Seismic velocity modeling

A system comprising:

• one or more computers;
• and
• one or more storage devices communicatively coupled to the one or more computers, wherein the one or more storage devices store instructions that, when executed by the one or more computers, cause the one or more computers to perform operations comprising:
• obtaining a current velocity model for a geological region that characterizes, for each of a plurality of spatial locations in the geological region, a respective velocity of seismic waves traveling through the spatial location;
• and
• obtaining:
• (i) pre-stack seismic data comprising a plurality of seismic traces characterizing the geological region, and (ii) post-stack seismic data generated based on the pre-stack seismic data using a seismic stacking technique;
• for each of a plurality of iterations:
• identifying a plurality of reflection events from the post-stack seismic data and the current velocity model, wherein each reflection event corresponds to:
• (i) a position of a seismic source that transmits a seismic wave, (ii) a local reflection surface in the geological region, and (iii) a position of a seismic receiver that receives a reflection of the seismic wave from the local reflection surface;
• determining a respective observed travel time for each of the plurality of reflection events, comprising, for each reflection event:
• identifying a respective seismic trace included in the pre-stack seismic data based on the reflection event;
• and
• determining the respective observed travel time for the reflection event based at least in part on kinematic features derived from the respective seismic trace included in the pre-stack seismic data;
• and
• updating the current velocity model based at least in part on the observed travel times of the plurality of reflection events.

One or more non-transitory computer storage media storing instructions that when executed by one or more computers cause the one or more computers to perform operations comprising:

• obtaining a current velocity model for a geological region that characterizes, for each of a plurality of spatial locations in the geological region, a respective velocity of seismic waves traveling through the spatial location;
• obtaining:
• (i) pre-stack seismic data comprising a plurality of seismic traces characterizing the geological region, and (ii) post-stack seismic data generated based on the pre- stack seismic data using a seismic stacking technique;
• and
• for each of a plurality of iterations:
• identifying a plurality of reflection events from the post-stack seismic data and the current velocity model, wherein each reflection event corresponds to:
• (i) a position of a seismic source that transmits a seismic wave, (ii) a local reflection surface in the geological region, and (iii) a position of a seismic receiver that receives a reflection of the seismic wave from the local reflection surface;
• determining a respective observed travel time for each of the plurality of reflection events, comprising, for each reflection event:
• identifying a respective seismic trace included in the pre-stack seismic data based on the reflection event;
• and
• determining the respective observed travel time for the reflection event based at least in part on kinematic features derived from the respective seismic trace included in the pre-stack seismic data;
• and
• updating the current velocity model based at least in part on the observed travel times of the plurality of reflection events.