The paper is based on successful well placement in a mature gas field located in Middle Indus basin. The well was placed at a down-dip location in a water-drive compartment and yielded positive results. The paper provides comprehensive understanding of compartment’s complex dynamics, subsequent reservoir modelling, well location optimization and post well results.

Identification of infill location in the compartment of interest was challenging due to complicated dynamic behavior described by water encroachment and pressure re-charging mechanisms. The compartment has observed unusual water encroachment where water breakthrough occurred initially in up-dip wells. When analyzed in synergy with adjacent compartment, this unorthodox water encroachment mystery was resolved. In addition, the compartment has also observed significant gas pressure recharging from underlying tight sands. In fact, the compartment has produced substantially higher than its initial gas in-place implying enormous potential in these tight sands. Therefore, the infill well was planned with the aim to exploit this tight sand via conventional sand.

These above-mentioned understandings complemented in dynamic modelling which was accordingly history matched and subjected to sensitivity runs for location optimization. Forecast performed at different well locations helped in the identification of sweet spot at downdip location which ensured maximum recovery.

Subsequently down-dip location was preferred for drilling. Post well results came as per premised and validated pre-drill understanding of the compartment. Successful wells result provided sustainability to overall field production. In addition, it also helped in consolidating confidence in tight sand potential and its gas support and has provided further infill drilling opportunities.

The paper highlights the significance of utilizing all available historical datasets and conventional analyses to resolve an unorthodox problem which apparently depicted no further potential and development opportunity in an asset where significant resources were still to be exploited. The workflow adopted helped in de-risking the opportunity and identifying optimum location for downdip well placement against the intuition and general understanding.

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