Divided Zone field is producing using artificial methods (Sucker rod pump & Electrical submersible pump). The focus of this paper is on the performances of electrical submersible pumps in period of 4 years started in 1998 until Dec.2001.
Main producing reservoirs in the DZ area include Wara/Burgan sands and Ratawi carbonates. Some ESPs are also operating in heavy oil carbonate Eocene wells, Ratawi limestone in south Fuwaris and Marrat carbonate in Humma field. As these reservoirs are of different lithologies, depths and flow rates vary from 1,000 to 9,000 bfpd, thus all series/types of ESPs have been run.
The total number of ESPs installed at the end of year 2001 in DZ was 251 and the common reasons of ESP failures and approximate percentages are:
Motor Failures (40%)
Pump Failures (22%)
Cable Failure (26%)
The following case studies for wells in Ratawi and Wara Reservoirs will be presented. These wells had ESP failures either due to high GOR or excessive sand production.
Slim hole pump - Ratawi Reservoir - Case1.
Shroud Motor & XGC gas handler- Ratawi Reservoir - Cases 2 & 3.
Abrassion Resistance Material (Floater&Compression)-Wara Sand Reservoir Case 4 & 5.