黄骅拗陷中北部重磁异常特征及油气地质意义

Gravity and magnetic anomaly characteristics and oil & gas geological significance in the middle and northern part of the Huanghua Depression

本文根据黄骅拗陷中北部重磁异常资料,采用小波多尺度分析和功率谱分析方法提取与火成岩有关的局部异常。根据重磁局部异常发现了唐家河南部的火山机构和三维地震工区东部的侵入岩体,利用垂向二次导数突出局部异常,圈定了火成岩的平面分布位置;利用重磁异常水平方向导数发现了本区的两条南北向隐伏深大断裂(孔店—沈青庄—天津断裂和黄骅—板桥断裂),与中新生代火成岩的密集分布区具有很好的对应关系,是黄骅拗陷中北部最重要的控浆构造。此外,航磁异常的水平一阶方向导数还显示了一条由天津经塘沽向东延伸至渤海湾的北西西向的航磁异常梯度带,推测是深部基性火成岩体的反映。实际应用效果验证了利用小波多尺度分析和功率谱分析方法提取航磁局部异常的有效性。

Based on gravity and magnetic anomaly data in the middle and northern part of the Huanghua Depression,in this paper local anomalies which are related to igneous rocks were extracted by using wavelet multi-scale analysis and power spectrum analysis methods.Based on gravity and magnetic local anomalies igneous structure in the south of Tangjia River and intrusive rock body in the east of 3-d seismic survey area were founded,by utilizing vertical second derivative to enhance local anomaly,the distribution location of the igneous rock is determined.By using gravity magnetic anomaly horizontal derivation,two large-scale S-N trending concealed deep faults were founded (Kongdian-Shenqingzhuang-Tianjin Fault and Huanghua-Banqiao Fault),it can be seen that there is a good corresponding relationship between the two faults and the igneous rock dense distribution area,they are the most important magma control structures in the middle and northern part of the Huanghua Depression.In addition,the horizontal first directional derivative of the aeromagnetic anomaly shows a NWW trending aeromagnetic anomaly gradient belt which extends eastwards from Tangu,Tianjin to Bohai Bay,it is believed that the aeromagnetic anomaly gradient belt is related to the basic igneous rocks.The effectiveness of utilizing wavelet multi-scale analysis and power spectrum analysis methods to extract aeromagnetic local anomaly was validated by the field data application effects.