非达西流动对致密砂岩气藏压裂水平井产能的影响

Influence of non-Darcy flow on productivity of fractured horizontal wells in tight sandstone gas reservoir

致密砂岩气藏储层非达西渗流特征使得其不同珪常规气藏,准确预测致密砂岩气藏压裂水平井产能至关重要。基于致密砂岩气藏压裂水平井渗流机理,考虑应力敏感、滑脱效应、气体高速非达西流以及井筒压降对产能的影响,定义气体广义拟压力,建立了致密气藏储层—裂缝—井筒耦合产能计算新模型。实例分析表明,利用新模型计算无阻流量结果与产能测试结果相对误差仅为3.08%,相对误差较小,说明新模型具有较高的准确性。研究表明,随着裂缝条数、裂缝半长以及滑脱因子的增大,无阻流量增大,而随着应力敏感指数的增大,无阻流量逐渐减小,且井底流压较小时更加明显。研究为致密气葳压裂水平井流入动态研究以及裂缝参数优化设计提供了理论依据。

The non-Darcy seepage characteristic makes tight sandstone gas reservoir be different from conventional gas reservoir. It is important to accurately predict productivity of fractured horizontal wells in tight sandstone gas reservoir. According to percola- tion mechanism, considering the influence of stress sensitivity, slippage effect, high velocity non-Darcy and wellbore drawdown on productivity, gas generalized pseudopressure is defined. Moreover, new productivity calculation model of reservoir, fracture, well- bore coupling in tight sandstone gas reservoir is established. Example analysis shows that compared with productivity test results, relative error is only 3.08 % by using this new model. The small error indicates that this new model has good accuracy. Research shows that as the increasing of fracture number, fracture half length and slippage factors, absolute open flow（AOF） increases. How- ever, as the increasing of stress sensitivity index, the AOF decreases, especially when bottom hole flowing pressure（BHFP） is low. The researches provide theoretical basis for studying inflow performance relationship（IPR） and fracture parameter optimization of fractured horizontal wells in tight sandstone gas reservoir.