| On the basis of surveying on research actuality and advance of coalbed methane reservoirs geology, regional geological background and sedimentary characteristic of Jurassic coal reservoirs, this dissertation proceeded integrative study on low-rank coal reservoirs and preliminary probing into its coalbed methane pool forming mechanism in Zhungaer basin, northwest China.First of all, the substance foundation of low-rank coal CBM generation in the basin has been discussed according to the development of coal reservoir, coal petrography, coal properties, coal rank, coal genera,coal facies feature of lower Jurassic Badaowan formation(Jlb) and middle Jurassic Xishanyao formation (J2x).Multi-hierarchical, multimeans, Comprehensive and deepened research on the macrofractures, microfractures system and pores system features, capacity of CBM storage and osmosis, adsorption characteristic, as well as physical properties of surrounding rocks of coal reservoirs have been made. Furthermore, classifying standard and identifying characteristics for fractures-pores system of low coal rank coal reservoirs in Zhungaer basin has been put forward as well. In this process, some routine instrument are used, such as viewing coal mine scene and hand specimen, observing polished section and surface which are made from lump coal and powder coal samples, observing and image analyses under the common microscope's transmitted light, reflection light and fluorescence. Advanced instrument and testing techniques including adopting mercury injection apparatus, specific surface analyses apparatus, porosity-permeability measurement apparatus, isothermal adsorption instrument and drill core flow experiment system, etc., are also adopted.On the basis of study on gas zoning, known CBM show and its component, generating mechanism of low coal rank CBM are discussed. The author pointed out that generated CBM should consist of primary biogenic methane gas in lignite stage, thermogenic methane gas in long-flame coal to gas/fat coal stage, and deuterogenic biogenic methane gas in coal seam imbedded stage. Then I discussed methane desorption properties including CBM-bearing saturation, critical desorption pressure, the ratio between critical desorption pressure and original coal reservoirs pressure and difference of terra decompression; CBM-bearing characteristics of coal seams including measured/academic CBM-bearing content, coalbed methane resources content and CBM resources abundance, etc.The author respectively gave a brief account of the basic characteristics of ancient and today's geothermic field at 1000m and 2000m depth, coal measure strata pressure field at the depth less than 1600m, structural stress field from Jurassic to present, and ancient and today's fluid potential field (that is water potential and gas potential distributing in coal measure strata). Then the relationship between these properties and its reaction relations each other among the " four fields" and physical properties of coal reservoirs, recoverability as well as CBM accumulation were discussed.Tectonic controls of coalbed methane in Zhungaer basin were dissertated from the several aspects, which are tectonic background, tectonic evolution and structural types.Sedimentary control of coalbed methane in this region were expounded according to the control and influence of sedimentation on coal gathering action (thickness of coal reservoirs, distributing and coal-bearing characteristics), on forming and distributing, maceral, organic facies and coalfacies, cap formation types and their sealing capability of adjoining rock. Hydrogeological control of coalbed methane in Zhungaer basins were also simply discussed from the influence both hydrogeological conditions on CBM accumulation; CBM diffusion and seepage flow in multiphase medium coal. It was indicated that the feasibility of occurring CBM pool which was sealing off by hydraulic pressure maybe very small.Qualitative and quantitative recoverability comprehensive assessment of every Jib and J2X coal reservoi...
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