Identification of the Composition and Assessment of the Influence of the Solid Hydrocarbon Phase in the Reservoir on the Behavior of the Mobile Fluid of the Bazhenov Formation During the Reservoir Development

The purpose of the work is to identify the composition of the initial reservoir hydrocarbon (HC) system of the Bazhenov formation, as well as to assess the influence of the presence of a heavy solid hydrocarbon phase (bitumen) in the formation on the production of mobile fluids using PVT modeling methods. The article describes the necessary experiments to determine the component composition of the C81+ fraction and the PVT properties of the formation mobile fluid taken from the well and the bitumen extract from the rock, and also presents their results. In addition, the properties of fractions up to C81+ were calculated depending on the molecular weight for PVT modeling (extension of the Katz-Firuzabadi table). One of the important parts of the article is the assessment of the ratio of bound and free oil in the original reservoir system. Based on geochemical research data, an analysis was performed to assess the component composition of the original system (using the example of the Bazhenov Formation) using rock pyrolysis and studying formation fluid and bitumen. Using the results of studies of reservoir fluid samples, a PVT model was built and tuned. This PVT model was used to assess the properties of the initial reservoir hydrocarbon system and was adjusted to the fraction of the solid phase in the reservoir at the initial reservoir conditions. After this, based on the PVT model, an assessment was made of the influence of the presence of a solid phase in the composition of the reservoir system on the behavior of a mobile hydrocarbon fluid during reservoir development for depletion, as well as on the use of enhanced oil recovery methods (injection of associated petroleum gas and thermal methods of influencing the reservoir).