摘要
No shale-rock physical model has been established in the observation coordinate system.To this end,this paper carried out anisotropic wave velocity tests on shale rock and compared the Thomsen,Daley,and Berryman solutions to characterize anisotropic acoustic wave velocity.Finally,the Daley solution was selected.Based on basic rock physical models,such as SCA and DEM methods,and combined with the Daley solution,an anisotropic shale-rock physical model was established in the observation coordinate system and applied in Well B1 in the Luzhou area,Sichuan Basin.Our research conclusions were as follows:1.for the samples from the same core,the P-wave velocities in three directions were in the order VP11>VP45>VP33,shear wave velocity VS11 was the largest,but VS33 and VS45 did not follow the law of Vs33>Vs45 for some samples;2.the Daley solution,which not only considers the accuracy requirements but also has a complete expression of P-,SV-,and SH-waves,is most suitable for characterization of anisotropic wave velocity in this study area;3.the rock physical model constructed in the observation coordinate system has high accuracy,in which the absolute value of the relative error of the P-wave slowness was between 0%and 5.05%(0.55%on average),and that of shear-wave slowness was between 0%and 6.05%(0.59%on average);4.the acoustic waves recorded in Well B1 in the observation coordinate system were very different from those in the constitutive coordinate system.The relative difference of the P-wave was between 6.76%and 30.84%(14.68%on average),and that of the S-wave was between 7.00%and 23.44%(13.99%on average).The acoustic slowness measured in the observation coordinate system,such as in a deviated well or a horizontal well section,must be converted to the constitutive coordinate system before it can be used in subsequent engineering applications;5.the anisotropic shale-rock physical model built in the observation coordinate system proposed in this paper can provide basic data and guidance for subsequent pore pressure predict
针对目前观测坐标系下页岩岩石物理模型缺乏的现状,本文开展了页岩各向异性波速测试,优选了页岩各向异性波速表征方法,建立了观测坐标系下的各向异性页岩岩石物理模型,并将该模型在四川盆地泸州区块B1井进行了应用和验证。通过本文研究,得出了以下主要结论:对于同一组岩心,三个方向的纵波波速满足VP11>VP45>VP33,横波波速VS11最大,VS33和VS45互有大小;精确的各向异性波速解最适合用来表征本工区的各向异性波速。本文构建的观测坐标系下各向异性页岩岩石物理模型精度较高,在B1井中岩石物理模型预测的纵波时差和测井测量的纵波时差相对误差绝对值介于0-5.05%,预测的横波时差和测井测量的横波时差相对误差绝对值介于0-6.05%;B1井观测坐标系下和本构坐标系下的声波时差差异较大,其中纵波差异百分比介于6.76-30.84%,横波差异百分比介于7.00-23.44%,斜井及水平井段等观测坐标系下测量到的声波时差必须经过岩石物理建模并转换到本构坐标系下才能用于后续的工程应用;本文构建的观测坐标系下页岩岩石物理模型,可为后续斜井、水平井地层的孔隙压力预测、地质力学建模、压裂优化设计等提供基础数据和指导依据。
基金
supported by the Post Doctoral Project of Southwest Oil and Gas Field Research on Geomechanics and Effective Fracturing Factors of Deep Shale” (No. 20210302-31)
the Scientific Research Project of Southwest Oil and Gas Field Branch “Geological Engineering Integration of Well Block Yang101”。
