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- Title
亨利定律与壳源氦气弱源成藏——以渭河盆地为例.
- Authors
李玉宏; 张文; 王利; 赵峰华; 韩伟; 陈高潮
- Abstract
Crust-derived helium is generated from the radioactive decay of uranium, thorium and other helium-derived elements in geological bodies. Compared with conventional natural gas, helium is a typical weak source gas as a result of extremely slow generation rate and absence of generation peak. It is associated with methane or carbon dioxide reservoirs frequently and related to groundwater closely. Helium can reach the industry standard with 0.1% in volume fraction. In order to study the accumulation mechanism of helium, the previous results on Henry's coefficient and solubility of helium, nitrogen and methane are summarized and the key roles of Henry's Law in the helium migration, accumulation and preservation are discussed by simulating calculation in Weihe Basin. According to the Law, the gas solubility in dilute solution is controlled by the gas partial pressure and Henry coefficient. Compared with the carrier gases, the Henry constant of helium is high, with striking difference in low and high temperature and the helium partial pressure is greatly different in helium source rocks and gas reservoirs, resulting in the great differences of helium solubility in the two places. The accumulation progresses are as follows. Firstly, helium can dissolve into water and migrate out of helium source rocks due to the high partial pressure and high temperature, causing high solubility. Secondly, when water soluble helium is transported to the shallow gas reservoir, it is prone to be out of solution and into reservoir due to the extremely low partial pressure and low temperature. Meanwhile part of carrier gas dissolves into water, as if the helium is “replaced” out. Furthermore, the low concentration funnel of dissolved helium is formed near the gas reservoir and other dissolved helium continues to migrate towards the gas reservoir, which greatly improves the helium accumulation coefficient. Finally, when entering the gas reservoir, helium is difficult to dissolve into water of cap layers due to the low partial pressure, resulting in the preservation of helium in reservoir. The results show that the helium enrichment mechanism in the aspects of migration, accumulation and preservation, providing theoretical basis for helium resource exploration.
- Publication
Natural Gas Geoscience, 2017, Vol 28, Issue 4, p495
- ISSN
1672-1926
- Publication type
Article
- DOI
10.11764/j.issn.1672-1926.2017.02.015