Migration Velocity Analysis Method for VSP Data
AssigneeHalliburton Energy Services, Inc.
InventorsMark E. Willis, Yue Du
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Abstract
Vertical Seismic Profile (VSP) analysis is a technique commonly used to conduct geophysical surveys of subterranean features. The processing of a VSP includes several steps, usually including a final step of depth migration. In order to properly process and image VSP data using depth migration, a velocity model of the subsurface must be known or derived. A variety of criteria can be used to ascertain whether the velocity used for migration is accurate.
Claims32
A method of processing vertical seismic profile data using depth migration comprising:
- obtaining vertical seismic profile data for each of at least two geophones;
- migrating the vertical seismic profile data of each geophone using a first velocity model to produce migrated data for each geophone;
- stacking the migrated data of each geophone to produce a stacked migrated trace having one or more events for each geophone;
- determining a degree of accuracy of the first velocity model based on at least one of the following characteristics:
- a flatness of each event in the migrated traces, a complexity of each event in the migrated traces, a curvature of each event in the migrated traces, and an alignment of peak amplitudes of the events in the migrated traces;
- and
- selecting a second velocity model based on the degree of accuracy of the first trial velocity model.
A method of processing vertical seismic profile data using simulated time migration comprising:
- obtaining vertical seismic profile data for each of at least two different geophones;
- determining data related to a residual moveout based on one or more arrival time values and a first trial velocity value;
- determining a degree of accuracy of the first trial velocity value;
- selecting a second trial velocity value based on the degree of accuracy of the first velocity model;
- and
- determining an interval velocity based on the second trial velocity value.
A method of processing vertical seismic profile data comprising:
- obtaining vertical seismic profile data for each of at least two geophones;
- performing a depth migration, comprising:
- migrating the vertical seismic profile data of each geophone using a velocity model to produce migrated data for each geophone;
- stacking the migrated data of each geophone to produce a stacked migrated trace having one or more events for each geophone;
- determining a first degree of accuracy of the velocity model based on at least one of the following characteristics:
- a flatness of each event in the migrated traces, a complexity of each event in the migrated traces, a curvature of each event in the migrated traces, and an alignment of peak amplitudes of the events in the migrated traces;
- and
- selecting at least a portion of the vertical seismic profile data based on the degree of accuracy determination;
- performing a simulated time migration comprising:
- determining data related to a residual moveout corresponding to the portion of the vertical seismic profile data, based on one or more arrival time values and a first trial velocity value;
- determining a second degree of accuracy of the first trial velocity value;
- selecting a second trial velocity value based on the second degree of accuracy of the first velocity value;
- determining an interval velocity based on the second trial velocity value;
- and
- updating the velocity model based on the second trial velocity value;
- and
- repeating the depth migration and the simulated time migration until the first degree of accuracy exceeds a pre-determined value.
Dependencies are inferred from the claim text.