Xia G.,Chengdu University of Technology |
Xia G.,State Key Laboratory of Oil Gas Reservoir Geology and Exploitation |
Ji C.,Chinese Academy of Geological Sciences |
Chen L.,Chongqing University of Science and Technology |
And 2 more authors.
Oil Shale | Year: 2017
The organic-rich black shale in the Qiangtang Basin, northern Tibet, has long been the focus of petroleum geologists. This paper discusses the characteristics and maturity parameters of such biomarkers of the shale as n-alkanes, acyclic isoprenoids, terpenoids and steranes, using gas chromatographic (GS) and mass spectrometric (MS) techniques. n-Alkanes are characterized by a typical unimodal distribution, with dominant low carbon numbers of nC16–nC19, which suggests that the organic matter sources are mainly algae and planktonic organisms along with terrestrial higher plants. Furthermore, acyclic isoprenoid alkanes pristane (Pr) and phytane (Ph) are the most abundant, the Pr/Ph ratio being 0.06–0.70. The phytane dominance indicates that organic matter deposited in a reducing environment. In addition, the C3122S/(22S + 22R) hopanes ratio is 0.58– 0.59, that of C2920S/(20S + 20R) regular steranes 0.43–0.59, and αββ/(αββ + ααα) 0.39–0.65. These maturity parameters show that organic matter is in the maturity stage, while it is slightly more mature in the Biluocuo (BLC) section of the Qiangtang Basin than in the Ganbeixiama (GB) section. As indicated by the biomarkers values, the Jurassic source rocks in the two researched sections have a certain hydrocarbon potential. © 2017 Estonian Academy Publishers.
Ji C.,Chengdu University of Technology |
Yi H.,Chengdu University of Technology |
Yi H.,State Key Laboratory of Oil Gas Reservoir Geology and Exploitation |
Chen Z.,Petrochina |
And 4 more authors.
Shiyou Xuebao/Acta Petrolei Sinica | Year: 2013
The Qiang D-2 well is the first geological well which penetrates an oil-bearing horizon of the Jurassic Buqu Formation in the Qiangtang Basin. By systematic sampling and analyzing core samples from the dolomite oil-bearing horizon, two types of crude oils in the well can be classified. The oil-source correlation based on biomarker distributions of isoprenoid alkanes, steranes and terpanes indicated that these two types of crude oils are probably derived from source rocks deposited in different environments. The first type is an oil derived from an open marine environment dominated by lower aquatic organisms and its source rock shows a close affiliation with the Lower Jurassic Quse Formation and the Middle Jurassic Buqu Formation; while the second type is an oil derived from an estuarine environment with significant freshwater influence and terrestrial higher plant input and its source rock may be related with the Middle Jurassic Quemocuo Formation or Xiali Formation. The results of this study are of importance in the source kitchen identification and resource potential assessment of the Qiangtang Basin.
Lian C.,Southwest Petroleum University |
Qu F.,Southwest Petroleum University |
Tan X.,Southwest Petroleum University |
Tan X.,State Key Laboratory of Oil Gas Reservoir Geology and Exploitation |
And 5 more authors.
Scientia Geologica Sinica | Year: 2012
The sandstone reservoir characteristics of Dainan 1 Formation of Yongan area in Gaoyou sag are analyzed based on the data of core, casting film, electron microscope scanning, poroperm analysis and pore image analysis, and the main controlling factors of the reservoir quality are studies from the aspects of sedimentation and diagenesis. The results show that the sandstones are mainly feldspathic litharenite with low compositional maturation, fine grain, and medium-bad sorting degree. The reservoirs are mainly of low porosity and low permeability, and supplemented of medium porosity and medium permeability. The pores are mainly intergranular pores, intergranular dissolved pores, intragranular dissolved pores and moldic pore, with the average pore diameter of 37.53 p, m. The throats are mainly the shrink parts of the feasible end faces, then the laminated throat and the curved lamellar throat, with the average throat radius of 10.25μm, throat pore coordination number of 3, and good sorting. The research indicates that the sedimentary factor is one of the main controlling factors of the sandstone reservoir quality of Dainan 1 Formation of Yongan area in Gaoyou sag, and the sandstone formed in the sedimentary environment with high hydrodynamic intensity has good reservoir quality with large grain and good sorting. Different kinds of diagenesis have different effects on reservoir quality. Compaction and cementation make the reservoir quality become worse, while the dissolution make the reservoir quality become better by producing secondary porosity. The secondary porosity zones are obvious in the depth of 2500~2700 and 2850~2950 m.