Method and device for evaluating contribution rate of coal series and sapropel type hydrocarbon source rocks of complex multi-source gas reservoir

Abstract

The invention provides a method and a device for evaluating contribution rate of coal series and sapropel type hydrocarbon source rocks of a complex multi-source gas reservoir. The method comprises the steps: obtaining alkane series carbon isotope data in a natural gas sample of a complex high-evolution multi-source gas reservoir in a research region, and judging whether carbon isotope inversion exists in the natural gas sample according to the data; if carbon isotope inversion exists in the natural gas sample, obtaining a methane carbon isotope distribution range in the complex high-evolutionmulti-source gas reservoir natural gas sample in the research area and the average value of the methane carbon isotope data; obtaining the maximum end member value of methane carbon isotope data in the single coal series hydrocarbon source rock contribution gas reservoir positive sequence carbon isotope natural gas close to the complex high evolution multi-source gas reservoir; obtaining the minimum end member value of the methane carbon isotope data in the single marine facies sapropel type hydrocarbon source rock contribution gas reservoir positive sequence carbon isotope natural gas closeto the complex high-evolution multi-source gas reservoir; and calculating to obtain the contribution rate of the complex high-evolution multi-source gas reservoir coal series hydrocarbon source rock and the marine facies sapropel type hydrocarbon source rock in the research area.

Description

technical field [0001] The invention relates to a method and device for evaluating the contribution rate of coal measures and sapropelic source rocks in complex multi-source gas reservoirs, and belongs to the technical field of gas source comparison and resource evaluation in natural gas exploration. Background technique [0002] From a global perspective, the global oil and gas reserves are dominated by marine strata, mainly from marine sapropelic source rocks; while my country's oil and gas reserves are dominated by continental strata, mainly from coal-measure source rocks, lacustrine Sapropelic source rocks and marine sapropelic source rocks. Compared with oil and coal, the amount of pollutants generated by the combustion of natural gas with the same heat is much lower than that of oil and coal. Therefore, natural gas is a clean, low-carbon, and environmentally friendly green energy. At present, the proportion of natural gas in my country's energy structure is still lower...

AI Technical Summary

Problems solved by technology

Deep complex multi-source gas reservoirs are generally highly evolved natural gas, which is dry gas dominated by methane, with extremely low content of ethane and above heavy hydrocarbons, high drying coefficient, and inversion or inversion of carbon and hydrogen isotopes of alkane gas The geochemical characteristics are abnormal, the origin of natural gas is complex, the conventional classical identification indicators and methods are no longer applicable, and the identification results are inconsistent (for example, some scholars believe that the Ordovician natural gas in the Lower Paleozoic of the Ordos Basin is mainly coal-derived gas, Some scholars also believe that it is mainly oil-type gas, and some scholars believe that it is mainly crude oil cracking gas)

Therefore, it is very difficult to determine the origin, source and contribution of natural gas in complex and highly evolved multi-source gas reservoirs, which restricts the selection of favorable directions for the exploration of complex multi-source gas reservoirs in key gas-bearing basins and the evaluation of play areas

Images