oa Study of Favorable Conditions for Shale Oil and Gas Formation in Nenjiang Formation in South-Eastern Uplift Area of Songliao Basin

Recently, three wells have all produced over 10m³ oil per day, which are deployed in the Cretaceous shale horizons in the Songliao Basin, indicating great potential for unconventional shale oil in that area. Great progress has been made in understanding the formation mechanisms of oil shale in the basin in terms of petrography, minerals, and sedimentary facies. However, comparatively little research has been carried out on the rock types of the provenance, which is significantly enriched in organic matter, and their influence on the shale. To assist in unravelling its geochemical characteristics and formation mechanisms, 21 rock samples were selected from the late Cretaceous Nenjiang Formation (K2n) in the southeastern uplift of the basin for analysis. The K2n dark mud shale was formed in a brackish, strongly reducing, algae enriched sedimentary environment. The lacustrine paleo-environment had high productivity and a large sedimentation rate, which was conducive to the generation and preservation of organic matter. The input of large amounts of iron, magnesium, and calcium materials to the provenance promoted the formation of oil shale. The source rock contains high levels of transition metals, which played a significant role in catalysing the evolution of kerogen and thus in hydrocarbon generation.