The low rank coalbed methane (CBM) has great potential for exploration and development in China, but its exploitation level is low at present stage. The pores are the storage space of CBM, so recognizing its structura...The low rank coalbed methane (CBM) has great potential for exploration and development in China, but its exploitation level is low at present stage. The pores are the storage space of CBM, so recognizing its structural characteristics has very important practical significance for the development of CBM. The samples of No. 4 and upper No. 4 coalbed in Dafosi were selected to carry out the analysis of mercury injection test, nitrogen adsorption test and scanning electron microscopy to study the different lithotypes of the pore structure, pore throat distribution and fracture character of low rank coal reservoir. The results showed that micropore of low rank coal in Dafosi relatively developed and the pore volume of vitrain was equivalent to durain. The pore throat of durain was larger than vitrain, the connectivity was better and the fissures were more developed. The percolation capacity and reservoir performance of upper No. 4 coal was better than No. 4 coal. Generally, the potential of exploration and development of upper No. 4 coal in the study area was better than that of No. 4, and the developed area of durain was more beneficial for the development of CBM.展开更多
Vitrain and its pyridin-extracted products (i. e. both the pyridin-soluble and-inso1ubleconstituents) were investigated by means of solid state ^(13)C CPMAS and ~1H CRAMPS NMRtechniques. From the measurements, twelve ...Vitrain and its pyridin-extracted products (i. e. both the pyridin-soluble and-inso1ubleconstituents) were investigated by means of solid state ^(13)C CPMAS and ~1H CRAMPS NMRtechniques. From the measurements, twelve structural parameters of the carbon skeleton wereobtained and the size of aromatic clusters for each sample was estimated. It is shown that theaverage size of aromatic clusters in pyridin-soluble part of vitrain is relatively small, contain-ing only 2--3 aromatic rings, while that in pyridin-insoluble part is relatively high, contain-ing five fused aromatic rings and its carbon aromaticity is apparently higher than that ofthe pyridin-soluble constituents. Measurement of carbon (^(13)C) and proton (~1H) spin-latticerelaxation times (T_1~H and T_1~C) shows that the relaxation in vitrain is mainly caused by para-magnetic centers. Therefore, pyridin extracting process effectively takes away the paramagneticcenters in vitrain, hence the concentration of free radicals for both the pyridin-solubleand -insoluble constituents are decreased. However, the decrement for pyridin-soluble constit-uent is even larger than that of the insoluble one.展开更多
文摘The low rank coalbed methane (CBM) has great potential for exploration and development in China, but its exploitation level is low at present stage. The pores are the storage space of CBM, so recognizing its structural characteristics has very important practical significance for the development of CBM. The samples of No. 4 and upper No. 4 coalbed in Dafosi were selected to carry out the analysis of mercury injection test, nitrogen adsorption test and scanning electron microscopy to study the different lithotypes of the pore structure, pore throat distribution and fracture character of low rank coal reservoir. The results showed that micropore of low rank coal in Dafosi relatively developed and the pore volume of vitrain was equivalent to durain. The pore throat of durain was larger than vitrain, the connectivity was better and the fissures were more developed. The percolation capacity and reservoir performance of upper No. 4 coal was better than No. 4 coal. Generally, the potential of exploration and development of upper No. 4 coal in the study area was better than that of No. 4, and the developed area of durain was more beneficial for the development of CBM.
基金Project supported by the National Natural Science Foundation of China.
文摘Vitrain and its pyridin-extracted products (i. e. both the pyridin-soluble and-inso1ubleconstituents) were investigated by means of solid state ^(13)C CPMAS and ~1H CRAMPS NMRtechniques. From the measurements, twelve structural parameters of the carbon skeleton wereobtained and the size of aromatic clusters for each sample was estimated. It is shown that theaverage size of aromatic clusters in pyridin-soluble part of vitrain is relatively small, contain-ing only 2--3 aromatic rings, while that in pyridin-insoluble part is relatively high, contain-ing five fused aromatic rings and its carbon aromaticity is apparently higher than that ofthe pyridin-soluble constituents. Measurement of carbon (^(13)C) and proton (~1H) spin-latticerelaxation times (T_1~H and T_1~C) shows that the relaxation in vitrain is mainly caused by para-magnetic centers. Therefore, pyridin extracting process effectively takes away the paramagneticcenters in vitrain, hence the concentration of free radicals for both the pyridin-solubleand -insoluble constituents are decreased. However, the decrement for pyridin-soluble constit-uent is even larger than that of the insoluble one.
