摘要
电缆声波远探测测井已取得了长足进展,将这种技术应用于随钻声波测井,特别是随钻地质导向方面,具有潜在的应用价值。针对偶极声源随钻反射声波成像测井,基于偶极声源在井外无限大地层中产生的SH横波和SV横波的位移远场渐近解,对比分析了有无钻铤时井外地层辐射声场及井内声场,以及相应的偶极声场激发频带;结合三维有限差分数值模拟方法,讨论了井旁存在声阻抗不连续面时,井内接收的随钻偶极全波波形的SH反射横波变化特征。分析表明:与裸眼情况下相比,随钻条件下的SH和SV横波辐射指向性除受钻井井孔的调制外,同时还受到钻铤的强烈调制。尽管如此,随钻偶极横波同样适用于远探测成像测井,其中偶极声源存在一个优势激发频带,在仪器设计上应考虑和利用。
Great progresses have been made in cable acoustic remote detection logging.This technology has a potential application value for acoustic logging-while-drilling（LWD）,especially for LWD geo-steering.Aiming at the dipole-acoustic-source reflection acoustic imaging logging while drilling,based on the asymptotic far-field solution for displacement of SH and SV shear waves generated by dipole acoustic source in outside-borehole infinite formation,a comparative analysis was performed on the radiated acoustic field in outside-borehole formation and borehole acoustic field with or without drill collar as well as the corresponding dipole-acousticfield excitation frequency band.In combination with3 D finite difference numerical simulation method,the variation characteristics of the reflected SH shear waves with LWD dipole full waveforms received in the borehole were discussed in case of acoustic impedance discontinuity on borehole side.The analysis results show that compared with open hole,the SH and SV shear wave radiation directivity is not only modulated by drill borehole,but also strongly modulated by drill collar under LWD conditions.Nevertheless,LWD dipole shear wave can be also used in remote detection imaging logging,and a dominant excitation frequency band exists in dipole acoustic source,which should be considered and applied in apparatus design.
出处
《石油学报》
EI
CAS
CSCD
北大核心
2016年第9期1152-1158,1178,共8页
Acta Petrolei Sinica
基金
国家重点基础研究发展计划(973)项目(2014CB239006)
国家自然科学基金项目(No.41404091)
山东省自然科学基金项目(ZR2014DQ004)
青岛市应用基础研究计划项目(15-9-1-63-jch)资助
关键词
随钻偶极
声波远探测
辐射声场
反射声场
优势频带
LWD dipole
acoustic remote detection
radiation wave field
reflected wave field
dominant frequency band
