| Coal is contained within about 1.0 thousand km2 area in Huaibei(North Huai)district.Difficulties in both geologically selecting zone and reservoir strengthening bring a lot of trouble in exploring and developing coal-formed gas in North Huai area.Great potentiality CBM exploration and development is predicted by many favorable geologic conditions,such as multiple layers,high gas-bearing,rich resource,middle coal grade close by saturation and outstanding district advantage and high value on research.The coal measures in the Huaibei have the features of multiple seams and large seam thickness,and the material conditions for forming the CBM reservoir are more advantageous.The total thickness of the coal-bearing strata is about 1200m,including more 5-25seams,the total seam thickness is about 7.1-21.95m,and the main seams are Nos.3,5,7,8 and 10 seams.In this area,the coal species are varied,from the gas coal,fat coal,coking coal,lean coal,meager coal,anthracite to the natural coke,they all are distributed,and dominated by the gas coal and fat coal.the permeability of the area is low,permeability is ranging in 0.3?3.2md.The adsorption capacity of coal in the area is stronger,the gas content is higher,averaging in more 6m3/t.These features exhibits that in the Huaibei the CBM has the better storage conditions.lt adopts the volume method to conduct the calculation on the CBM resources quantity of the Huaibei,by the calculation,the total CBM resources quantity of 17 mines is 145.33×108m3,the CBM exploitable resources quantity is 39.77×108m3.According to the exploration and exploitation data collected from the Huaibei area,we comprehensively analyzed various factors influencing coalbed methane(CBM)exploration potential.Define nine indices for the assessment of CBM exploration potential.A multi-layered evaluation model was built for the assessment of CBM exploration potential by using AHP and grey clustering methods,the model was applied to the assessment of CBM exploration potential in sixteen CBM mines of Huaibei area.The results show that the optimal level exploration potential have 2 mines,mainly concentrated in the Southeast of huaibei and the good grade exploration potential has 11 mines,poor level of prospecting potential have 3 mines,mainly concentrated in Suixiao mine.The evaluation results can guide future CBM exploitation in the study area.According to the production date and related parameters,the parameter sensitivity analysis has been made by the COMET3 numerical simulation software.We also did some history matching of wells in Huaibei area.Through the adjusted the related parameters such as permeability and porosity,assurance that the simulation results matched well to the production date.Besides,the optimization of well pattern and well distance is done.Finally,a square well pattern and 300×300m well distance is the optimal selection.Productivity prediction of production well is made.The results show that No.8 coal seam single well production capacity is 1290m3/d,the stable production stage is 7 years,15 years accumulative gas production is 638×104m3,recovery is more than 55%.No.8+10 coal seam single well production capacity is 1454m3/d,the stable production stage is 8 years,15 years accumulative gas production is 720×104m3,the recovery is more than 50%.Single well production capacity is high,has great potentiality CBM exploration and development. |
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