海底管道磁异常正演与实测结果分析

Analysis of Forward and Measured Magnetic Anomalies of Submarine Pipeline

采用重磁位场的泊松公式法推导了海底管道磁异常的理论计算模型,以两段已知的输气管道为研究对象进行了正演模拟计算和海上实测验证。正演结果表明,在距海底管道约8.0 m的观测平面上能产生跨度约20.0 m、辐值分别高达329.8 nT和362.4 nT的正磁异常。实测的海底管道磁异常分布跨度与正演的结果基本一致,但其分布的细节特征存在不同,既存在正异常,也存在负异常。通过分析磁异常极值点的分布特征推测可能是管道连接处的热剩磁导致了实测磁异常的细节特征。

The theoretical calculation model of magnetic anomaly of submarine pipeline is derived by Poisson formula method of gravity and magnetic field.For two known submarine gas pipelines,the forward simulation calculation and sea test verification are carried out.The forward results show that positive magnetic anomalies with a span of about 20.0 m and up to 329.8 nT and 362.4 nT respectively are produced on an observation plane of about 8.0 m from the submarine pipeline.The measured distribution spans of magnetic anomalies of submarine pipeline are consistent with the results of forward modeling,but the details of their distributions are different.Both positive and negative magnetic anomalies exist.By analyzing the distribution characteristics of the extreme points of magnetic anomalies,it is speculated that the thermal residual magnetism at the junctions of the pipeline may lead to the detailed characteristics of the measured magnetic anomalies.