中国海域煤型油气成因理论

Theory on genesis of coaliferous petroleum in the China Sea

张功成 陈莹 李增学 李友川 兰蕾 刘世翔 孙瑞

Gongcheng Zhang Ying Chen Zengxue Li Youchuan Li Lei Lan Shixiang Liu Rui Sun

对中国海区及邻域14个含煤盆地组成的巨型含煤盆地带的煤型油气进行了系统分析。该巨型含煤盆地带经历了古新世、始新世、早渐新世、晚渐新世和中新世—上新世等5个成煤期，发育了三角洲、扇三角洲和潮坪-潟湖3种成煤环境。巨型含煤盆地带以煤型烃源岩为主，煤系与海相烃源岩具有“二元结构”发育模式。通过对烃源岩、凝析油、天然气样品的实验分析，发现该巨型含煤盆地带煤成烃具有“四阶段”生烃模式，并且煤型烃源岩生气极限（镜质体反射率）可达到4.38 %，极大地拓展了天然气生成范围。该巨型含煤盆地带煤型烃源岩形成了凹陷边缘煤系和凹陷内部陆源海相两种油气成藏模式，在这两种成藏模式控制下，形成了多个大型煤型油气富集区。

The study systematically analyzes coaliferous petroleum in a giant coal-bearing basin belt consisting of 14 coal-bearing basins in the China Sea and its surroundings. The evolution of the giant coal-bearing basin belt spanned five periods of coal formation， that is the Paleocene， the Eocene， the Early Oligocene， the Late Oligocene and the Miocene-Pliocene， in coal-forming environments of deltas， fan deltas and tidal flat-lagoons. The coaliferous source rocks dominate in the giant basin belt， featuring a “dual structure” of coaliferous and marine source rocks development. Experimental analysis of source rock， gas condensate， and natural gas samples indicates that the coal-bearing basin belt is characterized by a “four-stage” hydrocarbon generation model， and the coal-generating limit of the coaliferous source rocks （reflectance of vitrinite ） can reach up to 4.38 %， greatly expanding the lower limit of natural gas generation. The coaliferous source rocks in the basin belt feature two modes of hydrocarbon accumulation， that is， accumulation of hydrocarbons from the coal measures on the margin of the sag and that from the terrigenous marine source rocks within the sag， under the guidance of which multiple large-scale coaliferous hydrocarbon enrichment zones are developed.

10.11743/ogg20220306