Assessing rock brittleness and fracability from radial variation of elastic wave velocities from borehole acoustic logging

Tang, Xiaoming; Xu, Sheng; Zhuang, Chun‐Xi; Su, Yongbin; Chen, Xuelian

doi:10.1111/1365-2478.12377

Cited by 10 publications

(4 citation statements)

References 16 publications

(38 reference statements)

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“…The natural potential is influenced by the shale content. 47,48 4.2. Correlation Analysis of Logging Parameters and Rock Mechanical Parameters.…”

Section: Acquisition and Analysis Of The Logging Parameters Of Coal M...mentioning

confidence: 99%

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Analysis of Rock Mechanical Characteristics and Establishment of an Evaluation System for Coal Measures in the Longtan Formation, Guizhou Province

Liang,

Cao,

Sang

et al. 2024

ACS Omega

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The mechanical properties of coal measure rocks and their evaluation significantly impact the process and efficacy of coal measure exploration and development. This study focuses on the Guizhou Longtan Formation coal measure. The mechanical and fracturing characteristics of coal measure rock samples are analyzed via well coring, geophysical logging, and indoor experiments. Additionally, predictive models for rock mechanical parameters are developed, and an evaluation system for the Longtan Formation coal measure rock mass is established. The findings are as follows: (1) Coal measure rocks in Guizhou's Longtan Formation exhibit a relatively low elastic modulus and tensile strength, but a substantial variation in compressive strength. The triaxial compressive strength, elastic modulus, and residual strength increase nonlinearly with increasing confining pressure. As the confining pressure increases, the failure mode of the mudstone and siltstone transitions from primarily splitting failure to shearing failure. (2) Strong correlations are calculated between logging parameters and rock mechanical parameters and are used to construct three regression prediction models, yielding an average prediction accuracy of approximately 85% for rock mechanical properties. (3) Considering the rock mechanical properties, rock mass structure and stratigraphic characteristics, and the occurrence environment related to the characteristics of rock mass affecting coal measure gas development, eight evaluation indices are selected. The analytic hierarchy process−entropy weighting method is used to determine the weights of the comprehensive evaluation indices, and a coal measure rock mass evaluation system is established by utilizing gray clustering analysis. The evaluation results categorize the mudstone group (mudstone and silty mudstone) as Classes III−IV, the fine sandstone group as Classes I and II, and the siltstone group (muddy siltstone and siltstone) as Classes II and III. A comparative analysis with fuzzy comprehensive evaluation results and extenics theory evaluation results demonstrated a high level of consistency. These findings benefit coal measure rock mechanics classification and quantitative research on rock mechanics properties, providing a solid foundation for efficient coal measure gas exploration and development.

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“…The natural potential is influenced by the shale content. 47,48 4.2. Correlation Analysis of Logging Parameters and Rock Mechanical Parameters.…”

Section: Acquisition and Analysis Of The Logging Parameters Of Coal M...mentioning

confidence: 99%

“…These differences can be attributed to the acoustic time difference, compensated neutrons, and resistivity logging curves, which are related to the development of pore fractures and rock compactness within each rock type. The natural potential is influenced by the shale content. , …”

Section: Establishment Of Logging-based Prediction Models For Rock Me...mentioning

confidence: 99%

Analysis of Rock Mechanical Characteristics and Establishment of an Evaluation System for Coal Measures in the Longtan Formation, Guizhou Province

Liang,

Cao,

Sang

et al. 2024

ACS Omega

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“…However, abnormal in-situ stress, mud invasion, and borehole damage would result in radial changes in formation velocity around the borehole, thereby bringing inaccurate interpretation results [1]. Based on a dipole waveform obtained by multipole array acoustic logging data, a formation's shear-velocity radial profile can be inverted for evaluating the borehole stability, estimating in-situ stress, and reflecting mud invasion [2][3][4][5][6][7]. Consequently, it is crucial to study the inversion method of the formation's S-wave velocity radial profile around the borehole.…”

Section: Introductionmentioning

confidence: 99%

“…This method constrains a high-frequency band and increases the contribution of a high-frequency component in the objective function, which can effectively improve the accuracy of inversion the results, especially in the formation around the borehole. This constrained inversion method is then applied in a logging-while-drilling quadrupole waveform processing to obtain the formation radial velocity, and to assess the rock-brittleness and fracability of the near-borehole formation [4,5]. In real data processing, the acoustic tool in the borehole has a great impact on the dispersion characteristics of the dipole waveform.…”

Section: Introductionmentioning

confidence: 99%

Study on Shear Velocity Profile Inversion Using an Improved High Frequency Constrained Algorithm

Sun

Jin

et al. 2022

Energies

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The formation shear-wave (S-wave)’s velocity information around a borehole is of great importance in evaluating borehole stability, reflecting fluid invasion, and selecting perforation positions. Dipole acoustic logging is an effective method for determining a formation S-wave’s velocity radial profile around the borehole. Currently, the formation S-wave’s radial-profile inversion methods are mainly based on the impacts of radial velocity changes of formations outside the borehole on the dispersion characteristics of dipole waveforms, without considering the impacts of an acoustic tool on the dispersion curves in the inversion methods. Accordingly, the inversion accuracy is greatly impacted in practical data-processing applications. In this paper, a novel inversion algorithm, which introduces equivalent-tool theory into the shear-velocity radial profile constrained-inversion method, is proposed to obtain the S-wave’s slowness radial profile. Based on the equivalent-tool theory, the acoustic tool can be modeled using two parameters, radius and elastic modulus. The tool's impact on the dipole waveform’s dispersion is eliminated first by using the equivalent-tool theory. Then, the corrected dispersion curve is used to carry out the constrained inversion processing. The results of this processing on the simulation data and the real logging data show the validity of the proposed algorithm.

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Experimental study on predicting rock properties using sound level characteristics along the borehole during drilling

Yue

Yan

et al. 2023

Bull Eng Geol Environ

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Assessing rock brittleness and fracability from radial variation of elastic wave velocities from borehole acoustic logging

Cited by 10 publications

References 16 publications

Analysis of Rock Mechanical Characteristics and Establishment of an Evaluation System for Coal Measures in the Longtan Formation, Guizhou Province

Analysis of Rock Mechanical Characteristics and Establishment of an Evaluation System for Coal Measures in the Longtan Formation, Guizhou Province

Study on Shear Velocity Profile Inversion Using an Improved High Frequency Constrained Algorithm

Experimental study on predicting rock properties using sound level characteristics along the borehole during drilling

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