T23 Unconventional Energy Resources (Posters)

Sunday, 4 November 2018
9:00 AM - 5:30 PM
Halls J-K

ORIGIN OF THE URANIUM ELEMENT IN THE EARLY CAMBRIAN AND ITS GEOLOGICAL SIGNIFICANCE IN SHALE GAS EXPLORATION: A CASE STUDY OF THE LOWER CAMBRIAN SHALES IN THE YANGTZE AREA IN SOUTH CHINA

Paper number: T23-21
Program: Technical Sessions
Time: 9:00 AM – 5:30 PM

Authors

  • Xiaoxue Liu Presenting Author
    China University of Petroleum (Beijing), Beijing
  • Xuelian Xie
    Guangzhou Marine Geological survey, Guangzhou
  • Zhenxue Jiang
    China University of Petroleum (Beijing), Beijing
  • Kun Zhang
    University of Petroleum (Beijing), Beijing
  • Lin Wei
    institute of unconventional natural gas, Beijing
  • Yizhou Huang
    China University of Petroleum (Beijing), Beijing
  • Ming Wen
    China University of Petroleum (Beijing), Beijing
  • Xin Wang
    China University of Petroleum (Beijing), Beijing
  • Qixiang Xuan
    China University of Petroleum (Beijing), Beijing
  • Tianlin Liu
    China University of Petroleum (Beijing), Beijing

Abstract

The Lower Cambrian shales have always been the main target of marine shale gas exploration in South China. However, there are a number of low production wells and even failed wells. A large reason is the lack of material basis in the shale gas reservoir process; therefore finding the organic rich shale (i.e., TOC content > 2%) development area is an important issue that needs to be solved.

Considering that the Lower Cambrian shales in the Yangtze area contain many elements such as silicon, calcium, aluminum, uranium, thorium, potassium, iron and manganese, In this study, U, Si and Al log data, the total organic carbon (i.e., TOC) content, which come from three typical wells with different distances from the boundary line between the Yangtze plate and the Cathaysian plate, as well as the analysis of a lithofacies element in the Jiang ye-1 well, are selected as the basic data. Based on the Si and Al log data from the three wells, the excess siliceous mineral content from a non-terrigenous clastic source is calculated, and the siliceous source with excess siliceous mineral layers is analyzed with a Al-Fe-Mn ternary plot. Through further analysis of the relationship between excess silicon and uranium, the source of uranium in the Lower Cambrian shale is clarified, the tectonic setting of uranium and its relationship with the enrichment of organic matter is elucidated.

The results show that both uranium and excess silicon come from a hydrothermal solution at the junction of the Yangtze plate and the Cathaysian plate. Radioactive uranium can enhance biological productivity, which is conducive to the enrichment of sedimentary organic matter. For the exploration of shale gas in the Lower Cambrian, it is necessary to conduct exploration among target areas near the junction of the two plates that have moderate maturity and good preservation conditions.

Geological Society of America Abstracts with Programs. Vol. 50, No. 6

doi: 10.1130/abs/2018AM-321995

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