本文通过有机质的丰度、类型及成熟度三个方面对珠江口盆地白云凹陷烃源岩进行初步评价,并创新性设定指数"Z",来综合表征有机质丰度.研究认为白云凹陷的烃源岩主要为较好—好的烃源岩.统计分析了Z值在平面上的总体变化规律,可得洼陷地区的烃源岩优于凸起地区.并利用放射性测井钍铀比值(Th/U)分析烃源岩沉积的古氧相环境,可得凸起地区的烃源岩氧化性沉积环境明显;而洼陷地区还原性沉积环境明显.自下而上来看,珠海组烃源岩古氧相的还原性较珠江组更强;文昌组较恩平组更强.通过对比分析指数Z及古氧相发现:古氧相还原性越强的地区,其Z值越大.具体表现为古氧相的还原性越强,烃源岩有机质丰度越高,烃源岩的品质越高.%This paper evaluates the source rocks of the Baiyun depression in the Pearl River Mouth Basin via three aspects:abundance,type and maturity of organic matters,and sets an innovative index"Z"to comprehensively represent the abundance of organic matters.It is concluded that the source rocks in Baiyun depression are mainly good-good source rocks.The general variation law of Z value in the plane is statistically analyzed,and the source rock of the sag is superior to the raised area.Also,the ratio of thorium to uranium(Th/U)is used to analyze the ancient sedimentary environment of source rocks.The ancient sedimentary environment of source rocks in raised area is mainly oxidation,and that in sag is reducibility. From the bottom up,the reducibility of the paleo-oxygen phase of the hydrocarbon source rocks in Zhuhai is stronger than that in the Pearl River formation;the Wenchang formation is stronger than the Enping formation.By comparing the index Z and the paleo-oxygen phase,the Z value is larger in the region with the strong reducibility of the paleo-oxygen phase.The specific representation is that the higher reducibility of the organic matter,the higher the organic matter abundance of the source rock and the higher the quality of the source rock.
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