Seismic data processing

A non-transitory computer-readable medium having stored thereon computer-executable instructions which, when executed by a computer, cause the computer to:

• receive an earth model that comprises elastic properties;
• receive seismic data for a region of interest, wherein the seismic data were acquired in a seismic survey;
• determine at least one exclusion criterion that provides one or more rules for selecting shot points in the acquired seismic data;
• determine sparse seismic data using statistical sampling based at least in part on the at least one exclusion criterion and the acquired seismic data;
• determine simulated seismic data based at least in part on the earth model for the region of interest and shot points corresponding to the sparse seismic data;
• determine an objective function that represents a mismatch between the sparse seismic data and the simulated seismic data;
• determine a gradient of the objective function;
• determine a smoothed gradient of the objective function based at least in part on at least one of the at least one exclusion criterion;
• perform a search based at least in part on the smoothed gradient wherein the search comprises a search direction and a step size found by a line search method;
• update values of the elastic properties of the earth model based at least in part on the search to generate an updated earth model wherein the step size corresponds to an amount of change for elastic properties as model parameters in the updated earth model;
• and
• based at least in part on the updated earth model, determine a presence of hydrocarbons in the region of interest.

A system comprising:

• a processor;
• memory accessible to the processor;
• processor-executable instructions stored in the memory executable to instruct the system to:
• receive an earth model that comprises elastic properties;
• receive seismic data for a region of interest, wherein the seismic data were acquired in a seismic survey;
• determine at least one exclusion criterion that provides one or more rules for selecting shot points in the acquired seismic data;
• determine sparse seismic data using statistical sampling based at least in part on the at least one exclusion criterion and the acquired seismic data;
• determine simulated seismic data based at least in part on the earth model for the region of interest and shot points corresponding to the sparse seismic data;
• determine an objective function that represents a mismatch between the sparse seismic data and the simulated seismic data;
• determine a gradient of the objective function;
• determine a smoothed gradient of the objective function based at least in part on at least one of the at least one exclusion criterion;
• perform a search based at least in part on the smoothed gradient wherein the search comprises a search direction and a step size found by a line search method;
• update values of the elastic properties of the earth model based at least in part on the search to generate an updated earth model wherein the step size corresponds to an amount of change for elastic properties as model parameters in the updated earth model;
• and
• based at least in part on the updated earth model, determine a presence of hydrocarbons in the region of interest.