致密油多级压裂水平井流-固全耦合产能数值模拟

基于多孔介质弹性理论与流-固耦合作用机理，建立了致密油储集层多重孔隙介质变形与流体流动的全耦合数学模型，采用有限元方法对模型进行数值求解并验证了模型的准确性。对致密油储集层多级压裂水平井进行产能数值模拟研究，结果表明：致密油井生产过程中近人工裂缝区域储集层物性大幅度降低，其中人工裂缝开度和人工裂缝导流能力损失幅度分别达到52.12%和89.02%；模拟致密油储集层水平井生产3000d，全耦合模型与未耦合模型的产能预测误差达38.30%，忽略流-固耦合效应的影响会使产能预测结果产生严重偏差；致密油储集层水平井产能对启动压力梯度最敏感，人工裂缝开度次之，提高人工裂缝初始导流能力有助于提高致密油井产能；压裂施工设计需考虑人工裂缝导流能力、间距、数量、长度的综合影响，片面追求增加裂缝条数无法取得预期的增产效果。

Fully coupled fluid-solid productivity numerical simulation of multistage fractured horizontal well in tight oil reservoirs

A mathematical model,fully coupling multiple porous media deformation and fluid flow,was established based on the elastic theory of porous media and fluid-solid coupling mechanism in tight oil reservoirs.The finite element method was used to determine the numerical solution and the accuracy of the model was verified.On this basis,the model was used to simulate productivity of multistage fractured horizontal wells in tight oil reservoirs.The results show that during the production of tight oil wells,the reservoir region close to artificial fractures deteriorated in physical properties significantly,e.g.the aperture and conductivity of artificial fractures dropped by 52.12%and 89.02%respectively.The simulations of 3000-day production of a horizontal well in tight oil reservoir showed that the predicted productivity by the uncoupled model had an error of 38.30%from that by the fully-coupled model.Apparently,ignoring the influence of fluid-solid interaction effect led to serious deviations of the productivity prediction results.The productivity of horizontal well in tight oil reservoir was most sensitive to the start-up pressure gradient,and second most sensitive to the opening of artificial fractures.Enhancing the initial conductivity of artificial fractures was helpful to improve the productivity of tight oil wells.The influence of conductivity,spacing,number and length of artificial fractures should be considered comprehensively in fracturing design.Increasing the number of artificial fractures unilaterally could not achieve the expected increase in production.