Miscible Displacement as an Approach to Increase the Development Efficiency of the Remote Oil Fields

Abstract

The development of oil fields is accompanied by the production of associated petroleum gas (APG), that requires it rational use. For the remote deposits, in the conditions of unprofitable transportation of APG, new solutions are needed that make it possible to use the infrastructure of fields for the production, preparation and transportation of both oil and gas. This paper describes an approach to the integrated optimization of the technical and economic efficiency of the development a group of remote oil fields by organizing the miscible injection of APG on one of the fields. At the first stage, an object for the potential organization of the reverse gas injection was selected from a group of remote field based on a number of parameters. On the basis of numerical compositional modeling, the mixing ability of gases and oil (slim-tube experiment) was estimated taking into account the variability of the composition of APG from each field and the change in the volumes of gas produced from each of them. Further, for the potential volumes of gas supplies based on the developed algorithm, the optimization of the gas injection strategy and the cycling process was performed. Based on the uncertainty analysis, a preliminary assessment of the efficiency of technology implementation has been carried out. The developed program of laboratory studies of miscible processes, aimed at removing the main uncertainties, was implemented, and the analysis of the results allowed us to refine the forecast indicators. The main result of the work is to evaluate the alternative (alternative to transporting gas for the purpose of monetization) of using associated gas produced in order to organize a miscible displacement at one of the group of the remote fields. The net present value of the proposed option is estimated at 50% above the base scenario. In the course of the work, an algorithm has been developed for the optimal distribution of gas flows between injection wells in order to increase oil production, given the restrictions on the volume of the cycling process. The application of this algorithm allowed to increase the cummulative oil production by 11% for the field. A program of laboratory studies was developed to remove the main uncertainties in the processes of miscible oil displacement by gas, the implementation of which allowed us to clarify the miscibility pressure ranges and the optimal composition of the gas for injection. All final calculations are performed and confirmed on a tuned compositional simulation model taking into account the sensitivity to the input data. The accuracy of the numerical realization of the experiments is analyzed. The recommendations for improving the evaluation of the miscible processes of both numerical and physical are formulated. In this paper, it is shown that the integrated use of associated gas production can lead to an increase in the attractiveness of the project as a whole, especially for small oil fields remote from the developed oil and gas infrastructure. Optimization of the strategy and operating modes of gas injection wells allows to increase the efficiency of miscible displacement in the field. The implementation of laboratory research is of primary importance at the initial stage of assessing the effectiveness of technology and allows to significantly reduce the range of uncertainties in the forecast.