四川盆地震旦系灯影灰岩黑色沥青与油气勘探

本文从震旦系灯影组灰岩普遍赋存的黑色沥青产状,类别调查入手,根据室内获得的物理化学多项信息,结合天然沥青块体的热模拟实验参数,论证了黑色沥青属石油演化的系列产物—沥青类,并对此进行了成因分类。盆地边缘尚有软沥青,地沥青分布,向盆地过渡渐变为脆沥青,黑沥青,焦沥青,盆地内分布的主要是焦沥青,与所处演化阶段吻合。威远,龙女等处所产天然气仍属热演化(降解—裂解)气,是两极分化的产物。根据区域性显示特征,对灯影灰岩油气勘探的有利地区进行了讨论,认为川西北龙门山断褶带靠盆地一侧(天井山古隆起)可望钻获液态烃,乐山—龙女寺古隆起区及川东高陡构造带,对天然气勘探有利,建议选择乐山—龙女古隆起西端的熊坡—汉王场构造带进行优先钻探。

BITUMEN AND OIL-GAS EXPLORATION IN SINIAN"DENYING LIMESTONE" IN SICHUAN BASIN

Deepenning well Wei-Key in 1964, industrial gas flow at "Denying Limestone" Formation (Sinian) in Sichuan Basin was obtained. Since then the old aged strata have been explored continuously, and one of the large gas fields in China was discovered Afterwards, migrabitumen freguently appears in drill hole and in outcrops. This paper discusses the geological conditions and the classification of the bitumen, including various parameters such as colour, luster, configuration, density, softening point, solubility, fluorescence and (DTA), valatile carbon ratio, carbon-hydrogen elements, carbon Osotopes and so on. These data are integrated with those from thermal simulation tests to give a genetic classification of the natural bitunen, as migrabitumen soft asphaltic, asphaltic, gilsonite, grabluation, albertite, impsonite and so on. They are the products from a series of petroleum evolution. This classification is simular to Jacb's (Migtabitumen, 1985) one. From the northern boundary to the center of the basin the soft asphalt and asphalt changes gradually into grabluation, albertite and impaonite. Natural gas in the basin are considered as thermal evolution gas. It corresponds to the evolution stages and is the decomposed products of liquid hydrocarbons. It is suggested that the moderate thermal evolution area in the basin (R₀<4～5%) is the favorable region for natural gas exploration.