用于预测水力裂缝缝高的新拟三维流场模型

A NEW PSEUDO THREE-DIMENSION FLOW FIELD MODEL FOR PREDICTING HEIGHT OF FRACTURE

针对原有拟三维流场模型在控层较差时预测缝高过大的问题 ,根据水力压裂裂缝延伸机理 ,基于原拟三维数值模型生成的初始裂缝几何形态 ,采用从假定虚源发出的呈放射状径向流动的近似二维流场 ,对原拟三维模型的一维流场进行了修正 ,建立了新的拟三维流场模型。实例计算表明 ,由于考虑了压裂液在缝高方向上的流动 ,在控层较差的情况下 ,新模型对缝高的预测精度可达到全三维的计算精度 ,这对水力压裂施工和设计有实用意义。

The former pseudo three dimension (PTD) hydraulic fracturing models could not accurately predict the height of the poorly contained fractures. On the basis of the geometry of the original fracture obtained from PTD model and the fracture propagation mechanism, a new PTD hydraulic fracturing model was developed by modifying the original one dimension fluid flow field with an approximately 2D fluid flow field started from a local imaginary source and flowing in the radial direction. Due to consideration of the fluid flow in the vertical direction, the modified model can be used to predict the height of fractures perfectly. Especially for the poorly contained fractures, the calculating accuracy of the new method nearly equates to that of the fully 3D model. This model has some practical significance for the hydraulic fracturing process and the fracturing design.