A method for determining the lower limit of organic carbon content in shale oil and gas "sweet spots"

Abstract

The invention provides a determination method for a lower limiting value of the organic carbon content in a shale oil and gas 'dessert area'. The determination method comprises the following steps that vertical well core analysis parameters and horizontal well EUR are measured; plotting is performed with Ro average and the EUR as the horizontal coordinate and the vertical coordinate respectively, so that Ro_limt is obtained; plotting is performed with the Ro and Sw as the horizontal coordinate and the vertical coordinate respectively, so that the upper limit value of water saturation of Ro>=a% is obtained; plotting is performed by selecting Sw data and Ph data of a%<=Ro<(a+b)%, so that Ph3,Ph1 and Ph2 corresponding to intersection points of Sw_a with an external envelope line, an internal envelope line and a mid-value line are obtained; plotting is performed by selecting Ph data and TOC data of a%<=Ro<(a+b)%, so that TOC3, TOC1 and TOC2 corresponding to the intersection point between the Ph3 and the external envelope line, the intersection point between the Ph1 and the internal envelope line and the intersection point between the Ph2 and the mid-value line are obtained, wherein the minimum value is a TOC lower limiting value of a%<=Ro<(a+b)%. According to the determination method, errors of experience values are avoided.

Description

technical field [0001] The invention relates to the technical field of evaluation methods for petroleum exploration and development, in particular to a method for determining the lower limit of organic carbon content in shale oil and gas "sweet spots". Background technique [0002] With the development of oil and gas exploration and development from conventional oil and gas reservoirs to unconventional oil and gas, shale oil and gas has gradually become an important field of oil and gas exploration and development. my country has a large amount of shale oil and gas resources. The recoverable resources of shale gas are about 12 trillion cubic meters, and the recoverable resources of shale oil exceed 200 billion tons (Chinese Academy of Engineering, 2012). The exploration and development potential of shale oil and gas is huge. In the exploration and development of shale oil and gas, under the current economic and technical conditions, the area where commercial oil and gas flow...

AI Technical Summary

Problems solved by technology

[0006] The purpose of the present invention is to overcome the deficiency in the prior art that the lower limit of organic carbon content in the "sweet spot" of shale oil and gas cannot be accurately determined, and to provide a determination of the lower limit of organic carbon content in the "sweet spot" of shale oil and gas method

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