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[2018-05-01]


[2018-05-01]

Monitoring of cyclic steam stimulation by inversion of surface tilt measurements

Inversion of induced reservoir pore-pressure changes from deformation measurements may provide a potentially powerful reservoir-monitoring tool if the issues of measurement noise, uncertainty in model parameterization, and numerical accuracy and stability can be resolved. We discuss inverting injection-induced reservoir pressure changes from observable surface deformations using a linear poroelastostatic model of a subsurface reservoir.


Monitoring of cyclic steam stimulation by inversion of surface tilt measurements


[2017-08-17]


[2017-08-17]

Multiscale time-domain time-lapse full-waveform inversion with a model-difference regularization

Another one of my upcoming SEG 2017 talks in Houston.


Presentation Date: Wednesday, September 27, 2017
Start Time: 10:10 AM
Location: 361F

We present a multiscale time-lapse full-waveform inversion (4D FWI) technique based on a cascaded time-domain simultaneous inversion of multiple surveys with a model-difference regularization. In our cascaded approach, different model scales are recovered using different objective functions and regularization penalties. We apply our method to a synthetic example, and demonstrate a robust recovery of production-induced velocity changes in the presence of repeatability issues and errors in the amplitude information.


Multiscale time-domain time-lapse full-waveform inversion with a model-difference regularization (full article PDF)


[2017-08-17]


[2017-08-17]

Time-domain broadband phase-only full-waveform inversion with implicit shaping

My upcoming talk at SEG 2017 in Houston.


Presentation Date: Monday, September 25, 2017
Start Time: 3:30 PM
Location: 361F

We propose a new full-waveform inversion (FWI) method that approximates broadband tomographic inversion and has a reduced sensitivity to errors in the observed-data amplitude information. The method is based on fitting the observed-data phase spectrum while automatically shaping forward-modeled wave fields to the observed-data amplitude spectrum. This is achieved by using a phase-only objective function that allows broadband time-domain inversion of the observed-data phase information. We demonstrate our methodís reduced sensitivity to dynamic information under the traveltime approximation, and compare the new objective function to the normalized L2 FWI objective function in an experiment on synthetic data with a frequency-dependent attenuation.


Time-domain broadband phase-only full-waveform inversion with implicit shaping (full article PDF)


[2017-03-11]


[2017-03-11]

Full Waveform Inversion for Reservoir Monitoring

Check out extended abstract of the talk given at the First EAGE Workshop on Practical Reservoir Monitoring, 6-9 March 2017, Amsterdam, The Netherlands. Fluid movement in the subsurface and the associated changes in saturation translate into changes of the subsurface elastic parameters. Stress changes, whether due to fluid extraction/injection or deformation such as slips on preexisting faults, affect the elastic parameters as well. Detecting and inverting the imprint of changing subsurface elastic parameters on seismic data lies at the heart of time-lapse seismic imaging for reservoir monitoring. In this work we demonstrate that the recently proposed technique of simultaneous time-lapse full-waveform inversion with a model-difference regularization can be used to extract high-resolution information on magnitude and location of subsurface velocity and stress anomalies, potentially providing valuable input for reservoir monitoring and assessment of geohazards.


Amsterdam 2017 Extended Abstract


[2016-12-01]


[2016-12-01]

Time-lapse Inverse Theory with Applications

My recent Geophysics paper that presents a systematic development of "Time-lapse Inverse Theory". The proposed theory and derived computational techniques provide a framework for stable and accurate resolution of model changes in the presence of measurement noise and repeatability issues, even for inaccurate baseline inversions. While primary application of the proposed method is 4D seismic analysis, the underlying theory and mathematical apparatus of multi-scale inversion allows for a wide range of generalizations for applications in Natural Sciences and Engineering....display full article text


Time-lapse Inverse Theory with Applications (full paper in PDF)


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