广角反射在塔中地区的应用

The Application of wide-angle reflection method in central Tarim Basin

西北分公司工程监督中心物探工程部,新疆乌鲁木齐 830011

Project Supervise Center. Northwest Company of SINOPEC, Urumchi 830011, China

塔里木盆地中东部地表沙丘、沙梁连绵起伏,高差变化剧烈;地下地质构造复杂,断裂发育;奥陶系内幕无明显的波阻抗界面,地震反射能量较弱;主要目的层(T₄⁷)埋藏较深.地震波吸收衰减严重;构造主体部位断裂破碎,奥陶系内幕反射杂乱,落实构造困难。针对以上地震地质条件及采集难点,采用了大井深和大药量、小组合检波器基距、超长排列高叠加次数观测系统等地震采集技术,以利用广角反射信息.增强深层有效信号叠加次数,提高地震剖面的中、深层信噪比。所获得的地震剖面较以前相比.中、深层波组的能量、信噪比及连续性均有明显的改善。

There exist some sand hill and sand girder undulation on surface. Elevation has variety. Geological structure is complex, growth in fracture in the area of middle and east of Tarim Basin. This is no obvious wave-impedance interface, weak seismic reflect energy, main aim layer (T₄⁷) imbed deeper, seismic wave absorb and attenuation severity in dope of Ordovician. There have fracture fragmentation and reflect disorder in the principal part of structure, so difficulty to carry out the structure form. This is a typical area of low signal-noise ratio. We use a series of new techniques of seismic acquisition in field construction, aim at bad conditions on surface, seismic and complex geological conditions subsurface, as well as acquisition difficulties, in order to prove up reflect in dope of Ordovician and find out tip of calcareous rock in Ordovician. The wide-angle reflect is used in seismic prospect especially, it can be increase stacking fold of effective signal and improve signal-noise ratio in deeper of seismic section.