利用地震和测井信息预测和评价烃源岩——以渤海湾盆地富油凹陷为例

Using seismic and log information to predict and evaluate hydrocarbon source rocks: An example from rich oil depressions in Bohai Bay

长期以来,烃源岩的识别和评价主要依靠岩石样品的实验分析,这对于有钻井取心的地区而言比较容易实现,但有些含油气盆地的烃源岩分布在凹陷的中心或最深部位,往往没有取心井或没有钻井资料,烃源岩的评价和识别较难开展。研究发现地球物理资料中蕴含了烃源岩的诸多地球化学信息,利用地震反射特征可以追踪烃源岩的空间展布;利用声波时差、电阻率和密度等测井信息可以计算出烃源岩的有机质丰度。利用测井资料计算出的TOC值与岩心样品实测值非常接近,因此,利用地震资料和测井信息可以确定出烃源岩的空间展布并评价烃源岩的品质。该方法克服了由于烃源岩的非均质性而给取样分析带来的影响,并可在非取心井、没有地化分析资料的井段进行有效烃源岩评价。

The prediction and evaluation of hydrocarbon source rocks have long been depending on rock samples analysis. Relatively, this method is easily achieved provided that there are boring samples in study area, while it is otherwise without cores or any drilling data. The research shows that geophysical data embraces a large amount of geochemical information： the seismic reflection can help track source rocks distribution; and SDT, resistivity, DEN and other parameters could be utilized to figure out OM richness. This technique is proved to be effective, and the calculated value is close to the true value. It overcomes the affection and deviation by the heterogeneity of source rocks, and can be used to evaluate the hydrocarbon rocks in regions with no cores and little geochemical information.