Patent ID: 8463568

Claim:
A seawater capacitance detection method for rapidly mapping and characterizing hydrocarbon plumes in seawater, the method comprising: towing a streamer array having three or more vertically stacked streamer cables at three or more depths, respectively, through a seawater column containing a hydrocarbon plume; energizing two or more transmitter electrodes on each streamer cable with an electrical current signal, the transmitter electrodes injecting electrical current into the seawater column; episodically turning off transmission of the electrical current signal; arranging a plurality of receiver electrodes on each streamer cable into one or more receiver sets, each receiver set sampling a volume of seawater surrounding it and detecting any returned secondary signals produced by a capacitive effect resulting from injecting the electrical current into the seawater column and turning off the transmission of the electrical current signal, and each receiver set successively sampling a larger volume of water as the receiver sets are positioned further away from the transmitter electrodes; processing the returned secondary signals, for each adjacent pair of receiver sets, by subtracting the smallest volume of seawater from the next smallest volume of seawater to yield a capacitance value of a donut-shaped sampling volume of seawater outside the smallest volume, the receiver sets positioned further away from the transmitter electrodes providing increasingly larger donut-shaped sampling volumes of sampling data of the capacitance of the seawater column through which the streamer cables are towed; processing and geometrically correcting the capacitance values of the donut-shaped sampling volumes of seawater to yield a frequency-varying final seawater capacitance value for the volume of seawater sampled by each receiver set; and mapping and characterizing the hydrocarbon plume using the final seawater capacitance values of the receiver sets.