Mechanical Isolation of a Challenging Reservoir: First Installation of High Expansion Straddle Packer in Indonesia

Well N-1 in Mahakam Sisi Nubi field, East Kalimantan, had a problem with water and condensate production up to 11,000 BLPD which instantly rendered the production facility overwhelmed despite the high 34 MMSCD gas rate. To solve this, reservoir production profiling using production logging tool was first carried out. Selection of existing zone isolation method was then compared, yet none satisfies the challenges in this well due to restriction and cost issues. A relatively new technology, High Expansion (HEX) Straddle Packer, was introduced as another alternative. A series of engineering design and followed by operation design was then carried out to solve the well problem safely. A dummy tool run with 2.875" OD and 30ft of length passed through the restriction safely. Caliper logging observes reduction in tubing ID from 3.9" to 3.0". Temperature of the borehole reached 115 deg C at 3417 mBRT of this well. The two water producing zones were next to each other with a total top reservoir to bottom reservoir length of 11 m. With these values, a custom 2.7" straddle packer was built and tested to required temperature and passed. Production simulation with 0.7" ID, indicated the well could still flow over its critical flow regime. After installation, the well flows with 11 MMSCFD of gas with ~1800 BLPD liquid produced, a 83% reduction over previous liquid flowrate. Despite the well flows only 30% from initial gas rate, this well can now flow at an acceptable liquid rate. The successful installation of the first HEX Straddle expands the portfolio of mechanical water shut off methods in Mahakam and in Indonesia as this was the first HEX Straddle installed in Indonesia. Further study and replications are needed, yet this method can be a viable alternative if other has failed for wells with similar problems.