Criteria for assessment of hydrocarbon saturation of compact sand-aleurite rocks under DDB conditions
Abstract
Introduction. In the modern period, the increase in the resource base is largely associated with the exploration of deposits that are under development. The latter process includes the study of non-traditional reservoirs, among which of considerable interest are compacted sand-silt rocks. Steady growth in raw material consumption has led to the search for alternative sources of hydrocarbons. The development of the industry is aimed at studying existing deposits with the introduction and involvement of the latest, advanced technologies. In this regard, the development of this area is relevant. Undoubtedly, the search for hydrocarbons in compacted sand-silt rocks within the Dnieper-Donetsk basin will develop. Purpose. To propose the main geological criteria for detecting hydrocarbon saturation of compacted rocks, which are accompanied by certain indicators. Analysis of previous works. Until recently, information on compacted hydrocarbon-unsaturated sand-silt rocks was most often found only in foreign publications. In the 60's of the XX century, employees of UkrNDIgaz tried to study in detail the compacted hydrocarbon-saturated rocks, but at that time this area was not developed. These studies are associated with the names of Mukharinskaya I, Kharchenko S, Lagutina A. In recent decades, issues regarding compacted sand-siltstone rocks in Dnieper-Donetsk basin have been considered during gas-type gas research. Until recently, the detection of gas in compacted rocks was of a general nature and was not substantiated by actual material. Presenting main material. The nature of the compacted sand-silt varieties is very diverse. Due to the peculiarities of lithological packs, compacted rocks should be considered both separately and in combination with direct contact with traditional reservoir rocks. Scientific and theoretical research and factual material allow us to identify promising stratigraphic complexes in terms of hydrocarbon saturation in compacted sand-silt rocks. Compacted sand-siltstone rocks acquire the greatest development within the Lower Permian-Upper Coal and Middle-Lower Coal complexes. The main criteria for detecting compacted rocks should be considered the degree of saturation of rocks and the nature of hydrocarbons. Consider the indicators that characterize these two processes. Due to the fact that geological criteria and their indicators (a kind of indicator) often interact, complement each other and are "hostages" of causal processes. Conclusions. The proposed criteria are based on a number of geological indicators, such as ascending migration of hydrocarbons, features of lithological composition, conditions of conversion of imported and own organic matter, low water content of the stratum. The activity of most processes, which are indicators of the proposed basic criteria of oil and gas, are accompanied by an increase in the temperature of the local zone of development of compacted sand-silt rocks. In one of these zones the connection of temperature anomaly with the main indicators of prospects for oil and gas bearing capacity of compacted sand-silt rocks is considered. One of the methods of practical detection of the degree of hydrocarbon saturation in compacted sand-silt rocks, especially in the zone of elevated temperatures, can be a direct method of geological-gas-geochemical research, based on the simultaneous study of geological properties and gas-geochemical features.
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