Development of a Remote Oil Field Through ESP Installation: Lessons Learnt

Abstract

The ONGC operated XYZ field is the farthest oilfield from shore located in western offshore of India. Based on the remoteness and marginal nature of the field, it was developed by deploying an Early Production System and brought on production in 2006. Concurrent exploration and development activities resulted in horizontal & vertical growth of the field, nearly doubling the in-place reserves. Subsequently, the field development strategies were revised and the Early Production System was replaced with FPSO in 2013. Post FPSO installation, back pressure in the field increased leading to sub-optimal production from the self-flowing wells necessitating early installation of artificial lift. The reservoir is multi-layered limestone in a depth span of 2100–2850m. Reservoir pressure is almost hydrostatic and temperature ranges from 120–140°C. The crude is light and highly under saturated with bubble point pressure less than 100 kg/cm2. With low production GOR (~40 v/v) and no nearby source of gas, possibility of using gas lift was eliminated. However, highly under saturated crude with favourable reservoir conditions made it an attractive proposition to install ESP as artificial lift in the field. ESP installation campaign kicked off in May-13. The campaign suffered initial setbacks in the form of premature/frequent ESP failures resulting in production downtime. Completion of the new wells with predesigned ESP since inception led to sub-optimal production performance of some wells. The early ESP failures warranted a comprehensive review of ESP design and installation strategies followed in the field. Accordingly, accelerated mid-course corrections were made and new strategies were formulated for optimized ESP design. ESP installation methodologies were also reviewed to minimize operational hiccups. This was followed by close monitoring of ESP performance for further optimization opportunities in accordance with dynamic reservoir conditions. The performance of ESPs designed and installed using revised methodology was in line with the expectations. With improved ESP design and installation practices, sustained production could be realized and the field witnessed turnaround in production with peak oil rate of 32000 bopd through 28 wells in Feb-15. The paper discusses lessons learnt while overcoming the challenges and procedures implemented in design, installation, operation and monitoring of ESPs in XYZ field which led to a successful endeavor to revive the field to its anticipated potential.