Suchergebnisse

Natural processes contradictive to the common organic (sedimentary and migrational) theory of oil formation were concluded to take place based on the study of the hydrocarbons-biomarkers distribution regularities at the molecular level in the dispersed organic matter of rocks, petroleum and kerogen thermolysis products.Here specific examples of the generation of oil (concentrated organic matter) directly in the reservoir, i.e. reduced scheme of naphthydogenesis, excluding the process of migration were presented. At the same time, these examples do not exclude the migration of organic matter from the «oil source strata», but are an exception that confirms the general rule. It was shown that the study of organic matter, organic carbon (TOC), chloroform-soluble bitumen, pyrolysis "Rock-Eval", etc., necessarily supporting the conclusions with data from a detailed study of the hydrocarbon composition at the molecular level.

The experimental results on the synthetic oil production from Domanik Formation rocks under hydrothermal conditions are given. Oil fractions extracting potential of the rocks under hydrothermal was shown to be up to 60 mg/g or 6,0 wt.%. Inorganic additives (sodium carbonate or silica) incorporation does not influence on the oil recovery factor. Meanwhile the amount of recoverable oil products depends on the mineral composition of the rock. The dependence between the percentage of hydrocarbons emission and mineral composition of the rocks was determined. Clay minerals and silica increase the yield of synthetic oil, carbonates, conversely, inhibit the process.

In this paper the temperature treatment impact on Bazhenov formation core samples are shown. Impact was performed by pyrolysis in a temperature range of 300-480 °C and in the closed autoclave in the presence of water at reservoir pressure. It is shown that as a result of thermal exposure at 400 °C pyrolytic peak S2 is reduced by 90-95% and generation potential of rocks almost completely implemented. The microtomographic samples studies combined with scanning electron microscopy allowed to establish the dependence of permeability and porosity of the rocks. It demonstrated that even at 350 °C the fracture system formed in core samples also the porosity and permeability due to impact may increase from several times to several ten times. The results will allow for a more accurate simulation of enhanced oil recovery treatment on Bazhenov formation rocks to increase oil recovery.

The paper presents a study of the structure and reservoir properties of rocks of the Bazhenov formation in the sections of three wells located in different structural zones of the Priobskoye field. It is shown that the porosity of the samples varies from 0.02% to 6.95%, the absolute gas permeability of the rocks reaches 1.364 mD. It is established that the collectors in the Bazhenov formation are confined to silicite-radiolarites (possessing porosity associated with the leaching of radiolarian shells) and kerogen-clay-siliceous rock and kerogen-clay silicite (porosity is associated with the release of space between the clay-siliceous matrix and kerogen by ripening organic matter). The following secondary processes influenced the formation of voids in these lithotypes: recrystallization of radiolarians and local warming up.

This article presents the results of studies of the material constitution and physical properties of rocks of foundation of the West Siberian Plate. It is shown that anthraxolite and kerite groups are present in bitumen rocks. We assume that the bitumens create a Late Paleozoic paleo-deposit, transformed under the conditions of apocatagenesis. Impregnation with highly transformed organic matter leads to a significant decrease in electrical resistivity to values of 1–30 Ohm metre, which must be taken into consideration when interpreting low-resistivity zones on log data.

One of the most famous and promising shale formations in Russia is the Bazhenov formation. The ambiguity of ideas about its geological features, caused by the complex, heterogeneous structure of the strata, attracts the attention of many researchers. In this work, the Bazhenov formation is singled out in conjunction with its stratigraphic counterparts in the Bazhenov high-carbon formation (BVCHF). In this were considered the main characteristics of its allotment and distribution over the area, as well as the geological structure. Being an unconventional reservoir of hydrocarbons, BVCHF has properties of a petroleum-bearing rock, one of the main characteristics of which is organic matter, its type and maturity. The paper presents the results of the study of organic matter by various methods at the micro level, as well as their integration with larger-scale studies. The need for detailed consideration of the organic matter of the BVCHF is justified by the fact that it has a mixed composition and, as a consequence, a different degree of transformation and spatial distribution.

Possible reservoir type of Bazhenov formation relative to the intervals with increased content of phosphate is described in the resent work. It is shown that phosphate formations have highly connected pore space, porosity may achieve values up to 14%. These rocks also have explicit geochemical characteristics of oil reservoir rocks in comparison with other rock samples in the well. For example, the productivity index and oil saturation index for phosphates is twice higher. The composition of such species may slightly vary, fluorine may present in phosphate minerals, meanwhile rocks are always maintain high content of organic matter (more than 8 wt%).

The Bazhenov Formation rocks contain thin luminescent layers enriched in type I kerogen, which is unique for the bulk of the organic matter of the Bazhenov Formation of the West Siberian petroleum basin. The article provides a detailed characterization of the mineral and organic parts and proposed origin of these layers, called by the authors "alginite-rich layers". The wide distribution of the luminescent alginite-rich layers over the central part of Western Siberia in a single stratigraphic range allows them to be used as marking horizons, as well as for assessing the thermal maturity of kerogen. This study contributes to understanding the diversity of processes that form the organic-rich deposits of the Bazhenov Formation.