High-Precision Seismic Imaging of Western Qiulitag Structural Belt in Kuqa Depression

摘要/Abstract

摘要： The western Qiulitag structural belt is an important successive area for oil and gas exploration in the Kuqa depression, Tarim basin. Its complex surface and underground geological conditions bring challenges to seismic survey. It has been less explored in the main structural belt, where the high steep structural features and complex fault systems cannot be depicted by using previous 2D (single-line and wide-line) seismic data. To address this problem, a combination of wide-frequency band, wide-azimuth and high-density 3D seismic survey and high-density cable 3D seismic survey is used to increase the effective folds in the complex, high, steep structural areas. The microlog-constrained shallow surface velocity modeling is conducted to improve the static correction accuracy in complex mountainous areas and thick gravel-covered piedmont areas. The six-division method for denoising is adopted to improve the signal-to-noise ratio of seismic data in inter-salt and pre-salt structures. The five-dimensional interpolation and regularization technique is applied to mitigate the impact of irregular observation system in mountainous areas on pre-stack depth migration imaging. Moreover, two-way wave reverse time-migration is performed to increase the migration imaging precision of highly steep formations. Through acquisition-processing integration and seismic-geological fusion, the seismic imaging precision in the western Qiulitag structural belt can be significantly improved.

关键词: western Qiulitag structural belt, wide-azimuth, wide frequency band, high-density, velocity model, denoising, five-dimensional interpolation, regularization, reverse time migration

Abstract: The western Qiulitag structural belt is an important successive area for oil and gas exploration in the Kuqa depression, Tarim basin. Its complex surface and underground geological conditions bring challenges to seismic survey. It has been less explored in the main structural belt, where the high steep structural features and complex fault systems cannot be depicted by using previous 2D (single-line and wide-line) seismic data. To address this problem, a combination of wide-frequency band, wide-azimuth and high-density 3D seismic survey and high-density cable 3D seismic survey is used to increase the effective folds in the complex, high, steep structural areas. The microlog-constrained shallow surface velocity modeling is conducted to improve the static correction accuracy in complex mountainous areas and thick gravel-covered piedmont areas. The six-division method for denoising is adopted to improve the signal-to-noise ratio of seismic data in inter-salt and pre-salt structures. The five-dimensional interpolation and regularization technique is applied to mitigate the impact of irregular observation system in mountainous areas on pre-stack depth migration imaging. Moreover, two-way wave reverse time-migration is performed to increase the migration imaging precision of highly steep formations. Through acquisition-processing integration and seismic-geological fusion, the seismic imaging precision in the western Qiulitag structural belt can be significantly improved.

Key words: western Qiulitag structural belt, wide-azimuth, wide frequency band, high-density, velocity model, denoising, five-dimensional interpolation, regularization, reverse time migration

ZHANG Xiangquan, GU Yongxing, LIU Jun, PEI Jiading, GU Xiaodi. High-Precision Seismic Imaging of Western Qiulitag Structural Belt in Kuqa Depression[J]. 新疆石油地质, 2023, 44(zk(English)): 148-155.

ZHANG Xiangquan, GU Yongxing, LIU Jun, PEI Jiading, GU Xiaodi. High-Precision Seismic Imaging of Western Qiulitag Structural Belt in Kuqa Depression[J]. Xinjiang Petroleum Geology, 2023, 44(zk(English)): 148-155.

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