油气成藏^(40)Ar-^(39)Ar定年难题与可行性分析

The puzzledom and feasibility in determining emplacement ages of oil/gas reservoirs by ^(40)Ar-^(39)Ar techniques

油气成藏作用伴生的矿物种类少,主要为碳酸盐矿物,以及少量石英和黄铁矿等,这些矿物均不适合用传统同位素年代学方法进行年龄测定,因此,油气成藏年龄是同位素年代学尚未解决的一大科学难题。40Ar-39Ar(K-Ar)法是可能应用于油气成藏年龄测定的首选同位素定年方法。从40Ar-39Ar法的优点和实验技术的角度,讨论了油气田样品40Ar-39Ar定年面临的主要技术难题、测定对象、测定方法和可行性。有机杂质气体纯化装置的研制成功,为开展油气成藏40Ar-39Ar年代学研究,并获得可靠的同位素年龄数据奠定了实验技术基础。

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.