Seismic data processing including internal multiple modeling without subsurface information

Patent metadata

Field	Value
Publication number	US-9366775-B2
Application number	US-201313739489-A
Country	US
Kind code	B2
Filing date	Jan 11, 2013
Priority date	Jan 12, 2012
Publication date	Jun 14, 2016
Grant date	Jun 14, 2016

Abstract

A system and method are disclosed for substantially eliminating the influence of internal multiples when seismic mapping under-water geographical areas of interest without a priori knowledge of subsurface information. The system and method iteratively locate multiple-generating horizons for predicting internal multiples and uses a lower-higher-lower relationship between the multiple generating horizons. The system and method provide an appropriate and cost-effective means for internal multiple attenuation without subsurface information.

First claim

We claim:

1. A method for substantially eliminating an influence of internal multiple reflections in determining undersea geography in a geographical area of interest without a priori knowledge of subsurface information, the method comprising:
(a) generating a series of seismic signals by a plurality of source transmitters;
(b) receiving raw data at a plurality of receivers based on the generated series of seismic signals;
(c) creating a set of M windows that corresponds physically to a space below the plurality of receivers and includes a geographical area of interest;
(d) assigning received raw data to respective ones of the set of windows based on received time of the raw data, to generate M window data frames, wherein a first uppermost window data frame incorporates raw data that corresponds to an uppermost wavefield closest to the plurality of receivers, and an M th window data frame incorporates raw data that corresponds to a lowermost wavefield farthest from the plurality of receivers;
(e) iteratively generating an internal multiple model, using a sliding set of three window data frames, wherein for each iteration, the internal multiple model includes a first product of a convolution of data from a first window data frame and a second window date frame, and a correlation of data from a third window data frame with the first product;
(f) summing all of the iteratively generated internal multiple models to create a complete internal multiple model, and continuing the summing until all of the window data frames have been used; and
(g) subtracting the complete internal multiple model from the raw data to substantially eliminate the influence of internal multiples in determining the geography of the geographical area of interest.

2. The method according to claim 1 , further comprising:
processing the raw data to suppress surface related multiples prior to generating the internal multiple model.

3. The method according to claim 2 , wherein the step of processing to suppress surface related multiples comprises:
using a method of surface related multiple elimination to suppress the surface multiples.

4. The method according to claim 1 , further wherein the step of determining the set of M windows is based on travel time of the series of seismic signals from the plurality of sources to the plurality of receivers, and further wherein each of the M window time frames is substantially similar in duration.

5. The method according to claim 1 , wherein the step of generating an internal multiple model using window data from a first set of three window data frames includes performing the following equation:

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wherein
in each iteratively defined set of three window data frames, a higher wavefield generated by data in the uppermost window data frame is defined as Pw j , a first lower wavefield generated by data in the second window data frame is defined as P wk , and a second lower wavefield generated by data in the third window data frame is defined as P wl l, and further wherein,
P wj is a source side wavefield that represents an downward reflection of an internal multiple reflected from the first window,
P wk is a source side wavefield that represents an upward reflection of an internal multiple reflected from the second window, and
P wl is an receiver side wavefield that represents a upward reflection of an internal multiple reflected from the third window.

6. The method according to claim 5 , wherein each of the M windows has as length and depth component, and wherein the length component is less than or equal to a distance between a first source and a last source, and further wherein
the depth component correlates to a first number of samples that correlates to a first depth in distance, and further wherein
adjacent windows overlap by a second number of samples less than the first number of samples, which corresponds to an overlap in depth defined as a second depth, and still further wherein
the second depth is less than the first depth, and still further wherein
for an increasing value of M the depth of the window increases.

7. The method according to claim 5 , wherein each of the plurality of sets of windows satisfies a pseudo-depth monotonicity condition of lower-higher-lower windows, wherein Pwj is a higher window, and P wk and P wl are both lower windows.

8. A system for substantially eliminating an influence of internal multiple reflections in determining undersea geography in a geographical area of interest without a priori knowledge of subsurface information, the system comprising:
(a) a plurality of source transmitters configured to generate a series of seismic signals;
(b) a plurality of receivers configured to receive raw data based on the generated series of seismic signals; and
(c) a processor configured to,
create a set of M windows that corresponds physically to

Assignees

• Cggveritas Services Sa
• Cgg Services Sa

Inventors

• Hung Barry
• Wang Min

Classifications

• G01V2210/56

  De-ghosting; Reverberation compensation · CPC title

• G01V1/364 Primary

  Seismic filtering (G01V1/37 takes precedence) · CPC title

• G01V1/38 Primary

  specially adapted for water-covered areas (G01V1/28 takes precedence) · CPC title

• G01V1/30 Primary

  Analysis (G01V1/50 takes precedence) · CPC title