Productivity Analysis On Horizontal Wells With Multistage Fractures In Low Permeability Reservoirs

Oil reservoirs with low permeability play an important role in the development of our country’s petroleum industry. But these reservoirs have difficulties in developing owing to low permeability, large seepage resistance, low connectivity, low natural deliverability, low absorbing capacity and low flowing capacity. Horizontal wells with multistage fractures can increase the contact area with oil and gas, decrease seepage resistance and increase the efficience of economy, which get wide attention. So this article make the analysis on horizontal wells with multistage fractures in low permeability reservoirs based on seepage theory of oil.First, pressure transient curve is given to show the characteristics of different seepage stages, and during the analysis of seepage theory of oil, the effect of pressure gradient is shown in low permeability reservoirs. Then the seepage mathematical models of horizontal wells with multistage fractures in low permeability reservoirs are built and solved by finite element method. During the solutions, rock strata is dispersed by tetrahedron elements and fractures are dispersed by triangle elements, which improves the computing accuracy. After that, the impacts of reservoir parameters and fracture paremeters on the productivity and seepage field are described. At last, mathematical models of 2 actual wells are built to analyze the characteristics of productivity and seepage field of horizontal wells based on field data. There is heterogeneity of permeability and the angles between wells and fractures are different in the 2 wells.The characteristics of productivity with reservoir parameters and fracture paremeters are given. The productivity and seepage field of heterogeneous reservoirs with horizontal well which has fractures of different shapes are given, which provides a basis for the analysis of productivity of fractured horizontal wells.