Study On Reservoir Characteristics Of Lower Shihezi Formation In Panji Deep Mining Area In Huainan

Coalbed Methane(CBM)is a clean energy source that can effectively supply the conventional energy sources.The development and utilization of CBM not only benefits the safe production of mines and the protection of the environment,but also helps to improve the energy structure of China.With the deepening of coal mining depth and the continuous deepening of CBM related research,more and more scholars have begun to study the deep CBM resources.Coal samples of Lower Shihezi Formation coal seam of deep of Panji are selected as the research object.The coal samples are collected at the drilling site and downhole.In order to analyze the coal characteristics of coal samples,pore characteristics,permeability characteristics and adsorption-desorption characteristics,coal samples were subjected to a series of experiments such as industrial analysis of coal,mercury injection,low-temperature nitrogen adsorption and isothermal adsorption experiments in the laboratory.By studying the effects of temperature,pressure,moisture content,ash content,and pore structure on the volume of coal samples,the effect of various factors on the adsorption characteristics of deep coal reservoirs was revealed.In order to further study the effect of coal reservoir characteristics on the adsorption and desorption characteristics of CBM,a comparative study of deep coal reservoirs and shallow coal reservoirs was conducted.Relevant data of Xinji Mine which has a shallow depth of coal seam were collected.The coal-rock characteristics,pore characteristics and adsorption characteristics of Xinji coal seam were analyzed.Based on this,the characteristics of coal seams in the Lower Shihezi Formation of Panji were compared to investigate their reservoirs characteristics and the adsorption characteristics.The causes of their differences were also analyzed.It can be concluded from the research that Lower Shihezi Formation coal seam is mainly semi-dark coal-semi-bright coal and the metamorphic stage is low metamorphic bituminous coal to medium metamorphic bituminous coal.The average permeability is about 0.44 × 10-3?m2 which belongs to medium permeability coal seam.The micropores and small pores in each coal seam develop well and they occupy an advantage,while the mesopores and macropores develop poorly.By comparison,it has also been found that compared with shallow coal seams,deep coal seams have a higherdegree of metamorphism,higher vitrinite content,and lower moisture and ash content,and the adsorption pore content is also generally larger.The deep coal seam is more conducive to the adsorption of CBM,and thus has better development and utilization value.