Look-ahead vsp elastic waveform inversion
AssigneeSchlumberger Technology Corporation
InventorsYu CHEN, Takashi MIZUNO
Life of this patent
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Abstract
Systems and methods for processing vertical seismic profile (VSP) data based on an elastic waveform inversion (EWI). The EWI uses P-wave or S-wave velocity and density information above a total depth of a well and the VSP data to invert parameters including a one dimensional (ID) depth, P-wave or S-wave velocity, density, and attenuation below the total depth. The EWI includes computing a template reflection and searching potential reflections using a cross-correlation between the template reflection and the VSP data. The EWI includes a grid search used to invert the parameters for each subsurface layer below the total depth and a fine-tuning to optimize the inverted parameters based on a downhill simplex method.
Claims20
A system, comprising:
- a memory configured to store at least a template-based search algorithm, a grid search algorithm, and a downhill simplex algorithm;
- one or more processors configured to:
- receive a plurality of input models associated with a subsurface layer above a total depth of a well;
- calculate a reflection template based at least in part on the plurality of input models;
- receive vertical seismic profile (VSP) data acquired at the well;
- employ the template-based searching algorithm to detect a plurality of reflections below the total depth of the well, wherein the plurality of reflections are associated with the subsurface layer and a plurality of subsequent subsurface layers below the subsurface layer;
- based on the plurality of reflections, employ the grid search algorithm to determine a depth of the subsurface layer and a set of parameters associated with the plurality of subsequent subsurface layers;
- employ the downhill simplex algorithm to invert the set of parameters for the plurality of subsequent subsurface layers simultaneously;
- and
- generate a plurality of output models comprising the set of parameters being inverted.
A method, comprising:
- receiving a plurality of input models associated with a subsurface layer above a total depth of a well;
- calculating a reflection template based at least in part on the plurality of input models;
- receiving vertical seismic profile (VSP) data acquired at the well;
- determining a number and polarities of a plurality of reflections below the total depth of the well based on the vertical seismic profile (VSP) data and the reflection template, wherein the plurality of reflections are associated with the subsurface layer and a plurality of subsequent subsurface layers below the subsurface layer;
- determining a depth of the subsurface layer and a set of parameters associated with the plurality of subsequent subsurface layers based on the plurality of reflections;
- inverting the set of parameters for the plurality of subsequent subsurface layers simultaneously;
- and
- generating a plurality of output models comprising the set of parameters being inverted.
A non-transitory computer-readable medium comprising instructions that, when executed by one or more processors, cause the one or more processors to:
- receive a plurality of input models associated with a subsurface layer above a total depth of a well;
- receive vertical seismic profile (VSP) data acquired at the well;
- calculate a reflection template based at least in part on the plurality of input models;
- detect a plurality of reflections below the total depth of the well, wherein the plurality of reflections are associated with the subsurface layer and a plurality of subsequent subsurface layers below the subsurface layer;
- determine a number and polarities of the plurality of reflections based on the vertical seismic profile (VSP) data and the reflection template;
- determine a depth of the subsurface layer and a set of parameters associated with the plurality of subsequent subsurface layers based on the plurality of reflections;
- invert the set of parameters for the plurality of subsequent subsurface layers simultaneously;
- and
- generate a plurality of output models comprising the set of parameters being inverted.
Dependencies are inferred from the claim text.