Here we present six key parameters that have been applied to evaluate the Silurian Longmaxi shale gas accumulations of southern Sichuan Province.These parameters include richness of organic matter,single layer shale t...Here we present six key parameters that have been applied to evaluate the Silurian Longmaxi shale gas accumulations of southern Sichuan Province.These parameters include richness of organic matter,single layer shale thickness,burial depth of the shale,maturity,shale properties,and brittle mineral content.In combination with drilling data,the lower limits of these six parameters for marine shale gas have been evaluated and the following conclusions are drawn:(1)Organic carbon recovery, gas content inversion,and production tests have been applied for the first time to measure the lower limit of TOC,which is determined to be 1.0%.(2)Based on the hydrocarbon generation and expulsion theory for source rocks and the characteristics of Longmaxi shale,the lower limit of the single-layer thickness is estimated to be 30 m,of which a thickness of at least 15 m should contain high-quality shale.(3)Based on the correlation of TOC and porosity,the lower limit of gas-filled porosity is 1.2%.(4)Other parameters,such as maturity,burial depth,and brittle mineral content have also been studied with regard to the geologic conditions of southern Sichuan.Based on the study results,an evaluation index system has been established for highly evolved marine shale gas,and the system has been applied successfully to geologically screened shale gas occurrences in southern Sichuan Province.展开更多
早产是指妊娠孕周不满37周分娩,即≤36^(+6)周[1]。早产儿或未成熟儿的定义是指出生体重<1000g。1976年,世界卫生组织(World Health Organization,WHO)和国际妇产科联盟(International Federation of Gynecology and Obstetrics,FIGO...早产是指妊娠孕周不满37周分娩,即≤36^(+6)周[1]。早产儿或未成熟儿的定义是指出生体重<1000g。1976年,世界卫生组织(World Health Organization,WHO)和国际妇产科联盟(International Federation of Gynecology and Obstetrics,FIGO)首次提出早产新生儿这一概念,目前已沿用了40多年。展开更多
Estimation of the plant-available water capacity(PAWC)of soils at a regional scale helps in adopting better land use planning,developing suitable irrigation schedules for crops,and optimizing the use of scarce water r...Estimation of the plant-available water capacity(PAWC)of soils at a regional scale helps in adopting better land use planning,developing suitable irrigation schedules for crops,and optimizing the use of scarce water resources.In the current study,72 soil profiles were sampled from the Barossa region of South Australia to estimate pedo-transfer functions deduced from easily estimated soil properties.These functions were then used to estimate the fixed(10 and 33 kPa)and dynamic pressure head(h_(fc))water contents at field capacity(FC)for minimum drainage flux(0.01 and 0.001 cm d^(-1)),which serves as the upper boundary for plant-available water in soils.The estimated residual water content was corrected for subsoil constraints,especially the exchangeable sodium percentage(ESP).The results showed that the mean values of h_(fc)in sand-dominated light and medium textured soils(i.e.,sand,loamy sand,sandy loam,and loam)varied in a narrow range(15.8-18.2 kPa),whereas those in the clay-dominated heavy textured soils(i.e.,clay loam)showed a wide range(11.3-49.3 kPa).There were large differences in PAWC for dynamic FC(PAWC_(fc))and fixed FC at 10 kPa(PAWC10),33 kPa(PAWC33),and a mix of 10and 33 kPa(PAWC_(10,33))pressure heads depending on soil texture.Normally,the difference between PAWC at 10 kPa and h_(fc)(ΔPAWC_(10))was positive,whereas that between 33 kPa and h_(fc)(ΔPAWC_(33))was negative across all sites.Nevertheless,the estimation of PAWC assuming a fixed FC at 10 and 33 kPa pressures(i.e.,PAWC_(10,33))for sandy,clay,and silty soils reduced the difference between fixed and dynamic pressure PAWCs to<10% across the region.The estimation of PAWC was improved by incorporating the impact of subsoil constraints,such as high ESP,which was more pronounced for clay and silty soils.These findings demonstrate the inherent inconsistencies between static pressure and flux-based dynamic FC estimations in soils.Soil heterogeneity,intra-texture variability,subsoil constraints,and swell-shrink clays can have great impacts on the wa展开更多
基金supported by National Science Foundation for Distinguished Young Scholars of China(Grant No.51125019)
文摘Here we present six key parameters that have been applied to evaluate the Silurian Longmaxi shale gas accumulations of southern Sichuan Province.These parameters include richness of organic matter,single layer shale thickness,burial depth of the shale,maturity,shale properties,and brittle mineral content.In combination with drilling data,the lower limits of these six parameters for marine shale gas have been evaluated and the following conclusions are drawn:(1)Organic carbon recovery, gas content inversion,and production tests have been applied for the first time to measure the lower limit of TOC,which is determined to be 1.0%.(2)Based on the hydrocarbon generation and expulsion theory for source rocks and the characteristics of Longmaxi shale,the lower limit of the single-layer thickness is estimated to be 30 m,of which a thickness of at least 15 m should contain high-quality shale.(3)Based on the correlation of TOC and porosity,the lower limit of gas-filled porosity is 1.2%.(4)Other parameters,such as maturity,burial depth,and brittle mineral content have also been studied with regard to the geologic conditions of southern Sichuan.Based on the study results,an evaluation index system has been established for highly evolved marine shale gas,and the system has been applied successfully to geologically screened shale gas occurrences in southern Sichuan Province.
文摘早产是指妊娠孕周不满37周分娩,即≤36^(+6)周[1]。早产儿或未成熟儿的定义是指出生体重<1000g。1976年,世界卫生组织(World Health Organization,WHO)和国际妇产科联盟(International Federation of Gynecology and Obstetrics,FIGO)首次提出早产新生儿这一概念,目前已沿用了40多年。
文摘Estimation of the plant-available water capacity(PAWC)of soils at a regional scale helps in adopting better land use planning,developing suitable irrigation schedules for crops,and optimizing the use of scarce water resources.In the current study,72 soil profiles were sampled from the Barossa region of South Australia to estimate pedo-transfer functions deduced from easily estimated soil properties.These functions were then used to estimate the fixed(10 and 33 kPa)and dynamic pressure head(h_(fc))water contents at field capacity(FC)for minimum drainage flux(0.01 and 0.001 cm d^(-1)),which serves as the upper boundary for plant-available water in soils.The estimated residual water content was corrected for subsoil constraints,especially the exchangeable sodium percentage(ESP).The results showed that the mean values of h_(fc)in sand-dominated light and medium textured soils(i.e.,sand,loamy sand,sandy loam,and loam)varied in a narrow range(15.8-18.2 kPa),whereas those in the clay-dominated heavy textured soils(i.e.,clay loam)showed a wide range(11.3-49.3 kPa).There were large differences in PAWC for dynamic FC(PAWC_(fc))and fixed FC at 10 kPa(PAWC10),33 kPa(PAWC33),and a mix of 10and 33 kPa(PAWC_(10,33))pressure heads depending on soil texture.Normally,the difference between PAWC at 10 kPa and h_(fc)(ΔPAWC_(10))was positive,whereas that between 33 kPa and h_(fc)(ΔPAWC_(33))was negative across all sites.Nevertheless,the estimation of PAWC assuming a fixed FC at 10 and 33 kPa pressures(i.e.,PAWC_(10,33))for sandy,clay,and silty soils reduced the difference between fixed and dynamic pressure PAWCs to<10% across the region.The estimation of PAWC was improved by incorporating the impact of subsoil constraints,such as high ESP,which was more pronounced for clay and silty soils.These findings demonstrate the inherent inconsistencies between static pressure and flux-based dynamic FC estimations in soils.Soil heterogeneity,intra-texture variability,subsoil constraints,and swell-shrink clays can have great impacts on the wa
