Rosneft Oil Company pays special attention to the application of a systematic approach to search for the most effective enhanced oil recovery (EOR) methods. This article continues series of articles devoted to the problems of substantiation and implementation of gas injection. The authors consider the regression dependence development for rapid assessment of the increase in the oil recovery as a result of gas injection.
Recently, there has been an increased interest in the use of gas injection and water-alternating-gas (WAG) technology as EOR methods. Such methods are very expensive in terms of both capital costs for field infrastructure and equipment, and the cost of operation, process control, laboratory tests and design study. When it is necessary to study a significant number of potential objects and injection options, it is important to perform preliminary upper-level technical and economic assessments. Such assessments should contain, firstly, the possible risks of the WAG application, secondly, calculations of the expected technological effect, and thirdly, the production profiles obtained promptly in order to calculate the economic feasibility of the event. Earlier the authors have considered various geological, technological and organizational risks, as well as the principles of ranking objects according to the order of application. In this article the oil recovery factor increase as a result of WAG is assessed. Existing expert systems for assessing WAG effect on oil recovery factor are poorly accessible or use a limited data set. In addition, a number of parameters are interrelated and describe the spatial and volumetric characteristics of the object, but at the same time they do not contain regional features of deposits. Based on a series of multivariate calculations using sector hydrodynamic model and comparison with the actual results, the authors proposed new regression dependence for determining oil recovery increase, linking the displacement pressure and a number of key filtration properties into a single formula.
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