Changqing Gas Field, The Dynamic Characteristics Of Non-homogeneous Gas Reservoir Pressure And Capacity Analysis Method

This paper is to study deliverability analysis methods appropriate to heterogeneous gas reservoir. Firstly, five types heterogeneous gas reservoir models are proposed after investigating the native and alien studies of heterogeneous oil and gas reservoir; and the corresponding gas flow model in heterogeneous reservoir and their solutions are deeply studied; then pressure response characteristics on the five types of heterogeneous gas reservoir models are studied; Following that, this dissertation investigated deliverability analysis methods of heterogeneous gas reservoir; at last with the test data of gas well all models are testified. On the base of systematically investigating references and analyzing deeply present study situations, this paper draws following conclusions through studying systematically and deeply with the knowledge of oil & gas reservoir geology, gas flow theory through porous media, partial differential equation, optimization theory, calculation mathematics and mathematical physical statistics.①Systematically clarify percolation mathematical model and solutions of gas reservoir under the conditions of infinite boundary, constant pressure boundary and sealed boundary in dual-porosity gas reservoir, dual-permeability gas reservoir, compound gas reservoir, radial heterogeneity gas reservoir and general heterogeneity gas reservoir, study relevant pressure dynamic features, and provide theoretical base for well test analysis and explanation of gas well in heterogeneity gas reservoir.②According to Oliver method, with perturbation theory and Laplace transform theory, approximate analytical solution of general heterogeneity gas reservoir is deduced. Meanwhile, ISA method, YA method and MYA method to resolve permeability of radial heterogeneity gas reservoir are deduced③Optimization model and calculation method are proposed to determine the permeability distribution in radial heterogeneity gas reservoir. Calculation shows that it's more accurate than ISA method, meanwhile, it overcomes drawback of ISA method, YA method and MYA method when there is noise in test data, and can be applied effectively in oil and gas field.④With relevant theory of statistics analysis, superposition in space principle is proposed: in a heterogeneous reservoir caused by variation of permeability, its heterogeneity can always be considered as a homogeneous reservoir (matrix) superpositoned by several reservoirs (variances) with different permeability. Superposition in space principle shows that when a well produces at a constant rate in heterogeneous reservoir, the difference between its draw down derivation and that when there is matrix is equal to algebraic sum of the difference when each single variance superposition respectively on matrix.⑤Auto-match model to recognize formation parameters in heterogeneous gas reservoir is established and relevant resolution method is proposed. Illustration shows that though there is much noise in the test process, formation parameters calculated with this model are approximate to real ones. So this method is not only accurate and reliable but also of utilities.⑥On the base of heterogeneous gas reservoir percolation mathematical model and the parameter identification method of auto-match model in heterogeneous gas reservoir proposedbefore, two new methods—simulation test method and direct simulation method to determine the deliverability in heterogeneous gas reservoir are proposed. There is no need to do isochronal tes and modified isochronal test with these two methods.