Productivity Evaluation In Low Permeability Reservoir Horizontal Well Pressure

After decades of exploration and practice, hydraulic fracturing horizontal well technology has been greatly developed and widely used, and has gradually become an important choice in the exploitation of low permeability and unusual low permeability reservoirs. Productivity predicting is used to instruct fracturing designs and optimize design. With fractured horizontal wells increases every year, how to accurately predict the production performance of these wells has been one of the current research focuses.Based on Darcy flow law, a few scholars have figured out some analytical formulas or numerical simulation results on productivity calculation, which have greatly promoted the hydraulic fracturing horizontal well technology. However, in low permeability reservoirs, due to threshold pressure, flow is nonlinear, in most cases it is low-speed non-Darcy flow. In this case productivity prediction of fractured horizontal well faces some new challenges. Taking a single well in a low permeability reservoir as the research object, integrating some results on low-speed non-Darcy flow in the research of fracturing vertical wells with the general fractured horizontal well productivity prediction method, this paper has completed the following tasks:(1)Based on the non-Darcy flow in low permeability reservoirs, established singe-phase unsteady seepage flow mathematical models under the three commonly used boundary conditions and get the pressure field distribution equations by solving the models using Laplace transformation method.(2)According to superposition principle of potential, considering the effect of a variety of factors such as threshold pressure, fractures number, fracture's space, fracture azimuth, pressure drop of the lateral well, established the productivity predicting model based on the non-Darcy flow in low permeability under he three commonly used boundary conditions.(3)The models are verified according to the existing examples.(4)The effect on productivity of fractures number, fracture's space, fracture azimuth, threshold pressure, etc. is analyzedThe results in this paper are verified to some extent. They can direct the optimization design and site treatments. In addition, the efforts in this paper are also instructive for the hydraulic fracturing horizontal well productivity predicting of two-phase or multiphase flow.