Fifteen oil seepage and solid bitumen samples in the Southern Guizhou Depression were analyzed with GC–MS. Characteristics of molecular markers and carbon isotopes are discussed systemically. The results showed that the oil seepage and solid bitumen samples in the Southern Guizhou Depression could be divided into two families: Ordovician and Siluric samples, and Permian samples. The two families are different in alkanes distribution, biomarkers, aromatic hydrocarbon composition,and stable carbon isotopes; differences mainly caused by source rock variation.
Ningxi LiGuangli WangBo GaoXianqing LiShengbao ShiTieguan Wang
The main reservoirs of Majiang fossil deposits consist of the Silurian Wengxiang group,dominantly sandstones,and the Ordovician Honghuayuan formation,dominantly carbonate rocks,and the Lower Cambrian Niutitang Formation mudstones serve as the major source rocks.Thermochemical sulfate reduction(TSR)might have taken place in the Paleozoic marine carbonate oil pools,as indicated by high concentrations of dibenzothiophenes in the extracts(MDBT=0.27 4.32 g/g extract,and MDBT/MPH=0.71 1.38).Hydrocarbons in the Pojiaozhai Ordovician carbonate reservoirs have undergone severe TSR and are characterized by higher quantities of diamondoids and MDBT and heavier isotopic values(13C=28.4‰).The very large amounts of dibenzothiophenes might be products of reactions between biphenyls and sulfur species associated with TSR.
WANG GuangLiLI NingXiGAO BoLI XianQingSHI ShengBaoWANG TieGuan
Heavy biodegraded crude oils have larger numbers of coeluting compounds than nonbiodegraded oils, and they are typically not resolved with conventional gas chromatography（GC）. This unresolved complex mixture（UCM） has been investigated using comprehensive two-dimensional gas chromatography–time-of-flight mass spectrometry（GC×GC-To FMS） within a set of biodegraded petroleums derived from distinct sedimentary basins, including northwestern Sichuan（Neoproterozoic, marine）, Tarim（Early Paleozoic, marine）, Bohai Bay（Eocene, saline/brackish） and Pearl River Mouth（Eocene, freshwater）. In general, the hydrocarbons that constitute the UCM in petroleum saturate fractions can be classified into three catalogues based on the distributions of resolved compounds on two dimensional chromatograms. Group 1 is composed mainly of normal and branched alkanes, isoprenoid alkanes and monocyclic alkanes; Group 2 comprises primarily terpanes ranging from two to five rings, and Group 3 is dominated by monoaromatic hydrocarbons such as tetralins and monoaromatic steranes. In addition, the UCM is source dependent and varies between oil populations. i.e., the UCM of petroleum derived from Precambrian and Early Paleozoic marine, Eocene saline/brackish and freshwater source rocks is specifically rich in higher homologues of A-norsteranes, series of 1,1,3-trimethyl-2-alkylcyclohexanes（carotenoid-derived alkanes）, and tetralin and indane compounds, respectively.
WANG GuangliBernd Rolf Tatsuo SIMONEITSHI ShengbaoWANG TieguanZHONG NingningWANG Peirong
1 Introduction Biological markers or biomarkers(Eglinton et al.,1964;Eglinton and Calvin,1967)are molecular fossils,which were derived from once living organisms through the earth history.They occur in sediments,rocks,and crude
WANG GuangliZHANG QinYANG XiaofaMA ZhongzhenXIE Yinfu
