Y地区龙马溪组一段-五峰组页岩元素分类方法研究与应用

Study and application of element classification method for shale in the first member of Longmaxi formation-Wufeng formation of Y area

Y地区龙马溪组-五峰组页岩颜色相似,肉眼难以区分。通过研究建立元素与岩石组分之间的数学模型,形成了基于XRF元素录井的三端元图板,将工区内的页岩划分为石英+长石、碳酸盐、黏土、混合4种类型。该图板显示龙马溪组一段-五峰组页岩自上而下主要集中在黏土区、混合区、石英+长石区,划分出的页岩类型与综合评价的Ⅲ类、Ⅱ类、Ⅰ类储集层对应性较好。在该地区两口井中应用结果表明,基于XRF元素录井的三端元图板能有效区分页岩类型,为页岩气的评价提供依据。

In Y area,the shale color of Longmaxi formationWufeng formation is similar and the unaided eye is difficult to distinguish.Based on the study,the mathematical model between elements and rock constituents was established,and a ternary chart based on XRF element logging was formed.The shale in the working area was divided into four types:quartz +feldspar,carbonate,clay and mixing.The chartshows that the shale from the first member of Longmaxi formation to Wufeng formation is mainly concentrated in clay area,mixed area and quartz+feldspar area from top to bottom.The classified shale types correspond well with typeⅢ,typeⅡand type Ⅰ reservoirs of comprehensive evaluation.The application of two wells in this area showed that the ternary chart based on XRF element logging can effectively distinguish shale types and provide reference for shale gas evaluation.