The BZ oilfield in the Bohai Sea is a rare,highly volatile reservoir with fractures in the metamorphic rocks of buried hills.Clarifying the mechanism of gas injection for improving oil recovery and determining the opt...The BZ oilfield in the Bohai Sea is a rare,highly volatile reservoir with fractures in the metamorphic rocks of buried hills.Clarifying the mechanism of gas injection for improving oil recovery and determining the optimal way to deploy injection-production well networks are critical issues that must be urgently addressed for efficient oilfield development.Experimental research on the mixed-phase displacement mechanism through gas injection into indoor formation fluids was conducted to guide the efficient development of gas injection in oil fields.We established a model of dual-medium reservoir composition and researched the deployment strategy for a three-dimensional well network for gas injection development.The coupling relationship between key influencing factors of the well network and fracture development was also quantitatively analyzed.The results show that the solubility of the associated gas and strong volatile oil system injected into the BZ oilfield is high.This high solubility demonstrates a mixed-phase displacement mechanism involving intermediate hydrocarbons,dissolution and condensation of medium components,and coexistence of extraction processes.Injecting gas and crude oil can achieve a favorable mixing effect when the local formation pressure is greater than 35.79 MPa.Associated gas reinjection is recommended to supplement energy for developing the highly volatile oil reservoirs in the fractured buried hills of the BZ oilfield.This recommendation involves fully utilizing the structural position and gravity-assisted oil displacement mechanism to deploy an injection-production well network.Gas injection points should be constructed at the top of high areas,and oil production points should be placed at the middle and lower parts of low areas.This approach forms a spatial threedimensional well network.By adopting high inclination well development,the oil production well forms a 45°angle with the fracture direction,which increases the drainage area and enhances single-well production capacity.The optimal injection-production well spacing along the fracture direction is approximately 1000 m,while the reasonable well spacing in the vertical fracture direction is approximately 800 m.The research results were applied to the development practice of the buried hills in the BZ oilfield,which achieved favorable development results.These outcomes provide a valuable reference for the formulation of development plans and efficient gas injection development in similar oil and gas fields in buried hills.展开更多
The formation mechanism of methane （CH4） during coal evolution has been investigated by density functional theory （DFT） of quantum chemistry. Thermogenic gas, which is generated during the thermal evolution of med...The formation mechanism of methane （CH4） during coal evolution has been investigated by density functional theory （DFT） of quantum chemistry. Thermogenic gas, which is generated during the thermal evolution of medium rank coal, is the main source of coalbed methane （CBM）. Ethylbenzene （A） and 6,7-dimethyl-5,6,7,8-tetrahydro-1-hydroxynaphthalene （B） have been used as model compounds to study the pyrolysis mechanism of highly volatile bituminous coal （R）, according to the similarity of bond orders and bond lengths. All possible paths are designed for each model. It can be concluded that the activation energies for H-assisted paths are lower than others in the process of methane formation; an H radical attacking on β-C to yield CH4 is the dominant path for the formation of CH4 from highly volatile bituminous coal. In addition, the calculated results also reveal that the positions on which H radical attacks and to which intramolecular H migrates have effects on methyl cleavage.展开更多
Studying on the pore size distribution of coal is vital for determining reasonable coalbed methane development strategies.The coalbed methane project is in progress in the southern Junggar Basin of northwestern China,...Studying on the pore size distribution of coal is vital for determining reasonable coalbed methane development strategies.The coalbed methane project is in progress in the southern Junggar Basin of northwestern China,where high volatile bituminous coal is reserved.In this study,with the purpose of accurately characterizing the full-scale pore size distribution of the high volatile bituminous coal of the southern Junggar Basin,two grouped coal samples were applied for mercury intrusion porosimetry,low-temperature nitrogen adsorption,low-field nuclear magnetic resonance,rate-controlled mercury penetration,scanning electron microscopy,and nano-CT measurements.A comprehensive pore size distribution was proposed by combining the corrected mercury intrusion porosimetry data and low-temperature nitrogen adsorption data.The relationship between transverse relaxation time(T2,ms)and the pore diameter was determined by comparing the T2 spectrum with the comprehensive pore size distribution.The macro-pore and throat size distributions derived from nano-CT and rate-controlled mercury penetration were distinguishingly analyzed.The results showed that:1)comprehensive pore size distribution analysis can be regarded as an accurate method to characterize the pore size distribution of high volatile bituminous coal;2)for the high volatile bituminous coal of the southern Junggar Basin,the meso-pore volume was the greatest,followed by the transition pore volume or macro-pore volume,and the micro-pore volume was the lowest;3)the relationship between T2 and the pore diameter varied for different samples,even for samples with close maturities;4)the throat size distribution derived from nano-CT was close to that derived from rate-controlled mercury penetration,while the macro-pore size distributions derived from those two methods were very different.This work can deepen the knowledge of the pore size distribution characterization techniques of coal and provide new insight for accurate pore size distribution characterization of high volatile bituminous coal.展开更多
In Houston, a combination of urban emissions from a city of 4 million people, coupled with emissions from extensive petroleum refining and chemical manufacturing, leads to conditions for photochemistry that are unique...In Houston, a combination of urban emissions from a city of 4 million people, coupled with emissions from extensive petroleum refining and chemical manufacturing, leads to conditions for photochemistry that are unique in the United States, and historically, the city had experienced some of the highest ozone concentrations recorded in the United States. Large air quality field studies （the Texas Air Quality Studies or TexAQS I and II） were conducted to determine root causes of the high ozone concentrations. Hundreds of air quality investigators, from around the world, deployed instruments on aircraft, on ships, and at fixed ground sites to make extensive air quality measurements; detailed photochemical modeling was used to interpret and assess the implications of the measurements. The Texas Air Quality Studies revealed that both continuous and episodic emissions of light alkenes, which came to be called highly reactive volatile organic compounds, played a critical role in the formation of ozone and other photochemical oxidants in the region. Under- standing and quantifying the role of these emissions in regional air quality required innovations in characterizing emissions and in photochemical modeling. Reducing emissions required innovative policy approaches. These coupled scientific and policy innovations are described, and the result, substantially cleaner air for Houston, is documented. The lessons learned from the Houston air quality experience are relevant to cities with similar population and industrial profiles around the world.展开更多
文摘The BZ oilfield in the Bohai Sea is a rare,highly volatile reservoir with fractures in the metamorphic rocks of buried hills.Clarifying the mechanism of gas injection for improving oil recovery and determining the optimal way to deploy injection-production well networks are critical issues that must be urgently addressed for efficient oilfield development.Experimental research on the mixed-phase displacement mechanism through gas injection into indoor formation fluids was conducted to guide the efficient development of gas injection in oil fields.We established a model of dual-medium reservoir composition and researched the deployment strategy for a three-dimensional well network for gas injection development.The coupling relationship between key influencing factors of the well network and fracture development was also quantitatively analyzed.The results show that the solubility of the associated gas and strong volatile oil system injected into the BZ oilfield is high.This high solubility demonstrates a mixed-phase displacement mechanism involving intermediate hydrocarbons,dissolution and condensation of medium components,and coexistence of extraction processes.Injecting gas and crude oil can achieve a favorable mixing effect when the local formation pressure is greater than 35.79 MPa.Associated gas reinjection is recommended to supplement energy for developing the highly volatile oil reservoirs in the fractured buried hills of the BZ oilfield.This recommendation involves fully utilizing the structural position and gravity-assisted oil displacement mechanism to deploy an injection-production well network.Gas injection points should be constructed at the top of high areas,and oil production points should be placed at the middle and lower parts of low areas.This approach forms a spatial threedimensional well network.By adopting high inclination well development,the oil production well forms a 45°angle with the fracture direction,which increases the drainage area and enhances single-well production capacity.The optimal injection-production well spacing along the fracture direction is approximately 1000 m,while the reasonable well spacing in the vertical fracture direction is approximately 800 m.The research results were applied to the development practice of the buried hills in the BZ oilfield,which achieved favorable development results.These outcomes provide a valuable reference for the formulation of development plans and efficient gas injection development in similar oil and gas fields in buried hills.
基金supported by the Major Projects of National Science and Technology(Grant No.2011ZX05040-005-002-001)the National Natural Science Foundation of China(Grant No.21276171 and 21276003)+1 种基金the National Younger Natural Science Foundation of China(Grant No.21103120)China Postdoctoral Science Foundation(Grant No.2012M520608)
文摘The formation mechanism of methane （CH4） during coal evolution has been investigated by density functional theory （DFT） of quantum chemistry. Thermogenic gas, which is generated during the thermal evolution of medium rank coal, is the main source of coalbed methane （CBM）. Ethylbenzene （A） and 6,7-dimethyl-5,6,7,8-tetrahydro-1-hydroxynaphthalene （B） have been used as model compounds to study the pyrolysis mechanism of highly volatile bituminous coal （R）, according to the similarity of bond orders and bond lengths. All possible paths are designed for each model. It can be concluded that the activation energies for H-assisted paths are lower than others in the process of methane formation; an H radical attacking on β-C to yield CH4 is the dominant path for the formation of CH4 from highly volatile bituminous coal. In addition, the calculated results also reveal that the positions on which H radical attacks and to which intramolecular H migrates have effects on methyl cleavage.
基金supported by the Opening Fund of Key Laboratory of Continental Shale Accumulation and Development(North-east Petroleum University),Ministry of Educationthe National Science and Technology Major Project of the Ministry of Science and Technology of China(No.2016ZX05043-004-001)the National Natural Science Foundation of China(Grant No.41772158).
文摘Studying on the pore size distribution of coal is vital for determining reasonable coalbed methane development strategies.The coalbed methane project is in progress in the southern Junggar Basin of northwestern China,where high volatile bituminous coal is reserved.In this study,with the purpose of accurately characterizing the full-scale pore size distribution of the high volatile bituminous coal of the southern Junggar Basin,two grouped coal samples were applied for mercury intrusion porosimetry,low-temperature nitrogen adsorption,low-field nuclear magnetic resonance,rate-controlled mercury penetration,scanning electron microscopy,and nano-CT measurements.A comprehensive pore size distribution was proposed by combining the corrected mercury intrusion porosimetry data and low-temperature nitrogen adsorption data.The relationship between transverse relaxation time(T2,ms)and the pore diameter was determined by comparing the T2 spectrum with the comprehensive pore size distribution.The macro-pore and throat size distributions derived from nano-CT and rate-controlled mercury penetration were distinguishingly analyzed.The results showed that:1)comprehensive pore size distribution analysis can be regarded as an accurate method to characterize the pore size distribution of high volatile bituminous coal;2)for the high volatile bituminous coal of the southern Junggar Basin,the meso-pore volume was the greatest,followed by the transition pore volume or macro-pore volume,and the micro-pore volume was the lowest;3)the relationship between T2 and the pore diameter varied for different samples,even for samples with close maturities;4)the throat size distribution derived from nano-CT was close to that derived from rate-controlled mercury penetration,while the macro-pore size distributions derived from those two methods were very different.This work can deepen the knowledge of the pore size distribution characterization techniques of coal and provide new insight for accurate pore size distribution characterization of high volatile bituminous coal.
文摘In Houston, a combination of urban emissions from a city of 4 million people, coupled with emissions from extensive petroleum refining and chemical manufacturing, leads to conditions for photochemistry that are unique in the United States, and historically, the city had experienced some of the highest ozone concentrations recorded in the United States. Large air quality field studies （the Texas Air Quality Studies or TexAQS I and II） were conducted to determine root causes of the high ozone concentrations. Hundreds of air quality investigators, from around the world, deployed instruments on aircraft, on ships, and at fixed ground sites to make extensive air quality measurements; detailed photochemical modeling was used to interpret and assess the implications of the measurements. The Texas Air Quality Studies revealed that both continuous and episodic emissions of light alkenes, which came to be called highly reactive volatile organic compounds, played a critical role in the formation of ozone and other photochemical oxidants in the region. Under- standing and quantifying the role of these emissions in regional air quality required innovations in characterizing emissions and in photochemical modeling. Reducing emissions required innovative policy approaches. These coupled scientific and policy innovations are described, and the result, substantially cleaner air for Houston, is documented. The lessons learned from the Houston air quality experience are relevant to cities with similar population and industrial profiles around the world.
