A novel parametric coupled pressure and temperature inversion method for combined perforation and well test system

Abstract

Combined perforation and well test system is commonly used in oil and gas fields, especially in reservoirs with low energy and transmissibility. For the conventional inversion method in a combined perforation and well test system, only the pressure data are used to perform the type curve matching, with the variation in temperature being neglected. This may complicate the matching procedure and result in errors in the inversion results. Thus, we proposed a new inversion method in this study, where the gas volume and flow rate terms substituted the pressure and pressure derivative terms to perform type curve matching. This was because the variation in gas volume coupled the variations in pressure and temperature. To make the type curve matching feasible, on the one hand, we need the type curves that depict dimensionless gas volume and flow rate; on the other hand, the field data of pressure and temperature should also be transformed into gas volume and flow rate data, which are the core contents of this paper. A corresponding mathematical model is established and the analytical solutions of gas volume and flow rate are derived with the Laplace transformation. Based on the solutions, the flow regimes analysis and sensitivity analysis on controlling parameters are conducted. Next, a workflow that can convert the pressure and temperature data into gas volume and flow rate data is proposed. Last, the application on a well from Puguang gas field is presented to show the feasibility of our method. Results show that our method successfully interpret the field data comparing to the conventional method that only uses the pressure data. Moreover, comparisons between the results of our method and other field data calibrate the reliability and accuracy of our method.