MARINE SOURCE TO BOREHOLE ELECTROMAGNETIC MAPPING OF SUB-BOTTOM ELECTRICAL RESISTIVITY

摘要

A towed marine source to borehole electromagnetic survey system and method for surveying employing the same is disclosed. The system includes a sea vessel adapted for traversal of sea water over a subsea formation, a power supply affixed to the sea vessel and a high moment loop source coupled to the power supply, and a signal generator by a tow cable; said signal generator being affixed to the sea vessel configured to control operating parameters of the high moment loop source. The system also includes a wellbore drilled in the subsea formation, a series of electromagnetic (EM) receivers positioned in the wellbore. Each receiver includes a sensor module having sensing elements to measure one or more of electric fields, electric currents, and magnetic fields produced by the high moment loop source when towed by the sea vessel, and a storage device configured to store data from measurements made by the sensor module. The system further includes a computer processor configured to receive stored data from the receivers and analyze the stored measurement data to determine a location of an electrically resistive formation anomaly at a depth of between 1 to 5 km.