Pore structure characterization and main control factors of deep coal reservoir of Xishanyao Formation in Baijiahai area,Junggar Basin
Understanding the pore structure characteristics of deep coal reservoir is crucial for exploring and developing deep coal bed methane.This study focuses on the coal seam of the Jurassic Xishanyao Formation in Baijiahai Bulge and its sur-rounding areas in the Junggar Basin,employing various experimental methods such as porosity and permeability under over-burden pressure,scanning electron microscopy,high-pressure mercury injection,low-temperature liquid nitrogen adsorp-tion,and carbon dioxide isothermal adsorption to analyze coal reservoir characteristics.The results indicate that the coal of Xishanyao Formation features low water content,ultra-low ash content,low volatile matter,and a low degree of evolution,predominantly comprising vitrinite and inertinite macerals.The coal reservoir of Xishanyao Formation exhibits a dual medium of pore-fracture reservoir space,demonstrating favorable reservoir properties.The coal reservoirs of Xishanyao Formation can be classified into three types.Types I has high porosity but poor permeability.Types II is the predominant reservoir type in the study area,which is further divided into Types II1 and Types II2.Types II1 has medium porosity with good permeability.Types II2 and Types III are characterized by micropores and poor reservoir properties.The pore structure of these coal reser-voirs in Xishanyao Formation is primarily controlled by factors such as ash mass fraction,vitrinite volume fraction,inertinite volume fraction,and burial depth.
deep coal reservoirpore structureJunggar BasinBaijiahai BulgeXishanyao Formation
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