二连盆地乌兰花凹陷火成岩区三维地震采集技术

3D Seismic Acquisition Technology of Igneous Rock Area in Wulanhua Depression of Erlian Basin

二连盆地乌兰花凹陷发育的火成岩属于以新近系中新统汉诺坝组基性玄武岩为代表的喷发岩,浅层属于侵出相,中深部属于火山通道相;火成岩覆盖区地表起伏剧烈,喷发物杂乱堆积,风化层较薄,横向速度变化较快,造成原始单炮信噪比低,资料品质较差。针对以上地质地球物理特征,从3个方面开展技术攻关工作:基于增强火成岩深层弱小信号的宽方位、大炮检距、高覆盖的观测系统优化技术;基于提高原始资料品质的井震联合激发因素优选技术;基于解决表层结构复杂多变的精细表层结构调查与综合静校正技术。攻关结果表明,该技术可以解决乌兰花凹陷火成岩覆盖区三维地震勘探的难题。

Igneous rock developed in Wulanhua depression of Erlian Basin. It belongs to eruption rock represented by basic basalt of the Neogene Hannuoba Formation. The shallow layers are of the extrusive facies while the middle and deep layers are of the volcanic aisle facies. The surface of the igneous rock area fluctuates significantly, with eruptive rock piled miscellaneously, the weathering layer is thin and the lateral velocity changes quickly, causing a low original single-shot signal-noise ratio. Therefore, the quality of data is relatively poor. In the light of the above stated geologically geophysical characteristics, technological study is made in three areas - the optimization technology for the observation system with wide azimuth, large offset and high fold to enhance weak signal of deep igneous layer, the optimization technology for vibroseis and explosive excitation factors to improve the quality of original data, and the accurate surface structural investigation and comprehensive static correction technology to solve the complexity and changeability of surface structure. The results of the study indicate that those technologies can solve the bottlenecks in 3D seismic exploration of Wulanhua depression covered with igneous rock.