Fine Description And Physical Properties Main Controlling Factors Of Coal Reservoir In South Of Qinshui Basin

This paper took south of Qinshui Basin for region of interest. First of all, through the instrumentations of mercury penetration experiment, low temperature liquid nitrogen adsorption experiment, nuclear magnetic resonance and scanning electron microscope and so on, the pore-fracture system of coal reservoir was fine described. Then combined with the test result of coal samples from eastern margin of Ordos Basin and north and center of Qinshui Basin, the affection of coal metamorphic process on pore system was researched. Then researched the influence factors of pore system of coal reservoir in south of Qinshui Basin. Then researched the control effect of the development characteristics of pore-fracture system on permeability. Finally combined with the test result of coal samples from west of Guizhou and east of Yunnan, researched the mechanism of control effect of coal metamorphic process on adsorptive capacity.The result about pore system development in coal abtained by mercury penetration experiment was basically identical with the result abtained by nuclear magnetic resonance. In the light of the form of adsorption loop of low temperature liquid nitrogen adsorption, divided the pore configuration of coal samples from south of Qinshui Basin into three types. Utilized light microscope to observe and statistics, found that the microcrack was very developed in coal reservoir of south of Qinshui Basin, but type A and type B were not developed, type C and type D were developed. Utilized scanning electron microscope to abserve the coal samples from south of Qinshui Basin, found that the microcrack was very developed, but the primary fractures were less, most were secondary fractures. In addition, also found that these microcracks were filled rifely, the filler was clay mineral, calcite and so on.The porosity values, the volume of micropore abtained by low temperature liquid nitrogen adsorption experiment and the BET specific surface area of coal present a trend of high-low-high variation along with the rising of coal rank. When researched the affecting factors of pore system development in south of Qinshui Basin coal reservoir, found that the porosity values present a trend of high-low-high variation along with the rising of vitrinite content in most cases, when Ro=1.5%-2.0%, and ash content is 5%-10%, the BET specific surface area of coal also present a trend of high-low-high variation along with the rising of vitrinite content; there is a negative correlation between the porosity values and ash content in most cases, and the BET specific surface area of coal present a trend of low-high-low variation along with the rising of ash content.In pore system of coal reservoir, the macroporous porosity values is the main control factor of permeability, the permeability of coal present a linear increase along with the increasing of the macroporous porosity values. There is not apparent relationship between the density of fracture and the permeability of coal. Comprehensive the various affecting factors, found that the macroporous porosity values, the density of fracture and the filling degree of fracture all control the permeability of coal reservoir.When Ro=0.68%-3.31%, the adsorptive capacity of coal increases along with the increasing of coal metamorphic grade, and present positive correlation with foxed carbon and vitrinite content. The adsorptive capacity of coal reservoir in south of Qinshui Basin under control of coal metamorphic grade, mainly affected by foxed carbon, Langmuir sorption increases along with the increasing of foxed carbon. The adsorptive capacity of coal reservoir in south of Qinshui Basin was little affected by water content, ash content and vitrinite content.