Design of WAG Parameters

Abstract

Abstract When an oilfield reaches the final development stage it becomes crucial to plan enhanced recovery methods. In case of low and medium viscous oil in depleted reservoirs it is feasible to use water-alternating-gas (WAG) treatment. Application of the method depends, first of all, on the availability of non-commercial supply of associated gas. To evaluate the amount of gas necessary for the treatment, it is required to estimate the operation's efficiency. The important thing here is to decide on the optimal ratios of the injected water and gas. This work is dedicated to the methods of planning the required ratios of injected water and gas, which can be used for further estimations. The issue in question is studied using the oilfields in Kogalym region as an example. Analytical evaluations, numerical and experimental simulation were employed to reach the work's objectives. The analytical approach enabled to define the efficient ratio for gas water as a mixture with the minimal mobility or with equal mobility of water and gas in a porous media. The numeric simulation was done using a 2D model of a parallel flow calculated in ECLIPSE software. The laboratory testing was done using a standard porous flow model with dry and wet gas. As a result, the ratios of injected water and gas were found and compared, recommendations on WAG planning for Kogalym oilfields were issued. The studies enabled to estimate the need for the gas to be used for the treatment, detailed and justified to different degrees. Prioritizing the fields depending on the amount of gas reserves enabled to define the ones best suited for applying gas EOR methods. The novelty of the study is the complex approach to the injected gas water ratio estimation. Comparing analytical, numerical and laboratory studies enabled to adequately consider the parameters affecting the process and to justify the means of sweep enhancing.