The Estimation of the Generation Potential of the Low Permeable Shale Strata of the Maikop Caucasian Series
The article is devoted to the estimation of the generation potential of the low permeable shale strata of the Maikop Caucasian series, with which favorable conditions for the formation of «shale» HC accumulations are associated. Unconventional hydrocarbon resources in shale low-permeability strata are often associated with the development areas of immature, but «rich» and «very rich» potentially petroleum-based rocks that are at the initial stage of the main phase of oil formation or on the approaches to it. The concentration of TOC in them can reach the first tens of percent. By «shale oil» is meant the oil of parachute congestions in low-permeable high-bituminous, enriched sapropel OM strata. For a reliable estimation of the generation potential of the parent rock, it is necessary to take into account the initial values of TOC and HI. The recovered hydrocarbons from the oil-and-gas-bearing shales will be contained in the formation at the concentration that has arisen as a result of their generation of insitu. The main criterion for the search for shale hydrocarbons is not a trap, where hydrocarbons accumulate and deposits are formed, but directly the oil-bearing rocks in which hydrocarbons were formed, but from which their emigration did not occur. Based on the analysis of the geophysical and geochemical characteristics of the shale low-permeability reservoirs of the Khadum Formation of the Ciscaucasia, a methodical approach was proposed for estimating TOC values from them in accordance with gamma-ray logging data. This significantly expands the possibilities for TOC estimation in the well sections, since core sampling is limited. There is an opportunity to more quickly identify promising areas for the search for hydrocarbon accumulations in them.