Variable aperture estimation using bottom-up ray tracing

Patent metadata

Field	Value
Publication number	US-11255993-B2
Application number	US-201816189711-A
Country	US
Kind code	B2
Filing date	Nov 13, 2018
Priority date	Dec 28, 2017
Publication date	Feb 22, 2022
Grant date	Feb 22, 2022

Abstract

A method and apparatus for imaging seismic data includes obtaining an initial model of a subsurface formation, wherein the model includes a plurality of nodes that form at least part of a grid; an initial dip value for the nodes; and a set of origin coordinates for each of the nodes; performing bottom-up ray tracing for each node in the model, resulting in a set of arrival coordinates for each node; identifying a plurality of gathers from the seismic data; for each gather: calculating a set of midpoint coordinates; defining a midpoint vicinity surrounding the set of midpoint coordinates; identifying the nodes having arrival coordinates within the midpoint vicinity; and estimating a unique aperture for each of the gathers based on the respective origin coordinates; storing the estimated apertures in a table; and generating a subsurface volume or image with subsurface reflectors determined with apertures of the respective gathers.

First claim

The invention claimed is:

1. A method of imaging seismic data for a subsurface formation comprising:
obtaining an initial model of the subsurface formation, wherein the initial model comprises:
a plurality of nodes that form at least part of a grid;
an initial dip value for the plurality of nodes; and
a set of origin coordinates for each of the plurality of nodes;

performing bottom-up ray tracing for each node in the initial model, resulting in a set of arrival coordinates for each node;
identifying a plurality of gathers from the seismic data;
for each gather from the seismic data:
calculating a set of midpoint coordinates;
defining a midpoint vicinity surrounding the set of midpoint coordinates;
identifying nodes having arrival coordinates within the midpoint vicinity; and
estimating a unique aperture for each of the plurality of gathers based on the respective origin coordinates;

storing the estimated aperture for each gather in an aperture table; and
generating a subsurface volume or image with subsurface reflectors determined with the estimated apertures of the respective gathers.

2. The method of claim 1 , further comprising causing a well to be drilled at a location determined from the subsurface volume or image.

3. The method of claim 1 , further comprising performing Full Wavefield Inversion with the aperture table to image the seismic data.

4. The method of claim 3 , further comprising:
obtaining additional seismic data for the subsurface formation, wherein the additional seismic data is acquired at a different point in time from the imaged seismic data;
performing Full Wavefield Inversion with the aperture table to image the additional seismic data; and
comparing the imaged seismic data with the imaged additional seismic data to identify changes in the subsurface formation over time.

5. The method of claim 1 , further comprising generating an aperture padding map.

6. The method of claim 5 , further comprising applying smoothing techniques to the aperture padding map.

7. The method of claim 1 , wherein the plurality of nodes represent a subset of chosen points from the initial model.

8. The method of claim 7 , wherein the subset of chosen points consists of equally-spaced points.

9. The method of claim 1 , wherein the initial model is a coarse-grid velocity model.

10. The method of claim 1 , wherein the plurality of gathers are common shot gathers.

11. The method of claim 1 , further comprising identifying a hydrocarbon potential of the subsurface formation.

12. A non-transitory computer readable medium comprising executable instructions that when executed cause a processor to:
obtain an initial model of a subsurface formation, wherein the initial model comprises:
a plurality of nodes that form at least part of a grid;
an initial dip value for the plurality of nodes; and
a set of origin coordinates for each of the plurality of nodes;

perform bottom-up ray tracing for each node in the initial model, resulting in a set of arrival coordinates for each node;
identify a plurality of gathers from a seismic data set;
for each gather from the seismic data set:
calculate a set of midpoint coordinates;
define a midpoint vicinity surrounding the set of midpoint coordinates;
identify nodes having arrival coordinates within the midpoint vicinity; and
estimate a unique aperture for each of the plurality of gathers based on the respective origin coordinates;

store the estimated aperture for each gather in an aperture table; and
generate a subsurface volume or image with subsurface reflectors determined with the estimated apertures of the respective gathers.

13. The non-transitory computer readable medium of claim 12 , wherein the executable instructions further cause the processor to invert the seismic data set with the aperture table to produce a graphical representations of the seismic data set.

14. A seismic data analysis system comprising:
a processor; and
a display configured to display graphical representations of a seismic data set, wherein the seismic data analysis system is configured to:
obtain an initial model of a subsurface formation, wherein the initial model comprises:
a plurality of nodes that form at least part of a grid;
an initial dip value for the plurality of nodes; and
a set of origin coordinates for each node;

perform bottom-up ray tracing for each node in the initial model, resulting in a set of arrival coordinates for each node;
identify a plurality of gathers from the seismic data set;
for each gather from the seismic data set:
calculate a set of midpoint coordinates;
define a midpoint vicinity surrounding the set of midpoint coordinates;
identify nodes having arrival coordinates within the midpoint vicinity; and
estimate a unique aperture for each of the plurality of gathers based on the respective origin coordinates;

store the estimated aperture for each gather in an aperture table; and
invert the seismic data set with the aperture table to produce a graphical representations of the seismic data set.

15. The seismic data analysis system of claim 14 , wherein the seismic data analysis system is further configured to generate a subsurface volume or image with subsurface reflectors determined with the estimated apertures of the respective gathers.

Assignees

• Brytik Valeriy V
• Tang Yaxun
• Gaines David
• Song Fuxian
• Spirkin Anton
• Exxonmobil Upstream Res Co

Inventors

• Brytik Valeriy V
• Tang Yaxun
• Gaines David
• Song Fuxian
• Spirkin Anton

Classifications

• G01V2210/671

  Raytracing · CPC title

• G01V1/368

  Inverse filtering · CPC title

• G01V1/345

  Visualisation of seismic data or attributes, e.g. in 3D cubes · CPC title

• G01V1/282 Primary

  Application of seismic models, synthetic seismograms · CPC title

• G01V1/303

  for determining velocity profiles or travel times · CPC title