The article is devoted to the description of studies aimed at studying the process of separation of associated petroleum gas into fractions by the method of low-temperature separation. The work uses Aspen Hysys software, which allows to model technological schemes containing various types of equipment, solve problems by selected numerical mathematical methods and thus to study the progress of practically any physical and chemical processes. Consideration of this problem is a pressing task, as it aims to save and improve the quality of valuable hydrocarbon materials. At the same time, the influence of various factors on the process of separation of heavy hydrocarbons has not been studied yet and there is no developed and simple method of monitoring the state and composition of oil and gas products at different stages of processing. To demonstrate the developed method, the composition of the initial mixture is specified and a simplified computer model of the process of extracting heavy hydrocarbons is created. The influence of one of the main factors acting in this process, temperature, on methane yield and heavy hydrocarbon fractions was investigated. Based on the results of the work, recommendations for improvement of this technological process are proposed. The methodology and results of the carried out studies can be used for further study of processes of associated petroleum gas processing, including using more complex technological schemes. This technique can also be useful for research of processes of processing of any hydrocarbon raw materials (for example, oil of different deposits), as well as other commercial chemical products.