苏北盆地盐城凹陷兴桥1井烃源岩特征及气源分析

盐城凹陷兴桥1井钻遇二叠系孤峰组和栖霞组两套烃源岩。孤峰组为暗色泥岩,视厚度11.3m,有机碳最高为1.44%,平均0.74%,有机质类型偏向Ⅲ型;栖霞组为暗色碳酸盐岩,厚度较大,其中TOC>0.4%的地层的折算厚度大于42m,有机质类型主要为Ⅱ2型。这两套烃源岩的有机质热演化程度较低,至今仍具一定的生烃能力。兴桥1井上白垩统浦口组及下二叠统栖霞组见到多层气显示,浦口组的气源可能为深部二叠系,栖霞组的气体则可能受到更深部寒武系气源的侵入。

Characteristics of Permian Source Rock and Analysis of Gas Source of Well XQ-1 in Yancheng Sag, Subei Basin

Permian Gufeng and Qixia source rocks were drilled in Well XQ-1 in Yangcheng Sag, Subei Basin. Gufeng Formation is only 11.3m thickness of dark mudstone with the average 0.74% TOC( maximum 1.44%), which shows Type Ⅲ kerogen. Qixia Formation is dark carbonate rock with larger than 42m thickness that is converted by TOC>0.4%, mainly showing Type Ⅱ2 kerogen. These source rocks are relatively low in thermal maturity and so still within oil-generating window. Several beds of gas showings are met in Upper Cretaceous Pukou and Lower Permian Qixia reservoirs. Research indicates that the gas in Pukou Formation is likely to derive from deep Permian source rock and the gas in Qixia Formation maybe comes from deeper Cambrian source rock, which is significant to oil and gas exploration if it is identified and proved.