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    川中古隆起北斜坡超深层气藏地震高分辨成像与岩性圈闭识别技术

    High-resolution seismic imaging and lithologic trap identification for ultra-deep gas reservoirs in northern slope of Central Sichuan Paleo-Uplift

    • 摘要: 川中古隆起北斜坡下古−震旦系岩性圈闭埋深超6000 m,地震信号高频衰减现象显著,主频小于30 Hz,60 Hz以上频段的能量损失超过70%,同时,白云岩、灰岩与硅质层的纵波阻抗重叠率较高,导致岩性圈闭识别存在强多解性。针对超深层弱信号保真恢复以及复杂岩性叠置等难题,提出了高分辨成像−智能解释−定量评价一体化技术体系。其中,基于多尺度信息蒸馏网络的智能去噪技术可使峰值信噪比提升10 dB以上,小波变换时频域能量补偿技术将地震信号主频提升至35 Hz、有效频带拓宽27%,全波形叠前反演多次波压制技术使井震标定吻合度达到92%,实现了超深层弱信号的高保真恢复与复杂波场的准确重构;相位旋转层序解释方法与地质−地球物理协同反演体系使储层预测误差小于15%,有效提高了超深层复杂圈闭的识别精度。应用结果表明,研究区岩性圈闭识别符合率从62%提升至81%。人工智能驱动的地震数据处理及资料解释技术为超深层弱信号恢复与岩性差异表征提供了智能化解决方案,对于国内其他区域的复杂油气藏勘探具有重要借鉴意义。

       

      Abstract: The Lower Paleozoic–Sinian lithologic traps on the northern slope of the Central Sichuan Paleouplift, at depths exceeding 6,000 m, exhibit significant high-frequency seismic attenuation. This is evidenced by dominant frequencies below 30 Hz and over 70% energy loss in the 60 Hz band. Furthermore, the P-impedance distributions of dolomites, limestones, and siliceous layers show an overlap over 70%, resulting in great uncertainties of lithologic trap identification. To address the challenges of ultra-deep weak signal recovery and complex lithology discrimination, this study proposes an integrated technical suite comprising true signal recovery, high-resolution imaging, intelligent interpretation, and quantitative evaluation. Intelligent denoising using a multi-scale information distillation network boosts the peak signal-to-noise ratio by over 10 dB. The wavelet transform-based time-frequency energy compensation technique elevates the dominant frequency to 35 Hz and broadens the effective band by 27%. The FWI-based multiple suppression technique, which reconstructs multiples' travel paths via wave equation-based forward modeling and FWI, achieves a 92% well-to-seismic correlation. These techniques collectively enable high-fidelity recovery of ultra-deep weak signals and accurate reconstruction of complex subsurface wavefields. The integration of phase rotation-based sequence interpretation (with vertical resolution of 10 m) and a geological-geophysical co-inversion strategy (with reservoir prediction error below 15%) facilitates a dramatic improvement in both qualitative and quantitative identification of ultra-deep complex lithologic traps. Field applications in the gas field demonstrate a significant increase in lithologic trap identification accuracy from 62% to 81%. This AI-driven seismic data processing and interpretation system provides an intelligent solution for ultra-deep weak signal recovery and lithology differentiation, and its success offers a valuable reference for the exploration of other complex hydrocarbon reservoirs in China.

       

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