准噶尔盆地东南缘页岩油储层脆性预测与评价

Brittleness Prediction and Evaluation of Shale Oil Reservoir in Southeastern Margin of Junggar Basin

准噶尔盆地东南缘二叠系中下部发育页岩油致密储层,脆性预测与评价对其勘探和开发有重要意义。本文利用岩石物理实验、测井资料和叠前地震资料计算了准噶尔盆地东南缘二叠系页岩油致密储层脆性指数,对Rickman经典公式法、杨氏模量与泊松比比值法、拉梅系数法和剪切模量法进行了比较、分析与评价。研究认为:1)杨氏模量相对泊松比对岩性有更好的区分度,由拉梅系数表征的泥岩分布率较高;2)根据文献所得测井多参数计算脆性指数的方法应用效果不佳,在Castagna经验公式换算横波速度基础上计算的脆性指数具有较好的应用效果;3)由YPD(Young's modulus-Poisson's ratio-density)式和LMR(拉梅系数-密度)式反演的弹性参数变化率也能较好地指示有利储层,尤以密度变化率为最佳,该属性在扇三角洲前缘及分流河道特征上得到很好的展示;4)岩石物理实验和实际资料应用均表明,ρE/σ为研究区脆性的最佳表征公式,效果好于Rickman经典公式与其他方法。

Shale oil tight reservoirs are developed in the middle and lower part of Permian in southeastern margin of Junggar basin.Brittleness prediction and evaluation are of great significance to its exploration and development.In this paper,the brittleness index of Permian tight reservoir in southeastern margin of Junggar basin is calculated by using petrophysical experiments,well logging data and prestack seismic data,and the Rickman classical formula method,the method of ratio of Young's modulus and Poisson's ratio,the Lamécoefficient method and the shear modulus method are compared,analyzed and evaluated.The results show that:1)Compared with Poisson s ratio,Young s modulus has a better discrimination of lithology,and the mudstone distribution resolution represented by Lamécoefficient is higher;2)The method of calculating brittleness index based on logging multi-parameters obtained in the literature has a poor application effect,but the brittleness index calculated on the basis of converting shear wave velocity by Castagna s formula has a good application effect;3)The change rates of elastic parameters inverted by YPD(Young s modulus-Poisson s ratio-density)formula and LMR(Lamécoefficient-density)formula can also indicate favorable reservoir,especially the density change rate is the best,and the characteristics of upper fan delta front and distributary channel can be well demonstrated by this attribute;4)Petrophysical experiments and actual data applications show thatρE/σis the best characterization formula of brittleness in the study area,and the effect is better than Rickman s classic formula and other methods.