Wu Xiaoqi1, Wang Ping1, Tao Cheng1, Qiu Qi1, Jia Cunshan1, Zhu Dongya2, Han Qiang3, Li Zhenming1
(1 Wuxi Research Institute of Petroleum Geology, Petroleum Exploration and Production Research Institute, SINOPEC,Wuxi 214126, Jiangsu, China
2 Institute of Petroleum Exploration, Petroleum Exploration and Production Research Institute, SINOPEC, Beijing 102206, China
3 Research Institute of Exploration and Development, Northwest Branch, SINOPEC, Urumqi, 830011, Xinjiang, China)
Abstract: Helium plays a distinctive role in industries such as national defense and high technology, and extracting helium from helium-bearing natural gas is currently the only industrial method for producing helium. In this study, natural gas samples were collected from the west side to the Manjar Sag in the Tarim Basin, and the origin, source, and main controlling factors of helium were investigated based on natural gas geochemistry. Results indicate that the main gas to the west of the Manjar Sag has a medium content of helium (0.03%≤He%<0.1%). The average helium content in the natural gas from Shunbei, Tahe, and Yakela is 0.046%, 0.044%, and 0.057% respectively. Except for the 3He/4He ratio of the natural gas from the Yakela gas field being mainly at the order of 10-7 and R/Ra ranging from 0.1 to 0.2, the 3He/4He ratios in the natural gas from regions such as Shunbei and Tahe are mainly at the order of 10-8 and R/Ra<0.05. The helium in natural gas to the west of the Manjar Sag mainly comes from the radioactive decay of U and Th in both the basement rocks and the mudstone source rocks in the Yuertusi Formation. The helium gas reservoirs are of a crustal source homogenous and heterogeneous composite type. The helium accumulation is mainly controlled by the factors such as the development of deep faults, the intensity of gas charging, and exsolution from formation water under differential burial/uplift. Deep faults serve as favorable channels for connecting helium source rocks and reservoirs. Large-scale gas charging dilutes the helium content in the gas reservoirs. The exsolution in formation water may be the main reason for the coupling of He and N2 in the reservoir. The higher the mineralization degree, the more unfavorable it is for the dissolution and exsolution of helium gas. The greater the stratum uplift, the more favorable it is for the exsolution and accumulation of helium in the gas reservoirs. This work was supported by the project “Helium Enrichment and Detection in Natural Gas Reservoirs Related to Oil and Gas Fields” (Grant No. 2025ZD1010500), and National Natural Science Foundation of China (U2244209).
Author Profile (first author):
Wu Xiaoqi, Male, Senior Engineer, PhD, mainly engaged in natural gas geochemistry research. E-mail: xqwu@163.com
