Geo-fluid model formation groundwater OF petroleum horizons Western megablock of the West Siberian megabasin

Abstract:

West megablock West Siberian megabasin refers to Elysion lithostatic the water pressure system with the elements of the geodynamic system in the lower sedimentary cover.

Geo-fluid model of groundwater is based on the example of Talin and Kamenny deposits of Krasnoleninsk oil and gas area.

The geological structure presented by the pre-Jurassic basement rocks and Mesozoic-Cenozoic clastic sediments of the platform cover (with a thickness of about 2.5 km). Hydrogeological stratification is presented in the form of seven limited hydrogeological complexes: Oligocene-Quaternary, Turonian-Oligocene, Aptian-Albian-Cenomanian, Neocomian, the Upper, Lower-Middle Jurassic, Triassic-Paleozoic.

The main features of the geological structure associated with the presence «Frolovsky barrier» (clay Neocomian age with thickness of 650-700 m) and numerous faults in the foundation. The faults continue in the sedimentary cover. As a result of crustal extension in the era of tectonic activation fault were "enhanced" magmatic intrusions.

Geo-fluid model of groundwater Western megablock is based on the idea of the "pushed out" from the clay Neocomian age huge amounts Elysion water under the influence of increasing geostatic load. Then Elysion water came in Jurassic reservoirs. The result is an extensive development of the sodium bicarbonate-water type (of V.A. Sulin) with mineralization up to 10 g/l and the presence of abnormally high reservoir pressures (in excess of 4 - 5 MPa).

The second circumstance in determining the structure of the construction of geo-fluid model, is the impact of deep fluids probably periodically coming along faults in the foundation of the lower classes of the sedimentary cover. Deep fluids are mixed in the aquifer formation waters. They change the background hydrogeological field forming section with its abnormal parameters.

Presented geo-fluid model was used in the calculation of reservoir pressure maintenance system for the selection of oil. Also, the model helps to explain the contrast of hydrogeodynamic hydrogeochemical fields in the study area.