An Overview of Successful Fit to Purpose Tubing Stem Test Operation on MUFFIN-X Appraisal Well to Unlock Gas Potential of Deep Formation with HPHT & High CO2-H2S Environment in MTJDA, North Malay Basin

This paper will share a success story of a well-test operation performed on MUFFIN-X, an appraisal well located at the northern part of the Malaysia-Thailand Joint Development Area (MTJDA). The well was drilled in Q4-2020 and penetrated two fault blocks of northern MTJDA to appraise the area for further field development study and proposal. The objective of the test itself is to acquire new data to reduce the subsurface uncertainties and unlock the gas potential from deep formations of the area, which is well known for its multilayer reservoirs, High Pressure-High Temperature (HPHT), and high CO2-H2S content. These conditions are the key challenges to developing the area. To cope with the challenges, Carigali-PTTEPI Operating Company (CPOC) has been using a Tubing-Stem-Test (TST) approach that provides secured wellbore conditions and multiple accessibilities to multiple reservoirs, straightforward operation, and realistic production simulation. The TST of MUFFIN-X was designed to complete each zone within 24-to-36 hours for deliverability and pressure transient tests. The TST performed on MUFFIN-X has successfully unlocked 20 MMscf/d of gas and 5000 bbl/d of oil potentials from the deep formations of the block. The job was completed 16 hours earlier than the design, bringing approximately 40K USD of cost optimization.