低渗油藏不规则缝网压裂水平井产能预测模型

A Production Prediction Model for Fractured Horizontal Wells with Irregular Fracture Network in Low Permeability Reservoirs

  • 摘要: 考虑压裂形成的非均匀复杂裂缝网络,引入分形理论并结合裂缝系统应力敏感特征刻画流体渗流能力,建立了低渗油藏压裂水平井三区耦合渗流产能预测模型。采用拉普拉斯变换、摄动理论和数值反演的方法求得产能模型解析解,并推导水平井均匀布缝和非均匀布缝两种情况下单井产能公式。基于海上油田某压裂水平井基本参数和真实生产数据验证了所建产能预测模型的可靠性,并对水平井产能影响因素进行分析。研究结果表明:应力敏感系数和启动压力梯度越小,产油量越大;分形维数越大,水平井产量越大;产油量随裂缝数量和裂缝半长的增大而增大,但增长幅度减缓,参数存在最优值。

     

    Abstract: A non-uniform complex fracture network structure formed by fracturing is considered with introducing the fractal theory and combining the stress sensitivity of fracture system to demonstrate the change of fluid flow capacity, and a production prediction model for three-zone compound seepage flow in fractured horizontal wells in low permeability reservoirs is established successfully in this paper. Laplace transform, perturbation theory, and numerical inversion are applied to obtain the analytical solution of the proposed production model, and the productivity formulas for single well under two situations of uniform and non-uniform distribution of fractures in horizontal wells are derived. The reliability of the production prediction model is verified with the real production data and basic parameters of a fractured horizontal well in Bohai oilfield, and the effects of related influential parameters on production of horizontal well are analyzed. The research results show that smaller the stress sensitivity coefficient and threshold pressure gradient results in larger the oil production. Larger the fractal dimension contributes to larger the horizontal well production. Additionally, the oil production increases with the increase of the number of fractures and fracture half-length, but the growth rate slows down, which means these parameters have optimal values.

     

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