Method to calculate acquisition illumination

A method for obtaining seismic acquisition illumination, comprising:

• placing a plurality of source locations and a plurality of receivers in a survey field, wherein the plurality of receivers comprise one or more zero-offset receivers, each zero-offset receiver is placed at one of the plurality of source locations;
• deploying a plurality of shots in the survey field, each shot is deployed at one of the plurality of source locations and generates seismic waves that cover a volume of earth formation;
• collecting seismic signals from the volume of earth formation using the plurality of receivers;
• applying one or more decimation factors to the plurality of receivers to obtained a set of decimated receivers;
• calculating a wavefield propagation for each of the set of decimated receivers;
• calculating an illumination of each of the plurality of source locations according to the following equation:
• D
• s
• i
• ≈
• G
• s
• i
• 2
• *
• ∑
• j
• =
• 1
• Nri
• mx
• *
• my
• ⁢
• (
• G
• r
• j
• 2
• )
• wherein Dsi is an illumination for shot number i among the plurality of shots, the volume of earth formation has a grid size (Nx, Ny, Nz) in the xyz coordinate system, Gsi and Grj are respectively the wavefield propagation of the source location at which shot number i is deployed and the wavefield propagation of the receivers in the volume of earth formation, Nri is a total number of receivers located in the volume of earth formation, mx and my are decimation factors in X- and Y- directions, respectively;
• and
• summing up illuminations of all of the plurality of source locations to obtain an illumination of the survey field, wherein the illumination of the survey field is used to improve images outputted from a reverse time migration (RTM) process.

A method for calculating seismic acquisition illumination, comprising:

• conducting a seismic survey to collect seismic signals from a survey field, wherein the seismic survey deploys a plurality of shots at a corresponding number of source locations;
• performing reverse time migration (RTM) of seismic signals collected in the seismic survey;
• obtaining a wavefield propagation for each of the plurality of source locations;
• assigning the wavefield propagation for each of the plurality of source locations to be the wavefield propagation for a zero-offset receiver located at a corresponding source location;
• calculating an illumination of each of the plurality of source locations according to the following equation:
• D
• s
• i
• ≈
• G
• s
• i
• 2
• *
• ∑
• j
• =
• 1
• Nri
• mx
• *
• my
• ⁢
• (
• G
• r
• j
• 2
• )
• wherein Dsi is an illumination for shot number i among the plurality of shots, the volume of earth formation has a grid size (Nx, Ny, Nz) in the xyz coordinate system, Gsi and Grj are respectively the wavefield propagation of the source location at which shot number i is deployed and the wavefield propagation of the receivers in the volume of earth formation, Nri is a total number of receivers located in the volume of earth formation, mx and my are decimation factors in X and Y directions, respectively;
• and
• summing up illuminations of all of the plurality of source locations to obtain an illumination of the survey field.