ZHANG Xing-ya1, ZHAO Long2, DANG Si-si3, SUN Ping-an4,1, CAO Jian1
1. School of Earth Sciences and Engineering, Nanjing University, Nanjing 210023, China;
2. Research Institute of Petroleum Exploration and Development, PetroChina Xinjiang Oilfield Company, Karamay, Xinjiang 843000, China;
3. Exploration and Production Division of Luliang, PetroChina Xinjiang Oilfield Company, Karamay, Xinjiang 834000;
4. Institute of Karst Geology, Karst Dynamics Laboratory (Ministry of Land and Resources), Chinese Academy of Geological Sciences, Guilin, Guangxi 541004, China
Abstract: The Cretaceous petroleum system in the Junggar Basin holds exploration potential theoretically, but has relatively limited research. In order to provide basic data for petroleum exploration of the Cretaceous petroleum system in the Junggar Basin, this paper studied the potential hydrocarbon resources by comprehensive geochemical analyses on source rocks and crude oils in combination with geological background. Analytical results indicated that the Cretaceous strata hosted a certain number of source rocks, whose TOC contents are greater than 1.0%, organic matters are mainly type II kerogen and currently are lowly mature to mature. The Cretaceous is expected to have certain hydrocarbon, especially oil-generation potential. The oil-source correlation supports this conclusion. The representative Cretaceous-derived oils have main geochemical characteristics as follows: light carbon isotopes (-29.6‰~-27.9‰), low Pr/Ph values (0.54-1.01), high gammacerane abundance (gammacerane/C30 hopane=0.29-0.53). These reflected that the oils were formed in reducing and saline environment. Cretaceous-sourced oils distributed mainly in the southern margin of the basin, in particular the sedimentary center of the Cretaceous source rocks, showing the source-control characteristics. In summary, the petroleum exploration of the Cretaceous petroleum system in the Junggar Basin should be focused on oil and in the southern basin margin. These results and understandings can also be referred by other studies relevant to Cretaceous hydrocarbon geology.
Keywords: lacustrine source rock oil-source biomarker saline lacustrine organic matter petroleum system
Bulletin of Mineralogy, Petrology and Geochemistry Vol. 34, No.3, 2015, page 626-632