Transient Pressure Analysis Of A Vertical Fractured Well In A Radial, Composite Reservoir

After the treating of hydraulic fracture, the flow event of the fluid in reservoir is complicate. At the same time, the formation property is different between inner and outer areas. Wherefore, it's obvious that the dynamical analysis is difficult about the vertical fractured well in a radial, composite reservoir. In this paper, the pressure feature about a common fractured well is researched, then the composite reservoir. And each influential factor is analyzed.First of all, the error and exponential integral function are discussed which are referred in the computing model process. The dimensionless quantities which are presented in this paper are introduced. The effects of well bore storage effect and flow conductivity are analyzed.Secondly, for the research of a fractured well in common reservoir, fetching the point source solution of radial influent in infinitely large reservoir. Integrating in the fraction of the fracture, the pressure functions of the infinite conductivity fractured well and uniform flux fracture in infinitely large reservoir.Thirdly, obtain the point source solution in composite reservoir. On the basis of different fracture length, deriving the pressure solutions of two situations, which are the fracture half-length is less than the inner-zone radius and the fracture half-length is more than the inner-zone radius. And the pressure feature of the two situations is analyzed. Such as the inner-zone radius, the storage coefficient ratio, flow coefficient ratio, closed boundary, flow conductivity. The solutions in this paper are all analysis solution. Only at considering the influence of the flow conductivity, the flow coefficient ratio is laplace scope function. Through analysis inversion, we can get the analysis solution. Then the pressure solution about finite conductivity vertical fracture is obtained.Finally, we list two examples for verifying the accuracy of the vertical fractured well in common and composite reservoirs. Through the matching analysis of two models, we obtain the commensurable formation parameter. And this can provide reliable criterion both to estimate the characters of gas reservoirs and to establish thedevelopment program.