Influence of recent geodynamics to gas productivity of Irkineevo-Chadobets riftogenic trough

The area of research is located within the Irkineyevo-Chadobetc riftogenic trough (IcHRT) in the west of the Siberian Platform. Here deposits of gas and gas condensate were discovered in the Neoproterozoic sediments of Taseeva group. Productivity of these deposits within large anticlinal structures largely controlled by facies distribution of reservoir rocks, intensity and direction of secondary processes, mainly fracturing. Prediction of fracturing based on the reconstruction of the fault-block structure of the IcHRT. Identified lineaments were analyzed from the position of modern geodynamic. Application of structural and geomorphological method allowedto identify areas of modern geodynamic compression and tension. It was found that "tension" zones correspond to intervals of maximum gas permeability.
Materials and methods
GIS data (50 wells). 1,200 meters of corematerial, about 1,500 petrographic thin sections. The results of petrophysical studies. Digital composite images, digital modelmap of relief, seismic data, gravimetric and magnetic maps, production data. Methods: lithological, methods of fracture prediction based on reconstruction of fault-block structure, tectonophysical (structural and geomorphological methods).
Results
Studies of modern geodynamics of the IcHRT led to the assumption of the close relationship between gas-productivity and areas of modern geodynamic "stretching".The obtained regularities also are proven in study of lithological features of productive deposits. It was found that the gritsand sandstones in the areas of modern geodinamic compression much more intensively sealed, between the grains marked conformal, regeneration, incorporational and microstylolite contacts.
Сonclusions
The carried out complex research of natural reservoirs of the IcHRT allow expect to the close relationship between modern geodynamic processes and gas-bearing of sedimentary cover. Based on these views, it must be assumed that the most prospective gas-bearing zones are associated with modern geodynamic tensions zones generated as a result of divergent shear deformations.Based on the results of complex lithology, cosmo-geological and geodynamic studies within the IcHRT it was found eight zones of porous-fractured and fractured reservoirs located in areas of modern geodynamic tension, most perspective for geological exploration to identify gas fields.