Study On The Reservoir Characteristics And The Exploration Potential Of Low Rank Coal In The Western China

The reservoir capability were studied by the tested data which are from sometypical low rank coal bearing basins in the western China to speed up the CBMexploration. Three CBM richness model were given basis on the analysis of coalreservoir, some potential targets will be the emphases for the next exploration stage inthe future. The main points of this paper are as follows:1. Ash content is lower although VM and moisture content are as similar with theother research work, it indicates that it is available for adsorption and reservation ofCBM. The density is becoming lighter with increasing of vitrinite content anddecreasing the mineral content. The pore capacity is becoming smaller with increasingthe vitrinite content.2. Micro-porosity is dominated in the total pore capacity, which takes more than50%. There is not relationship among pore capacity and specific surface with otherfactors such as Maceral and R0, which shows that the distribution and shapes of poreare not influenced by the composition of the coal.3. The pore is opened for the coal of Ordos Basin, the order is from durain to clarainthen samples to vitrain. Others are belong to half-opened and thin throat.4. The adsorption content of gas is increasing with the higher pressure, and the freegas content is decreasing;The adsorption content of gas is decreasing with thehigher temp, and the free gas content is increasing;The adsorption content of gas isincreasing with higher vitrinite content for the kennel coal when temp. and pressurekeep same status.5. The permeability of kennel coal is higher than brown coal, but lower than fatcoal. The vertical permeability is higher than horizontal. The irreducible watersaturation is lowest comparing with other rank coals, it shows that it is available forproducing gas, but it would be influence in some degree for the gas recovery ratebecause of the lower balance point of the irreducible water saturation.6. Three CBM richness model were predicted basin on the analysis of coal reservoirand the experiences of CBM exploration, which are anticline type, rift-subsidencetype and depression type respectively.7. There are totally 21 potential targets and 5.2 trillion m3 of CBM resources for thewestern basins of China. The very potential basins are Zhungeer and Tuha.