The commercial exploitation of natural gas hydrates is currently facing several challenges,including low production rates,limited recovery areas,and brief periods of continuous production.To address these issues,we pr...The commercial exploitation of natural gas hydrates is currently facing several challenges,including low production rates,limited recovery areas,and brief periods of continuous production.To address these issues,we propose a novel dual-enhanced stimulation(DES)method for marine hydrate reservoirs.This method involves injecting a special slurry that solidifies into porous,high-permeability,and highstrength slurry veins.These veins not only enhance permeability,allowing for faster gas and water flow,but also improve reservoir stability.This study experimentally investigated the split grouting of clayey-silty sediments with dual-enhanced slurry to assess the feasibility of DES and to explo re the slurry diffusion mechanism and micro-pore structure of the veins.The results showed that split grouting with dual-enhanced slurry exhibited frequent fracture initiation with quick pressure spikes and sharp declines,suggesting shorter fractures in clayey-silty sediments.As vertical stress increased,the primary diffusion direction of the dual-enhanced slurry shifted from horizontal to vertical,aligning with fracture propagation patterns observed during fracturing.Unlike hydraulic fracturing in hard rocks,split grouting in clayey-silty sediments encountered more difficult conditions.These veins formed through a recurring cycle of splitting into fractures and filling with slurry,occurring more frequently in weaker sediments with slower injection rates and higher vertical stress.Increased vertical stress hindered slurry vein diffu sion,easily resulting in compaction grouting near the grouting pipe.Additionally,three-dimensional laser scanning of the veins showed that those formed through split grouting were continuous and stable,with their thickness decreasing as diffusion distance increased.The morphology of these veins was shaped by factors such as grouting rate,formation stress,and elastic modulus,with higher rates and elastic moduli facilitating the formation of complex vein networks.Mercury intrusion porosimetry demonstrated that the DES method resulted in veins with consistent effective porosity between 65%and70%and median pore sizes of 11-15μm across different locations.These veins formed a well-connected porous network of smaller pores,significantly enhancing both permeability and sand control.The research findings validate the effectiveness of the DES method for marine hydrate reservoirs,providing a strategy for the safe and efficient exploitation of NGH resources.展开更多
Grouting is an important method to reinforce soft coal roadway,and the presence of primary cracks in the coal body has an important influence on the grouting effect.With the discrete element simulation method,the grou...Grouting is an important method to reinforce soft coal roadway,and the presence of primary cracks in the coal body has an important influence on the grouting effect.With the discrete element simulation method,the grouting process of the soft coal seam was simulated.The mechanism of primary cracks on grouting was revealed,while the influence of fracture characteristics and grouting pressure on the grouting effect was analyzed.The results demonstrated that grouting in the soft coal seam involves the stages of seepage,rapid splitting,slow splitting,and stability.Due to the presence of primary cracks,the grouting diffusion radius increased significantly.Under the slurry pressure,the tensile stress concentration was formed at the crack tip,and the slurry split the coal once the splitting pressure was reached.In addition,the distribution characteristics of fractures are found to have a great influence on the grouting effect.It is observed that smaller fracture spacing is associated with a larger slurry diffusion radius and thus easier penetration of the primary crack tips.The fracture angle affects the direction of fracture propagation.The secondary fracture formed by splitting is a tensile fracture,which is more likely to extend along the direction parallel to the maximum principal stress.Overall,these simulation results have guiding significance for the setting of reasonable spacing of grouting holes in the practice of grouting engineering.展开更多
The grouted bolt,combining rock bolting with grouting techniques,provides an effective solution for controlling the surrounding rock in deep soft rock and fractured roadways.It has been extensively applied in numerous...The grouted bolt,combining rock bolting with grouting techniques,provides an effective solution for controlling the surrounding rock in deep soft rock and fractured roadways.It has been extensively applied in numerous deep mining areas characterized by soft rock roadways,where it has demonstrated remarkable control results.This article systematically explores the evolution of grouted bolting,covering its theoretical foundations,design methods,materials,construction processes,monitoring measures,and methods for assessing its effectiveness.The overview encompassed several key elements,delving into anchoring theory and grouting reinforcement theory.The new principle of high pretensioned high-pressure splitting grouted bolting collaborative active control is introduced.A fresh method for dynamic information design is also highlighted.The discussion touches on both conventional grouting rock bolts and cable bolts,as well as innovative grouted rock bolts and cables characterized by their high pretension,strength,and sealing hole pressure.An examination of the merits and demerits of standard inorganic and organic grouting materials versus the new inorganic–organic composite materials,including their specific application conditions,was conducted.Additionally,the article presents various methods and instruments to assess the support effect of grouting rock bolts,cable bolts,and grouting reinforcement.Furthermore,it provides a foundation for understanding the factors influencing decisions on grouted bolting timing,the sequence of grouting,the pressure applied,the volume of grout used,and the strategic arrangement of grouted rock bolts and cable bolts.The application of the high pretensioned high-pressure splitting grouted bolting collaborative control technology in a typical kilometer-deep soft rock mine in China—the soft coal seam and soft rock roadway in the Kouzidong coal mine,Huainan coal mining area,was introduced.Finally,the existing problems in grouted bolting control technology for deep soft rock roadways are analyzed,and the future development trend of grouted bolting control technology is anticipated.展开更多
基金financial support received from the National Natural Science Foundation of China(Nos.51991364,and 42202347)。
文摘The commercial exploitation of natural gas hydrates is currently facing several challenges,including low production rates,limited recovery areas,and brief periods of continuous production.To address these issues,we propose a novel dual-enhanced stimulation(DES)method for marine hydrate reservoirs.This method involves injecting a special slurry that solidifies into porous,high-permeability,and highstrength slurry veins.These veins not only enhance permeability,allowing for faster gas and water flow,but also improve reservoir stability.This study experimentally investigated the split grouting of clayey-silty sediments with dual-enhanced slurry to assess the feasibility of DES and to explo re the slurry diffusion mechanism and micro-pore structure of the veins.The results showed that split grouting with dual-enhanced slurry exhibited frequent fracture initiation with quick pressure spikes and sharp declines,suggesting shorter fractures in clayey-silty sediments.As vertical stress increased,the primary diffusion direction of the dual-enhanced slurry shifted from horizontal to vertical,aligning with fracture propagation patterns observed during fracturing.Unlike hydraulic fracturing in hard rocks,split grouting in clayey-silty sediments encountered more difficult conditions.These veins formed through a recurring cycle of splitting into fractures and filling with slurry,occurring more frequently in weaker sediments with slower injection rates and higher vertical stress.Increased vertical stress hindered slurry vein diffu sion,easily resulting in compaction grouting near the grouting pipe.Additionally,three-dimensional laser scanning of the veins showed that those formed through split grouting were continuous and stable,with their thickness decreasing as diffusion distance increased.The morphology of these veins was shaped by factors such as grouting rate,formation stress,and elastic modulus,with higher rates and elastic moduli facilitating the formation of complex vein networks.Mercury intrusion porosimetry demonstrated that the DES method resulted in veins with consistent effective porosity between 65%and70%and median pore sizes of 11-15μm across different locations.These veins formed a well-connected porous network of smaller pores,significantly enhancing both permeability and sand control.The research findings validate the effectiveness of the DES method for marine hydrate reservoirs,providing a strategy for the safe and efficient exploitation of NGH resources.
基金The authors acknowledge the financial support provided by the National Natural Science Foundation of China(No.51604094 and 51674098)the Shandong Provincial Natural Science Foundation(No.ZR2020QE118).
文摘Grouting is an important method to reinforce soft coal roadway,and the presence of primary cracks in the coal body has an important influence on the grouting effect.With the discrete element simulation method,the grouting process of the soft coal seam was simulated.The mechanism of primary cracks on grouting was revealed,while the influence of fracture characteristics and grouting pressure on the grouting effect was analyzed.The results demonstrated that grouting in the soft coal seam involves the stages of seepage,rapid splitting,slow splitting,and stability.Due to the presence of primary cracks,the grouting diffusion radius increased significantly.Under the slurry pressure,the tensile stress concentration was formed at the crack tip,and the slurry split the coal once the splitting pressure was reached.In addition,the distribution characteristics of fractures are found to have a great influence on the grouting effect.It is observed that smaller fracture spacing is associated with a larger slurry diffusion radius and thus easier penetration of the primary crack tips.The fracture angle affects the direction of fracture propagation.The secondary fracture formed by splitting is a tensile fracture,which is more likely to extend along the direction parallel to the maximum principal stress.Overall,these simulation results have guiding significance for the setting of reasonable spacing of grouting holes in the practice of grouting engineering.
基金the National Natural Science Foundation of China(Nos.52304141 and 52074154)。
文摘The grouted bolt,combining rock bolting with grouting techniques,provides an effective solution for controlling the surrounding rock in deep soft rock and fractured roadways.It has been extensively applied in numerous deep mining areas characterized by soft rock roadways,where it has demonstrated remarkable control results.This article systematically explores the evolution of grouted bolting,covering its theoretical foundations,design methods,materials,construction processes,monitoring measures,and methods for assessing its effectiveness.The overview encompassed several key elements,delving into anchoring theory and grouting reinforcement theory.The new principle of high pretensioned high-pressure splitting grouted bolting collaborative active control is introduced.A fresh method for dynamic information design is also highlighted.The discussion touches on both conventional grouting rock bolts and cable bolts,as well as innovative grouted rock bolts and cables characterized by their high pretension,strength,and sealing hole pressure.An examination of the merits and demerits of standard inorganic and organic grouting materials versus the new inorganic–organic composite materials,including their specific application conditions,was conducted.Additionally,the article presents various methods and instruments to assess the support effect of grouting rock bolts,cable bolts,and grouting reinforcement.Furthermore,it provides a foundation for understanding the factors influencing decisions on grouted bolting timing,the sequence of grouting,the pressure applied,the volume of grout used,and the strategic arrangement of grouted rock bolts and cable bolts.The application of the high pretensioned high-pressure splitting grouted bolting collaborative control technology in a typical kilometer-deep soft rock mine in China—the soft coal seam and soft rock roadway in the Kouzidong coal mine,Huainan coal mining area,was introduced.Finally,the existing problems in grouted bolting control technology for deep soft rock roadways are analyzed,and the future development trend of grouted bolting control technology is anticipated.
