正交裂缝网络中渗流特征实验研究

Experimental study on fluid flow characteristic in orthogonal fracture network

为研究正交裂缝网络模型中渗流特征和模型结构对渗透率的影响,利用大理石和不锈钢垫片组建了不同结构的正交裂缝网络模型,并在自行研制的物理模拟实验装置上进行了一系列单相和两相流动实验。研究表明:低渗流速度下裂缝网络模型中渗流服从线性渗流规律,随着渗流速度不断增大,渗流曲线向压力梯度轴弯曲,呈现非线性渗流特征;平行于渗流方向的裂缝数越多,模型渗透率越大;平行于渗流方向的裂缝数越少,最终采出率和注采压差越大,含水上升较缓;裂缝网络中水驱油主要靠注水驱动压力梯度和重力作用进行,平行于渗流方向的裂缝中流动满足达西定律,竖直裂缝中重力起重要作用。

In order to investigate fluid flow characteristic in orthogonal fracture network model and the effect of structure on permeability,fracture network models with different structure were made by marble and stainless steel filling piece.A series of single and two-phase fluid flow experiments were conducted on fracture network models by using of special physical simulation installment.The results show that fluid flow follows Darcy flow when velocity is low,however,fluid flow curves bend to pressure gradient axis with the velocity creasing and fluid flow presents nonlinear characteristics.Permeability is bigger in fracture network model with more fractures parallel to fluid flow.In fracture network model with fewer fractures parallel to fluid flow,final recovery efficiency and the injection-production pressure difference are bigger,and water cut increases slowly.Oil in fracture network is displaced by pressure gradient and gravity.Fluid flow in parallel fracture follows Darcy law.And gravity plays an important role in vertical fracture.