Abstract

When ranking the attractiveness of projects for the development of high-viscosity oil fields, a need has been identified for creating a single approach to the selection and rapid assessment of the efficiency of the technology of thermal methods for enhancing oil recovery (EOR). The purpose of this work is to create a convenient and fast tool for solving this problem.

In this paper, a comparative analysis of existing analytical methods for planning thermal EOR: steam assisted gravity drainage (SAGD), steam flooding, cyclic steam injection and heating of the reservoir by borehole heaters is carried out. The limits of applicability of the models most often used in the literature are determined. For cases where we do not allow the use of analytical approaches due to necessary take into account the entire range of physical effects occurring in the reservoir under the influence of the thermal fluid, a new engineering tool is proposed. Its implementation is based on solving the equations of two-dimensional multicomponent multiphase non-isothermal filtration in an anisotropic reservoir. At the same time, the proposed tool allows us to directly use empirical relations and correlations obtained from the results of laboratory studies of core and oil or on reservoir-analogues.

As a result of the work, software was created for performing rapid engineering calculations on simplified two-dimensional thermohydrodynamic models, which allows modeling and evaluating the effectiveness of various thermal methods for enhancing oil recovery. The developed algorithms significantly reduce the calculation time, without losing accuracy, take into account the type of completion of wells and the geometry of the "reservoir-well" system under various conditions at the reservoir boundaries and at the well. The possibility of cumulative accounting of the influence of physical effects in the process of thermal action is realized: change in wettability and relative permeability (including residual oil saturation), thermal expansion of fluid and rocks, oil distillation, change in the initial shear gradient for oil, and others.

The proposed tool allows to solve the basic engineering tasks:

  • forecasting of well performance;

  • comparative analysis of the effectiveness of various thermal EOR;

  • selection of optimal parameters for the selected EOR technology;

  • determination of the distribution of the heated zone and mobile oil in the reservoir;

  • the dynamics of the distribution of the steam chamber and others.

Among the results of the work performed, it is possible to include a comparative literature analysis of analytical models for planning the efficiency of thermal EOR. Approximately seventy papers most cited on this topic are considered. An engineering tool for predicting oil recovery as a result of the application of thermal EOR has been created, which makes it possible to directly use correlations and empirical relationships obtained from laboratory studies. Verification of calculations with commercial simulators on model examples showed high convergence and accuracy sufficient for engineering calculations. Examples are given of the practical use of the engineering tool under consideration in solving problems of developing high-viscosity oil fields.

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