The Influence of the Composition of Rocks from High-Carbon Formations on the Process of Oil and Gas Generation: The Results of Laboratory Modeling

The results of laboratory modeling of hydrothermal processes of organic matter transformation in the rocks of the Bazhenov Formation and the Domanik horizon are presented. Short-term exposure of the samples to high temperature (350°C) and high pressures (300 atm) in the presence of water made it possible to simulate the processes that could occur in the reservoir and to reach 70% transformation of kerogen in the rocks that initially contained immature kerogen or kerogen at the beginning of the oil window. It has been found that the quantity of liquid hydrocarbon compounds generated during cracking in general linearly depends on the content of organic matter in the rock, while the gas generation is described by a rate function. The mineral composition of the rocks does not affect the sizes of the formed pores; however, in some cases, it additionally controls the quantity of formed hydrocarbon compounds and the composition of the liquid products. It is shown that the increase in the amount of carbonate material in the rocks decelerates the process of oil and gas generation; the products contain fewer light components and have no series of hopanes. A high concentration of silicious material in the rock at a small fraction of other components and probably the presence of pyrite can stimulate the generation process, which in some cases increases the amount of produced “synthetic” oil and gas, and can achieve a greater variety of reaction products. These results make it possible to examine the processes of forming individual hydrocarbon compounds during hydrothermal processes, to identify catalysts and inhibitors of the generation mechanism, and, from a practical point of view, to propose conditions for reservoir stimulation and the development of technologies for increasing oil production and generation of oil with a controlled composition.