The puzzledom and feasibility in determining emplacement ages of oil/gas reservoirs by ~(40)Ar-~(39)Ar techniques
QIU Hua-ning1,2 , WU He-yong1,3, FENG Zi-hui1,3, SHI He-sheng4, YUN Jian-bing1,2, WANG Qiang1,2 and ZHAO Ling-hao1,2 1. Guangzhou Institute of Geochemistry, Chinese Academy of Sciences-Daqing Oilfield Company Ltd. Joint Geochronology Center of Oil & Gas Emplacement, Guangzhou 510640, China;2. Guangzhou Institute of Geochemistry, Chinese Academy of Sciences (GIGCAS), Guangzhou 510640, China;3. Institute of Petroleum Exploration and Development, Daqing Oilfield Company Ltd. (DOFCL), Daqing 163712, China;4. School of Ocean and Earth Science, Tongji University, 1239 Siping Road, Shanghai 200092, China
Carbonate (calcite, gypsum and dolomite), quartz and pyrite are the few types of minerals associated with the formation, migration and emplacement of oil or gas reservoirs, which are not suitable for dating by the traditional isotopic geochronological methods, i.e., U-Pb, Rb-Sr, Sm-Nd and K-Ar methods. Therefore, it is very difficult to determine the emplacement ages of oil/gas reservoirs. 40Ar-39Ar (or K-Ar) method is the first one of the possible geochronology techniques to solve this difficult scientific problem. In this paper, we discuss the main technical problems, the measuring objects, determination methods and the feasibility for dating the oil/gas emplacement ages, based on the advantages and experimental techniques of 40Ar-39Ar method. A special purification apparatus has been made to clean up the organic gases efficiently, which makes them possible to determine samples from oil/gas reservoirs and to obtain reliable age results.