利用X荧光元素录井资料评价页岩脆性的新方法

A New Method of Evaluation Shale Brittleness Using X-ray Fluorescence Element Logging Data

为了对页岩气藏的可压性进行评价,指导储层改造选层,研究了评价页岩地层脆性的方法。基于矿物组成与岩石力学性质之间的关系,根据页岩矿物组成来表征其脆性的思路,在测得页岩地层化学元素组成后,经过相关性分析,选取能代表砂质、泥质和钙质的元素,采用适当的计算方法来求取砂质、泥质和钙质含量,并建立基于矿物组成的页岩脆性评价方法。利用该方法对3口页岩气井的元素录井资料进行了分析,其结果和ECS测井解释结果之间有较好的线性关系;与X衍射矿物测试进行了对比,数值整体趋势一致,可对比性强,能够满足现场实时评价页岩脆性的要求。这表明利用元素录井资料对矿物组成进行建模来表征页岩脆性的方法是可行的,可为页岩气藏压裂改造选层提供一种手段。

In order to evaluate the fracability of shale gas reservoir and provide recommendation for fracturing,this paper made a study on evaluation method of shale brittleness.Based on relationship between mineral composition and rock mechanics properties,the way of using mineral composition to characterize its brittleness was considered.After measuring chemical elements composition of rock,making correlation analysis,selecting the elements which could respectively represent sandy,argillaceous and calcareous,using appropriate method to calculate the content of different minerals.Subsequently,the evaluation method of shale brittleness was established based on mineral composition.Applying this method to three wells of shale gas and performing element logging,comparing with ECS logging,a better linear relationship was presented.Compared with X-ray diffraction tests,the same trend was shown.It is able to meet the demands of realtime evaluation of shale brittleness.This indicated that the way of using element data to model minerals and thus characterizing shale brittleness was feasible,which provided a new means of technology for selecting favorable shale intervals to fracture.