The article describes the method of studying the parameters of the rectification process in the production of butane from associated petroleum gas. The method allows to optimize this process in terms of reduction of energy and operating costs and to achieve the goal of increasing efficiency of separation of hydrocarbon components of raw materials – mixture of gases. These tasks are relevant, as their solution saves expensive energy and valuable commodity products. However, mathematical modeling of rectification processes is very complex and problematic without the application of modern numerical methods and computer programs solving systems of hundreds of nonlinear equations. One of the most suitable programs for such modeling is Aspen Hysys, which also allows to create visual diagrams of technological processes used in the oil and gas industry. This paper considers one of the problems solved in butane production – reduction of operating costs by reducing power consumption when selecting the number of plates of the rectification column and the number of the feed plate to which the initial product is supplied. The composition of the gas mixture is taken for one of the oil and gas deposits, which is char-acterized by a high proportion of butane in the associated gas composition. Aspen Hysys has developed a process model for producing butane that meets product requirements. Based on the results of the work, recommendations are given on the application of the developed methodology for the study of the influence of various factors on the efficiency and cost of technological processes in which rectification columns are used.