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US 9,804,281 B2Granted
Migration velocity analysis method for VSP data
AssigneeHalliburton Energy Services, Inc.
InventorsMark E. Willis, Yue Du
Life of this patent
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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.
Claims17
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 to image the vertical seismic profile data, 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 to estimate velocity updates, comprising:
- deteanining 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;
- detemiining 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 wherein the method is performed by a control module and the velocity model is used to create an accurate image of a subsurface reservoir proximate to a wellbore during drilling or operation of a well.
16 more elements
A system comprising:
- at least one seismic source for directing seismic energy towards a subterranean region during operation of the system;
- at least two geophones each for obtaining vertical seismic profile data during operation of the system;
- and
- a control module programmed to:
- perform a depth migration to image the vertical seismic profile data, 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 estimation;
- perform a simulated time migration to estimate velocity updates, 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 simulated time migration until the first degree of accuracy exceeds a pre-determined value wherein the velocity model is used to create an accurate image of a subsurface reservoir proximate to a wellbore during drilling or operation of a well.
20 more elements
Dependencies are inferred from the claim text.