The Zhongjiang gas field is a typical large gas field in terrigenous strata of the Western Sichuan Depression.It remains debatable which member of the Upper Triassic Xujiahe Formation served as the source rocks and ho...The Zhongjiang gas field is a typical large gas field in terrigenous strata of the Western Sichuan Depression.It remains debatable which member of the Upper Triassic Xujiahe Formation served as the source rocks and how significant the member contributed to the gas accumulations in the Zhongjiang gas field.In this study,we analyzed the essential characteristics of the Lower Jurassic source rocks and the geochemical features of light hydrocarbons in natural gas from the 2nd(T_(3)χ^(2))and 4th members(T_(3)χ^(4))of the Upper Triassic Xujiahe Formation(T_(3)χ),as well as the Middle Jurassic Shaximiao(J_(2)s)and Qianfoya(J_(2)q)formations.Based on this,we explored the sources of the natural gas in the Zhongjiang gas field and determined the natural gas migration patterns and their effects on the properties of light hydrocarbons in the natural gas.The results indicate that the Lower Jurassic lacustrine source rocks of the Zhongjiang gas field contain humic organic matter,with vitrinite reflectance(R_(0))values ranging from 0.86%to 0.98%.Samples meeting the criterion for effective source rocks[total organic carbon(TOC)content≥0.75%]exhibited an average TOC content of merely 1.02%,suggesting significantly lower hydrocarbon generation potential than source rocks in the underlying T3x,which show higher thermal maturity and TOC contents.For natural gas samples from T_(3)χ^(2),T_(3)χ^(4),J_(2)s,and J_(2)q reservoirs,their C_(5-7)iso-alkane content was significantly higher than their n-alkane content,and their methylcyclohexane(MCH)index ranged from 59.0%to 77.3%,indicating the predominance of methylcyclohexane in C_(7)light hydrocarbons.As indicated by the origin identification and gas-source correlation based on the geochemical features of light hydrocarbons,the natural gas in the Zhongjiang gas field is typical coal-derived gas.The gas from the primary pay zone of the Shaximiao Formation,with significantly high K_(1),(P_(2)+N_(2))/C_(7),and P_(3)/C_(7)values,predominantly originated from the 5th member of the T3x and migrated in the free phase,with a small amount possibly sourced from the Lower Jurassic source rocks.The dissolution and adsorption during gas migration led to a decrease in the aromatic content in C_(6-7)light hydrocarbons and an increase in the isoheptane values.Therefore,their effects must be considered when determining the gas origin and thermal maturity based on the aromatic content in C_(6-7) light hydrocarbons and iso-heptane values.展开更多
In order to solve the problem of gas overlimit in corner corners of coal and gas prominent mines, through thecombination of air leakage mechanism in the goaf, near-field fissure expansion and rich area division, blockin...In order to solve the problem of gas overlimit in corner corners of coal and gas prominent mines, through thecombination of air leakage mechanism in the goaf, near-field fissure expansion and rich area division, blockingmaterial development and optimization, performance measurement of blocking materials and on-site test, westarted to study the causes of gas concentration in corner corners, analysis of roof collapse and transparency incorners and performance test of blocking materials, and optimized the blocking materials by combining laboratory test and engineering test. Considering the thickness of the sealing film, the attenuation ratio of the sealingfilm thickness, the gelation time, and the gelation viscosity under different ratios, we designed a multi factororthogonal experiment to optimize the optimal ratio suitable for the engineering site. Factors affecting blockingeffectiveness, such as gel water retention and gel flame resistance, were also tested. The sealing scheme wasimplemented in the 2109 working face of a coal and gas outburst mine in Gansu, China. Through on-sitemonitoring of the changes in temperature, gas concentration, and air leakage at each monitoring point beforeand after the use of sealing materials, the analysis of the detection results shows that the temperature changes ateach monitoring point after the use of sealing materials do not exceed 0.2C;The change in oxygen concentrationis less than 0.27 %;The gas concentration has decreased by more than 60 %, with a decrease of 71.32 % in the gasconcentration in the upper corner. The air leakage has decreased by more than 53 %, and the proportion ofdecrease in air leakage at the upper corner is as high as 56.83 %. This air leakage control technology hasremarkable blocking effect, meets the requirements of corner near-field fissure blocking material, and is easy toprepare, inexpensive, non-toxic, tasteless and green, providing a successful experience for the treatment of similarcoal and gas outburst mines that can be referenced.展开更多
基金funded by the National Natural Science Foundation of China(No.42172149,No.U2244209)the SINOPEC Science and Technology Project(No.P22132,No.P21077-1).
文摘The Zhongjiang gas field is a typical large gas field in terrigenous strata of the Western Sichuan Depression.It remains debatable which member of the Upper Triassic Xujiahe Formation served as the source rocks and how significant the member contributed to the gas accumulations in the Zhongjiang gas field.In this study,we analyzed the essential characteristics of the Lower Jurassic source rocks and the geochemical features of light hydrocarbons in natural gas from the 2nd(T_(3)χ^(2))and 4th members(T_(3)χ^(4))of the Upper Triassic Xujiahe Formation(T_(3)χ),as well as the Middle Jurassic Shaximiao(J_(2)s)and Qianfoya(J_(2)q)formations.Based on this,we explored the sources of the natural gas in the Zhongjiang gas field and determined the natural gas migration patterns and their effects on the properties of light hydrocarbons in the natural gas.The results indicate that the Lower Jurassic lacustrine source rocks of the Zhongjiang gas field contain humic organic matter,with vitrinite reflectance(R_(0))values ranging from 0.86%to 0.98%.Samples meeting the criterion for effective source rocks[total organic carbon(TOC)content≥0.75%]exhibited an average TOC content of merely 1.02%,suggesting significantly lower hydrocarbon generation potential than source rocks in the underlying T3x,which show higher thermal maturity and TOC contents.For natural gas samples from T_(3)χ^(2),T_(3)χ^(4),J_(2)s,and J_(2)q reservoirs,their C_(5-7)iso-alkane content was significantly higher than their n-alkane content,and their methylcyclohexane(MCH)index ranged from 59.0%to 77.3%,indicating the predominance of methylcyclohexane in C_(7)light hydrocarbons.As indicated by the origin identification and gas-source correlation based on the geochemical features of light hydrocarbons,the natural gas in the Zhongjiang gas field is typical coal-derived gas.The gas from the primary pay zone of the Shaximiao Formation,with significantly high K_(1),(P_(2)+N_(2))/C_(7),and P_(3)/C_(7)values,predominantly originated from the 5th member of the T3x and migrated in the free phase,with a small amount possibly sourced from the Lower Jurassic source rocks.The dissolution and adsorption during gas migration led to a decrease in the aromatic content in C_(6-7)light hydrocarbons and an increase in the isoheptane values.Therefore,their effects must be considered when determining the gas origin and thermal maturity based on the aromatic content in C_(6-7) light hydrocarbons and iso-heptane values.
基金support of the S&T Program of Hebei(Grant No.23567602H).
文摘In order to solve the problem of gas overlimit in corner corners of coal and gas prominent mines, through thecombination of air leakage mechanism in the goaf, near-field fissure expansion and rich area division, blockingmaterial development and optimization, performance measurement of blocking materials and on-site test, westarted to study the causes of gas concentration in corner corners, analysis of roof collapse and transparency incorners and performance test of blocking materials, and optimized the blocking materials by combining laboratory test and engineering test. Considering the thickness of the sealing film, the attenuation ratio of the sealingfilm thickness, the gelation time, and the gelation viscosity under different ratios, we designed a multi factororthogonal experiment to optimize the optimal ratio suitable for the engineering site. Factors affecting blockingeffectiveness, such as gel water retention and gel flame resistance, were also tested. The sealing scheme wasimplemented in the 2109 working face of a coal and gas outburst mine in Gansu, China. Through on-sitemonitoring of the changes in temperature, gas concentration, and air leakage at each monitoring point beforeand after the use of sealing materials, the analysis of the detection results shows that the temperature changes ateach monitoring point after the use of sealing materials do not exceed 0.2C;The change in oxygen concentrationis less than 0.27 %;The gas concentration has decreased by more than 60 %, with a decrease of 71.32 % in the gasconcentration in the upper corner. The air leakage has decreased by more than 53 %, and the proportion ofdecrease in air leakage at the upper corner is as high as 56.83 %. This air leakage control technology hasremarkable blocking effect, meets the requirements of corner near-field fissure blocking material, and is easy toprepare, inexpensive, non-toxic, tasteless and green, providing a successful experience for the treatment of similarcoal and gas outburst mines that can be referenced.
