以凝析油轻烃和天然气碳同位素特征判断气源

本文首先根据C4～C7轻烃的成分指出四川盆地含油(凝析油)的天然气藏中的油的来源,然后再与天然气的碳同位素特征相互印证,共同判断气源。这一方法特别对混源气的气源判断是很合理的。 四川盆地一些含油(凝析油)的天然气藏以往都认为是自生自储的。然而用本方法判断气源后,我们发现,混源气是非常普遍的。从天然气的运移特征来看,盆地中下三叠统有工业价值的天然气的聚集往往都与断层有关。

IDENTIFICATION OF SOURCES OF NATURAL GASES BASED ON COMPONENTS OF C4-7C LIGHT HYDROCARBONS IN OILS (CONDENSATES) AND CARBON-ISOTOPIC CHARACTERS OF NATURAL GASES

In this paper we first indicate the sources of oils (condensates) in gas reservoirs containing oil or condensate in Sichuan basin according to the components of C4—C7 light hydrocarbons, and then combine them with the carbon-isotopic data of natural gases to determine their gas sources. This method is reasonable especially for judging the different sources in a gas. The oil-(condensate-) bearing gases in Sichuan basin were originally thought indigenous. From the identification of gas sources by this method,however, we have found out that sources--mixed gases are widespread.Inview of gas migration，the accumulation of commercial gases of the Middleand Lower Triassic formation in Sichuan basin is frequently related tofaults