Research On The Tansient Porous Flow Model Of Fractued Well And Analysis Method Of Well Test For Complex Formations

The porous flow theory of underground oil and gas is the basis of reservoir development. Well testing analysis technology can provide technical support for the efficient development. Many wells were put into production after fracturing for many complicated reservoirs which include multi-tight reservoir, vuggy carbonate reservoirs and CBM (coal bed methane) reservoir and so on. To settle problems of porous flow caused by fractured well production in these reservoirs, theoretical models of transient flow and well test analysis method was conducted in this dissertation. According to the characteristics of different reservoirs, a series of porous flow models of fractured well were established and solved, the typical type curves of well test analysis were drew, the flow stages were studied, and the sensitive characteristics of type curves for model parameters was analyzed.Main research models as follows:(1)4 transient flow models of fractured wells in a multilayer reservoir (vertical fracture model with infinite conductivity in a commingled fractured multilayer reservoir; vertical fracture model with finite conductivity in a commingled fractured multilayer reservoir; vertical fracture model with infinite conductivity in a multilayer reservoir fractured separately for each layer; vertical fracture model with finite conductivity in a multilayer reservoir fractured separately for each layer). The sensitive characteristics of type curves for model parameters was especially studied, which include fracture conductivity, fracture skin, interlayer storage coefficient and interlayer flow coefficient. (2) 5 transient flow models of fractured wells in 3 different types of multi-media reservoirs (pseudo-steady inter-porosity flow model of the reservoir composed by fractures and matrix; unsteady inter-porosity flow model of the reservoir composed by fractures and matrix; transient flow model of the reservoir composed by vugs and matrix; pseudo-steady inter-porosity flow model of the reservoir composed by fractures, vugs and matrix; unsteady inter-porosity flow model of the reservoir composed by fractures, vugs and matrix). The sensitive characteristics of type curves for model parameters was especially studied, which include fracture conductivity, fracture skin, interlayer storage coefficient and interlayer flow coefficient. (3) 9 transient flow models of fractured wells in 4 different types of heterogeneous composite reservoirs (composite multilayer reservoir model with commingled; composite multilayer reservoir model with separate fracturing for each layer; composite model of multilayer reservoir composed by fractures and matrix with pseudo-steady inter-porosity flow and unsteady inter-porosity flow considered separately; composite model of multilayer reservoir composed by vugs and matrix; composite model of multilayer reservoir composed by fractures, vugs and matrix with pseudo-steady inter-porosity flow and unsteady inter-porosity flow considered separately). The sensitive characteristics of type curves for model parameters was especially studied, which include composite radius, mobility ratio and diffusivity coefficient ratio. (4) 2 transient flow models of fractured wells of coal gas reservoirs (pseudo-steady diffusion model and unsteady diffusion model of metrical CBM). The sensitive characteristics of type curves for model parameters was especially studied, which include storage coefficient of natural cleat system, inter-porosity flow coefficient of matrix to cleat and adsorption coefficient.The research finding can be developed into professional well test interpretation software that can be applied widely in the field, which will serve the production and development of oil and gas field. Research results can also provide reference and guidance for the complex porous flow theory and application around the world.