Yankuang ceshi (May 2018)
Study on Shale Organic Porosity in the Longmaxi Formation, AnYe-1 Well Using Field Emission-Scanning Electron Microscopy and PerGeos System
Abstract
BACKGROUND AnYe-1 well is a geological survey parameter well implemented by China Geological Survey. It has achieved shale gas breakthrough in the Wuling complex structural area outside the southern basin of China. BAOBJECTIVES To quantitatively characterize micro-and nano-pore structure and development characteristics of organic matter, by researching organic matter pore on Longmaxi shale of AnYe-1 well. METHODS Field Emission-Scanning Electron Microscope was used to study the reservoir type of the organic-rich shale of the Longmaxi Formation at the periphery of the basin in the Upper Yangtze region, and the PerGeos digital rock treatment system was introduced into the organic pores quantitative analysis. RESULTS The organic pore is the most important reservoir space of the organic-rich shale of the Longmaxi Formation in Anye-1 well. It is characterized by organic matter interstitially forming in the authigenic siliceous organic matter with uniform sponge-like pore structure, or organic matter that interacts with clay minerals with a bubble-like pore structure. Pores in two different types of organic matter are extremely developed. The PerGeos digital rock system reveals that the pore sizes of the two organic pores show a bimodal distribution, in which the pore size of the organic pores with the sponge-like structure is 5 to 10 nm, and the pore size of the organic pores with the bubble-like structure is 51 to 100 nm. The organic pores are mainly in the mesopore to macropore category. CONCLUSIONS The abundant development of organic matter pores in the Longmaxi Formation in AnYe-1 well indicates that the Longmaxi Formation shale in the periphery of the basin has experienced a strong hydrocarbon generation process and has a good storage capacity, showing a potential for development in the future.
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