Hydrogeochemical conditions of the Mesozoic hydrogeological basin within the Ravninnoe oil field

Abstract

Studies of the hydrogeochemical features of groundwater in deep horizons of the West Siberian megabasin are important. They are closely related to applied and fundamental issues of oil and gas hydrogeology and allow studying the processes of formation, accumulation and migration of hydrocarbons.The article deals with our analysis of the hydrogeochemical conditions of the Mesozoic hydrogeological basin within the Ravninnoe oil field. The ion-salt composition of groundwater in deep horizons in the territory is variable. Basically groundwater are of the calcium chloride type (according to V. A. Sulin's classification), but magnesium chloride and sodium bicarbonate types of water are locally distributed. The hydrogeological conditions of the field are manifested in the change in the chemical composition of groundwater and in the vertical hydrochemical zonality. The article describes the features of the regional distribution of reservoir temperatures and reservoir pressures of the Aptian-Albian-Cenomanian, Neocomian and Jurassic hydrogeological complexes. The study of the formation factors of the hydrogeochemical field of these deposits was carried out taking into account paleotectonic, paleogeomorphological and paleohydrogeological reconstructions of the conditions that influenced the accumulation of fluids. Faults are widespread in the deposits of the pre-Jurassic complex, as well as angular unconformities between rocks of different ages, which predetermined the migration of hydrocarbons and the formation of their deposits.