Based on the theory of nonlinear dynamic finite element,the control equation ofcoal and water jet was acquired in the coal breaking process under a water jet.The calculationmodel of coal breaking under a water jet was...Based on the theory of nonlinear dynamic finite element,the control equation ofcoal and water jet was acquired in the coal breaking process under a water jet.The calculationmodel of coal breaking under a water jet was established;the fluid-structure couplingof water jet and coal was implemented by penalty function and convection calculation.The dynamic process of coal breaking under a water jet was simulated and analyzed bycombining the united fracture criteria of the maximum tensile strain and the maximal shearstrain in the two cases of damage to coal and damage failure to coal.展开更多
For the question of applying high-pressure water injection to increase gas extraction efficiency by increasing the permeability of water to drive gas action, an independently designed gas desorption experimental measu...For the question of applying high-pressure water injection to increase gas extraction efficiency by increasing the permeability of water to drive gas action, an independently designed gas desorption experimental measuring device was used under the condition of external solution invasion. The law of water effect on gas desorption was obtained after water invasion through experiment for the first time. The results show that water＇s later invasion not only can make the quantity of gas dcsorp- tion greatly reduced, but also can make gas desorption end early. Therefore, when evaluating the applications of high-pressure water injection to increase gas extraction efficiency, we should take water damaging effects on gas desorption into account.展开更多
A method of hydraulic grid slotting and hydraulic fracturing was proposed to enhance the permeability of low permeability coal seam in China. Micro-structural development and strength characteristics of coal were anal...A method of hydraulic grid slotting and hydraulic fracturing was proposed to enhance the permeability of low permeability coal seam in China. Micro-structural development and strength characteristics of coal were analysed to set up the failure criterion of coal containing water and gas, which could describe the destruction rule of coal containing gas under the hydraulic measures more accurately. Based on the theory of transient flow and fluid grid, the numerical calculation model of turbulence formed by high pressure oscillating water jet was used. With the high speed photography test, dynamic evolution and pulsation characteristics of water jet water analysed which laid a foundation for mechanism analysis of rock damage under water jet. Wave equation of oscillating water jet slotting was established and the mechanism of coal damage by the impact stress wave under oscillation jet was revealed. These provide a new method to study the mechanism of porosity and crack damage under high pressure jet.Fracture criterion by jet slotting was established and mechanism of crack development controlled by crack zone between slots was found. The fractures were induced to extend along pre-set direction,instead of being controlled by original stress field. The model of gas migration through coal seams after the hydraulic measures for grid slotting and fracking was established. The key technology and equipment for grid slotting and fracking with high-pressure oscillating jet were developed and applied to coal mines in Chongqing and Henan in China. The results show that the gas permeability of coal seam is enhanced by three orders of magnitude, efficiency of roadway excavation and mining is improved by more than 57%and the cost of gas control is reduced by 50%.展开更多
A fully-mechanized coal mining (FMCM) technology capable of filling up the goaf with wastes (including solid wastes) is described. Industrial tests have proved that by using this technology not only can waste be re-us...A fully-mechanized coal mining (FMCM) technology capable of filling up the goaf with wastes (including solid wastes) is described. Industrial tests have proved that by using this technology not only can waste be re-used but also coal resources can be exploited with a higher recovery rate without removing buildings located over the working faces. Two special devices, a hydraulic support and a scraper conveyor, run side-by-side on the same working face to simultaneously realize mining and filling. These are described in detail. The tests allow analysis of rock pressure and ground subsidence when backfilling techniques are employed. These values are compared to those from mining without using backfilling techniques, under the same geological conditions. The concept of equivalent mining height is proposed based on theoretical analysis of rock pressure and ground subsidence. The upper limits of the rock pressure and ground subsidence can be estimated in backfilling mining using this concept along with traditional engineering formulae.展开更多
为了解决高压欠注水井降压增注中面临的难题,以定边油田低渗透油藏的主力区块为研究对象,研究该区块的高压注水井在线酸化增注技术。利用单步法酸液体系可以抑制二次、三次沉淀物和溶解堵塞物的特性,设计在线单步法酸化智能增注系统,通...为了解决高压欠注水井降压增注中面临的难题,以定边油田低渗透油藏的主力区块为研究对象,研究该区块的高压注水井在线酸化增注技术。利用单步法酸液体系可以抑制二次、三次沉淀物和溶解堵塞物的特性,设计在线单步法酸化智能增注系统,通过“监控表皮系数变化情况”判断“是否对目的层段持续酸化”,确保最佳酸化效果。室内实验和现场试验结果表明:G-智能复合酸对氟化钠和氟硅酸盐产生二次沉淀的抑制性最好,单步法酸液体系选择G-智能复合酸可以更好地抑制酸反应时二次沉淀物的产生;堵塞物在酸液+助渗透剂剂T影响下的溶蚀率在73.9%~79%之间,堵塞物溶蚀率高于仅加入酸液的,单步法酸液体系选择酸液+助渗透剂可提升堵塞物溶蚀率;与只注入助渗透剂T相比,注入G-智能复合酸+助渗透剂T的高压注水井的油压下降1.0~3.4 MPa,日注水量增加6.1~9.8 m 3,该技术优势显著。展开更多
基金Supported by the National Basic Research Program of China(973 Program)(2005CB221504)the National Natural Science Foundation of China(50534080)the National Science and Technology Supporting Program of China(the 11th Five-Year Program)(2006BAK03B03)
文摘Based on the theory of nonlinear dynamic finite element,the control equation ofcoal and water jet was acquired in the coal breaking process under a water jet.The calculationmodel of coal breaking under a water jet was established;the fluid-structure couplingof water jet and coal was implemented by penalty function and convection calculation.The dynamic process of coal breaking under a water jet was simulated and analyzed bycombining the united fracture criteria of the maximum tensile strain and the maximal shearstrain in the two cases of damage to coal and damage failure to coal.
文摘For the question of applying high-pressure water injection to increase gas extraction efficiency by increasing the permeability of water to drive gas action, an independently designed gas desorption experimental measuring device was used under the condition of external solution invasion. The law of water effect on gas desorption was obtained after water invasion through experiment for the first time. The results show that water＇s later invasion not only can make the quantity of gas dcsorp- tion greatly reduced, but also can make gas desorption end early. Therefore, when evaluating the applications of high-pressure water injection to increase gas extraction efficiency, we should take water damaging effects on gas desorption into account.
基金supported by the National Natural Science Foundation of China(Nos.51374258,51504046,51404045)Program for Changjiang Scholars and Innovative Research Team in University of China(No.IRT13043)the National Basic Research Program of China(No.2014CB239206)
文摘A method of hydraulic grid slotting and hydraulic fracturing was proposed to enhance the permeability of low permeability coal seam in China. Micro-structural development and strength characteristics of coal were analysed to set up the failure criterion of coal containing water and gas, which could describe the destruction rule of coal containing gas under the hydraulic measures more accurately. Based on the theory of transient flow and fluid grid, the numerical calculation model of turbulence formed by high pressure oscillating water jet was used. With the high speed photography test, dynamic evolution and pulsation characteristics of water jet water analysed which laid a foundation for mechanism analysis of rock damage under water jet. Wave equation of oscillating water jet slotting was established and the mechanism of coal damage by the impact stress wave under oscillation jet was revealed. These provide a new method to study the mechanism of porosity and crack damage under high pressure jet.Fracture criterion by jet slotting was established and mechanism of crack development controlled by crack zone between slots was found. The fractures were induced to extend along pre-set direction,instead of being controlled by original stress field. The model of gas migration through coal seams after the hydraulic measures for grid slotting and fracking was established. The key technology and equipment for grid slotting and fracking with high-pressure oscillating jet were developed and applied to coal mines in Chongqing and Henan in China. The results show that the gas permeability of coal seam is enhanced by three orders of magnitude, efficiency of roadway excavation and mining is improved by more than 57%and the cost of gas control is reduced by 50%.
基金supports for this work provided by Na-tional basic research program of China (No. 2007CB209400)the National Natural Science Foundation of China (No. 50834004)+1 种基金the National Natural Science Foundation of China (No. 50574090) SR Foundation of China University of Mining & Technology (No. 50634050)
文摘A fully-mechanized coal mining (FMCM) technology capable of filling up the goaf with wastes (including solid wastes) is described. Industrial tests have proved that by using this technology not only can waste be re-used but also coal resources can be exploited with a higher recovery rate without removing buildings located over the working faces. Two special devices, a hydraulic support and a scraper conveyor, run side-by-side on the same working face to simultaneously realize mining and filling. These are described in detail. The tests allow analysis of rock pressure and ground subsidence when backfilling techniques are employed. These values are compared to those from mining without using backfilling techniques, under the same geological conditions. The concept of equivalent mining height is proposed based on theoretical analysis of rock pressure and ground subsidence. The upper limits of the rock pressure and ground subsidence can be estimated in backfilling mining using this concept along with traditional engineering formulae.
文摘为了解决高压欠注水井降压增注中面临的难题,以定边油田低渗透油藏的主力区块为研究对象,研究该区块的高压注水井在线酸化增注技术。利用单步法酸液体系可以抑制二次、三次沉淀物和溶解堵塞物的特性,设计在线单步法酸化智能增注系统,通过“监控表皮系数变化情况”判断“是否对目的层段持续酸化”,确保最佳酸化效果。室内实验和现场试验结果表明:G-智能复合酸对氟化钠和氟硅酸盐产生二次沉淀的抑制性最好,单步法酸液体系选择G-智能复合酸可以更好地抑制酸反应时二次沉淀物的产生;堵塞物在酸液+助渗透剂剂T影响下的溶蚀率在73.9%~79%之间,堵塞物溶蚀率高于仅加入酸液的,单步法酸液体系选择酸液+助渗透剂可提升堵塞物溶蚀率;与只注入助渗透剂T相比,注入G-智能复合酸+助渗透剂T的高压注水井的油压下降1.0~3.4 MPa,日注水量增加6.1~9.8 m 3,该技术优势显著。
