Method and device for evaluating abundance of organic matter of hydrocarbon source rock

Abstract

The invention provides a method and a device for evaluating abundance of organic matter of a hydrocarbon source rock, wherein the method comprises the following steps: emitting high-energy neutron to a stratum; recording an inelastic scattering gamma-ray spectra generated by the interaction of nucleus of elements in the stratum and the high-energy neutron; analyzing the inelastic scattering gamma-ray spectra, to obtain the content of elements in the stratum; obtaining the content of inorganic carbon in the stratum by using the elements associated with the content of the inorganic carbon; deducting the content of the inorganic carbon from the total carbon content of the stratum, so as to obtain the content of the organic carbon in the stratum; evaluating the abundance of organic matter of the hydrocarbon source rock by using the content of the organic carbon element.

Description

technical field [0001] The invention relates to the field of geophysical logging, in particular to a method and device for evaluating the abundance of organic matter in source rocks. Background technique [0002] The main index to evaluate the abundance of organic matter in source rocks is the content of organic carbon, which refers to the content of organic carbon per unit mass of rock. Organic matter content is one of the important parameters in the study of source rocks, which can indicate the richness of organic matter in source rocks, judge the efficiency of oil and gas generation, and calculate the amount of oil and gas generation. [0003] At present, the methods for evaluating organic matter content in the petroleum industry mainly include: (1) Downhole coring and core analysis in the laboratory. Although the results obtained by this method have high accuracy, the cost of drilling and coring is high, core samples are limited, and analysis costs are high , It takes a...

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Problems solved by technology

[0003] At present, the methods for evaluating organic matter content in the petroleum industry mainly include: (1) Downhole coring and core analysis in the laboratory. Although the results obtained by this method have high accuracy, the cost of drilling and coring is high, core samples are limited, and analysis costs are high , It takes a long time, and the organic carbon content information of the formation cannot be continuously characterized; (2) The organic matter content is evaluated using conventional logging data. The commonly used classic method is the ΔlogR method. The principle is to overlap the porosity curve and the resistivity curve. Based on the size of the overlapping intersection area, the empirical equation is used to determine the organic carbon content. This method can obtain continuous organic carbon content information along the well profile. Although the accuracy is guaranteed, it requires a large number of drilling coring experiment data calibration in the area. , and this method is still regarded as an indirect determination method, and the accuracy is restricted by the well logging curve, for example: the well logging curve is affected by other factors such as the borehole, special minerals in the formation, and there are certain regional and vertical limitations on the horizon (3) Evaluate organic carbon content by using elemental spectroscopy logging. Currently, the most widely used elemental logging tools are Schlumberger’s element capture spectroscopy (ECS) and Halliburton’s geochemical elemental logging tools. (GEM), these instruments mainly use Am-Be chemical sources, which emit neutrons with low energy, and can only measure the capture spectrum of the formation, use the content of other elements and use empirical methods to indirectly evaluate the organic carbon content, and cannot directly evaluate the hydrocarbon source rock abundance

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