Based on the damage analysis of elliptical aperture,the mechanism of coal damagein the developing process of coal and gas outburst was researched.The results show thatthe damage to coal by gas is mainly caused by the ...Based on the damage analysis of elliptical aperture,the mechanism of coal damagein the developing process of coal and gas outburst was researched.The results show thatthe damage to coal by gas is mainly caused by the concentrated tensile stress appearing nearthe endpoint of the pores.Fractures in coal,gas pressure,ground stress and the tensilestrength of the coal matrix are the major controlling factors of this kind of damage.When theground stress releases abruptly and the gas pressure is high,tensile failure will occur aroundthe endpoint of the small pores due to gas pressure,and the coal may be broken up like powder;this is called pulverization.Otherwise,when the gas pressure is low,the tensile stress canonly occur around the endpoint of the large pores and fractures due to gas pressure,the fracturesin coal extend and link together,the fracture extension direction is statistically perpendicularto the direction of the minor principal stress.This kind of damage is shown as the stratifiedspall around the outburst hole.展开更多
The problem of water coning into the Tarim fractured sandstone gas reservoirs becomes one of the major concerns in terms of productivity, increased operating costs and environmental effects. Water coning is a phenomen...The problem of water coning into the Tarim fractured sandstone gas reservoirs becomes one of the major concerns in terms of productivity, increased operating costs and environmental effects. Water coning is a phenomenon caused by the imbalance between gravity and viscous forces around the completion interval. There are several controllable and uncontrollable parameters influencing this problem. In order to simulate the key parameters affecting the water coning phenomenon, a model was developed to represent a single well with an underlying aquifer using the fractured sandstone gas reservoir data of the A-Well in Dina gas fields.The parametric study was performed by varying six properties individually over a representative range. The results show that matrix permeability, well penetration(especially fracture permeability), vertical-to-horizontal permeability ratio, aquifer size and gas production rate have considerable effect on water coning in the fractured gas reservoirs. Thus, investigation of the effective parameters is necessary to understand the mechanism of water coning phenomenon. Simulation of the problem helps to optimize the conditions in which the breakthrough of water coning is delayed.展开更多
基金Supported by the National Basic Research Program(973)of China(2005CB221503)the Key Project of Natural Science Foundation of China(50534080)
文摘Based on the damage analysis of elliptical aperture,the mechanism of coal damagein the developing process of coal and gas outburst was researched.The results show thatthe damage to coal by gas is mainly caused by the concentrated tensile stress appearing nearthe endpoint of the pores.Fractures in coal,gas pressure,ground stress and the tensilestrength of the coal matrix are the major controlling factors of this kind of damage.When theground stress releases abruptly and the gas pressure is high,tensile failure will occur aroundthe endpoint of the small pores due to gas pressure,and the coal may be broken up like powder;this is called pulverization.Otherwise,when the gas pressure is low,the tensile stress canonly occur around the endpoint of the large pores and fractures due to gas pressure,the fracturesin coal extend and link together,the fracture extension direction is statistically perpendicularto the direction of the minor principal stress.This kind of damage is shown as the stratifiedspall around the outburst hole.
基金Project(50150503-12)supported by National Science and Technology Major Program of the Ministry of Science and Technology of ChinaProject(2010E-2103)supported by Research on Key Technology in Tarim Oilfield Exploration and Development,China
文摘The problem of water coning into the Tarim fractured sandstone gas reservoirs becomes one of the major concerns in terms of productivity, increased operating costs and environmental effects. Water coning is a phenomenon caused by the imbalance between gravity and viscous forces around the completion interval. There are several controllable and uncontrollable parameters influencing this problem. In order to simulate the key parameters affecting the water coning phenomenon, a model was developed to represent a single well with an underlying aquifer using the fractured sandstone gas reservoir data of the A-Well in Dina gas fields.The parametric study was performed by varying six properties individually over a representative range. The results show that matrix permeability, well penetration(especially fracture permeability), vertical-to-horizontal permeability ratio, aquifer size and gas production rate have considerable effect on water coning in the fractured gas reservoirs. Thus, investigation of the effective parameters is necessary to understand the mechanism of water coning phenomenon. Simulation of the problem helps to optimize the conditions in which the breakthrough of water coning is delayed.
