Shale organic heterogeneity evaluation method and its application to shale oil resource evaluation-a case study from Qingshankou Formation, southern Songliao Basin

It is well known that shale has strong organic heterogeneity. As the amount of measured geochemical data is imited by the available samples, it is hard to describe the spatial distribution of shale oil and gas precisely. Through evaluation of organic abundance and retained hydrocarbon content by using the improved ΔlgR model, the spatial distributions of enriched, low-efficiency and inefficient shale oil resources are well mapped respectively with reference to the shale oil resources grading evaluation standards. The heavy hydrocarbon and light hydrocarbon compensate coefficients for S1 are determined through correcting the experiments and component hydrocarbon generation thermal simulation experiment with pyrolysis chromatography parameters. Volume method is used to quantitatively evaluate different grade shale oil resources, and recognize favorable exploration areas. Research shows that the improved ΔlgR model enhances the accuracy and operability of evaluating geochemistry parameters with logging data. Application results show that the shale oil resources of the Qingshankou Formation in southern Songliao Basin occur in the lower-middle part of its first member. And the play fairways are distributed in Fuxin Uplift, Honggang terrace and northern Changling Sag, where the estimated shale oil resources is 4.808 billion tons, accounting for a third of the total resources. The method of evaluating distribution of shale oil/gas by describing organic heterogeneity not only can reveal the spatial distribution features of shale oil, but also can save the cost of laboratory test, and more important, it can provide substantial guidance for future exploration and development of shale oil.