Near-Surface Azimuthal Anisotropy and Seismic Imaging in the Southern Margin of Junggar Basin

摘要/Abstract

摘要： The Anjihai anticline in the southern margin of the Junggar basin is a typical complex oil exploration area where the near-surface heterogeneity is very strong, lithology changes fiercely, and the velocity of the weathered layer changes greatly. The complex near surface shooting and receiving conditions change the path and velocity of seismic waves and result in serious near surface azimuthal anisotropy, making effective seismic waves (events) not be superimposed. The accurate imaging of complex structure is the first problem to be solved in seismic processing. This study analyzed the characteristics of the first arrivals of original source points, and described the correspondence between gathers after NMO/static correction and source and receiver points based on geological outcrops and satellite images, and then built the close relationship with various gullies and near surface medium lithology, and finally established the weighted coefficient fields of different azimuth through azimuthal NMO/static correction and azimuthal weighted pre stack time migration imaging, so that the arcing phenomenon in pre stack time migration can be obviously suppressed, and the final migration imaging quality can be significantly improved. Using the results of pre stack time migration, the middle and lower trap combinations in the Anjihai anticline have been effectively identified.

关键词: Junggar basin, Anjihai anticline, azimuthal anisotropy, seismic imaging, pre-stack time migration, geological outcrop, satellite image, weighted coefficient

Abstract: The Anjihai anticline in the southern margin of the Junggar basin is a typical complex oil exploration area where the near-surface heterogeneity is very strong, lithology changes fiercely, and the velocity of the weathered layer changes greatly. The complex near surface shooting and receiving conditions change the path and velocity of seismic waves and result in serious near surface azimuthal anisotropy, making effective seismic waves (events) not be superimposed. The accurate imaging of complex structure is the first problem to be solved in seismic processing. This study analyzed the characteristics of the first arrivals of original source points, and described the correspondence between gathers after NMO/static correction and source and receiver points based on geological outcrops and satellite images, and then built the close relationship with various gullies and near surface medium lithology, and finally established the weighted coefficient fields of different azimuth through azimuthal NMO/static correction and azimuthal weighted pre stack time migration imaging, so that the arcing phenomenon in pre stack time migration can be obviously suppressed, and the final migration imaging quality can be significantly improved. Using the results of pre stack time migration, the middle and lower trap combinations in the Anjihai anticline have been effectively identified.

Key words: Junggar basin, Anjihai anticline, azimuthal anisotropy, seismic imaging, pre-stack time migration, geological outcrop, satellite image, weighted coefficient

LUO Yong, TAN Jia, YANG Xiaohai, DOU Qiangfeng, LIU Yiwen. Near-Surface Azimuthal Anisotropy and Seismic Imaging in the Southern Margin of Junggar Basin[J]. 新疆石油地质, 2021, 42(zk(English)): 151-157.

LUO Yong, TAN Jia, YANG Xiaohai, DOU Qiangfeng, LIU Yiwen. Near-Surface Azimuthal Anisotropy and Seismic Imaging in the Southern Margin of Junggar Basin[J]. Xinjiang Petroleum Geology, 2021, 42(zk(English)): 151-157.

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