沙特复杂过渡带地震资料采集中的难点及对策

Difficulties in and strategies for seismic data acquisition in complex transitional zone, Saudi Arabia

（1.CNPC东方地球物理公司国际部,河北涿州072751；2.CNPC东方地球物理公司海上部,河北涿州072751；3.CNPC大庆物探公司研究所，黑龙江大庆163357；4.CNPC东方地球物理公司综合物化探部，河北涿州072751）

沙特过渡带勘探范围大，地表条件复杂，大部分地区含有高速石灰岩夹层，对地震波有较强的屏蔽作用。针对这一特点，探讨了地震资料采集的难点，并提出了解决难点的相应技术和措施。依据表层结构模型设计井深、优选炸药特性、合理设计气枪组合和确定沉放深度，增强地震波下传的能量；采用震检联合面积组合和海上双检接收的方法，提高资料的信噪比；在受限水域采用浅水气枪垂直叠加技术，以减少炮点的偏移或空炮，保证地震资料有均匀的覆盖次数；采用声波二次定位技术实时监测因海水深度、海流变化等因素造成的海底电缆（OBC）偏移，对偏移误差进行有效控制。

The transitional zone in Saudi Arabia has the characteristics of large prospecting area and complex surface conditions. High-velocity limestone interbed exists in most of the area, which causes strong shielding effect on seismic wave. Aiming at the problem, the difficulties in seismic data acquisition were analyzed; the corresponding technologies and strategies were proposed. Based on the surface layer structure model, the well depth was designed, the dynamite characteristics was optimized, the airgun array was reasonably arranged and the shooting depth was identified, which enhanced the down-going energy of seismic wave. In addition, the source-geophone combined areal array and offshore dual-sensor receiving method was adopted to improve the S/N of data. Thirdly, the shallow water airgun substack technique in the restricted water area to decrease the deviation of shot point or gunned shot and guarantee uniform folds of seismic data. Finally, acoustic secondary positioning technique was utilized to monitor the deviation of ocean bottom cable caused by the sea water depth and ocean current changes, and effectively controlled the offset error.