Oil production from some of wells in the White Tiger field producing from a fissured Basement reservoir; have been impaired by excessive water production. Excess water not only reduced the artificial lift efficiency, but also imposed various damages to the oil zones.
Since 2002, a joint industrial project was set up to study the feasibility of performing water shutoff treatments in the open-hole completion oil wells. The study involved evaluation of a high temperature polymer base water shut-off fluid for deep penetration of the fissure formation and a micro-fine cement system for sealing off the water entries. Based on this study, a cost-effective chemical treatment method was progressively developed. In 2005, the treatments were performed through-tubing with and without isolation packers.
Two Candidate wells were having 6.5″ open-hole size, at approximately 4,200 meter TD, and 150 deg C reservoir temperature. The water cut were 95% in one well and 30% in the other well. It was found that these two wells certainly had big difference in fluid injectivity, and original designed treatment was modified on site. This paper summarizes key lessons learnt including tool and packer conveyance, mixing and pumping of water shut-off fluids under offshore rig and wellsite conditions. It also shares a method of post treatment production evaluation and suggests operational change to improve the production.