OPTIMIZATION OF MARGINAL FIELD X DEVELOPMENT SCENARIOS APPLYING IMMISCIBLE FLOODING OF GAS AND WATER ALTERNATING GAS WITH HORIZONTAL PRODUCING WELLS

• Main Author: Arif Putra, Rizky
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/40053
• Institution: Institut Teknologi Bandung

There are many previous papers about developing marginal fields as a guideline for field development plan. This study focuses on Field X that is a marginal offshore oil field. It is known to have a low permeability reservoir so it would not be economic to develop the field in a few years ago. The good decision and plan to develop a marginal field should be considered comprehensively. Therefore, techno-economic optimization study is required to be done thoroughly for such a marginal field. The reservoir model is built to forecast and conduct sensitivity analysis using a commercial simulator. The reservoir model must be initialized and matched with production history data prior to generate reliable forecasting results. Analytical method resulting well productivity comparison is also used to select the best suited well type. The analysis of sensitivities is divided into two groups for primary and secondary depletion method that would be analyzed using creaming curve. The sensitivity parameters for primary depletion are location and number of wells, horizontal section length, gas lift rate as artificial lift method, tubing size, and facility limitation, while for the secondary depletion are injection fluid, location, and number of injection wells, injection rate, and injection cycle time for water alternating gas. The analytical method shows that the productivity of a horizontal well is far higher than a vertical well that could drain more hydrocarbon within a single-layered reservoir efficiently. The optimized field development scenario for primary depletion using horizontal wells could produce up to 7.8 million stock tank barrels (MMSTB) of oil representing 8.3% of recovery factor (RF). It shows a positive net-present-value (NPV) of project up to 4.6 million US dollars (MMUSD) with 10% discount factor. The optimized field development scenario for secondary depletion using water injection, gas injection, and water alternating gas (WAG) injection could produce hydrocarbon more than two times of primary depletion scenario those are 15.6 MMSTB, 11.9 MMSTB, and 17 MMSTB of oil representing 16.6%, 12.6%, and 18.5% of RF. It shows positive NPV of the project for WAG and gas injection scenario up to 0.3 and 31.4 million US dollars with 10% discount factor. The uncertainty analysis on reservoir characteristic for best scenario shows that initial in place and permeability are the most influential parameter to the value of oil recovery and NPV. Those parameters could give negative NPV of the project. Hence, it is should be confirmed to reduce uncertainty.