泥质烃源岩的有效排油门限及页岩油地质意义

Eeffective oil expulsion threshold of argillaceous source rocks and geological significance of shale oil

通过地质条件约束下不同类型、不同有机碳含量未熟—低熟烃源岩的生排烃物理模拟实验,结合排烃门限理论,建立一种有效排烃门限的确定方法,确定泥质烃源岩的有效排油门限值,并对其在页岩油勘探的地质意义进行探讨。研究表明:烃源岩发生有效排油的最低生油量门限值为5~8 mg/g(油/岩石),且有效排油门限值受控于有机质类型、丰度和演化程度三者之间的匹配;原始有机质含量小于1.5%的Ⅰ型烃源岩、小于2.0%的Ⅱ1型烃源岩和小于2.5%的Ⅱ2型烃源岩在整个生油阶段都达不到有效排油门限,生成的油滞留在烃源岩层系内,成为页岩油勘探的有利目标,由于其演化程度低、油品差,开采前景较差,原位加热转化开采技术可能是开发这部分页岩油资源的一种有利手段;页岩油的勘探开发当前要定位于已发生过有效排油、镜质体反射率(Ro)为1.0%~1.3%的烃源岩层系,由于成熟度的提高,滞留油气中含有较多的轻质油和天然气,气油比高,流动性较好,开采前景乐观。

A method of determining the effective hydrocarbon expulsion threshold was carried out by a series of simulation experiments on immature-low mature source rocks of different types and organic carbon content,and the geological significance to shale oil exploration were discussed.The results show that the minimum oil production is 5-8 mg/g（oil/rock） when the effective oil expulsion occurrs.Effective hydrocarbon expulsion threshold is controlled by the match of type,abundance and evolution of organic matter.Source rocks with original organic matter content less than 1.5% of type I,2.0% of type Ⅱ1,2.5% of typeⅡ2,respectively,can not reach the effective oil expulsion threshold in the whole oil generation stage.The remaining oil in the source rock strata would be as a favorable target for shale oil exploration.The poor exploitation prospect is due to the low degree of evolution and low quality,so the in-situ heating conversion mining technology could be a good way to develop this part of shale oil resources.The exploration and development of shale oil should focus on source rock strata where effective oil expulsion has occurred and evolution degree（Ro） is between 1.0%-1.3%.In these locations,there are more light oil and natural gas in detained hydrocarbon,and the high gas oil ratio and good fluidity imply optimistic mining prospect.