Rock shale mineral composition influence on oil and gas generation process (results from laboratory experiments)

Abstract

The paper presents the results of the hydrothermal processes of organic matter transformation in the rocks of the Bazhenov Formation and the Domanik horizon laboratory modeling. Shortterm exposure of samples to high temperatures (350 C) and reservoir pressures (300 atm) in the presence of water made it possible to simulate the processes that could take place in the reservoir, and to transform kerogen up to 70% in the rocks initially containing immature kerogen or kerogen in the beginning of the oil window. It was found that the amount of liquid hydrocarbon compounds generated during cracking mainly linearly depends on the content of organic matter in the rocks, while the gas generation is described by a rate function. The mineral composition of rocks does not affect the size of the formed pores, but in some cases it controls the amount 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 inhibits oil and gas generation process, there are lower amounts of light components in the products, and some of hopanes are absent. At the same time, high concentrations of siliceous material in the rocks with low amount of other components and, probably, the presence of pyrite can stimulate the generation process, in some cases allowing an increase in the amount of produced “synthetic” oil and gas, to achieve a greater variety of reaction products. The results obtained in general make it possible to examine the processes of individual hydrocarbon compounds formation during hydrothermal processes, to identify catalysts and inhibitors of the generation mechanism, and also, from a practical point of view, to propose conditions for reservoirs stimulation and development of technologies for increasing oil production and generation of oil with a controlled composition in situ.