电磁法在评估压裂液范围及裂缝形态时发挥着重要作用,在压裂监测中应用前景广泛。然而,对于川南地区的大深度页岩气水力压裂监测应用较少。为此,本文基于电磁监测理论,通过简化压裂模型进行数值模拟实验,在建立电磁监测技术的数据处理...电磁法在评估压裂液范围及裂缝形态时发挥着重要作用,在压裂监测中应用前景广泛。然而,对于川南地区的大深度页岩气水力压裂监测应用较少。为此,本文基于电磁监测理论,通过简化压裂模型进行数值模拟实验,在建立电磁监测技术的数据处理流程基础上,结合现场试验,从压裂液波及范围、用液强度、加砂强度、重复改造面积等多方面分析了压裂监测效果,进一步分析了电磁法进行水力压裂裂缝监测的有效性。其中,压裂监测段共计13段,获得各段波及面积4700~24042 m 2,波及宽度36~182 m,平均波及长度207 m。应用实例表明,电磁监测技术能实时了解压裂波及范围与展布形态,对压裂效果评价与施工参数的优化具有一定程度的指导意义。展开更多
矿集区采集的大地电磁信号极易受到各类噪声污染,导致其视电阻率-相位曲线在低频段出现紊乱现象或呈现出近源效应等。文中提出了一种优化固有时间尺度分解(Improved Intrinsic Time Decomposition,IITD)和小波阈值(Wavelet Threshold,WT...矿集区采集的大地电磁信号极易受到各类噪声污染,导致其视电阻率-相位曲线在低频段出现紊乱现象或呈现出近源效应等。文中提出了一种优化固有时间尺度分解(Improved Intrinsic Time Decomposition,IITD)和小波阈值(Wavelet Threshold,WT)的大地电磁(Magnetotelluric,MT)去噪方法及应用。首先将含噪信号进行IITD分解得到若干阶旋转(Proper Rotation,PR)分量;然后对PR分量进行小波去噪,叠加小波系数重构得到MT去噪数据。通过计算机模拟出不同类型的强噪声,并对小波阈值法设置不同的分解层数、基函数对强噪声进行处理,总结出该算法面对不同噪声时的去噪性能。对模拟大尺度方波和三角波噪声去噪后,信噪比最高可达24dB和17dB,所提方法去噪性能显著。将所提方法应用至MT实测数据的降噪,结果显示该方法能够有效去除隐藏在MT数据中的强噪声。由去噪前后视电阻率曲线对比可知,相较于远参考法和原始曲线,所提方法获得的视电阻率曲线更为光滑、连续,低频段的数据质量明显改善。展开更多
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 solut...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 prediction,geomechanical modeling,and fracturing stimulation design for deviated and horizontal wells.展开更多
文摘电磁法在评估压裂液范围及裂缝形态时发挥着重要作用,在压裂监测中应用前景广泛。然而,对于川南地区的大深度页岩气水力压裂监测应用较少。为此,本文基于电磁监测理论,通过简化压裂模型进行数值模拟实验,在建立电磁监测技术的数据处理流程基础上,结合现场试验,从压裂液波及范围、用液强度、加砂强度、重复改造面积等多方面分析了压裂监测效果,进一步分析了电磁法进行水力压裂裂缝监测的有效性。其中,压裂监测段共计13段,获得各段波及面积4700~24042 m 2,波及宽度36~182 m,平均波及长度207 m。应用实例表明,电磁监测技术能实时了解压裂波及范围与展布形态,对压裂效果评价与施工参数的优化具有一定程度的指导意义。
基金funded by the Southwest Oil and Gas Field Company Scientific Research Project"Research on the Mechanism and Prevention and Control Measures of Casing Deformation of Deep Shale Gas Wells"(No.20220304-20)the Southwest Oil and Gas Field Company Postdoctoral Project"Research on the Geomechanics and Effective Fracturing Factors of Deep Shale Gas Wells"(No.20210302-31).
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”。
文摘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 prediction,geomechanical modeling,and fracturing stimulation design for deviated and horizontal wells.
