Based on controls of structural style and the position in coalbed methane (CBM) development, we used a method of curvatures to study its relations with CBM development parameters. We calculated structural curvatures o...Based on controls of structural style and the position in coalbed methane (CBM) development, we used a method of curvatures to study its relations with CBM development parameters. We calculated structural curvatures of contours of the No.3 coal seam floor of the Shanxi Formation in the Zaoyuan block of the Qinshui Basin and analyzed its relations with development parameters of coalbed methane wells. The results show that structural curvature is negatively related to coal reservoir pressure, while positively related to permeability. With an increase in structural curvature, the average production of coalbed methane wells increases at first and then decreases, reaching the highest production at 0.02 m–1 of structural curvature. Therefore, structural cur-vature can be an important index for potential evaluation of coalbed methane development and provide a basis for siting coalbed methane wells.展开更多
Based on spontaneous desorption characteristic, the correlation of desorption time and gas content was analyzed and the application of it in production was researched. The desorption of high rank coalbed methane in Qi...Based on spontaneous desorption characteristic, the correlation of desorption time and gas content was analyzed and the application of it in production was researched. The desorption of high rank coalbed methane in Qinshui basin was periodic, and isotope fractionation effect also exists in the process. △δ^13C1 can be used to distinguish the stabilization of coalbed methane wells, associated with desorption rate, the individual well recoverable reserves can be calculated. Economically recoverable time can be predicted according to the logarithmic relationship between desorption gas content per ton and desorption time. The error between predicted result and numerical simulation result is only 1.5%.展开更多
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
Based on regional CBM geological characteristics and drainage data of three typical Coalbed Methane(CBM) wells in the southern Qinshui Basin,history matching,productivity prediction and factor analysis of gas producti...Based on regional CBM geological characteristics and drainage data of three typical Coalbed Methane(CBM) wells in the southern Qinshui Basin,history matching,productivity prediction and factor analysis of gas production control are conducted by using COMET3 reservoir modeling software.The results show that in the next 20 years,the cumulative and average daily gas production of the QN01 well are expected to be 800×104 m3 and 1141.1 m3/d,for the QN02 well 878×104 m3 and 1202.7 m3/d and 97.5×104 m3 and 133.55 m3/d for the QN03 well.Gas content and reservoir pressure are the key factors controlling gas production in the area;coal thickness,permeability and porosity are less important;the Langmuir volume,Langmuir pressure and adsorption time have relatively small effect.In the process of CBM recovery,the material source and driving force are the key features affecting gas productivity,while the permeation process is relatively important and the desorption process has some impact on gas recovery.展开更多
Based on the serial-parallel model of single-layer board and the lamination theory, the forces exerted on different layers of the high-pressure hose and the resulting deformations were analyzed when the hose was radia...Based on the serial-parallel model of single-layer board and the lamination theory, the forces exerted on different layers of the high-pressure hose and the resulting deformations were analyzed when the hose was radially stretched. An equation was proposed to calculate the anisotropic elastic constant of the composite layer with the wound steel wires. Furthermore, the finite element analysis （FEA） model of the high-pressure hose was established, followed by a simulation of the forces that act on different layers, and their deformations. The simulation results show that the stress imposed on the inner reinforced layer and external reinforced layer of the high-pressure hose are approximately 150 MPa and 115 MPa, respectively, in the presence of inner pressure. The stress of the rubber coating and polyethylene coating is lower. The lowest stress occurs on the inner surface of the high-pressure hose and the rubber coating between the two composite layers. The deformation of the rubber layer in the inner surface of the high-pressure hose decreases gradually along the radial direction from the inner surface to the external surface. The deformation of the reinforced composite layer is less than that of the external surface of the rubber coating. The equivalent stress of the reinforced composite layer is higher than that caused by the inner pressure, due to the presence of both inner pressure and axial tension.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
Hydraulic fracturing is one of the efficient means for the abundant low-permeability CBM （coal-bed methane） reserves in China, however, due to the unique features of coal seams （i.e., low temperature, strong adsorp...Hydraulic fracturing is one of the efficient means for the abundant low-permeability CBM （coal-bed methane） reserves in China, however, due to the unique features of coal seams （i.e., low temperature, strong adsorption and abnormal development of natural fracture systems） as compared with the conventional reservoirs, the fractures propagate is difficult and the risk of damage to coal seam itself and the hydraulic fractures would be extremely high in the course of fracturing. As a result, losses would be suffered on the post-frac production of CBM wells.With the mean of numerical simulation, in this paper, the main factors have impact on the post-frac results as well as the extent to which the impact is brought were researched, and the technical solutions for the improvement of the fracturing performance was put forwards.展开更多
基金support for this work, provided by the National Basic Research Program of China (No2009 CB219605)the National Major Research Program for Science and Technology of China (No2008 ZX05033-003)
文摘Based on controls of structural style and the position in coalbed methane (CBM) development, we used a method of curvatures to study its relations with CBM development parameters. We calculated structural curvatures of contours of the No.3 coal seam floor of the Shanxi Formation in the Zaoyuan block of the Qinshui Basin and analyzed its relations with development parameters of coalbed methane wells. The results show that structural curvature is negatively related to coal reservoir pressure, while positively related to permeability. With an increase in structural curvature, the average production of coalbed methane wells increases at first and then decreases, reaching the highest production at 0.02 m–1 of structural curvature. Therefore, structural cur-vature can be an important index for potential evaluation of coalbed methane development and provide a basis for siting coalbed methane wells.
文摘Based on spontaneous desorption characteristic, the correlation of desorption time and gas content was analyzed and the application of it in production was researched. The desorption of high rank coalbed methane in Qinshui basin was periodic, and isotope fractionation effect also exists in the process. △δ^13C1 can be used to distinguish the stabilization of coalbed methane wells, associated with desorption rate, the individual well recoverable reserves can be calculated. Economically recoverable time can be predicted according to the logarithmic relationship between desorption gas content per ton and desorption time. The error between predicted result and numerical simulation result is only 1.5%.
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the National Basic Research Program of China (No.2009 CB219605)the Key Program of the National Natural Science Foundation of China (No.4073042)the Key Program of the National Science and Technology of China (No.2008ZX05034-04)
文摘Based on regional CBM geological characteristics and drainage data of three typical Coalbed Methane(CBM) wells in the southern Qinshui Basin,history matching,productivity prediction and factor analysis of gas production control are conducted by using COMET3 reservoir modeling software.The results show that in the next 20 years,the cumulative and average daily gas production of the QN01 well are expected to be 800×104 m3 and 1141.1 m3/d,for the QN02 well 878×104 m3 and 1202.7 m3/d and 97.5×104 m3 and 133.55 m3/d for the QN03 well.Gas content and reservoir pressure are the key factors controlling gas production in the area;coal thickness,permeability and porosity are less important;the Langmuir volume,Langmuir pressure and adsorption time have relatively small effect.In the process of CBM recovery,the material source and driving force are the key features affecting gas productivity,while the permeation process is relatively important and the desorption process has some impact on gas recovery.
文摘Based on the serial-parallel model of single-layer board and the lamination theory, the forces exerted on different layers of the high-pressure hose and the resulting deformations were analyzed when the hose was radially stretched. An equation was proposed to calculate the anisotropic elastic constant of the composite layer with the wound steel wires. Furthermore, the finite element analysis （FEA） model of the high-pressure hose was established, followed by a simulation of the forces that act on different layers, and their deformations. The simulation results show that the stress imposed on the inner reinforced layer and external reinforced layer of the high-pressure hose are approximately 150 MPa and 115 MPa, respectively, in the presence of inner pressure. The stress of the rubber coating and polyethylene coating is lower. The lowest stress occurs on the inner surface of the high-pressure hose and the rubber coating between the two composite layers. The deformation of the rubber layer in the inner surface of the high-pressure hose decreases gradually along the radial direction from the inner surface to the external surface. The deformation of the reinforced composite layer is less than that of the external surface of the rubber coating. The equivalent stress of the reinforced composite layer is higher than that caused by the inner pressure, due to the presence of both inner pressure and axial tension.
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.
文摘Hydraulic fracturing is one of the efficient means for the abundant low-permeability CBM （coal-bed methane） reserves in China, however, due to the unique features of coal seams （i.e., low temperature, strong adsorption and abnormal development of natural fracture systems） as compared with the conventional reservoirs, the fractures propagate is difficult and the risk of damage to coal seam itself and the hydraulic fractures would be extremely high in the course of fracturing. As a result, losses would be suffered on the post-frac production of CBM wells.With the mean of numerical simulation, in this paper, the main factors have impact on the post-frac results as well as the extent to which the impact is brought were researched, and the technical solutions for the improvement of the fracturing performance was put forwards.
