盆缘构造复杂区页岩气保存条件分析与量化评价——以黔北地区海相页岩为例

Analysis and quantitative evaluation of the shale gas preservation conditions in the margin areas of Sichuan Basin

保存条件是我国南方构造复杂区页岩气地质评价中的关键,本文通过对四川盆地周缘断裂展布、地层产状、目的层埋深以及地层接触情况等多项参数进行分析,评价构造复杂区海相页岩气保存条件影响因素,建立保存条件参数体系,并通过模糊识别数学方法对各项参数赋予权重并进行排序,确定保存条件主控因素的重要性。其中,断裂分布、埋藏深度、压力系数及地层产状是最重要控制因素,上覆泥岩厚度、目的层地层接触关系及底部古岩溶等也具有一定影响。最后,本文以黔北长顺区域作为研究对象,对其保存条件参数指标的平面分布图进行量化叠加,获得保存条件有利区域量化评价图。通过对比,认为该方法与常规方法评价保存条件具有一定的一致性,但在清晰直观性方面以及有利区内的量化可对比性上具有更明显的优势。

Taking Changshun area in the north of Guizhou Province as an example,this paper has used fuzzy recognition mathematical methods to weight preservation condition parameters of shale gas in the western margin of Sichuan Basin.The results show that fracture distribution,buried depth,pressure coefficient and the dip of strata have the most important influences on preservation of shale gas,and the thickness of the overlying mudstone,contact relations of formations and ancient karst also have somewhat influences.This paper has quantified and modeled the distribution patterns of the parameters of preservation conditions in the area,and got the quantitative evaluation map of favorable areas of preservation conditions,providing a clearer and more intuitive evaluation method for the analysis and evaluation of the preservation conditions of shale gas in complex structural areas such as margins of a sedimentary basin.