库车地区宽线采集技术应用与效果

APPLICATION AND EFFECTS OF WIDE LINE ACQUISITION TECHNIQUE IN KUQA REGION

针对塔里木盆地库车坳陷地表和地下构造复杂、地震记录波场杂乱、资料信噪比低的问题,通常采用减小道距与炮距、增加接收道数来提高覆盖次数,但由于激发和接收条件难以改善,同时干扰波难以有效地压制和削弱,即使成倍地提高覆盖次数,二维地震采集对剖面品质也无明显改善。通过对该区地震地质条件分析,在查明地震信号信噪比低的原因基础上,提出了在观测系统设计时采用宽线采集技术,在野外施工中采用准确的近地表模型技术、分区埋置改善检波器接收条件技术、激发药量选取技术、控制环境噪音技术等方案。现场采集试验表明:与单线同区老资料对比,首次获得了较好的深层中生界地震反射,新生界的地层反射资料有明显改善,构造面貌更加清楚、构造高点断层分布情况更加可靠。

Aimed at the Kuqa Depression surface of the Tarim basin,complex subsurface structures,chaotic seismic wave field,and small signal-to-noise ratios,reducing the track width and shooting distance,and adding receiver tracks are used to raise coverage times.Because the shooting conditions and the receiving conditions are difficult to improve,disturbing waves are also difficult to constrain and reduce,though the coverage times' raising is double,the 2D seismic acquisitions can not improve the section quality obviously.Based on finding out the reasons for seismic signal-to-noise ratios,it proposes to use wide-line acquisition technique when design the observation system,and to use the accurate near-surface model,wave detectors' zoning embedding,shot charge selecting technique,and environmental noise control technique in field constructions.Field acquisition experiments shows that preferable seismic reflections of deep Mesozoic Erathem are obtained for the first time,seismic reflection information of Cenozoic Erathem is improving sharply,structural surfaces are more explicit,the distribution of structural high faults are more reliable.