火成岩覆盖区地震有效成像技术探讨及其在辽西金羊盆地油气调查中的应用

Effective seismic imaging technology in igneous rock coverage area and its application to oil and gas investigation in Jinyang Basin of western Liaoning

辽西金羊盆地是下辽河盆地外围盆地群中面积最大的中生代盆地,盆地浅层火成岩广泛发育、其厚度大、期次较多,受火成岩对地震信号屏蔽以及该地区复杂的地震地质条件的影响,使得地震勘探采集的原始资料信噪比低、火成岩下伏地层反射能量弱,给地震资料的有效成像带来了极大挑战。本文根据原始地震资料特点,采用针对性的采集、处理技术,首先从采集方面以大能量激发、低频检波器接收,并且处理中应用反射能量补偿、静校正、叠前多域去噪等几项技术进一步提高资料的深层反射能量和信噪比,最后通过高精度速度场建模与地震偏移成像技术的多种方法对比,优选叠前时间偏移技术进行最终成像。与以往地震资料比较,采用这套有效成像技术重新处理的地震剖面信噪比、分辨率明显提高,更重要的深层反射能量得以有效恢复,火成岩的下伏地层反射信号清晰、地层接触关系明确,特别是大倾角地层及断层的成像得以明显改善,为后续的构造解释和勘探潜力区评价提供了高质量的地震资料。

The Jinyang Basin of western Liaoning is the largest Mesozoic basin of the outer Lower Liaohe Basin.The shallow igneous rocks with great thickness and many periods are widely developed in the basin.The original data of seismic exploration has a low signal-to-noise ratio due to influencing of igneous rocks on seismic signal shielding and complex seismic geological conditions in the area.Meanwhile the reflected energy of the underlying strata of the igneous rock is weak,which brings about great challenges for effective imaging of seismic data.Based on the characteristics of the original seismic data,targeted acquisition and processing techniques were used to improve the deep reflection energy and signal-to-noise ratio of the data by low frequency geophone,static correction,pre-stack multi-domain denoising,reflected energy compensation and so on.The pre-stack time migration technique is optimized for final imaging through comparison by multiple high precision velocity modeling and seismic migration imaging techniques.Compared with the previous seismic data,the signal-to-noise ratio and resolution of the seismic section reprocessed by this effective imaging technology are significantly improved,the deep reflection energy is effectively restored,and the underlying strata of the igneous rock have clear reflection signals and clear contact between the strata.In particular,the imaging of the faults and strata with large dipping angle has been significantly improved in resolution,which provides highquality seismic data for subsequent structural interpretation and exploration potential area evaluation.