碳酸盐岩中石油形成的滞后现象

THE DELAYING PHENOMENON OF OIL GENERATION IN CARBONATE SOURCE ROCKS. PED

泌阳凹陷白云岩相区的生油门限深度比泥岩相区约深３００ｍ，其生油岩甾烷、萜烷的成熟度指标所反映的成熟度与岩石中的碳酸盐含量明显负相关，说明碳酸盐矿物造成有机质向油气转化过程的迟缓效应，是碳酸盐岩生油岩中油气生成过程滞后的重要原因。这种迟缓效应是碳酸盐岩生油岩中缺乏粘土矿物催化作用所造成的；此外，束缚沥青“Ｃ”的加入也会使处于较高演化阶段的生油岩降低其成熟度。

In Biyang depression, the oil window in carbonate factes is about 300m deeper than that in shale factes. This study shows that the maturity of the organic matters which can be reflected from maturation parameters of steranes and tipanes has a negative relationship with the contents of carbonate in rocks. This means that the carbonate minerals has a restrictive effect on the oil generation. This may be the reason for the delaying of oil generation in carbonate source rocks. In addition, the releasing of enclosed organic matter is one of the reasons that the maturity of organic matter in carbonates proceeds at a slower rate than that of organic matter in shales.