Optimization Design Of Horizontal Well In Low Permeability Reservoir

In this paper,stable productivity of horizontal wells in low permeability reservoir isderived by principle of superposition. In the process Seepage law of low permeabilityreservoir is analyzed by considering threshold pressure gradient and redefining the concept ofvelocity potential. The influencing factors of stable productivity of horizontal wells areanalysed including coefficient of deformation, threshold pressure gradient, horizontal welllength, anisotropy factor and reservoir thickness. Capacity of horizontal Wells of oil-watertwo phase in low permeability is usually studied by the conformal mapping method.The fluidflow about the horizontal Wells in low permeability reservoir can be divided into two parts.The horizontal well productivity formula can be obtained by dividing the fluid flow about thehorizontal Wells in low permeability reservoir into two parts.The influencing factors areanalysed including threshold pressure gradient and horizontal well length.Productivity ofhorizontal well was derived by Equivalent seepage resistance method in a condition offour-spot, five-spot, seven-spot and nine-spot well pattern with vertical well and horizontalwell combination. In addition, the influencing factors of productivity of horizontal well in acondition of areal well pattern are analysed including threshold pressure gradient, penetrationratio, formation thickness.Based on oil-water two phase flow theory and considering flowcharacteristics of fluid in both reservoir and wellbore, Mixing pressure drop calculationformula and the calculation model of wellbore pressure drop is deduced. And then thecoupled model of horizontal wellbore flow and reservoir percolation is established. Theproductivity calculation model is corrected by Considering the anisotropy of the reservoir.Optimization is studied for the horizontal well pattern in low permeabilit, including theoptimization of well pattern and well spacing parameter. Optimization is studied including theappropriate-matching of injection-production well patterns of vertical wells and horizontalwells, appropriate-matching of well pattern and crustal stress, length of the horizontalwells,vertical location of horizontal wells and producer-injector spacing. The indexes ofcumulative oil production and recovery degree are predicted by numerical simulation to getthe optimal matching of well array direction, pattern of spacing and density in low permeability.According to the geological characteristics of Camp11wellblock, the distribution ofremaining oil, the remaining oil distribution and the development potential of each layer areresearched by reservoir numerical simulation technology. Evaluation has been put intoproduction of horizontal well development effect, and the well pattern of horizontal well isoptimized. Then the horizontal section of the longitudinal position, the horizontal sectionextending direction and horizontal Wells well type and orientation of western area areAnalyzed.