摘要
准确预测储层的等效孔隙纵横比对页岩储层岩石物理建模及横波速度预测具有重要意义。为分析页岩储层孔隙纵横比及预测横波速度,提出了基于岩石物理模型的页岩孔隙纵横比反演及横波速度预测方法。本文首先通过岩石物理模型建立岩石的纵、横波速度与孔隙纵横比、孔隙度和矿物组分等参数之间的定量关系,寻找最佳孔隙纵横比;然后通过使理论预测与实际测量的纵波速度之间误差达到最小的方式反演孔隙纵横比,并以此为约束预测横波速度。实际测井数据反演结果表明,龙马溪组页岩地层的孔隙纵横比稳定,而围岩的孔隙纵横比变化范围较大;说明与围岩相比,页岩的孔隙结构更为稳定。同时,预测得到的页岩横波速度与实测横波速度的误差较小,另外对于缺少矿物组分资料的页岩层段,用平均矿物组分预测得到的横波速度误差仍较小;说明与矿物组分相比,龙马溪组页岩的纵、横波速度对孔隙纵横比参数更敏感。综上所述,利用该方法可预测到较为准确的等效孔隙纵横比和横波速度。
Accurate estimation of effective pore aspect ratio for shale reservoir is significant in rock-physics modeling and shear-wave velocity prediction.In order to estimate pore structure and S-wave velocity,a rock-physics-based method is proposed for effective pore aspect ratio and shear-wave velocity prediction in shale.We build a quantitative relationship among P-wave velocity,S-wave velocity,pore aspect ratio,porosity and mineral compositions through rock-physics model.Then,through finding the best estimation of pore aspect ratio by minimizing the error between theoretical predictions and field measurements,we invert the effective pore aspect ratio and the shear wave is predicted with this constraint.The inversion results of the well logging data show that the aspect ratio remains stable in Longmaxi shale formation,while the aspect ratio of the surrounding rock varies in wide range.It indicates that the micro-structure in shale is more stable than in surrounding rock.The error between the predicted and measured shear wave velocities is small.In addition,for shale formation lacking mineral components data,the error in prediction of shear wave velocity calculated by average mineral compositions is still small.This shows that compared with mineral compositions,Longmaxi shale is more sensitive to pore aspect ratio.In conclusion,the effective pore aspect ratio and shear-wave velocity can be predicted accurately by the method proposed in this study.
出处
《吉林大学学报（地球科学版）》
EI
CAS
CSCD
北大核心
2017年第2期606-615,共10页
Journal of Jilin University：Earth Science Edition
基金
国家自然科学基金重点项目(41430322)
国家自然科学基金青年科学基金项目(41404090)~~
关键词
页岩
岩石物理模型
孔隙纵横比
横波速度预测
shale
rock-physics model
pore aspect ratio
prediction of shear wave velocity
