Studies Of Flow Mechanism For Complicated Fractures

In the process of fracturing and stimulation in low permeable reservoir, the fracture generated is complicated and variable. How to properly depicribe the fracture shape and to simulate the production performance of fractured well is very significant to guide the development of low permeable reservoir. In recent years, there are too many studies of the production performance of fractured well. However most assumptions are that fracture stretches linearly, which doesn't reflect the real situation, and complicated fracture simulations aren't in depth, the proper description of fracture more in conformity with the reality is not acquired. Therefore, it needs to make a deep study.Finite Difference Method is the main numerical method of researching the flow in reservoirs, at the same time, Finite Element Method is a valid numerical method and has lots of superiority than Finite Difference Method, but it is not deeply studied in solving reservoir problems. Basing on theory of Finite element method and the characteristic of low permeability reservoirs, the application and theory of Finite Element Method in low permeability reservoir are studied systematically, specially, production performance of complicated fracture well are deeply studied. The single phase flow Finite element seepage equations are established.The simulation of fracture using anchor model and the output computation using reaction algorithm are done. Those equations are dispersed in space by iso-parameter element method and in time by using backward difference. A numerical simulator is established by Fortran, the ideas of high part make the of structure program clear, maintain easy, alculation effective. The linear equations are resolved by variable band Gauss Method, which makes full use of the symmetry and band of stiffness matrix to reduce the occupation of computer memories.Started with the basic radial flow model, it validates the practicability of simulator, provides basis for complicated fracture simulation. In this paper it is discussed that the effect of many variants on the production performance of fractured well, such as fracture number, length, angle, shape, flow conductivity and so on. As simulating linear fracture, it is studied that the semi-long fracture model by simulator, and makes significant conclusions. On the basis of the studies mentioned above, it makes an exploratory research on fractured well with complicated curve and anomalistic fractured well. The preliminary computing results show that the computation is reasonable. For complicated fracture with complicated shape, it simulates under the condition of isotropic homogeneity and aeolotropism respectively. The results analyzed and compared are rational. These conclusions are more significant in guiding the fracturing and reconstructing of low permeable reservoir.