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Episodes 2024; 47(2): 241-251

Published online June 1, 2024


Copyright © International Union of Geological Sciences.

Evaluation of organic matter abundance of source rocks of biogenic gas: a case from the Quaternary Qigequan Formation Shale, Sanhu Depression, Qaidam Basin

Xiaoxue Liu1,2,3, Zhenxue Jiang1,2*, Xianglu Tang1,2*, Kun Zhang4, Mingshuai Xu1,2

1 State Key Laboratory of Petroleum Resources and Prospecting, China University of Petroleum, Beijing 102249, China
2 Unconventional Oil and Gas Science Technology Research Institute, China University of Petroleum (Beijing), Beijing 102249, China
3 Department of Earth Sciences, Simon Fraser University, Burnaby V5A1S6, Canada
4 School of Geoscience and Technology, Southwest Petroleum University, Chengdu 610000, China

Correspondence to:*E-mail: zhenxuejiangedu@126.com

Received: November 13, 2023; Revised: March 4, 2024; Accepted: March 4, 2024

This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/4.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.


A correct understanding of organic matter abundance is key to understanding the conditions necessary for generating biogenic gas, seeking favorable exploration intervals and fields and evaluating resources correctly. The Qigequan Formation shale of the Quaternary in the Sanhu Depression of the Qaidam Basin is taken as the research object. The abundance of dissolved organic matter was determined through total carbon, pyrolysis and other experiments. The evaluation criteria were established and applied. The resource quality is calculated. The results are as follows. (1) Dissolved organic matter is the basis for biogenic gas generation and should be emphasized in the evaluation. (2) The shale has a relatively high dissolved organic carbon (DOC) content, with an average of 2.48 times that of insoluble organic carbon. (3) The DOC of the good source rock is more than 0.60%, that of the medium is 0.25~0.60%, and that of the poor is less than 0.25%. (4) The distribution of good source rocks is influenced by the position and depth of the water column and the paleoclimate. Favorable intervals are mainly in the upper sections of K10, K9 and K8 and the middle section of K7. The favorable areas are mainly the Tainan, Sebei and Sedong areas.