高邮凹陷中深层火成岩发育区宽方位采集与成像

Wide-azimuth acquisition and imaging of for the middle and deep strata of igneous rock of Gaoyou sag

高邮凹陷北斜坡阜宁组是主要勘探目的层,阜宁组及上部地层中发育多套火成岩。高速火成岩强屏蔽作用使得下伏地层反射能量弱、成像信噪比低、构造落实困难。针对火成岩下反射成像,过去多考虑增加覆盖次数增强岩下照明强度,而忽视了横向的宽方位作用。本文围绕北部斜坡带中深层火成岩发育区宽方位采集资料,利用沙埝宽方位三维开展了观测系统退化及相应的宽方位配套处理技术研究。研究认为,在高邮凹陷北斜坡要充分利用中深层火成岩空间分布的局限性和差异性,在保持一定覆盖次数的条件下采用较宽的方位采集,成像时充分利用宽方位信息构建最优的速度模型,可以实现岩下成像品质的有效提升。

The Funing Formation is the main exploration target layer at the northern slope of the Gaoyou sag.Many sets of igneous rocks are present in the Funing Formation and upper strata.The high-speed igneous rock shielding makes the reflection energy of the underlying stratum weak,the imaging signal-to-noise ratio low,and the structure implementation difficult.In the past,to enhance the lighting intensity under the rock,increasing the duration of coverage was considered,but the lateral direction was ignored.Based on the data collected in the middle and deep igneous rock development areas of the northern slope,the degradation of the observation system and the corresponding wide-range matching processing technology were studied via a wide-range three-dimensional sand dam.The results indicate that the limitations and differences of the spatial distribution of the medium and deep igneous rocks should be fully delineated in the northern slope of the Gaoyou Depression.Wide-azimuth acquisition was adopted at a constant coverage time.The best-speed model was constructed by making full use of the wide-azimuth information in imaging,which effectively improved the imaging quality below the rock formation.