Exxonmobil Upstream Research Company

Conocophillips Company

Conoco Inc.

Exxonmobil Technology and Engineering Company

Partha Sarathi Routh

Jerome R Krebs

Anatoly I Baumstein

Spyridon K Lazaratos

Sunwoong Lee

Phil Dean Anno

Christine E Krohn

Ramesh Neelamani

Pavel Dimitrov

Ke Wang

Thomas A Dickens

Carey M Marcinkovich

Jerry Lee Kisabeth

Gregory Joseph Jorgensen

Ivan Chikichev

Nathan Downey

Dennis E Willen

John E Anderson

Warren S Ross

Yaxun Tang

Anoop A Mullur

Reeshidev Bansal

Olivier M Burtz

Young Ho Cha

Ganglin Chen

William Curry

Martin J Terrell

Robert T Baumel

Gboyega Ayeni

Musa Maharramov

David H Johnston

William A Burnett

Jacob A Violet

Haiyang Wang

Gopalkrishna Palacharla

Juan Andres Chavarria

Spyridon Lazaratos

Spyridon Lazarato

Methods for inversion of seismic data to infer subsurface physical property parameters, comprising constructing an inhomogeneous anisotropy model and/or inhomogeneous V/Vor V/Vmodel; and inverting the seismic data in a sequential or simultaneous approach to obtain at least one subsurface physical property parameter using an elastic inversion algorithm and the inhomogeneous anisotropy model and/or inhomogeneous V/Vor V/Vmodel. Constructing an inhomogeneous anisotropy model may comprise deriving geobodies from at least one of seismic facies analysis, regional geologic information, or seismically derived earth models; and adjusting at least one of &#x3b5;, &#x3b4;, &#x3b3;, or parameters of the elastic stiffness tensor matrix in a homogeneous anisotropy model in areas corresponding to the geobodies. Constructing an inhomogeneous V/Vor V/Vmodel may comprise deriving geobodies and adjusting values in a homogeneous V/Vor V/Vmodel in areas corresponding to the geobodies.

Elastic full wavefield inversion with refined anisotropy and V/Vmodels

Provided is a method for determining convergence in full wavefield inversion (FWI) of 4D seismic (time-lapse seismic: 3D seismic surveys acquired at different times with the first survey termed as the baseline and subsequent surveys termed as monitors). FWI applied to field seismic data includes iteratively solving for subsurface property models and model difference between monitor and baseline. Iteration occurs until the model difference is sufficiently converged. Rather than determining convergence by examining an entire subsurface region of the models and/or the model difference, subparts of the subsurface region models and/or the model difference are examined in order to determine convergence. For example, different regions behave differently, include the target reservoir region (where hydrocarbon is present) and the background region that is outside the target reservoir region. Thus, transforming the subregions of the models and/or the model difference and analyzing the transformations may indicate convergence of the overall model difference.

Method for determining convergence in full wavefield inversion of 4D seismic data

A method, including: determining, with a computer, point spread functions for a plurality of parameter locations by performing at least a portion of a first iteration of an iterative full wavefield inversion process; determining at least one property for each of the point spread functions; and evaluating a candidate survey design based on the at least one property for each of the point spread functions.

Method to design geophysical surveys using full wavefield inversion point- spread function analysis

A method, including: obtaining initial estimates of a plurality of subsurface parameters; obtaining a recorded wavefield decomposed into a plurality of discrete components; performing, with a computer, a cascaded inversion where the initial estimates of the subsurface parameters are individually updated, wherein each of the subsurface parameters are updated using a different discrete component of the recorded wavefield of the plurality of discrete components; and generating, with the computer, updated subsurface models from the cascaded inversion for each of the subsurface parameters.

Estimating multiple subsurface parameters by cascaded inversion of wavefield components

Method for selecting an acquisition geometry for a seismic survey based on ability to resolve an a priori velocity model. Two or more candidate acquisition geometries are selected (), differing in areal coverage and cost to perform. Then compute a synthetic seismic dataset for each geometry using a detailed geometrical reference model of the subsurface (). Invert the synthetic seismic datasets preferably using simultaneous source FWI, and preferably with Volume of Investigation constraints, to determine model updates (). Quantitatively assess the value of the additional traces in a fuller dataset relative to a subset (), using one or more statistics based on the accuracy of the updated models, such as improved match to the reference model, better fit of seismic data, or rate of change in improvement with iterations. Inversions may be cascaded for further efficiency ().

Seismic survey design using full wavefield inversion

Method for performing simultaneous encoded-source inversion of geophysical data to estimate parameters of a physical property model (), especially adapted for surveys without fixed-receiver acquisition geometry, such as marine seismic surveys with moving source and receivers. The encoding functions () used on the sources to generate one or more simultaneous encoded-source gathers of data (), as well as to simulate the same (), are orthogonal or pseudo-orthogonal with respect to cross-correlation. In addition, receivers are also encoded, with the receiver encoding being designed to make a given receiver less sensitive to sources to which it was not listening during the survey (). The encoding functions may be temporal bandpass filters differing one from another by central frequency, phase, or both. Efficiency of the method may be further improved by grouping several sources into a super-source, grouping the corresponding gathers into a super-gather, and then applying the above encoding strategy.

Orthogonal source and receiver encoding

Method for acquiring, at reduced acquisition cost, seismic data using simultaneous, field-encoded sources in the field (), and then constructing pseudo source-records () that better meet the requirements for using additional simultaneous computer-encoded sourcing for computer simulations or forward modeling () as part of () iterative FWI (Full Wavefield Inversion) or RTM (Reverse Time Migration), with additional reduction in computational costs. By better meeting the requirements of simultaneous sourcing for FWI or RTM (), artifacts and crosstalk are reduced in the output. The method can be used for marine streamer acquisition and other non-fixed spread geometries to acquire both positive and negative offsets and to mitigate the 'missing data' problem for simultaneous-source FWI. It can also be used for land data to overcome issues with moving spreads and long continuous records.

Simultaneous sourcing during both seismic acquisition and seismic inversion

Method for using the full wavefield (primaries, internal multiples and free-surface multiples) in inversion of marine seismic data, including both pressure and vertical velocity data (), to infer a subsurface model of acoustic velocity or other physical property. The marine seismic data are separated () into up-going () and down-going () wavefields, and both wavefields are inverted in a joint manner, in which the final model is impacted by both wavefields. This may be achieved by inverting both wavefields simultaneously (), or one after the other, i.e. in a cascaded approach (, or), for the subsurface properties ().

Full-wavefield inversion of primaries and multiples in marine environment

The invention includes a method for reducing noise in migration of seismic data, particularly advantageous for imaging by simultaneous encoded source reverse-time migration (SS-RTM). One example embodiment includes the steps of obtaining a plurality of initial subsurface images; decomposing each of the initial subsurface images into components; identifying a set of components comprising one of (i) components having at least one substantially similar characteristic across the plurality of initial subsurface images, and (ii) components having substantially dissimilar characteristics across the plurality of initial subsurface images; and generating an enhanced subsurface image using the identified set of components. For SS-RTM, each of the initial subsurface images is generated by migrating several sources simultaneously using a unique random set of encoding functions. Another embodiment of the invention uses SS-RTM for velocity model building.

Seismic data processing

Method for speeding up iterative inversion of seismic data () to obtain a subsurface model (), using local cost function optimization. The frequency spectrum of the updated model at each iteration is controlled to match a known or estimated frequency spectrum for the subsurface region, preferably the average amplitude spectrum of the subsurface P-impedance. The controlling is done either by applying a spectral-shaping filter to the source wavelet () and to the data () or by applying the filter, which may vary with time, to the gradient of the cost function (). The source wavelet's amplitude spectrum (before filtering) should satisfy D(f)=fI(f)W(f), where f is frequency, D(f) is the average amplitude spectrum of the seismic data, and I(f) is the average amplitude spectrum for P-impedance in the subsurface region () or an approximation thereof.

Convergence rate of full wavefield inversion using spectral shaping

Method for simultaneous full-wavefield inversion of gathers of source (or receiver) encoded geophysical data to determine a physical properties model () for a subsurface region, especially suitable for surveys where fixed receiver geometry conditions were not satisfied in the data acquisition. Simultaneous source separation () is performed to lessen any effect of the measured geophysical data's not satisfying the fixed-receiver assumption. A data processing step () coming after the simultaneous source separation acts to conform model-simulated data () to the measured geophysical data () for source and receiver combinations that are missing in the measured geophysical data.

Simultaneous source encoding and source separation as a practical solution for full wavefield inversion

Method for simultaneous full-wavefield inversion of gathers of source (or receiver) encoded () geophysical data () to determine a physical properties model () for a subsurface region, especially suitable for surveys where fixed-receiver geometry conditions were not satisfied in the data acquisition (). The inversion involves optimization of a cross-correlation objective function ().

Simultaneous source inversion for marine streamer data with cross-correlation objective function

Method for simultaneous full-wavefield inversion of gathers of source (or receiver) encoded geophysical data to determine a physical properties model for a subsurface region, especially suitable for surveys where fixed receiver geometry conditions were not satisfied in the data acquisition. First, a shallow time window of the data () where the fixed receiver condition is satisfied is inverted by simultaneous encoded () source inversion (). Then, the deeper time window of the data () is inverted by sparse sequential source inversion (), using the physical properties model from the shallow time window () as a starting model (). Alternatively, the shallow time window model is used to simulate missing far offset data () producing a data set satisfying the stationary receiver assumption, after which this data set is source encoded () and inverted by simultaneous source inversion ().

Hybrid method for full waveform inversion using simultaneous and sequential source method

A method and system of seismic data processing includes acquiring first and second prestack seismic datasets wherein the seismic datasets have a time-lapse relationship. The first prestack seismic dataset is inverted to determine a first source wavelet data set and a first reflectivity parameters data set. A perturbation data set is obtained by simultaneously minimizing an Lp-Norm between a portion of the first reflectivity parameters data set and reflectivity parameters for the second data set, an Lp-Norm between the first source wavelet data set and a source wavelet for the second data set and an Lp-Norm for data misfit between the first prestack seismic data set and the second prestack seismic data set. The perturbation dataset may be inverted for petrophysical parameters and for determining time-lapse changes in a reservoir.

Direct time lapse inversion of seismic data

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Boise, ID, United States of America

Partha Sarathi Routh