Origin of immature sulfur-rich oil in Jianghan oil field

Chemical structure of immature sulfur-rich kerogen and composition of immature sulfur-rich crude oil in Jianghun oil field have been studied. In molecular level, crude oil differs from thermolysed and chemolysed products of kerogen but does resemble the bitumen in immature sulfur-rich source rock. Therefore, immature sulfur-rich oil may be derived from the expelling of bitumen rather than from thermal cracking of kerogen.     

Experimental evidence for aerobic bio-denitriflcation

Nitrate pollution of groundwater is paid more and more attention for its hazardous to environments and human health. A strain of DN11 was isolated from soil and used in the laboratory columns filled with various media for nitrate removal. The experimental results showed that DN11could reduce nitrate at different rates in different media under the aerobic condition. The mechanism for nitrate removal with DN11 is explained meanwhile.     

Bound lipids in lacustrine sediments in Guchenghu Lake, East China

Conclusion Lipids present in different modes of occurrence in lacustrine sediments vary obviously in their composition. The ester-bound and amide-bound lipids are more likely to be derived from autochthonous input such as bacteria, algae and fungi in the lake, and they were more stable than the free lipids in the process of early diagenesis. Bound lipids record the more actual information about the paleoclimatic and paleoenvironmental changes. Amide-bound P-hydroxy fatty acids can be used as a fingerprint of the past bacterial communities which is informative to the paleoenvironment.     

用柱面波模型探讨地震电磁信息

本文从理论上探讨了地壳波导中传播的柱面电磁波,发现地震电磁波没有TM型波,这一特点可以用来识别地震电磁信号,引入衰减因子后,得到kr<1的区域,高导电层的衰减随频率的升高而减小,从而可以定性地解释观测到高频地震电磁信息的现象。     

Two kinds of Carlin-type gold deposite in southwestern Guizhou, China

Based on the organic geochemical studies on two typical Carlin-type deposits in southwestern Guizhou, as well as the comparison between the two deposits in terms of geological background, igneous rock, paleo-oilfield, lithofacies and paleogeographical and geochemical features, two kinds of Carlin-type deposit were proposed: Lannigou Type and Getang Type. The former includes Lannigou, Banqi and Yata gold deposits. These deposits are hosted by turbidite, geographically situated in the southwest of the mineralized district, and related genetically to paleo-oilfields. The latter includes Getang, Zimudang and Dachang gold (mercury and thallium) deposits, situated geographically in the northwest of the mineralized district where Emeishan basalt commonly occurs. These deposits are associated with reduction of coaly organic matter.     

Long-chain alkenones in Hotong Qagan Nur Lake sediments and its paleoclimatic implications

The long-chain alkenones present in the shallow sediment of Hotong Qagan Nur Lake in China are reported. According to the similarity of compositions and distributions of the alkenones determined commonly in the sediment section to those of marine sediment, it is reasonably referred that the alkenones might also originate from Prymnesiophyceae. In addition, the parameter U37k of alkenone is in positive correlation to δ18O values of authigenic calcium and magnesium minerals. This indicates that the parameter U37k of long-chain alkenone is also available to indicate paleoclimate of high-salinity alkaline lake.     

聚胞藻热模拟产烃研究

采用ＧＣ和ＧＣＭＳ对蓝藻聚胞藻原生烃类及热解烃类进行了分析．聚胞藻在２５０ ℃～３００ ℃热解产气属于低熟气,以非烃气为主,产气组分参数反映了原核生物母质来源的特征．热解作用使其氯仿沥青“Ａ”含量和烷烃含量大幅度提高．原生烷烃以正烷烃为主,主峰为ｎＣ１７ ．热解烷烃仍以低碳数正烷烃为主,主峰为ｎＣ１７ ,反映了典型的藻类母质来源的烷烃特征．热解烷烃中还检出了丰富的二环倍半萜和五环三萜．五环三萜以Ｃ３０ 莫烷为主峰,并含有丰度较高的Ｃ３０藿烯,表明生成的烃类属于低熟油     

Geochemical characteristics and applications of 18a (H)-neohopanes and 17a (H)-diahopanes

Distributions and geochemical significances of 18α(H)-neohopanes and of 17α(H)-diahopanes in oils from west Xialiaohe depression of the Bohai Bay Basin have been studied. Relative abundance of 18α(H)-neohopanes and of 17α(H)-diahopanes can be effectively used as maturity parameters, in a range of medium-high mature stage, based on consideration on sedimentary-organic facies of source rocks. With a dual geochemical significance of maturity and sedimentary-organic facies, neohopane and diahopane parameters can be well used in oil-source correlation and in petroleum population division. Formation, primary concentration and preservation of precursors of rearranged hopanes are closely related to depositional conditions such as Eh-pH and clays content. A series of probable diahopanes (series D) was detected in the oils, which exhibits a similar distribution pattern and geochemical behavior as that of 17α(H)-diahopanes (series B).     

The carbon isotope study of biomarkers in the Maoming and the Jianghan tertiary oil shale

In terms of the individual carbon isotope data of biomarkers present in the typical freshwater lake sediment (Maoming oil shale) and saline lake sediment lake (Jianghan oil shale) of China, this paper discusses their precursors and depositional environments of biomarkers in both sediment samples. Our studies showed that phytane and pristane of the Maoming oil shale were derived from the phytol side chain of chlorophyll a. By comparing the isotopic composition of 4-methyl sterane with that of sterane and hopane, it is suggested that 4-methyl sterane which has a higher abundance in the Maoming oil shale come from bacteria. The isotopic composition of biomarkers from the Jianghan rock sample (saline lake sediment ) is significantly different from that of the Maoming oil shale (freshwater lake sediment). Gammacerane was derived from haloprotozoan, with δ13C being about -25.8‰, just in consistency with the value reported in previous studies. The isotopic composition of phytane and pristane in the Jianghan rock is similar to that of sterane and 4-methyl sterane derived from phytoplanktons, illustrating their commonprecursors were algae. This paper reported for the first time the carbon isotope data of porphyrin obtained by GC-IRMS techniques. The approximate δ13C of C32DPEP and C31DPEP porphyrin from the Jianghan Basin indicated that the porphyrin was derived from chlorophyll. In the Maomingoil shale C32DPEP was enriched in 13C relative to C32etio and C31DPEP, implying that C32DPEP came from chlorophyll, and C32etio and C31DPEP are of other origins.