叠前深度偏移技术对速度变化平缓的复杂构造清晰成像  

Applying prestack depth migration to complex gedogic structure Imaging gained by using velocity model with gradient

作　　者：吴小洲[1] 陈立康[1] 邹才能[1] 胡英[1] 梁宏[1] 

机构地区：[1]中国石油勘探开发研究院

出　　处：《石油勘探与开发》2002年第2期77-80,共4页Petroleum Exploration and Development

摘　　要：大港滩海地区的白东构造是右旋扭动成因的复“Y”型背斜构造,成藏组合类型是下生上储,中、浅层形成油气藏的关键条件是存在沟通深部油源层的断裂,因此,该区的断裂是否能延伸至深部油源层至关重要。该构造的第三系层速度变化平缓,深层断裂地震成像较差,因而提出是否有必要应用叠前深度偏移技术以改善供油断裂成像的问题。对叠前深度偏移改善白东构造深部成像的地质条件和方法特点进行分析,突出针对性的方法而设计了处理流程。在处理过程中的关键点是地质解释与地球物理处理一体化。时间域与深度域处理相互迭代、应用速度梯度分析速度变化缓慢区域等。最后取得了预期效果,明显改善了供油断裂的深部成像,并证实白东构造是晚第三纪之前形成的古构造,为该区的成藏分析和油气勘探提供了可靠依据。这一实例不但拓宽了叠前深度偏移技术的应用范围,而且进一步加深了对叠前深度偏移方法的认识。图4参3（吴小洲摘）Since 1990's, 3D depth migration has become a key seismic imaging technique in those areas that have severe lateral velocity variation in subsurface medium. However, in East China, there are some complex fault-block oil fields which have subtle velocity variation both laterally and vertically in the upper formation; their oil source rock is in the deeper formation; and their migration pathway is some dominated by faults. Hence, to find the dominant faults is the most important task in these kinds of oil fields. 3D prestack and poststack time migration have been used to image these faults, but the result is not as accurate as geologists expect because of the complex faulting system. 3D prestack depth migration was tested using velocity model with gradient, and reasonable result was achieved. Baidong structure is presented as a case study to demonstrate that 3D prestack depth migration is an effective technique to image those complex faults.

关 键 词：叠前深度偏移技术 复杂结构清晰成像 地震勘探 第三系 层速度 深层地质体成像 三维地震资料 

分 类 号：P631.443[天文地球—地质矿产勘探]