Logarithmic spectrum transmitter waveform for controlled-source electromagnetic surveying
AssigneeExxonMobil Upstream Research Company
InventorsXinyou Lu, Leonard Srnka
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Abstract
Waveforms for controlled source electromagnetic surveying. The waveforms have frequency spectra that include three or more frequencies spaced at substantially equal intervals on a logarithmic frequency scale and spanning a bandwidth of about one decade or more, at least three of which frequencies have approximately equal corresponding amplitudes.
Claims24
A periodic source waveform for electromagnetic surveys having a frequency spectrum comprising four or more frequencies spaced at substantially equal intervals on a logarithmic frequency scale and covering a bandwidth of about one decade or more, at least three of the frequencies having corresponding amplitudes A that are substantially equal and larger than the amplitudes of any other frequencies in the spectrum, and any remaining frequencies of said four or more having corresponding amplitudes at least 0.2 A.
A method for generating a periodic source waveform for an electromagnetic survey of a subsurface region comprising switching a substantially constant voltage DC power source and changing the source's output polarity according to a pre-selected sequence, said sequence being designed to provide a frequency spectrum comprising three or more frequencies spaced at substantially equal intervals on a logarithmic frequency scale and covering a bandwidth of about one decade or more, at least three of the frequencies having corresponding amplitudes A that are substantially equal and larger than the amplitudes of any other frequencies in the spectrum, and any remaining frequencies of said three or more having corresponding amplitudes at least 0.2 A.
Dependencies are inferred from the claim text.