Method and system for deriving receiver separation and depth dual phone seismic surveys
AssigneeBaker Hughes Incorporated
InventorJosef Paffenholz
Life of this patent
Estimating the term…
Abstract
A method for accurately determining travel time separation between dual vertically spaced hydrophones below a water surface to achieve separation of pressure wavefields into an up-going and a down-going wavefield in the frequency domain, and for accurately determining the depth of a vertical mid-point between the dual hydrophones below the water surface.
Claims13
A system for determining an optimal vertical travel time τd and a vertical mid-point depth dmp of dual vertically separated hydrophones below a surface of a body of water, which comprises:
- a storage medium;
- a recording system for receiving electrical signals from said dual vertically separated hydrophones indicative of pressure waves induced into said body of water, and storing said electrical signals in said storage medium;
- and
- a data processing system for accessing said electrical signals from said storage medium for determining said optimal vertical travel time τd of a pressure wave from a mid-point between said dual vertically separated hydrophones to one of said dual vertically separated hydrophones, and for determining said vertical mid-point depth dmp of said mid-point below said surface.
A method of determining a travel time τd from a mid-point between dual hydrophones vertically separated below a water surface to one of said dual hydrophones, which comprises the steps of:
- integrating over time electronic signals received from said dual hydrophones to generate Fourier transforms of said electronic signals as functions of a temporal frequency f;
- selecting a travel time τ for a pressure wave in water to travel from said mid-point to aid one of said dual hydrophones;
- generating an up-going wavefield function Uo and a down-going wavefield function Do as functions of said travel time τ and said Fourier transforms;
- generating a transfer function FUD between said up-going wavefield function Uo and said down-going wavefield function Do;
- performing a least squares fit to an argument PF of said transfer function FUD to determine an optimal linear frequency function f(ω);
- measuring and recording an RMS error between said linear frequency function f(ω) and said argument PF;
- repeating the above steps beginning with the step of selecting said travel time τ for a range of values for said travel time τ;
- and
- selecting said travel time τd as a travel time τ corresponding to a minimum recorded RMS error.
Dependencies are inferred from the claim text.