Theoretical Study On The Production Performance Of Non-Darcy Flow In The Low Permeability Reservoirs

The flow mechanism in the low permeability reservoirs is different from middle-high permeability reservoirs, mathematical model based on Darcy flow is invalid for non-Darcy flow in the low permeability reservoirs. Large numbers of experiments show that Threshold Pressure Gradient (TPG) is character of low permeability reservoirs, and the seepage flow in the low permeability reservoirs is nonlinear flow. Based on the significance of exploitation of the low permeability reservoirs, it becomes extremely important to predict production ability of the low permeability reservoirs.Based on the achievements of the middle-high permeability reservoirs and the low permeability reservoirs, and the particularity of the low permeability reservoirs, single well is looked as research object in the thesis, flow mechanism of the non-Darcy flow and production ability of the low permeability reservoirs are discussed.Under the condition of the constant flowing pressure at bottom hole, mathematical models of non-Darcy flow in the homogeneous reservoirs, the double porosity reservoirs and the composite systems, the vertical fracture well in the homogeneous reservoirs and the vertical fracture well in the double-porosity media reservoirs have been established. Infinite outer boundary, constant pressure outer boundary and closed outer boundary reservoirs are considered in the homogeneous reservoirs, the double porosity reservoirs and the composite systems; and bilinear flows and trilinear flows are considered in the homogenous reservoirs vertical fracture well and the double-porosity media reservoirs vertical fracture well. The Laplace space solutions of mathematical models about the flow rate and the cumulative production in the different reservoirs have been obtained by Laplace transform; The numeral conversion is conducted with the solution by Stehfest algorithm, flow rate and cumulative production curves are plotted; The differences between non-Darcy flow and Darcy flow were analyzed, and effecting factors to the flowrate and the cumulative production were discussed in the thesis. The effecting factors are TPG, skin effect and others. Advisable conclusion was obtained.The advisable conclusions are obtained from the thesis by studying the low permeability reservoirs, which are important theoretical references to exploit the low permeability reservoirs, and have important academic value and practical value.