Discussion on taking remanent magnetic inclination anomaly as reference frame for locating hydrocarbon microseepage zone
Guo Youzhao1, Chen Benchi1, Yu Qinfan2, Tan Chengze2
Research Institute of Geophysical & Geochemical Exploration, Ministry of Geology and Minerals, No. 84 Jinguang Street, Langfang City, Hebei Province, 065000
Abstract：Remanent magnetism of soil layer is taken as a reference frame for locating hydrocarbon seepage zone. Palaeogeomagnetic field is a geocentric dipole field and magnetic inclination is a function of latitude;therefore,taking magnetic inclination as reference coordinate for locating hydrocarbon seepage zone is of universal significanoe. In a given area,magnetic inclination of one formation is constant and it may be used as a standard of geomagnetism analysis,just like standard sample in geochemistry survey. If there exists a hydrocarbon seepage zone,both the inclination of natural remanent magnetism and the inclination of demagnetized remanent magnetism deviate from the original inclination of palaeogeomagnetic field,and the inclination of viscous remanent magnetism also obviously deviates from zero. If there is no hydrocarbon seepage zone,the inclinations of natural remanent magnetism and demagnetized remanent magnetism is nearly equal to the inclination of depositional remanent magnetism,and the inclination of viscous remanent magnetism is nearly equal to zero .The effectiveness of this reference frame has been proved by trial results in Langfang-Guan depression and Linnan oil field.
