The shale gas productivity model based on shale gas nonlinear seepage mechanism is an effective way to reasonably predict productivity. The incomplete gas nonlinear effects considered in the current production prediction models can lead to inaccurate production prediction. Based on the conventional five-zone compound flow model, comprehensive gas nonlinearities were considered in the improved compound linear flow model proposed in the paper and a semianalytical solution for productivity was obtained. The reliability of the productivity model was verified by the field data, and then, the 20-year production performance analysis of the gas well was studied. Ultimately, the key influencing factors of the fracture control stage and matrix control stage have been analyzed. Research indicated the following: (1) the EUR predicted by the productivity model is higher than the EUR that the comprehensive nonlinear effects are not considered, which demonstrated that the various nonlinear effects cannot be neglected during the production prediction to ensure the greater calculation accuracy; (2) during the early production stage of shale reservoir, the adsorbed gas is basically not recovered, and the cumulative adsorption contribution rate does not exceed 10%. The final adsorption gas contribution rate is 23.28%, and the annual adsorption rate can exceed 50% in the 20th year, showing that free gas and adsorbed gas are, respectively, important sources of the early stage of production and long-term stable production; (3) the widely ranged three-dimensional fracturing reformation of shale reservoirs and reasonable bottom hole pressure in the later matrix development process should be implemented to increase the effective early production of the reservoir and ensure the earlier gas production process of the matrix development. The findings of this study can help for better ensuring the prediction accuracy of the estimated ultimate recovery and understanding the main influencing factors of the dynamic performance of gas wells so as to provide a theoretical reference for production optimization and development plan formulation of the shale gas reservoirs.

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页岩气井半解析生产预测模型及动态性能分析

基于页岩气非线性渗流机理的页岩气产能模型是合理预测产能的有效途径。当前产量预测模型中考虑的不完全气体非线性效应会导致产量预测不准确。在常规五区复合流动模型的基础上，本文提出的改进复合线性流动模型考虑了综合气体非线性，得到了生产率的半解析解。通过现场数据验证了产能模型的可靠性，并对气井20年生产动态进行了研究。最后，分析了裂缝控制阶段和基质控制阶段的关键影响因素。研究表明：(1) 产能模型预测的EUR高于未考虑综合非线性效应的EUR，说明生产预测时不能忽略各种非线性效应，以保证更高的计算精度；(2)页岩储层生产初期，吸附气基本未回收，累计吸附贡献率不超过10%。最终吸附气贡献率为23.28%，第20年年吸附率可超过50%，说明游离气和吸附气分别是前期生产和长期稳定生产的重要来源；(3) 开展大范围的页岩储层三维压裂改造和后期基质开发过程中合理的井底压力，提高储层早期有效生产，保证基质开发的早期产气过程。本研究结果有助于更好地保证估算的最终采收率的预测精度，了解影响气井动态性能的主要因素，为页岩气藏的生产优化和开发方案制定提供理论参考。 .