页岩气藏数值模拟模型研究进展

以页岩油气为代表的低品位油气资源勘探与开发不断取得重大突破,已经成为中国重要的接替性资源。开展页岩气渗流机理和数值模拟模型研究有助于实现页岩气藏开发的动态变化过程,为认识页岩气渗流规律、优化数学模型、产能评价和预测奠定技术基础。围绕页岩气多尺度多流态多重介质下的运移机理,系统地阐述了页岩气数值模拟模型的研究进展,页岩气数值模拟模型可分为等效连续介质模型、离散裂缝网络模型和混合模型,总结了这3类数值模拟模型的优缺点。等效连续介质模型原理简单,追求宏观尺度的等效,忽略了储层内部真实流态,适用于裂缝发育程度低的均质页岩气藏;离散裂缝网络模型准确反映复杂裂缝网络的渗流特征,可以描述高度离散裂缝的形态规律,适用于勘探程度高且裂缝高度发育的页岩气藏;混合模拟模型结合两者的优点,能够准确反映复杂裂缝网络和流体运移规律,在满足计算精度的同时又节约了大量的计算资源,随着计算处理能力的增强,混合模拟模型是今后的发展趋势。最后分析了页岩气藏数值模拟模型中存在的问题,并指出了发展方向。

Research progress of numerical simulation models for shale gas reservoirs

The exploration and development of low grade oil and gas resources which have become important alternative resources in China have made great breakthrough. Research on numerical simulation of shale gas is helpful to realizing the dynamic process of shale gas development, laying a technical foundation for understanding seepage law of shale gas, optimizing mathematical model and evaluating as well as predicting productivity. Based on intensive investigation of literature from China and abroad, this paper systematically expounds the research progress of numerical simulation methods of shale gas and summarizes advantages and disadvantages of these methods. Shale gas numerical simulation models can be divided into equivalent continuous medium model, discrete fracture network model and mixed simulation model. The equivalent continuum model is simple in principle, pursues the macroscopic equivalent, neglects the true flow mechanism inside the reservoir, and is hence suitable for homogeneous shale gas reservoirs with low development of fractures. The discrete fracture network model accurately can reflect the porous flow characteristics of complex fracture networks and describe the objective regularity of highly discrete fractures and is hence suitable for shale gas reservoirs with completed exploration and high fracture development. The mixed simulation model combines the advantages of these two models to accurately reflect the complex fracture network and fluid migration law, meet the calculation accuracy, and save a lot of computing resources. With the improvement of computing and processing capabilities, the mixed simulation model is the future development trend. Finally, various problems in the numerical simulation model of shale gas reservoir are analyzed, and the development trends of shale gas numerical simulation are pointed out.