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Article Type

Research Paper

Corresponding Author

Fathi Khaleel Saleh Abdul Wahab

Highlights

  • High-resolution black oil simulation applied to heterogeneous reservoir

  • Robust history matching achieved using field production data

  • Impact of spatial heterogeneity on reservoir performance evaluated

  • Infill drilling strategy optimized for improved oil recovery

  • Enhanced recovery potential demonstrated for mature reservoirs

Abstract

Accurate representation of spatial reservoir heterogeneity is essential for reliable production forecasting and recovery optimisation in mature oil fields, particularly where fault compartmentalisation and stratigraphic discontinuities strongly influence fluid flow. In the Wadi Bana Field, Yemen, such complexity has historically limited the reliability of conventional reservoir models and reduced hydrocarbon recovery efficiency. This study develops a high-resolution three-dimensional black-oil reservoir simulation model to quantitatively evaluate the impact of spatial heterogeneity on reservoir performance. The model comprises 88,440 active grid cells and was calibrated through history matching of production and pressure data over the period 1992–2008. Calibration involved systematic adjustment of transmissibility multipliers, relative permeability functions, and well productivity indices within physically realistic limits. The quality of the history match was assessed using oil rate, water cut, and pressure data, achieving a root mean square error (RMSE) of 13.34 STB/day, corresponding to an average deviation of approximately 1.33%. Volumetric analysis estimates 47.07 MMSTB of original oil in place (OOIP) and 299.18 BSCF of original gas in place (OGIP) distributed across six stratigraphic zones. Basecase simulation results indicate declining oil production and increasing water production due to heterogeneity-controlled sweep inefficiency and reservoir compartmentalisation. An infill drilling scenario was subsequently evaluated using the calibrated model to improve drainage of bypassed oil. The results show that the additional infill well enhances sweep efficiency and increases cumulative oil production by approximately 0.55 MMSTB, corresponding to an improvement in the estimated recovery factor of about 1.1-1.2 % of OOIP relative to the base case. These results demonstrate that spatial heterogeneity exerts a dominant control on reservoir performance and that targeted infill drilling can significantly enhance oil recovery in structurally complex reservoirs. The novelty of this work lies in the integration of fine-scale geological heterogeneity with a rigorously history-matched black-oil simulation framework, providing a validated and transferable workflow for data-limited mature reservoirs.

Keywords

Reservoir simulation; History matching; Black oil model; Spatial heterogeneity; Infill drilling; Mature reservoirs

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