Based on the characteristics of the strong volatility of physical property in vertical direction, high gas content, high resource abundance and large exploitation potentiality of coal reservoir in Bide-Santang basin o...Based on the characteristics of the strong volatility of physical property in vertical direction, high gas content, high resource abundance and large exploitation potentiality of coal reservoir in Bide-Santang basin of Zhina coal field, we study the generation mechanism of interlayer interference, propagation rules of reservoir pressure drop and influencing factors of gas productivity in CBM multi-seam drainage in the paper. On the basis of the actual production data of X-2 well of Zhucang syncline in Bide-Santang basin,by simulating the gas production process of a CBM well under the condition of multiple seam with COMET3 numerical simulation software, we analyze the influencing factors of gas productivity during the process of multi-seam drainage, and illuminate the interlayer interference mechanism of multiseam drainage. The results show that permeability, reservoir pressure gradient, critical desorption pressure and fluid supply capacity of stratum have great influence on gas productivity of multi-seam drainage while coal thickness has little influence on it. Permeability, reservoir pressure gradient and fluid supply capacity of stratum affect the propagation velocity of reservoir pressure drop and thereby affect the final gas productivity. Moreover, the influence of critical desorption pressure on gas productivity of multiseam drainage is reflected in the gas breakthrough time and effective desorption area.展开更多
It is an important guarantee to enhance the production of coalbed methane （CBM） and reduce the project invest- ment by finding out the drainage feature about CBM wells in different hydrogeological conditions. Based ...It is an important guarantee to enhance the production of coalbed methane （CBM） and reduce the project invest- ment by finding out the drainage feature about CBM wells in different hydrogeological conditions. Based on the CBM explora- tion and development data on the Fanzhuang block in southeast Qinshui Basin and combined with the seepage principle and lithology on the roof and the bottom coalbed, the mathematical model of integrated permeability was established. By perme- ability experiments of the different lithologies on the roof and the floor within the 20 m range combined with the log curves, the integrated permeability of different lithological combinations were obtained. The starting pressure gradient and permeabi- lity of the roof and the floor for different lithologies was tested by ＂differential pressure-flow method＂. The relationships be- tween the starting pressure gradient and the integrated permeability were obtained. The critical distance of limestone water penetrating into coal reservoirs was calculated. According to the drainage feature of CBM wells combined with the drainage data of some CBM wells, the results show that, when limestone water can penetrate into coal reservoirs, the daily water production is high and the daily gas production is low although there is no gas at the beginning of the drainage process, the CBM wells stop discharging water within 6 months after the gas began to come out, and the gas production is steadily improved. When limestone water can not penetrate into coal reservoirs, the daily water production is low and the daily gas production is high at the beginning of the drainage process, and it almost stops discharging water after some time when the gas come out, the daily gas production increases, and the cumulative water production is much lower.展开更多
基金supported by the National Major Special Project of Science and Technology of China (No.2011ZX05034)the Innovation Projects of University Graduates in Jiangsu Province (No.CXLX13_948)+1 种基金the National Natural Science Foundation of China (No.41272178)the Natural Science Foundation of Hunan Province (No.2016JJ4031)
文摘Based on the characteristics of the strong volatility of physical property in vertical direction, high gas content, high resource abundance and large exploitation potentiality of coal reservoir in Bide-Santang basin of Zhina coal field, we study the generation mechanism of interlayer interference, propagation rules of reservoir pressure drop and influencing factors of gas productivity in CBM multi-seam drainage in the paper. On the basis of the actual production data of X-2 well of Zhucang syncline in Bide-Santang basin,by simulating the gas production process of a CBM well under the condition of multiple seam with COMET3 numerical simulation software, we analyze the influencing factors of gas productivity during the process of multi-seam drainage, and illuminate the interlayer interference mechanism of multiseam drainage. The results show that permeability, reservoir pressure gradient, critical desorption pressure and fluid supply capacity of stratum have great influence on gas productivity of multi-seam drainage while coal thickness has little influence on it. Permeability, reservoir pressure gradient and fluid supply capacity of stratum affect the propagation velocity of reservoir pressure drop and thereby affect the final gas productivity. Moreover, the influence of critical desorption pressure on gas productivity of multiseam drainage is reflected in the gas breakthrough time and effective desorption area.
基金Supported by the Major Projects of National Science and Technology Project ＂Development of Coal-bed Gas Dynamic Evaluation Model and Software System＂ （2011ZX05034-005） the National Natural Science Foundation of China （40902044）
文摘It is an important guarantee to enhance the production of coalbed methane （CBM） and reduce the project invest- ment by finding out the drainage feature about CBM wells in different hydrogeological conditions. Based on the CBM explora- tion and development data on the Fanzhuang block in southeast Qinshui Basin and combined with the seepage principle and lithology on the roof and the bottom coalbed, the mathematical model of integrated permeability was established. By perme- ability experiments of the different lithologies on the roof and the floor within the 20 m range combined with the log curves, the integrated permeability of different lithological combinations were obtained. The starting pressure gradient and permeabi- lity of the roof and the floor for different lithologies was tested by ＂differential pressure-flow method＂. The relationships be- tween the starting pressure gradient and the integrated permeability were obtained. The critical distance of limestone water penetrating into coal reservoirs was calculated. According to the drainage feature of CBM wells combined with the drainage data of some CBM wells, the results show that, when limestone water can penetrate into coal reservoirs, the daily water production is high and the daily gas production is low although there is no gas at the beginning of the drainage process, the CBM wells stop discharging water within 6 months after the gas began to come out, and the gas production is steadily improved. When limestone water can not penetrate into coal reservoirs, the daily water production is low and the daily gas production is high at the beginning of the drainage process, and it almost stops discharging water after some time when the gas come out, the daily gas production increases, and the cumulative water production is much lower.
