A method is proposed for interpreting the results of gas condensate well test data in two steady-state regime in order to determine the initial value of the reservoir effective permeability and its change factor. The described technique was developed on the basis of a binary filtration model, where the hydrocarbon system is represented as consisting of two pseudo-components and two phases, between the phases there is a mass transfer of hydrocarbons. To apply the proposed methodology, well production data is required, measured at two different steady-state well conditions for two different reservoir pressures. The technique has been tested on the example of PVT production data for the horizon X of the Bulla-Deniz field (Azerbaijan) at different compacting factors of reservoir rocks. The high reliability of the described method has been established. At the initial stages of development, the deviation of the calculated values of the considered parameters from their actual values did not reach 1%. And at later periods, i.e. when the reservoir pressure falls below than 80%, the deviations of the calculated initial permeability and permeability change factor were 2.3 and 4.6%, respectively. Unlike similar methods, the proposed approach is based on the idea of linear approximation. This made it possible to minimize the input data (the number of measurements) and at the same time increased the reliability of interpretation by eliminating the subjectivity factor. The proposed method is simple and reliable, as evidenced by the test results. It is easy to use in a computer, which is not unimportant when automating the process of interpreting measurement results.
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