Third International Conference on Geology of the Caspian Sea and Adjacent Areas

Paper gives a brief overview of the sedimentary cover of the Earth and summarizes volumes of sediments and mass contained in the Earth Sedimentary layer (stratisphere). Using available data author shows unique nature of the South Caspian Basin and other rapidly subsiding basins with attenuated crust. Sedimentary, crustal and lithospheric thickness correlations are discussed.

Digenesis has a great influence on reservoir quality of Sanduo formation of Gaoyou Sag, Jiangsu Basin, China. The methodology includes core description, thin section petrography, Fluorescence, Scanning Electron Microscope (SEM), Cathodoluminescence (CL), fluid inclusion and isotope/electron probing analysis to evaluate the diagenesis effect on reservoir quality. The Sanduo sandstone consists of medium to coarse-grained, moderately sorted lithic arkose and feldspathic litharenite. Quartz, calcite, and clay are more dominant pore occluding cement and occur as euhedral to sub-hedral crystals. Porosity and permeability values range from 0.3%-25% and 0.046mD-5000mD respectively. Compaction, alteration/dissolution of cement and unstable mineral in grains and fracturing are the main diagenetic events. Clay minerals resulted from the alteration of feldspar and volcanic lithic fragments. Porosity and permeability decrease with cementation either related to quartz overgrowth or precipitation of calcite, whereas increase with leaching of metastable grains, dissolution of cement and pore-lining by chlorite. Best reservoir portion is thicker sandstone bodies, medium to coarsegrained, well-sorted with low primary ductile grains and containing a minor amount of calcite cement. The present study shows several diagenetic changes in the Sanduo Formation, but the overall reservoir quality is well preserved.

Geological expedition trips – it was impossible to imagine the oil and gas exploration in the pre-war period without them. In the second half of the XX century, the hammer as an instrument of obtaining new knowledge was replaced by geophysical equipment. However, over the past 10 years there has been a tendency to resume the study of sections of target sedimentary complexes in outcrops. In this regard, the companies organize geological expeditions in the areas of exploration, both in the territorial part and in the water area (on adjacent land) for a period of 2 weeks to 2 months with the participation of their own and invited specialists. This is due to: a) the development and implementation of new laboratory methods of research, for their application requires the collection of new samples; b) the periodical appearance of new surface oil and gas seepages in regions with active seismicity and tectonic movements; C) the need to use the data of the structure and stratigraphy of sedimentary complexes in outcrops with seismostratigraphic models and simplify seismic interpretation.

The authors considered the geodynamic conditions for the formation of the structure of the Caspian basin. A geomechanical model of the formation of folding in geological bodies as a result of acquiring internal volumetric mobility, the ability to flow, is shown. The structural relationships between different-age formation complexes of deposits in a vertical section of the earth’s crust in the South Caspian basin are demonstrated.

The authors evaluated the generation potential of the Oligocene-Miocene deposits of the Caucasus. The aim of the present work is to assess the generation potential of low-permeable clay strata of the Oligocene-Miocene deposits of the Caucasus, which are associated with favorable conditions for the formation of “shale” hydrocarbon accumulations. Based on the results of pyrolytic studies, maps of the distribution of the main geochemical parameters were constructed.

According to estimates covered by RBC-Daily (https://plus.rbc.ru), about 5% of the extracted oil and oil products are lost during production and transportation. While water bodies are polluted, biological resources are damaged, and objects for decades can lose their fishery, recreational, and water management significance. To date, the results of numerous studies on the negative impact of hydrocarbon pollution on microorganisms and higher life forms, including humans, have been published (review by Tormoehlen et al., 2014). Hydrocarbon organic pollutants includes polycyclic aromatic hydrocarbons (PAHs), which are priority pollutants due to their high toxicity and persistence. Major accidents associated with oil spills in the waters attract public attention and become a matter of concern not only to scientists and environmentalists, but also to the public.

Fundamentally new results, connected with processes of natural and man-made degassing of the Earth, have been obtained. High level of natural dangers in the Arctic and the World Ocean has been justified, determined by presence of cryohydrosphere and cryolithosphere with wide distribution of gas hydrates. Forecast of gas hydrates distribution zones in the northern areas of the World Ocean has been conducted. Large-scale emission of gas from cryolithosphere to hydrosphere and atmosphere has been approved. Powerful blowouts, spontaneous ignition and explosions of gas with formation of giant craters, have been studied. New methods and technologies have been developed for revealing, monitoring of development and decreasing threats of dangerous natural and man-made objects.

Lithological and geochemical studies of Upper Jurassic-Lower Cretaceous and Paleogene organic rich shales located within the Northern part of West Siberia and Northern Caucasus accordingly show their high similarity in term of mineral composition, structure, texture and organic matter quality. These similarities reveal analogous deposition environment and climate settings within the very different areas and geological ages. For both formations main fundamental factors which control accumulation of hydrocarbons may be presence of the intervals with low organic matter content. These intervals probably restricted fluid sorption process by organic-rich laminas. Finally, investigation shows that Upper Jurassic shales may be characterized as a very perspective hydrocarbon bearing formation, particularly as a unconventional reservoir.

Production of hydrocarbons from unconventional reservoirs is one of the immediate problems which petroleum industry faces. The Assel-Arta Lower Permian deposits of the Astrakhan arch seem promising for oil and gas production. However, there are difficulties for seismic work conducting due to impermeable properties of salt layers; therefore industrial hydrocarbon accumulations were underestimated. In the current research, we have applied organic geochemistry methods for assessment of the generation potential of Lower Permian organic matter, as well as the overmature subsalt deposits. The molecular composition analyses of rock extracts indicated that the host rocks and extractable organic matter were syngenetic.