The Hanjiang Formation of Langhian age （middle Miocene） in the Pearl River Mouth Basin （PRMB）, South China Sea consists of deltaic siliciclastic and neritic shelf carbonate rhythmic alternations, which form one of...The Hanjiang Formation of Langhian age （middle Miocene） in the Pearl River Mouth Basin （PRMB）, South China Sea consists of deltaic siliciclastic and neritic shelf carbonate rhythmic alternations, which form one of the potential reservoirs of the basin. To improve stratigraphic resolutions for hydrocarbon prospecting and exploration in the basin, the present study undertakes spectral analysis of high-resolution natural gamma-ray （NGR） well-logging record to determine the dominant frequency components and test whether Milankovitch orbital signals are recorded in rhythmic successions. Analytical results indicate the orbital cycles of precession （~19 ka and ~23 ka）, obliquity （-41 ka）, and eccentricity （~100 ka and --405 ka）, which provide the strong evidence for astronomically driven climate changes in the rhythmic alternation successions. Within biochronological constraint, a high-resolution astronomical timescale was constructed through the astronomical tuning of the NGR record to recent astronomically calculated variation of Earth＇s orbit. The astronomically tuned timescale can be applied to calculate astronomical ages for the geological events and bioevents recognized throughout the period. The first downhole occurrences of foraminifers Globorotalia peripheroronda and Globigerinoides sicanus are dated at 14.546 Ma and 14.919 Ma, respectively, which are slightly different from earlier estimates in the South China Sea. When compared with the global sea-level change chart, the astronomical estimate for the sequences recognized based on microfossil distributions have the same end time but the different initiation time. This is probably due to the local or regional tectonic activities superimposed on eustatic rise which postponed the effect of global sea-level rising. Astronomical timescale also resolves the depositional evolution history for the Langhian Stage （middle Miocene） with a variation that strongly resembles that of Earth＇s orbital eccentricity predicted from 13.65 Ma to 15.97 Ma. We infer that the main factor controlling the variability of the sedimentation rate in the Hanjiang Formation is related to the ^-405-ka-period eccentricity.展开更多
背景与目的:肝切除术是治疗肝胆管结石的主要手段之一。然而,腹腔镜左侧肝切除术(LLH)是否优于开腹左侧肝切除术(OLH)仍有争议。因此,本研究通过倾向性评分匹配法(PSM)比较LLH和OLH治疗肝胆管结石的临床疗效。方法:回顾性分析南昌大学...背景与目的:肝切除术是治疗肝胆管结石的主要手段之一。然而,腹腔镜左侧肝切除术(LLH)是否优于开腹左侧肝切除术(OLH)仍有争议。因此,本研究通过倾向性评分匹配法(PSM)比较LLH和OLH治疗肝胆管结石的临床疗效。方法:回顾性分析南昌大学第一附属医院2016年1月-2021年7月331例施行左侧肝切除术(包括左肝外叶切除术和左半肝切除术)的肝胆管结石患者的临床资料。使用PSM法对腹腔镜手术患者(LLH组)与开腹手术患者(OLH组)进行1∶1匹配,比较匹配后两组的相关临床指标。结果:PSM后,两组患者共124对匹配成功。与OLH组比较,LLH组的术中出血量(230.6 mL vs. 326.5 mL)、总体并发症发生率(9.7%vs. 23.4%)明显降低,恢复进食时间(1.9 d vs. 2.6 d)、下床活动时间(1.7 d vs.2.3 d)、术后住院时间(8.8 d vs. 10.2d)明显缩短,住院总费用(4.3万元vs. 5.7万元)明显减少(均P<0.05)。两组的手术时间、术中输血例数、胆总管结石取石方式、结石清除率和结石复发率差异均无统计学意义(均P>0.05)。两组均无再次手术和围手术期死亡。LLH组中转开腹率为4.0%。结论:与OLH相比,LLH可减少术中出血量,降低围手术期并发症发生率,节省住院总费用,是治疗左肝内胆管结石安全有效的手术方式。展开更多
Two comparative simulation experiments(a normal atmospheric-pressure opening system and a 20 MPa closed system)were conducted to study the geochemical evolution of n-alkane,sterane,and terpane biomarkers in the proces...Two comparative simulation experiments(a normal atmospheric-pressure opening system and a 20 MPa closed system)were conducted to study the geochemical evolution of n-alkane,sterane,and terpane biomarkers in the process of oil cracking into gas under different pressures.With an initial experimental temperature set at 300°C,the temperature was increased to 650°C at a heating rate of 30°C/h.The products were tested every 50°C starting at 300°C,and a pressure of 20 MPa was achieved using a water column.The low-maturity crude oil sample was from the Paleogene system in the Dongying sag in eastern China.The threshold temperature obtained for the primary oil cracking process in both pressure systems was 450°C.Before the oil was cracked into gas,some components,including macromolecular n-alkanes,were cracked into medium-or small-sized n-alkanes.The secondary oil cracking of heavy hydrocarbon gases of C2–5to methane mainly occurred between 550°C to 650°C,and the parameters Ln(C1/C2)and Ln(C1/C3),as well as the dry coefficients,increased.Overpressure inhibited the oil cracking process.In the 20 MPa system,the oil conversion rate decreased,the temperature threshold for gas generation rose,and oil cracking was inhibited.Compared with the normal pressure system,high-carbon n-alkanes and other compounds in the 20 MPa pressure system were reserved.Furthermore,the parameters∑C21-/∑22+,Ln(C1/C2),and Ln(C1/C3),as well as the dry coefficients,decreased within the main temperature range.During secondary oil cracking(550°C to 600°C),the Ph/nC18and Pr/nC17decreased.High pressure influenced the evolution of the biomarkers Ts and Tm,C31homohopane,C29sterane,and their related maturity parameters to different extents during oil cracking under different temperature ranges.展开更多
基金supported by Australian Research Council discovery grant(DP0770938 to ZQC)National Science and Technology Major Project (2011ZX05001-001-006)
文摘The Hanjiang Formation of Langhian age （middle Miocene） in the Pearl River Mouth Basin （PRMB）, South China Sea consists of deltaic siliciclastic and neritic shelf carbonate rhythmic alternations, which form one of the potential reservoirs of the basin. To improve stratigraphic resolutions for hydrocarbon prospecting and exploration in the basin, the present study undertakes spectral analysis of high-resolution natural gamma-ray （NGR） well-logging record to determine the dominant frequency components and test whether Milankovitch orbital signals are recorded in rhythmic successions. Analytical results indicate the orbital cycles of precession （~19 ka and ~23 ka）, obliquity （-41 ka）, and eccentricity （~100 ka and --405 ka）, which provide the strong evidence for astronomically driven climate changes in the rhythmic alternation successions. Within biochronological constraint, a high-resolution astronomical timescale was constructed through the astronomical tuning of the NGR record to recent astronomically calculated variation of Earth＇s orbit. The astronomically tuned timescale can be applied to calculate astronomical ages for the geological events and bioevents recognized throughout the period. The first downhole occurrences of foraminifers Globorotalia peripheroronda and Globigerinoides sicanus are dated at 14.546 Ma and 14.919 Ma, respectively, which are slightly different from earlier estimates in the South China Sea. When compared with the global sea-level change chart, the astronomical estimate for the sequences recognized based on microfossil distributions have the same end time but the different initiation time. This is probably due to the local or regional tectonic activities superimposed on eustatic rise which postponed the effect of global sea-level rising. Astronomical timescale also resolves the depositional evolution history for the Langhian Stage （middle Miocene） with a variation that strongly resembles that of Earth＇s orbital eccentricity predicted from 13.65 Ma to 15.97 Ma. We infer that the main factor controlling the variability of the sedimentation rate in the Hanjiang Formation is related to the ^-405-ka-period eccentricity.
文摘背景与目的:肝切除术是治疗肝胆管结石的主要手段之一。然而,腹腔镜左侧肝切除术(LLH)是否优于开腹左侧肝切除术(OLH)仍有争议。因此,本研究通过倾向性评分匹配法(PSM)比较LLH和OLH治疗肝胆管结石的临床疗效。方法:回顾性分析南昌大学第一附属医院2016年1月-2021年7月331例施行左侧肝切除术(包括左肝外叶切除术和左半肝切除术)的肝胆管结石患者的临床资料。使用PSM法对腹腔镜手术患者(LLH组)与开腹手术患者(OLH组)进行1∶1匹配,比较匹配后两组的相关临床指标。结果:PSM后,两组患者共124对匹配成功。与OLH组比较,LLH组的术中出血量(230.6 mL vs. 326.5 mL)、总体并发症发生率(9.7%vs. 23.4%)明显降低,恢复进食时间(1.9 d vs. 2.6 d)、下床活动时间(1.7 d vs.2.3 d)、术后住院时间(8.8 d vs. 10.2d)明显缩短,住院总费用(4.3万元vs. 5.7万元)明显减少(均P<0.05)。两组的手术时间、术中输血例数、胆总管结石取石方式、结石清除率和结石复发率差异均无统计学意义(均P>0.05)。两组均无再次手术和围手术期死亡。LLH组中转开腹率为4.0%。结论:与OLH相比,LLH可减少术中出血量,降低围手术期并发症发生率,节省住院总费用,是治疗左肝内胆管结石安全有效的手术方式。
基金supported by the National Natural Science Foundation of China(Grant Nos.40802026&41272140)Shandong Province Natural Science Foundation(Grant No.ZR2011DM004)
文摘Two comparative simulation experiments(a normal atmospheric-pressure opening system and a 20 MPa closed system)were conducted to study the geochemical evolution of n-alkane,sterane,and terpane biomarkers in the process of oil cracking into gas under different pressures.With an initial experimental temperature set at 300°C,the temperature was increased to 650°C at a heating rate of 30°C/h.The products were tested every 50°C starting at 300°C,and a pressure of 20 MPa was achieved using a water column.The low-maturity crude oil sample was from the Paleogene system in the Dongying sag in eastern China.The threshold temperature obtained for the primary oil cracking process in both pressure systems was 450°C.Before the oil was cracked into gas,some components,including macromolecular n-alkanes,were cracked into medium-or small-sized n-alkanes.The secondary oil cracking of heavy hydrocarbon gases of C2–5to methane mainly occurred between 550°C to 650°C,and the parameters Ln(C1/C2)and Ln(C1/C3),as well as the dry coefficients,increased.Overpressure inhibited the oil cracking process.In the 20 MPa system,the oil conversion rate decreased,the temperature threshold for gas generation rose,and oil cracking was inhibited.Compared with the normal pressure system,high-carbon n-alkanes and other compounds in the 20 MPa pressure system were reserved.Furthermore,the parameters∑C21-/∑22+,Ln(C1/C2),and Ln(C1/C3),as well as the dry coefficients,decreased within the main temperature range.During secondary oil cracking(550°C to 600°C),the Ph/nC18and Pr/nC17decreased.High pressure influenced the evolution of the biomarkers Ts and Tm,C31homohopane,C29sterane,and their related maturity parameters to different extents during oil cracking under different temperature ranges.
