四川盆地海相地层地震勘探采集技术

SEISMIC EXPLORATION ACQUISITION TECHNIQUE OF MARINE FORMAITON IN SICHUAN BASIN

在分析四川盆地地震勘探的基础上，着眼于海相地层的采集技术研究。四川盆地地表出露着不同地质年代的碳酸盐岩地层，地表起伏剧烈，地层倾角大，表层破碎，岩性复杂，激发和接收条件差；面波、折射波发育，次生线性干扰强，散射严重；目的层埋藏深度变化大、断层发育，地腹构造复杂，构造部位叠加成像效果差，地震波吸收衰减严重，反射能量弱，信噪比低。针对这些问题，重点结合四川盆地海相地层地震勘探的研究成果，着重研究讨论了四川盆地地震采集方法的适用性，通过特定的激发、接收及观测系统设计，对四川盆地典型地区进行了采集试验，大大提高了资料的信噪比和对地下断层、地腹构造的识别能力。研究表明：采用小道距、高覆盖次数、长排列接收，激发接收工艺优化是解决四川盆地海相地层地震勘探采集资料品质差的有效途径。

On the basis of analysis on seismic exploration of Sichuan Basin, acquisition technique of marine forma- tion is studied. Surface in Sichuan Basin exposes carbonate rock formations of different geologic ages. The surface has much relief, large dip angle, much surface break, and complex lithology, with poor excitation and receiving condition. Surface wave and refraction wave are developed, secondary linear interference is strong, and scattering is serious. Target layers have much variety of buried depth, fault developed, complex subsurface structure and poor stacked image of structural part, serious absorption attenuation of seismic wave, weak reflection energy and low signal/noise ratio. Aiming at these problems combining with study results of seismic exploration of marine formation in Sichuan, this paper discusses availability of this method. Through specific design of excitation, receiving and ob- servation system, acquisition test is carried out in typical area of Sichuan Basin, which largely increases signal/ noise ratio and identification capability for subsurface fault and subsurface structure. Results show that short station interval, hi tion acquisitio fold, long arrangement and excitation and receiving technique is an effective way to improve explora- n data quality of marine formation in Sichuan Basin.