Study Of Pressure Behavior And Productivity For Vertical Fractured Well In Complex Conditions

As to the reservior which in the middle process of its development or to the lowpermeability reservoir, hydraulic fracturing is one of effective way to stabilize the productionand make potential of the reservoir. From July of 1947 when the technique of fracturing wasfirst used in Delpper Well of Hugoton gas reservoir of Kensas in U.S.A., hydraulic fracturingaffect the exploitation and development heavily as a means of stabilizing and increasingproduction when low permeability reservoir was developed. When a well was fractured, theflow condition was improved, but the process of the flow become more complex. It's veryimportant for us to realize the flow characteristic regime correctly, and it is also true for us todefine the productivity of fractured well, so the following works were done:First, the theory of flow for fractured well was discussed by means of source function,the problem of time-consuming when the equation was settled, and then the result of theequation can be obtained quickly. All the above is a reference for applying the source functionon the area of fluid flow through porous medium. Mathematical model in complex conditionwas presented based on source function, which including vertical fracture with changingconductivity, fracture in double porosity, triple porous media and composite porous mediaunder the condition of close boundary, constant pressure and infinite boundary. The model offlow for fractured well in low permeability reservoir which considered the threshold pressuregradient was established by means of elliptical theory, by resolving the equation, type curvescan be obtained for well testing analysis.Second, pressure distribution of the vertical fractured well was analyzed, the character ofthe productivity and the pressure distribution were discussed under the condition of differentconductivity. By means of Duhamel method and Laplace inversion, productivity decline typecurves and its application method was obtained. The effect of the parameter of fracture on theproductivity was analyzed. By analyzing the productivity curve of vertical fractured well,optimization of the half-length and the conductivity was presented in this paper, and theoptimization curves under different condition were obtained, and the effect on the increase ofproduction of the half length and the conductivity was analyzed based on the optimizationcurve.Third, mathematical model of fractured horizontal well was presented by means of sourcefunction, the type curves of pressure were presented in this paper, based on this, the flowregime of fractured horizontal well was analyzed. By means of integral transformation,prediction of productivity of the fractured well was obtained, and the character of flowdistribution was discussed. Based on the above theory, the parameter which effect theproduction of fractured horizontal well was analyzed.