Petroleum reservoir parameters estimation using non-isothermal transient model and optimization methods

Traditionally, oil well tests aim to characterize the reservoir permeability field from pressure transient analysis (PTA) of drawdown and build up based on isothermal flow models in porous media. With the advancement of well test instrumentation, more accurate temperature records became available and have encouraged analyses based on non-isothermal models that made possible the temperature transient analysis (TTA). In addition to the characterization of reservoir parameters, such as permeability and porosity by TTA, taking non-isothermal effect into account on PTA represents better physical phenomena, especially in high transmissibility reservoirs and in cases where the pressure sensor is placed away from the sandface. This work consists in the development and numerical implementation of a non-isothermal model of well test considering a unidimensional radial reservoir coupled to a production well and in the use of this simulator, associated with multivariable optimization methods, to solve the inverse problem of reservoir parameters characterization. Nelder-Mead Simplex, NewtonRaphson and BGFS methods were used to evaluate reservoir parameters for one of the reservoir configurations analyzed and the first method presented better computational efficiency. It was then used to solve the inverse problem of radial composite reservoirs.

Automated summary

Traditionally, oil well tests rely on pressure transient analysis (PTA) based on isothermal flow models. With the availability of accurate temperature records, non-isothermal models are now used for temperature transient analysis (TTA) to better characterize reservoir parameters. This study develops a numerical simulator that incorporates a non-isothermal model for well test analysis and solves the inverse problem of reservoir parameter characterization using multivariable optimization methods.