四川盆地早、中三叠世有机相与天然气生成条件分析

AN ANALYSIS OF THE ORIGIN OF NATURAL GASES AND ORGANIC FACIES IN MIDDLE-UPPER TRIASSIC IN SICHUAN BASIN

本文从有机相——有机质丰度、类型、成熟度,对四川盆地早、中三叠世的成烃条件及其所产天然气的地化特征和天然气与围岩成熟度的相关性进行了讨论,认为盆地的早、中三叠世在局部地区仅局部甚段具有成烃条件;天然气与下伏二叠系相似性明显,但天然气成熟度明显高于围岩,从而论征其气源主要来自下覆地层。最后,从断裂的展布讨论了天然气向上(含横向)运移的可能性。

According to organic facies-abundance, type and maturity of the organic matter, hydrocarbon source condition in Middle-Upper triassic, geochemical characteristics of natural gases and the relationship between natural gases and organic matter maturity of surronding rocks in Sichuan Basin were discussed in this paper. The author considers that there are only elementary hydrocarbon source condition in part of layers in part of areas, but maturity of natural gases is obviously higher than that of the surronding rocks, thus it will lead to a conclusion that gas is mainly come from the underlying Permian. According to the distribution and development of fracture systems, the possib- lity of upward migration of natural gases is discussed also. This paper point- ed out that more attention should be paid to the path of migration, so as to increase the success ful ratio of exploration and enlarge gas-containing regions