基于地球物理和地球化学数据的页岩油甜点区综合预测:以泌阳凹陷核三段5号页岩层为例

Comprehensive Prediction of Shale Oil Sweet Spots Based on Geophysical and Geochemical Data: A Case Study of the Paleogene Hetaoyuan Formation,Biyang Depression,China

我国页岩油气勘探开发不断取得实质性进展,有望成为未来油气资源的重要接替能源.而提高页岩油储层钻遇率和油气产量的关键是甜点区的预测和评价.以泌阳凹陷核桃园组三段5号富有机质页岩层为研究对象,综合利用多种地球物理方法和地球化学指标,通过岩相、含油性、储集条件和地层压力等关键评价参数分析,探讨了综合信息叠合的页岩油甜点区预测方法.研究表明:(1)脆性矿物含量普遍大于50%,以灰质页岩和粘土质页岩夹粉砂质页岩为主的岩相是页岩油赋存的优势岩相;(2)低自由烃差值和高含油饱和指数均指示高含量游离态页岩油,指示了页岩含油性最好区域;(3)夹层主要发育在深凹区周缘,断裂控制的相互重叠区域或派生断裂控制区微裂缝更为发育;(4)异常高压对页岩油微距离运移和富集的影响较大;(5)基于不同参数门槛值对页岩储层进行综合评价划分,采用综合信息叠合法预测出3类甜点区.本文为多参数综合评价和识别陆相页岩油甜点区提供了有效范例,对指导陆相页岩油勘探具有重要的实践意义.

Shale oil and gas exploration and development in China makes substantive progress,and is likely to be an important successor for oil and gas resources in the future. And the key to improve the drilling encounter rate and oil and gas yield of shale oil is prediction and evaluation of sweet spot.In this paper,taking the 5 th organic-matter-rich interval（ ORI 5） in the third Member of the Paleogene Hetaoyuan Formation in the Biyang Depression,the key performance indicators are applied to map out sweet spots across the deep depression by comprehensive analysis of various geophysical and geochemical methods. The key indicators are based on a limited number of shale properties,such as lithofacies,oil content,reservoir conditions,and formation pressure. The results show that：（ 1） The content of brittle minerals is generally larger than 50%,and the calcareous shales and argillaceous shales with silty shales interlayersare advantageous lithofacies for shale oil storage;（ 2） The indexes of OSI values 〉200 mg/g TOC and ΔS1 values 〈-2 mg/g Rock indicate the higher content of free shale oil;（ 3） The interlayer is mainly developed in the periphery of the deep depression,and microfracture is more developed in the derived fracture controlled zones and overlapping areas controlled by faults;（ 4） Overpressure may have greater impact on the small scale migration and enrichment of shale oil;（ 5） Shale reservoirs are evaluated based on threshold values of various indicators,and three types of sweet spots are predicted. This paper provides a valid example for comprehensive evaluation and identification of continental shale oil sweet spots using multi-parameters,and has important practical significance for guiding the shale oil exploration.