oa Marine Transient EM Surveys

We describe transient electromagnetic (EM) surveys in water depths of about 100 m, where conventional Controlled Source EM (CSEM) has great problems with the air wave. Our proprietary method recovers the complete Earth impulse response, optimising signal strength with offset-dependent coded signals. Air wave removal is straightforward and our new method for removing magnetotelluric (MT) noise increases the low-frequency signal-to-noise ratio by about 20 dB. We demonstrate the techniques on real data from the North Sea.