VH reservoir mapping

Abstract

A method and system of detecting and mapping a subsurface hydrocarbon reservoir includes determining ratio data for a plurality of orthogonal spectral components of naturally occurring low frequency background seismic data. The ratio data may be compared, plotted, contoured and displayed as a subsurface hydrocarbon reservoir map or a hydrocarbon potential map. The ratio data may represent a vertical spectral component of the seismic data over a horizontal spectral component of the seismic data. The subsurface hydrocarbon reservoir map may include contouring the ratio data over a geographical area associated with the seismic data.

1 . A computerized method for determining a subsurface hydrocarbon reservoir location comprising: determining a subsurface hydrocarbon reservoir location based on ratio data from a plurality of orthogonal spectral components of naturally occurring low frequency background seismic data wherein the ratio data exceeding a predetermined threshold value indicates the location of the subsurface hydrocarbon reservoir, and storing the ratio data in a form for display. 
   
   
       2 . The method of  claim 1  wherein the ratio data are calculated from a vertical spectral component of the seismic data relative to a horizontal spectral component of the seismic data. 
   
   
       3 . The method of  claim 1  further comprising calculating ratio data representing vertical spectral components as a numerator with horizontal spectral components as a denominator wherein the ratio data associated with the presence of subsurface hydrocarbons are greater than the predetermined threshold value of 1.5. 
   
   
       4 . The method of  claim 1  further comprising calculating ratio data representing a horizontal spectral component as a numerator with a vertical spectral component of the seismic data as a denominator and the ratio data associated with the presence of subsurface hydrocarbons are less than the predetermined threshold value of 0.67. 
   
   
       5 . The method of  claim 1  wherein the ratio data are selected for a frequency range between 1 Hz and 5 Hz. 
   
   
       6 . The method of  claim 1  wherein the orthogonal spectral components are determined by: applying a data transform to a plurality of orthogonal components of motion for the naturally occurring low frequency background seismic data. 
   
   
       7 . The method of  claim 6  wherein the data transform is selected from the group consisting of: discrete Fourier transform, continuous Fourier transform, continuous wavelet transform, and discrete wavelet transform. 
   
   
       8 . The method of  claim 1  further comprising: processing the plurality of orthogonal spectral components by at least one selected from the group of: smoothing with a low pass filter, smoothing with a fixed bandwidth moving window, smoothing with a variable bandwidth moving window, averaging with an arithmetic mean, and averaging with a geometrical mean. 
   
   
       9 . A computerized method of mapping a subsurface hydrocarbon reservoir comprising: deriving a ratio data from a plurality of orthogonal spectral components of naturally occurring low frequency background seismic data; using a processing unit for determining ratio data which exceed a predetermined threshold value indicative of a subsurface hydrocarbon reservoir to determine subsurface hydrocarbon reservoir map location positions; and storing the map location positions in a form for display. 
   
   
       10 . The method of  claim 9  further comprising determining ratio data representing a vertical spectral component of the seismic data over a horizontal spectral component of the seismic data. 
   
   
       11 . The method of  claim 9  further comprising creating a subsurface hydrocarbon reservoir map by contouring the ratio data over a geographical area associated with the seismic data. 
   
   
       12 . The method of  claim 9  wherein the orthogonal spectral components are determined by: applying a data transform to a plurality of orthogonal components of motion for the naturally occurring low frequency background seismic data. 
   
   
       13 . The method of  claim 12  wherein the data transform is selected from the group consisting of: discrete Fourier transform, continuous Fourier transform, continuous wavelet transform, and discrete wavelet transform. 
   
   
       14 . The method of  claim 9  further comprising: processing the plurality of orthogonal spectral components by at least one selected from the group of: smoothing with a low pass filter, smoothing with a fixed bandwidth moving window, smoothing with a variable bandwidth moving window, averaging with an arithmetic mean, and averaging with a geometrical mean. 
   
   
       15 . An information handling system for determining the presence of subsurface hydrocarbons associated with an area of seismic data acquisition comprising: a processor configured to determine a ratio calculated from a plurality of orthogonal spectral components of naturally occurring low frequency background seismic data; further configured to determine when the ratio exceeds a predetermined threshold value associated with subsurface hydrocarbons; and a computer readable medium for storing the determined ratio. 
   
   
       16 . The information handling system of  claim 15  wherein the processor is configured to apply a data transform to the naturally occurring low frequency background seismic data to obtain a vertical spectral component and to obtain at least one horizontal spectral component. 
   
   
       17 . The information handling system of  claim 15  wherein the predetermined threshold value for the ratio is equal to or greater than 1.5. 
   
   
       18 . The information handling system of  claim 15  wherein the ratio is determined for vertical spectral component frequencies and horizontal spectral component frequencies between 1 Hz and 5 Hz. 
   
   
       19 . The information handling system of  claim 15  further comprising: a graphical display coupled to the processor and configured to present a view of the ratio as a function of position, wherein the processor is configured to generate the view by contouring the ratio over an area associated with the seismic data. 
   
   
       20 . A system for subsurface hydrocarbon reservoir mapping comprising: a machine readable medium storing naturally occurring low frequency background seismic data and map values associated with the seismic data; and a processor configured to determine a plurality of map values associated with the seismic data, each map value determined from a ratio of a vertical spectral component to at least one horizontal spectral component of the seismic data, wherein the processor is further configured to determine map values greater than a predetermined threshold representative of a subsurface reservoir. 
   
   
       21 . The system of  claim 20  wherein the processor is further configured to apply a data transform to naturally occurring low frequency background seismic data to obtain a vertical spectral component and to obtain at least one horizontal spectral component. 
   
   
       22 . The system of  claim 20  wherein the processor is further configured to contour the ratio over a geographical area associated with the seismic data to create values for a map of a subsurface hydrocarbon reservoir. 
   
   
       23 . The system of  claim 20  further comprising: a graphical display coupled to the processor and configured to present a view of the ratio as a function of position, wherein the processor is configured to generate the view by contouring the ratio data. 
   
   
       24 . The system of  claim 23  wherein the view generated by the processor differentiates map values greater than a preselected value from other map values. 
   
   
       25 - 30 . (canceled) 
   
   
       31 . The system of  claim 20  wherein a data transform used to determine a spectral component is selected from the group consisting of: discrete Fourier transform, continuous Fourier transform, continuous wavelet transform, and discrete wavelet transform.