Research On Inflow Performance Relationship Of Multiply Fractured Horizontal Wells For Low Permeability Reservoirs

At present, most newly discovered oil reservoirs in our country is low permeabilityreservoir, permeability, abundance and production ability of this kind reservoir is low, betteruse and development of low permeability reservoir plays an important role in energyreplacement of our country. When people use staged fracturing of horizontal well to increaseproduction in low permeability reservoir, its permeability law is different from normalhorizontal well, as IPR curve is the basis of determining reasonable working method of well,it is necessary to establish calculation method of using test points to backstep the IPR curve,and provide basis of artificial lifting design for horizontal well fracturing.In this paper, we use seepage equation of elasticity of slightly compressible liquid todeduce potential distribution of any point in pressure-sensitive layer. Through potentialsuperposition method combining flowing model of fluid flowing in fracture and wellbore, wededuce pressure drop equation of fracture tip considering mutual disturbing between fractures.Combining flow model of fluid flowing in fracture and wellbore, we establish unsteadyproductivity calculation equation along fracture distribution considering timeliness and flowconductivity of fracture, and give calculation methods of infinite conductivity condition andfinite conductivity condition of wellbore. Comparing unsteady state calculation result withsteady state production and numerical simulation result, we prove the reliability of unsteadystate production calculation method. The results indicate that: pressure sensitive coefficient offormation, pollution level of fracture, flowing pressure in bottom have great influence inproduction, the yield increasing effect will be better if we increase the outer length of fractureor flow conductivity.In this paper, we use numerical simulation software eclipse to simulate reservoir flow procession of multistage fractures in low permeability reservoir, come up with simulationoptimizing method of threshold pressure gradient, stress sensitivity and multistage fracture,on the basis of saturation and pressure distribution result we analyze flowing characters offractured horizontal wells. Using reservoir average pressure as failure indicator of reservoir,we establish drawing method of IPR curve of solution gas driving reservoir, analyze reasonsfor IPR curve changes in different fracture parameters and reservoir parameters. Using amount of data we match general dimensionless IPR curves of staged fracturing horizontalwell in low permeability reservoir, and form the calculation method of using test point tobackstep IPR curve. The results show that: curvature change of dimensionless IPR curve ofstaged fracturing horizontal well in low permeability reservoir is smaller than Vogel curve, soat the moment when flow pressure drop to below the bubble point, using Vogel curve willmake predicted production pressure smaller than actual value.