Perpustakaan Digital ITB

The development of unconventional reservoirs, such as shale oil reservoirs, typically relies on horizontal drilling with multi-stage hydraulic fracturing, which requires massive Capital Expenditures (CAPEX). However, in thick formations, such as Brown Shale in the Central Sumatra Basin, where the formation can exceed 580 meters in thickness, vertically fractured wells may provide a more economically viable alternative. Therefore, the core objective of this study is to evaluate and compare the technical recovery and economic profitability of hydraulically fractured vertical vs horizontal wells in a field under the Indonesian Production Sharing Contract Cost Recovery Scheme. To achieve this, a reservoir model with a dynamic Original Oil in Place of 50.46 MMSTB was constructed. Subsequently, a sensitivity analysis was conducted using the Response Surface Methodology – Box – Behnken Design to evaluate 82 simulation cases. This optimized five fracturing parameters: number of stages, fracture half-length, up/down fracture height, stimulated width, and fracture zone width. Although the optimum horizontal well physically recovered a higher Total Oil Production of 403.98 MSTB compared to the vertical well’s 384.98 MSTB, the excessive CAPEX required for horizontal directional drilling caused its NET Present Value (NPV) to fall to 3.1010 million USD. On the other hand, the vertically fractured well maximized the project’s profitability, yielding a superior NPV of 3.74 million USD. Furthermore, the RSM correlation heatmap conclusively identified fracture half-length as the most influential parameter driving both production and economic value. The absolute optimum fracture geometry for the best vertical well was at 7 stages of fractures, a 500 ft fracture half-length, a 110 ft fracture up/down height, a 40 ft stimulated width, and a 0.01 ft fracture zone width. This study demonstrates that maximizing physical oil recovery does not always equate to maximizing economic value, conclusively establishing that vertically fractured wells are a superior, more profitable field development strategy than horizontal wells for exceptionally thick shale reservoirs.