A VMD-TCN-Transformer Based Approach for Reconstructing Logging Curves Under Complex Conditions
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摘要:
【目的】声波测井曲线,尤其是纵波时差(DTC)与横波时差(DTS),是岩石物理分析、地震合成记录制作及储层精细表征的重要基础资料,但在实际钻井过程中,受井眼条件及复杂测量环境噪声等因素影响,声波测井曲线易发生畸变或缺失,从而制约其工程应用效果。传统经验公式与统计回归方法难以刻画测井曲线之间复杂的非线性关系,近年来引入的机器学习与深度学习方法虽在一定程度上提升了重构精度,但在复杂井况条件下,对测井信号非平稳特征、局部变化特征及长程地质相关性的综合表征仍存在一定局限。【方法】针对上述问题,本文提出一种基于变分模态分解(VMD)与时域卷积网络(TCN)-Transformer融合架构的声波测井曲线重构方法。该方法通过VMD对原始测井信号进行多尺度分解,实现地层有效响应与井径异常引起的低频畸变及环境噪声的分离,在改善信噪比的基础上,引入TCN刻画测井曲线的局部变化特征,并结合Transformer多头自注意力机制提取测井序列的长程依赖信息,从而实现对复杂沉积旋回特征的整体建模。基于山西某区块实测测井资料,开展模型对比分析、消融实验、井径异常条件下的曲线重构实验及盲井预测验证。【结果】结果表明,所提出方法在声波测井曲线重构精度与稳定性方面表现优异,测试井段中DTC与DTS预测的决定系数(R²)分别达到0.9142和0.9165;VMD信号分解与TCN-Transformer混合架构对模型性能提升均有显著贡献;在井径异常发育井段,模型能够有效抑制环境噪声干扰,重构的曲线形态连续合理;盲井预测结果生成的合成地震记录与实测地震剖面在波组特征与相位特征上具有较好一致性。【结论】该方法在复杂井况条件下具有较好的适应性与实用性,可为低质量测井资料校正、补全及后续地震反演与储层精细表征提供可靠基础数据支持。
Abstract:【Objective】Acoustic logging curves, particularly compressional wave slowness (DTC) and shear wave slowness (DTS), serve as fundamental data for petrophysical analysis, synthetic seismogram generation, and refined reservoir characterization. However, during actual drilling operations, these curves are prone to distortion or gaps due to factors such as borehole conditions and complex environmental measurement noise, which constrains their practical application. Traditional empirical formulas and statistical regression methods struggle to capture the complex nonlinear relationships between logging curves. Although machine learning and deep learning methods introduced in recent years have improved reconstruction accuracy to some extent, they still exhibit limitations in comprehensively representing the non-stationary features, local variations, and long-range geological dependencies of logging signals under complex borehole conditions.【Methods】To address these issues, this paper proposes an acoustic logging curve reconstruction method based on a fusion architecture combining Variational Mode Decomposition (VMD) with Temporal Convolutional Network (TCN)-Transformer. The method first decomposes the original logging signals into multiple scales using VMD to separate effective formation responses from low-frequency distortions caused by borehole rugosity and environmental noise, thereby enhancing the signal-to-noise ratio. Subsequently, TCN is introduced to characterize the local variation features of the logging curves, while the Transformer's multi-head self-attention mechanism is employed to extract long-range dependencies within the logging sequences, enabling holistic modeling of complex sedimentary cyclicity. Based on measured logging data from a block in Shanxi, comparative model analysis, ablation experiments, curve reconstruction experiments under conditions of severe borehole enlargement, and blind-well prediction validation were conducted.【Results】The results demonstrate that the proposed method excels in both accuracy and stability for acoustic logging curve reconstruction. The coefficients of determination (R²) for DTC and DTS predictions in the test intervals reached 0.9142 and 0.9165, respectively. Both the VMD signal decomposition and the TCN-Transformer hybrid architecture contributed significantly to the model's performance. In intervals with significant borehole enlargement, the model effectively suppressed environmental noise interference, producing reconstructed curves with continuous and geologically reasonable morphology. The synthetic seismograms generated from the blind-well prediction results showed good consistency with the actual seismic profile in terms of wavelet characteristics and phase features.【Conclusion】The proposed method exhibits strong adaptability and practicality under complex borehole conditions. It can provide reliable foundational data for the correction and completion of low-quality logging data, as well as for subsequent seismic inversion and refined reservoir characterization.
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