广域电磁法在扬子板块南部垭紫罗裂陷槽深部构造研究中的应用

Application of Wide Field Electromagnetic Method in the Deep Structure of Yaziluo Rift Trough in the Southern Yangtze Plate

钻探等资料表明垭紫罗裂陷槽页岩气潜力巨大,但构造复杂,深部构造不清晰,影响页岩气潜力评价。为了查明垭紫罗裂陷槽低阻异常分布、地球物理场分布和深部构造特征等,开展广域电磁法勘探。成果显示深部存在多套连续的低阻异常,高阻体或低阻体横向起伏较大,电阻率曲线扭曲,反应了深部构造复杂。通过广域电磁法骨架反演剖面的综合研究,基本查明了垭紫罗裂陷槽的深部构造及断裂体系,取得了泥盆系底界埋深分布规律,为页岩气潜力评价提供基础资料。

Drilling and other data indicate that the shale gas potential of the Yaziluo rift trough is huge,but the complex structure and unclear deep structure affect the evaluation of shale gas potential.The exploration of the wide field electromagnetic method is used to find out the distribution of low resistivity anomaly,geophysical field and the characteristics of deep structure in the Yaziluo rift trough.Wide field electromagnetic exploration shows that there are multiple sets of continuous low-resistance anomalies in the deep,the high-resistance body or the low-resistance body has large lateral fluctuations,and the resistivity curve is distorted,which reflects the complex deep structure.Through the comprehensive study of the wide-field electromagnetic method skeleton inversion profile,the deep structure and fault system of the Yaziluo rift trough were basically ascertained,and the depth distribution law of the Devonian bottom boundary was obtained,which provides basic data for the evaluation of shale gas potential.