Search

Developing of the exploration criteria for oil reservoirs and non-structural traps in the clinoform successions are the key target as for detailed field appraisal in the West-Siberia basin well as for exploration in the clinoform complexes in the new sedimentary basins without drilling. Based on complex analysis of the seismic, well logs, well tests and core data in the northern Priobskoye field, the correlation between clinoform geometry, edge trajectory and distribution pattern of the reservoirs in the productive formation AS is established. The highest flow rates and reservoir properties are typical for bar deposits, proximal fan and slope channels. Deposits of bars are formed at the high stand system tract and at the beginning of the falling system tract on the edges of tangential clinoforms with gently ascending, flat and descending edge trajectory. Deposits of basin floor fans and slope channels are confined to the drop in the relative sea level and its low stand; it is advisable to search for them at the bottomset of tangential clinoforms with a descending edge trajectory and in gently cross-bedded clinoforms.

Apparently, conceptual base of the sequence stratigraphy is one of the most acknowledged methodologies in the geological world at the present time for the sedimentary strata structure prediction. It is based on the complex analysis of the seismic, stratigraphic and sedimentary data on the depositional bodies where the structure and facies filling is regulated by the relative sea level changes. The Lower Cretaceous section of the Western Siberia in this regard is the unique object, as it is represented by the full range of the clastic depositional environments – from relatively deep-water to the continental, which are very sensitive to the conditions changes. Sequence-stratigraphic analysis results can be used to complete the pragmatic tasks in the petroleum geology as the analysis is based on the reconstruction of the sedimentogenesis processes in the past, and the understanding of that processes is the key to the generalized depositional model development. This model can be used to create the models, which can be applied to the unique local objects that occur in the Lower Cretaceous section.

The major lithological rock types that compose the highest-carbon part of the lower Silurian Longmaxi Formation section in the Sichuan province of the People’s Republic of China have been identified and characterized. The analyzed distribution of rare and trace elements in graptolite shales has made it possible to propose the redox conditions for high-carbon sedimentation.

The main lithological rock types typical of the highest carbon part of the section of the Lonmasi formation of the Lower Silurian age of the Sichuan province of the People’s Republic of China (PRC) were identified and characterized. An analysis of the distribution of rare and trace elements in graptolite schists allowed us to suggest the redox conditions for the formation of high-carbon sediments.

The petrophysical, geochemical, and lithological features of the structure of graptolite shales from the lower part of the Longmaxi Formation of the Lower Silurian age of the Sichuan Province of the People’s Republic of China are considered. The basic patterns of the formation of carbon-rich sediments in the intrashelf depressions are revealed.

Petrophysical, geochemical and lithological features of the Domanik formation rock structure are considered. Particular attention is paid to the formation of the pore space in the pelitic carbon-enriched deposits within the depressions. The latter are characterized by low reservoir properties, heightened content of organic matter and siliceous-carbonate composition. Sedimentation and post-sedimentation factors affecting formation of pores filled with micro-oil are identified. High generation potential of rocks capable of generating and giving off liquid hydrocarbons at early stages of catagenesis is singled out. The pore space in carbonate complexes of shallow-marine origin overlapping carbon-enriched deposits is described. In spite of oil and bitumen saturation of these rocks, the predominant migratory character of hydrocarbons was noted.

At present, the proven oil reserves from traditional Russian reservoirs are decreasing, leading to a steady fall in oil production. One of the possible ways to maintain the oil production at the present level is to produce tight oil, which is regarded as the category of oil from the Bazhenov Formation in the Kanty-Mansiysk region of Western Siberia, Domanik deposits in the Volga–Ural province, and Maikop deposits in the Fore-Caucasus.