Patent ID: 7002350

Claim:
A marine survey system for exploration of oil and gas, the survey system using natural telluric currents as an energy source, the survey system attached to a tow cable connected to a survey ship, the system comprising: a towed fish adapted for attachment to the tow cable, said towed fish including a waterproof housing and an outwardly extending tubular nose; an electric field sensor mounted on said tubular nose, said electric field sensor including electric dipoles mounted thereon, said electric dipoles measuring electric fields at 30 Hz and less; an angular motion detector mounted inside said housing and connected to said electric dipoles for compensating for errors caused by angular motion of said towed fish when in the presence of strong electric field gradients from the telluric currents; and a magnetometer mounted inside said housing for measuring low frequency electromagnetic fields at 30 Hz and less, said magnetometer connected to said motion detector.