The Cyclonic-Static Microbubble Flotation Column (FCSMC) is currently a widely used, novel type of flotation device. The self-absorbing microbubble generator is the core component of this device. The structure of the ...The Cyclonic-Static Microbubble Flotation Column (FCSMC) is currently a widely used, novel type of flotation device. The self-absorbing microbubble generator is the core component of this device. The structure of the microbubble generator directly influences flotation column performance by affecting bubble size and distribution as well as gas holdup in the column. However, the complicated flow inside the generator results in high R&D costs and difficulty in testing. Thus, the CFD software, FLUENT, was used to simulate the gas-liquid two-phase flow inside a self-absorbing microbubble generator. The effect of area ratio, a key structural parameter, was studied in detail. Critical flow-field parameters including velocity, turbulent kinetic energy, minimum static pressure and gas holdup were obtained. The simulation results demonstrate that the optimum area ratio is 3.展开更多
Shale gas reservoirs generally need to be fractured massively to reach the industrial production, however, the flowback ratio of fractured shalegas wells is low. In view of this issue, the effects of natural fracture ...Shale gas reservoirs generally need to be fractured massively to reach the industrial production, however, the flowback ratio of fractured shalegas wells is low. In view of this issue, the effects of natural fracture spacing, fracture conductivity, fracturing scale, pressure coefficient and shutintime on the flowback ratio were examined by means of numerical simulation and experiments jointly, and the causes of flowback difficulty ofshale gas wells were analyzed. The results show that the flowback ratio increases with the increase of natural fracture spacing, fracture conductivityand pressure coefficient and decreases with the increase of fracturing scale and shut-in time. From the perspective of microscopicmechanism, when water enters micro-cracks of the matrix through the capillary self-absorbing effect, the original hydrogen bonds between theparticles are replaced by the hydroxyl group, namely, hydration effect, giving rise to the growth of new micro-cracks and propagation of mainfractures, and complex fracture networks, so a large proportion of water cannot flow back, resulting in a low flowback ratio. For shale gas wellfracturing generally has small fracture space, low fracture conductivity and big fracturing volume, a large proportion of the injected water will beheld in the very complex fracture network with a big specific area, and unable to flow back. It is concluded that the flowback ratio of fracturedshale gas wells is affected by several factors, so it is not necessary to seek high flowback ratio deliberately, and shale gas wells with low flowbackratio, instead, usually have high production.展开更多
基金Financial supports for this work provided by the National High Technology Research and Development Program of China (No.2008BAB31B02) is gratefully acknowledged
文摘The Cyclonic-Static Microbubble Flotation Column (FCSMC) is currently a widely used, novel type of flotation device. The self-absorbing microbubble generator is the core component of this device. The structure of the microbubble generator directly influences flotation column performance by affecting bubble size and distribution as well as gas holdup in the column. However, the complicated flow inside the generator results in high R&D costs and difficulty in testing. Thus, the CFD software, FLUENT, was used to simulate the gas-liquid two-phase flow inside a self-absorbing microbubble generator. The effect of area ratio, a key structural parameter, was studied in detail. Critical flow-field parameters including velocity, turbulent kinetic energy, minimum static pressure and gas holdup were obtained. The simulation results demonstrate that the optimum area ratio is 3.
基金Extending result of Major Project of National Science and Technology“Study on the mechanism of fracture propagation and productivity prediction of shale gas reservoirs”(No.2012ZX05018-004).
文摘Shale gas reservoirs generally need to be fractured massively to reach the industrial production, however, the flowback ratio of fractured shalegas wells is low. In view of this issue, the effects of natural fracture spacing, fracture conductivity, fracturing scale, pressure coefficient and shutintime on the flowback ratio were examined by means of numerical simulation and experiments jointly, and the causes of flowback difficulty ofshale gas wells were analyzed. The results show that the flowback ratio increases with the increase of natural fracture spacing, fracture conductivityand pressure coefficient and decreases with the increase of fracturing scale and shut-in time. From the perspective of microscopicmechanism, when water enters micro-cracks of the matrix through the capillary self-absorbing effect, the original hydrogen bonds between theparticles are replaced by the hydroxyl group, namely, hydration effect, giving rise to the growth of new micro-cracks and propagation of mainfractures, and complex fracture networks, so a large proportion of water cannot flow back, resulting in a low flowback ratio. For shale gas wellfracturing generally has small fracture space, low fracture conductivity and big fracturing volume, a large proportion of the injected water will beheld in the very complex fracture network with a big specific area, and unable to flow back. It is concluded that the flowback ratio of fracturedshale gas wells is affected by several factors, so it is not necessary to seek high flowback ratio deliberately, and shale gas wells with low flowbackratio, instead, usually have high production.
