The Kutai Basin, has been under production for more than 40 years and many wells have been drilled to develop the area. This has resulted in reservoir-induced drilling problems, like kicks and lost circulation due to depletion, while some high-pressure zones still exist. This complexity makes pore-pressure and stress analysis difficult. To address this problem, a comprehensive reservoir-evaluation program was developed by adding formation pressure testing to the planned quad-combo logging-while-drilling (LWD) program. Pressure measurements in this development stage were planned to aid the operator's understanding of the field's current hydraulic communication pathways, to relate reservoir characterization to the geological model. Emphasis was on the insight of static reservoir pressures, which are important for confirming fluid contacts and fluid density gradients.
Methods of formation pressure testing have evolved over many years. Through this paper's case study, recent LWD and wireline pressure-testing technology are elaborated in depth, in relation to two sequential wells drilled offshore in the Kutai Basin. LWD pressure-testing operations were conducted in well XX-5 in a dedicated run after completion of drilling the section. The wireline test was conducted in well XX-4 as an open-hole logging run, along with the acquisition of fluid analysis data.
Both systems were successfully utilized in the 6-inch hole sections of the subject wells, in a depleted reservoir, with the pressure overbalance expected to reach around 3100 psi in the pre-job planning stage. The average mobility was low in both sets of pressure test results, as also align with the reservoir's current depletion state. Challenges related to tight tests and lost seals in this mature field were experienced with both systems. The drilling environment and the formation's exposure conditions may have presented varying challenges; nevertheless, the same relatable quality has been achieved with both types of testing (LWD and wireline).
This paper describes in detail the planning, design, and performance of pressure testing using LWD and wireline in the Kutai Basin. Comparisons between results are displayed to highlight the current character of the subject offshore field. This study aims to enhance future drilling and logging operations, by reviewing solutions from formation pressure testing technologies and to add value to mature and depleted field planning.
Technical Categories: Geotechnical, Geoscience & Geophysics; Drilling Technology