NATURAL GAS INDUSTRY, vol 27, no 10, 2007 October 25, 2007 SUBJECT HEADINGS: South China, Late Paleozoic, marine strata, characteristics of resource-reservoir-cap rocks, hydro carbon reservoiring, condition, exploration zone CHEN Yuarzhuang(senior engineer), born in 1965, holds a Ph, d degree and is engaged in research of geology and explora Add: China University of Geosciences. Beijing, No. 31, Xueyuan Rd, Haidian District, Beijing 100083, P. R. China Cell phone:13520601018 mail: chenyz(@ peris, cor MAIN FACTORS CONTROLLING HYDROCARBON ACCUMULATION AND DISTRIBUTION IN THE SECOND MEMBER OF NANTUN FORMATION, WUERXUN DEPRESSION DU Chun-guo', FU Guang( CNPC International Research Center;' Daqing Petroleum Institute). NA TUR. GAS IND. v. 27, no 10, pp 24-27, 10/25/2007.(ISSN 1000-0976: In Chinese) ABSTRACT, Main factors which control the hydrocarbon accumulation and distribution in the second tber of Nantun For- mation in Wuerxun depression are unclear due to the complex geologic conditions in the f ulied basit and he: limited knowl- edge, constraining the deepening of exploration in the study area. Based on the chara teristic analysis of regional petroleum ge- ologic conditions, the mechanisms of hydrocarbon reservoiring m he second member of Nait n Formation in Wuerxun depres sion are studied by using various techniq is, such as balanced cross sectins. hydrocarbon expulsion history modeling of the source rocks, authigenic illi e k-Ar io opie de ting, geochemical analysis and 3D modeling of hydrocarbon migration and accu- mulation. The results shew tl at structural trat sitional zone, temporal and spatial combination of cap rocks, features of lults and hydro: acb n migration and accumulation are the main control factors of hydrocarbon reservoiring in the study area. They also indicate that differences in the spatial combination of the quality of source-cap rocks, combination of fault and source rocks, fault sealing ability, source rock conditions and the forms of hydrocarbon migration and accumulation are the main cau- of the differential hydrocarbon distributions in the southern and northern parts of Wuerxun depression. SURJECT HEADINGS, Wuerxun depression, hydrocarbon reservoiring, structural transitional zone, source rocks, seal, faul combination, hydrocarbon migration and accumulation, form DU Chunguo. born in 1976, is studying for a Ph. D degree and is engaged in research of hydrocarbon distribution patterns and reservoiring mechanism, Add, CNPC International Research Center, Beijing 100083, P.R. China Cellphone13621198332E-mail:duchunguo126(@163.com CHARACTERISTICS OF CARBON AND OXYGEN ISOTOPIC COMPOSITIONS OF CARBONATE CE- MENTS IN TRIASSIC YANCHANG SANDSTONE IN ORDOS BASIN WANG Qi.2, ZHUO Xi-zhun', CHEN Guo-jun", LI Xiao-yan".(Key Laboratory of Gas Geochemis try, Institute of Geology and Geophysics, Chinese Academy of Sciences:' Graduate School of Chinese A cademy of Sciences). NATUR. GAS IND. V. 27, no 10, pp 28-32, 10/25/2007.(ISSN 1000-0976: In Chinese) ABSTRACT, Carbon and oxygen isotopic compositions of carbonate cements are useful for illustrating the mechanism of fluid rock interaction in the process of diagenesis. The genesis and origin of the carbonate cements common in the Triassic Yangchang Formation sandstone in the Ordos Basin are systematically studied by using petrological, mineralogical and geo- chemical methods. The results show that the early carbonate cements in the Yanchang Formation sandstone are mainly cor posed of calcite with relatively heavier carbon isotope with aO ranging from-0. 3%o to-0. 1%s, and lighter oxygen isotope with 8 O ranging from-22. 1% to-19. 5%o. Generally, they are closely related to the direet precipitation of oversaturated calcium carbonate from the alkaline lake water. They also indicate that ferroan calcites are characteristic of relatively lighter carbon isotope with C in the range from-8 02% to-3 23%, and lighter oxygen isotope with &O in the range from 2.9 9.7%,,and are obviously related to the decarboxylation of organic matter during the late period of early diage- tie stage to early period of late diagenetic stage. As the products of mid-late diagenesis, ferroan calcites in the study area are considered as the characteristic authigenic minerals for recognizing large-scale hydrocarbon influx and migration within clastic www.trqgy.en/e/abstracts.asp o1994-2007ChinaAcademicJOurnalElectronicPublishingHouse.Allrightsreservedhttp://www.cnki.net