LI Xianqing1, 2*, FENG Songbao1, XIAO Xianming2, TANG Yongchun3, XIAO Zhongyao4, MIJingkui5, TIAN Hui2, LIU Dehan2, and SHEN Jiagui2
1 State Key Laboratory of Coal Resources and Safe Mining, China University of Mining and Technology, Beijing 100083, China
2 State Key Laboratory of Organic Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China
3 Power, Environmental and Energy Research Center, California Institute of Technology, 738 Arrow Grand Circle, Covina, California 91722, USA
4 Research Institute of Exploration and Development, Tarim Oilfield Company, PetroChina, Korla 841000, China 5Research Institute of Petroleum Exploration and Development, PetroChina, Beijing 100083, China
Abstract The Kela-2 gas field, found in the Kuqa Depression of the Tarim Basin, northwestern China, is a large-sized dry gas field (C1/C1–5=0.992−0.999) and characterized by ultra-high pressure (pressure factor up to 2.0−2.2). The pyrolysis experiment was carried out under isothermal gold-tube closed system, with samples collected from the Jurassic coal, Jurassic mudstone and Triassic mudstone in the Kuqa Depression. The result of gas yield showed that the Middle and Lower Jurassic source rocks have higher gas generation potential than the Triassic source rocks. The kinetic modeling of gas generation and methane carbon isotope fractionation suggested that the Kela-2 gases belong to the products of high-over mature stages and were mainly derived from the Middle and Lower Jurassic coal-bearing strata. The Triassic source rocks made a minor contribution to the Kela-2 gases. The Kela-2 gases chiefly generated from coal-bearing source rocks with Ro values from 1.3% to 2.5%, and thus primarily accumulated after 5 Ma.
* Corresponding author, E-mail:Lixq@cumtb.edu.cn
CHINESE JOURNAL OF GEOCHEMISTRY Vol. 32, No. 2, 2013, page 157-169
© Science Press and Institute of Geochemistry, CAS and Springer-Verlag Berlin Heidelberg 2013
