抄録
Terrestrial tight oil reservoirs under atmospheric pressure commonly face challenges such as insufficient formation energy, high startup pressure gradients, and complex seepage mechanisms. Efficient development of these reservoirs is critical for advancing unconventional oil and gas exploitation and ensuring national energy security. This study addresses key scientific and engineering issues observed in the early development of the Lucao Formation tight oil reservoirs in the Jimusar Sag, including rapid pressure depletion and limited single-well recovery. Aiming to clarify the pressure evolution patterns and main controlling factors of estimated ultimate recovery (EUR) in atmospheric tight oil reservoirs, an integrated evaluation framework was established by combining multi-stage volumetric fracturing and monitoring data from horizontal wells, long-term production dynamics, and pressure buildup test analyses, incorporating non-Darcy flow theory and production decline analysis. Results indicate that the Lucao Formation tight reservoirs operate under a pronounced atmospheric pressure regime, with reservoir pressure exhibiting nonlinear, staged depletion during production. This behavior fundamentally reflects an energy imbalance between insufficient matrix recharge and rapid fluid loss through the induced fracture network. Moreover, well productivity evolution follows a characteristic pattern of high initial decline followed by a long-tail stable production phase, demonstrating the critical role of volumetric fracturing in reshaping the flow field and reducing startup pressure gradients. These findings provide theoretical support and engineering guidance for optimizing development strategies and enhancing recovery efficiency in the Jimusar Sag and similar terrestrial tight oil reservoirs.
