拟三维压降曲线分析方法

P3D Pressure Drop Curve Analysis Method

在压降曲线分析模型中 ,三维模型比二维模型更符合地下实际情况。建立的拟三维分析模型综合考虑了停泵后裂缝在高度和长度方向上的延伸 ,缝高为椭圆形分布且以椭圆形向前延伸 ;针对上下隔层与压裂层之间存在的最小主应力差引入当量椭圆截面的概念来计算裂缝体积 ;延伸停止后 ,裂缝的闭合受滤失控制 ,裂缝体积的减小即为总滤失量。由此确定出C ,tpr,ΔL ,L ,W ,η ,Kc,tc 等参数 ,从而可以为正式压裂提供较为准确的设计参数。

The 3D models are more accordant to the practical formational conditions than the 2D models in all kinds of pressure drop curve analysis models,although they are more complicated.The P3D analysis model being completed in this paper will include the fracture extensions along the direction of height and length after pumping,with fracture heights distributing and extending in the way of oval.A equivalent oval section will be adopted to calculate the fracture volumes with minimum principal stress difference between upper-lower zones and fracture zones.Fracture closure could be controlled by filtration after extending,with the reduction of fracture volumes being total filtration.