火山岩岩性宏观预测方法——以松辽盆地北部徐家围子断陷为例

Macroscopic prediction of volcanic rock lithology: A case from Xujiaweizi Faulted Depression,northern Songliao Basin

断裂、构造及岩性共同控制了油气的富集和高产,根据酸性岩到中性岩再到基性岩密度逐渐增大的特点,提出了利用重力地震剥层增强处理方法进行火山岩岩性宏观预测的新方法。首先,根据三维地震资料建立地球物理模型,通过重力地震剥层准确进行重力异常的分离,即去除与火山岩无关的由于地层之间的密度界面所产生的重力异常;在此基础上,对剩余重力异常进行弱信号增强,去除大区域场的影响并对埋藏较深的火山岩岩性所产生的微弱的重力异常进行增强。将反映火山岩宏观分布的航磁二次导数异常图与重力地震增强处理后的图件叠合,即可对火山岩的岩性进行预测。该方法在松辽盆地北部徐家围子断陷深层火山岩油气藏的应用取得了较好的效果。

Structure, fracture and lithology are the controlling factors for the accumulation and high productivuty of oil and gas. According to the increasing density in the order of acidic, intermediate and basic volcanic rocks, a scheme of macroscopic lithological prediction of volcanic rocks is proposed by using gravity seismic stripping enhancement. Based on a 3D density model constructed by seismic data, the stratigraphic gravity anomalies not relevant to volcanic formation are stripped off..The residual gravity anomaly is enhanced by narrow band-filtering to emphasize weak anomaly caused by deep-seated volcanic rocks and to remove regional background. By combining seismic, magnetic and drilling data, the macroscopic lithological distribution is predicted. The applicability of the scheme is demonstrated by a case from Xujiaweizi Faulted Depression, northern Songliao Basin.