Successful Development of Residual Gas Condensate Reservoir using First ESP in Deep High Pressure and Temperature in Rich Gas Condensate Wells

Abstract

A rich condensate gas field is located in the North of Oman, which penetrated the Amin sandstone reservoir at 4015 TVDmss. A study was conducted in the field and showed there is ¾ of GIIP trapped with paleo imbibition - over geological time - gas by the water encroachment in an approximately 80 m thick Paleo-Residual Gas zone (PRG), with very low mobility of hydrocarbons and high residual gas saturations. In order to mitigate the shortcomings of such unfavorable subsurface conditions, the study proposed Gas-Aquifer-Rate Management (i.e. co-production of gas and water) utilizing existing flank wells, as a potential field improvement option. The key business drivers for this project are to re-mobilize gas from PRG flank wells and to safeguard existing NFA by Aquifer pump off and production from high rate crestal wells. The optimum gas well deliquification method has been identified based on the highest UR considering connected GIIP and well completion size. The outcome of the study indicated that the ESP technology combined with well retubing was recommended as the optimum solution. Two wells have been selected as ESP candidates to test the new technology to produce water at deep depth (4000m) and high temperature (155°C). A special slim ESP was designed for this purpose. A successful pilot was completed in one well and gave conclusive results. The test showed that the well produced 3K m3/d of gas and 83 m3/d of liquid with 95% BSW. The second pilot is currently in the commissioning phase. The successful outcomes of the pilot succeeding in connecting the gas and restoring wells back with economic production rates will lead to expedite a full field implementation plan. This project will add a significant economic value of positive NPV at low UTC. This paper will highlight the full story of the PRG and ESP technology implementation and describe in details the entire process starting from the artificial lift selection, well candidate selection screening criteria, critical success factors, operating parameters, life-time cycle and the test results of gas and condensate and water production. Also, the learning and challenges in operating the ESP will be shared.