Collaboration in Extracting More Oil in Mature Dual Completion Wells

Abstract

The offshore state of Sarawak in Malaysia contains many mature wells that were completed 20-30 years ago with dual-strings and multiple packers to exploit the many layers of sand packages. The wells that were designed to exploit the main sand packages are currently depleted and producing at high water cut. The operator is now considering ways of exploiting the smaller intermediate sand packages in these wells. In many cases, this requires oriented perforating through one completion string while avoiding shooting another completion string that is still producing. Oriented perforating using analog orienting devices that were previously deployed has many operational problems that on several occasions have led to abandoning jobs, and ultimately deferment of additional production. As such, this has led to many of these mature wells that require oriented perforating being left unexploited for many years. The arrival of a new digital orienting device is expected to open the path to better exploitation of the intermediate sand packages.This paper is a case of deployment of this device for PETRONAS Carigali in Sarawak, Malaysia which required collaboration with the service contractor at many stages, from planning and characterizing the device responses in various completion configurations in Sarawak, to writing standard operational procedure and contingency planning, and to real-time decision making during operation.The results of operation of this device on two wells in Sarawak are also presented, as is how the collaboration in the planning stages contributed to their successes.While the success paves the way for future exploitation of the intermediate sand packages for PETRONAS Carigali, the exercise also provides a reference for similar operations in other places, from the point of collaboration and technicality of the service itself. IntroductionThe offshore state of Sarawak in Malaysia contains many mature fields that were drilled 20-30 years ago. Most have many packets of sands and were completed with dual-strings, multiple packers, and sliding side doors (SSD) to avoid commingling different oil zone reservoirs. If all the sands were to be produced from the same well, that would require a very complex completion string, something that could be very expensive or would be limited by the availability of technologies at that time. Furthermore some of the sand packets are small in comparison with the main sands. As such, only the main sands were perforated and produced in an optimized completion string. Fig. 1 and Fig. 2 show two typical dual completion wells in the state of Sarawak.