Detection and Removal of Delayed Seismic Travel Times Produced by Velocity Inversions

A data processing system detecting and removing effects of seismic velocity inversions in near surface earth layers from seismic survey data in the form of a set of seismic survey traces obtained from records of seismic energy travel from seismic sources to an array of seismic detector geophones during a seismic survey, comprising:

• a memory storing computer operable instructions causing the data processing system to detect and remove the effects of the seismic velocity inversions in the near surface earth layers from seismic survey data;
• a processor performing under control of the computer operable instructions stored in the memory steps of:
• (a) determining a measure of travel times of the seismic traces of the first break dataset as a function of offset of the detector geophones from the seismic sources;
• (b) forming a measure of travel time at individual offset locations in the seismic survey;
• (c) determining a measure of rate of travel of the seismic energy at the individual offset locations;
• (d) removing from the first break dataset seismic traces at the individual offset locations indicating the presence of seismic velocity inversions based on the determined measure of the rate of travel of the seismic energy to form a corrected first break dataset;
• (e) forming a seismic velocity model of seismic velocity as a function of depth the subsurface formation based on the corrected first break data set;
• (f) forming an image of the subsurface strata by performing a tomographic inversion on the corrected first break dataset;
• and
• the memory further receiving for storage the formed model of seismic velocity as a function of depth the subsurface formation based on the corrected first break data set.

A data storage device having stored in a non-transitory computer readable medium computer operable instructions for causing a data processing system comprising a memory and a processor to detect and remove effects of seismic velocity inversions in near surface earth layers from seismic survey data in the form of a set of seismic survey traces obtained from records of seismic energy travel from seismic sources to an array of seismic detector geophones during a seismic survey, the instructions stored in the data storage device causing the data processing system to perform the following steps:

• storing in the memory computer operable instructions causing the data processing system to detect and remove effects of seismic velocity inversions in near surface earth layers from seismic survey data;
• performing in the processor, under control of the stored computer operable instructions, steps to detect and remove effects of seismic velocity inversions in near surface earth layers, comprising:
• (a) determining a measure of travel times of the seismic traces of the first break dataset as a function of offset of the detector geophones from the seismic sources:
• (b) forming a measure of travel time at individual offset locations in the seismic survey;
• (c) determining a measure of rate of travel of the seismic energy at the individual offset locations;
• (d) removing from the first break dataset seismic traces at the individual offset locations indicating the presence of seismic velocity inversions based on the determined measure of the rate of travel of the seismic energy to form a corrected first break dataset;
• (e) forming a seismic velocity model of seismic velocity as a function of depth the subsurface formation based on the corrected first break data set;
• and
• (f) forming an image of the subsurface strata by performing a tomographic inversion on the corrected first break dataset.