Primary organic matter and secondary organic matter distinguishing method

Abstract

The invention discloses a method for distinguishing primary organic matters from secondary organic matters. The distinguishing method comprises the following steps: (1) acquiring organic matter scanning electron microscope petrology characteristics and organic matter atomic composition characteristics of a rock sample; and (2) distinguishing primary organic matters and secondary organic matters based on organic matter scanning electron microscope petrology characteristics and organic matter atomic composition characteristics of the rock sample. According to the method disclosed by the invention, an excellent high-power micro-area observation technology of the scanning electron microscope is combined with a real-time energy spectrum quantitative detection technology, so that the primary organic matters and the secondary organic matters can be accurately distinguished.

Description

technical field [0001] The invention belongs to the technical field of oil and gas geological exploration, and more particularly relates to a method for distinguishing primary organic matter and secondary organic matter. Background technique [0002] High-maturity shale usually undergoes long and complex burial thermal alteration, and the original sedimentary organic matter has undergone significant changes in both morphology and chemical composition. Along with burial thermal alteration, the primary organic matter generates hydrocarbons, producing a large amount of secondary organic matter (oil and bitumen), and the oil will further undergo cracking reaction to generate natural gas and tar pitch. Therefore, the organic matter in the high-maturity shale can be basically divided into two categories: primary organic matter and secondary organic matter, and their morphology, distribution and optical characteristics have similar characteristics, resulting in organic petrology me...

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Problems solved by technology

For marine shale in the oil window stage, it is an effective method to identify secondary organic matter based on the filling form of organic matter and the contact relationship with minerals. With the intensification of thermal alteration of organic matter, high-maturity marine shale The organic matter particles in rocks are getting smaller and smaller, and the petrological characteristics are basically similar. High-power scanning electron microscope technology has been widely used in the study of organic matter (Loucks R.C., Reed R.M., Ruppel S.C., Jarvie D.M., 2009. Morphology, genesis, and distribution of nanometer-scale pores in siliconousmudstones of the Mississippian Barnett Shale.J.Sediment.Res.,79:848-861), but the SEM petrological characteristics of organic matter cannot distinguish primary organic matter from secondary organic matter (Hackley P.C., CardottB.J., 2016.Application of organic petroleum in North American shalepetroleum systems: A review. Int. J. Coal Geo. 163:8-51)

Therefore, there are great limitations in the application of organic petrology methods in high-maturity marine shale, which hinders the in-depth study of the source and evolution of organic matter in high-maturity marine shale, and further affects the development of marine shale reservoirs. evaluation of characteristics

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