考虑迂曲度的页岩气储层裂缝渗透率

Fracture permeability of shale gas reservoir considering tortuosity

何岩峰 田鑫荣 窦祥骥 王相 陶磊 赵虹宇

常州大学石油工程学院，江苏 常州 213164

School of Petroleum Engineering, Changzhou University, Changzhou 213164, China

岩气储层中，天然裂缝往往呈现迂曲状几何形态。为了研究页岩储层裂缝网络中的气体流动性变化规律，文中基于迂曲毛细管束模型和分形二叉树模型，对气体在裂缝毛细管中的流动长度进行了修正，引入了裂缝毛细管长度修正系数；根据气体非线性稳定渗流的公式，推导不同迂曲度的二叉树裂缝网络渗透率模型，并利用微观刻蚀模型设计了相关实验，对模型进行了验证。结果表明：在页岩气储层中，裂缝毛细管长度修正系数越小，裂缝网络分形维数越大，裂缝网络分叉角度越小，裂缝网络的渗透率就越高。该研究建立的页岩裂缝网络渗透率模型对合理制定页岩气藏的开发方案具有一定的指导意义。

In shale gas reservoirs, natural fractures tend to present a tortuous geometry. In order to study the dynamic change of gas flow in the shale reservoir fracture network, based on the tortuous capillary bundle model and the fractal binary tree model, the flow length of gas in the cracked capillary was corrected. The correction coefficient of crack capillary length was introduced. At the same time, according to the formula of gas nonlinear stable seepage, the network permeability model of binary tree crack with different tortuosity was deduced, and the model was verified by micro-etching model. The results show that in the shale gas reservoir, as the crack capillary length correction coefficient decreases, the fracture network fractal dimension increases, while the crack network bifurcation angle decreases, and the fracture network permeability increases. This research established a reasonable shale fracture network permeability model, which has certain guiding significance for the development of reasonable shale gas reservoir development plan.

10.6056/dkyqt202005013