Natural gas characteristics and gas-source comparisons of the Lower Triassic Feixianguan Formation,Eastern Sichuan Basin,China

There is great controversy regarding the origin and source of natural gas in the Lower Triassic Feix-ianguan Formation in the Eastern Sichuan Basin.This seriously restricts the study of natural gas dy-namics in the Feixianguan Formation and thus hampers natural gas exploration in the region,so further study is urgently required.Using experimental tests of natural gas composition,stable isotopes,and noble gas isotopes with gas chromatography(GC)and mass spectrometry(MS)studies of source rock and reservoir asphalt saturated hydrocarbons,the natural gas geochemical characteristics,the genetic identification and a gas-source comparison of the Feixianguan Formation were studied.Then,con-strained by the thermal history,the histories of gas generation and expulsion were restored by basin simulation technology.Finally,a gas accumulation model was established for the Feixianguan Formation.The results showed that(1)the H_(2)S-rich and H2S-poor gas reservoirs of the Feixianguan Formation are distributed on the east and west sides of the Kaijiang-Liangping trough in the Eastern Sichuan Basin,respectively.The carbon and hydrogen isotope compositions of the natural gas in the gas reservoirs are generally heavy and have typical characteristics of high-maturity dry gas reservoirs.(2)The natural gas of the Feixianguan Formation is organic thermogenic gas,which is mainly oil-type gas generated by the secondary cracking of crude oil.The gas-generating parent material is mainly type II kerogen.(3)The natural gas of the Feixianguan Formation in the Eastern Sichuan Basin was mainly generated by argil-laceous source rocks of the Upper Permian Longtan Formation.(4)Natural gas accumulation occurred as follows:the paleo-structure heights were filled with crude oil in the Early Jurassic,and paleo-oil res-ervoirs were formed in the Feixianguan Formation;during the Middle-Late Jurassic,the paleo-oil res-ervoirs were cracked when the reservoir temperatures rose above 160 C,and paleo-gas reservoirs were formed.Since the end of the Late Jurassic,the paleo-gas reservoirs have been adjusted and reformed to form the present-day natural gas reservoirs.These results provide a basis for studying natural gas accumulation dynamics of the Feixianguan Formation in the Eastern Sichuan Basin.

Hydrocarbon generation history constrained by thermal history and hydrocarbon generation kinetics:A case study of the Dongpu Depression,Bohai Bay Basin,China

With the increasing exploration and development of typical hydrocarbon-rich depressions,such as the Dongpu Depression,the exploitation difficulty of shallow formations is increasing.There is an urgent need to clarify the hydrocarbon generation mode and hydrocarbon generation histories in deep formations.In this study,a gold tube-autoclave closed system was used to simulate the hydrocarbon generation processes and establish the hydrocarbon generation mode of different types of kerogen.Then,constrained by the thermal history and hydrocarbon generation kinetics,hydrocarbon generation histories were modeled.The results show that hydrocarbon generation evolution can be divided into five stages,and the maturity of each stage is different.The hydrocarbon generation history of the source rocks of the Shahejie 3 Formation mainly dates from the early depositional period of the Shahejie 1 Formation to the middle depositional period of the Dongying Formation.Hydrocarbon generation history constrained by thermal history and hydrocarbon generation kinetics is more in line with actual geological conditions.Moreover,this research can provide important hydrocarbon generation parameters for deep oil and gas exploration and exploitation of the Shahejie 3 Formation in the Dongpu Depression.

Extrinsic harmful residues in Chinese herbal medicines: types,detection, and safety evaluation

Chinese herbal medicines（CHMs）are playing important roles in the treatment of diseases and human health care throughout the world.However,the extrinsic harmful residues have been threatening the therapies by destroying CHMs qualtiy which hinders the international trades of CHMs.This review summarized the extrinsic harmful residues contaminating CHMs in types,detection methods,national and international regulations,and made safety evaluations according to their contaminated levels,aiming to establish understanding among nations or organizations and provide references for the formulation or amendment of relative regulations.

Enzyme-Linked Immunosorbent Assay and Immunochromatographic Strip for Rapid Detection of Atrazine in Three Medicinal Herbal Roots

Objectives:An enzyme-linked immunosorbent assay(ELISA)and colloidal gold-based immunochromatographic(ICG)strip assay will be developed for the rapid and high-throughput detection of atrazine(ATZ)in medicinal herbs.Methods:A monoclonal antibody against ATZ was obtained after the immunization of mice,cell fusion,and hybridoma screening,and the antibody was used to develop direct competitive ELISA(dcELISA)and the ICG strip assay.Results:Both dcELISA and ICG strip methods were established,optimized,and validated for the detection of ATZ in Salviae miltiorrhizae radix et rhizome,Astragali radix,and Isatidis radix.dcELISA had a half-maximum inhibition concentration of 10.56 ng/m L(Salviae miltiorrhizae radix et rhizome),7.6 ng/m L(Astragali radix),and 8.15 ng/m L(Isatidis radix).The limit of detection(LOD)of the ICG strip assay was 12.5 ng/mL(Salviae miltiorrhizae radix et rhizome),12.5 ng/mL(Astragali radix),and 6.25 ng/mL(Isatidis radix)in different herb matrices.Due to the recognition characteristics of the monoclonal antibody for the pesticides ATZ,propazine,sebuthylazine,and prometryn,the detection results of real samples by the two immunoassays were confirmed by liquid chromatography–tandem mass spectrometry,which proved the accuracy and reliability of the established methods.Conclusion:The proposed dcELISA and ICG strip methods were suitable for the rapid,convenient,and high-throughput detection of ATZ in these medicinal herbs.

Gas Chromatography–Mass Spectrometry for Quantitative and Qualitative Analysis of Essential Oil from Curcuma wenyujin Rhizomes

Objectives:A rapid and sensitive gas chromatography–mass spectrometry(GC–MS)method for quantitative and qualitative analysis of essential oil from Curcuma wenyujin rhizomes was established.Methods:The essential oil of C.wenyujin rhizomes was extracted by supercritical CO2 extraction(SFE).Six main bioactive compounds(eucalyptol,β-elemene,curzerene,germacrone,curdione,and curcumol)were analyzed in selected ion monitoring mode(SIM).Results:Curzerene is not originally present in C.wenyujin rhizomes,but is a product of the transformation of furanodiene at high temperature.The six target components demonstrated good linearity(R2>0.9979)over a relatively wide concentration range.The interday and intraday variations had relative standard deviation values less than 5%and the average recovery ranged from 96.95%to 100.04%.The limit of quantitation ranged from 0.032 to 0.235μg/mL.The developed method was successfully used to analyze the six compounds in 17 samples collected from different origins.Significant variation was observed for the concentrations of the six compounds.In addition,51 constituents were identified in C.wenyujin rhizome essential oil,consisting of 87.66%of the total essential oil,including curdione,curzerene,dehydrocurdione,germacrone,1,4-bis(2-benzimidazoyl)benzene,neocurdione,curcumenone,andβ-elemene.Conclusions:The proposed method will be useful in the quality control of C.wenyujin rhizome essential oil production.