渤中地区天然气成因

Origin of natural gas in Bozhong Depression

系统研究了渤中地区已发现的天然气地球化学特征。天然气主要为烃类气体,纵向上,古近系及以下储集层中的天然气为湿气,新近系的天然气多为干气。天然气甲、乙烷碳同位素变化较大,其中QHD30-1构造天然气乙烷碳同位素最重,而BZ28-1构造天然气甲烷碳同位素最重。天然气成熟度为成熟—高成熟;天然气中烃类气为有机成因气,可分为油型气、煤成气和混合气3类,但以混合气为主。

This paper discusses the geochemical characteristics of natural gas discovered in Bozhong Depression.The natural gas is mainly composed of hydrocarbon gases,of which the gases in the Paleogene and older reservoirs are wet gases,while those in the Neogene are dry gases.The carbon isotopic compositions of the methane and ethane in the gases are greatly different.The methane carbon isotopic composition of the gases in the BZ28-1 structure and the ethane carbon isotopic composition of the gases in the QHD30-1 structure have the heaviest values,respectively.The maturity of natural gases are in the mature to high mature stage.The hydrocarbon gases are of organic and are divided into oil type gas,coal derived gas and mixed gas with the third type being the major part.