Exxonmobil Upstream Research Company

Other

Charlie Jing

Dennis E Willen

Thomas A Dickens

John E Anderson

Rebecca L Saltzer

Anoop A Mullur

Dmitriy A Pavlov

Jan Schmedes

Christopher J DiCaprio

Garrett M Leahy

Jerome R Krebs

Ramesh Neelamani

Christine E Krohn

David L Hinkley

Peter Traynin

Scott C Hornbostel

Xinyou Lu

Warren S Ross

James J Carazzone

Olivier M Burtz

Valeriy V Brytik

Hong Zhao

Eva-Maria Rumpfhuber

Jim J Carazzone

Jason Shaw

Rebecca Saltzer

Christopher Dicaprio

A method for efficient use of a computing system of parallel processors to perform inversion of geophysical data, or joint inversion of two or more data types. The method includes assigning at least one control processor to control sequence of operations and reduce load imbalance, assigning a group of one or more processors dedicated to updating one or more model parameters, and assigning another group of one or more processors dedicated to forward modeling simulated data.

Inversion of geophysical data on computer system having parallel processors

Method for generating an effective, efficient, and stable absorbing boundary condition in finite-difference calculations, such as model-simulation of predicted seismic data. The top surface and optionally the bottom surface of the computational domain or grid are treated with one or more layers of PML (), preferably 1D PML, assuming an orthorhombic medium in the PML implementation (). The side surfaces are handled with one or more ABC layers (). Further advantages may be realized by tapering earth model symmetry axis on the top and bottom of the model toward the vertical (). The invention provides a beneficial compromise between reducing artifacts in the image or physical property model and computational efficiency and stability.

Efficient and stable absorbing boundary condition in finite-difference calculations

A method, including: obtaining, with a processor, a seismic image of a subsurface region from a computer memory; predicting, with a processor, a dip of the seismic image of the subsurface region; and removing, with a processor, noise or artifacts from the seismic image of the subsurface region by applying a dip guided Laplacian filter, wherein the removing generates another seismic image of the subsurface region that has noise or artifacts removed relative to the seismic image of the subsurface region.

Method of removing noise in seismic reverse-time migration

Method for estimating geological properties in a subsurface region using multiple types of geophysical data (). An initial physical properties modelis constructed. Some parameters in the model are frozen () and optionally portions of the model wave number and spatial domains () and the data frequency and data time domains (), are also frozen. Then, a joint inversion () of the multiple data types is performed to calculate an update to the model only for the portions that are not frozen. The converged model () for this inversion is used as a new starting model, and the process is repeated (), possibly several times, unfreezing more parameters and data each time until the desired spatial and parameter resolution () has been achieved.

Domain freezing in joint inversion

Method for adaptive weighting of geophysical data types in iterative joint inversion to speed convergence and aid escape from local minima of the penalty (objective) function. Two or more geophysical data sets () representing a region of interest are obtained, and are jointly inverted to infer models of the physical properties that affect the particular types of data used. The misfit for each data type is a weighted tem in the penalty function (). The invention involves changing the weights () as the iteration cycles progress when the iteration convergence criteria are satisfied (), to see if they remain satisfied () with the modified penalty function.

Adaptive weighting of geophysical data types in joint inversion

Method for joint inversion of geophysical data to obtain 3-D models of geological parameters for subsurface regions of unknown lithology. Two or more data sets of independent geophysical data types are obtained, e.g. seismic and electromagnetic. Then they are jointly inverted, using structural coupling, to infer geophysical parameter volumes, e.g. acoustic velocity and resistivity. Regions of common lithology are next identified based on similar combinations of geophysical parameters. Then a joint inversion of the multiple data types is performed in which rock physics relations vary spatially in accordance with the now-known lithology, and 3-D models of geological properties such as shale content and fracture density are inferred. The computational grid for the last inversion may be defined by the lithology regions, resulting in average geological properties over such regions, which may then be perturbed to determine uncertainty in lithologic boundaries.

Joint inversion with unknown lithology

Method for building a seismic imaging velocity model, particularly at the boundary of a geo-body, and to perform imaging, by taking into account the elastic reflection and scattering information in the seismic data. More illumination of the base and flanks (or in general, the boundary) of the geo-body is provided from (a) inside of the geo-body (), with elastically converted waves at the geo-body boundary used (via elastic RTM flooding); and (b) from outside the geo-body (), by utilizing prism waves with elastic RTM to handle the phase correctly in the model building step. The increased illumination and correct elastic phase are used for geo-body boundary determination. Elastic RTM is then applied (), along with the elastically derived imaging velocity model, to maximize the use of elastic energy in the imaging step, and to obtain the correct image with the correct phase.

Seismic velocity model updating and imaging with elastic wave imaging

Method for using seismic data from earthquakes to address the low frequency lacuna problem in traditional hydrocarbon exploration methods. Seismometers with frequency response down to about 1 Hz are placed over a target subsurface region in an array with spacing suitable for hydrocarbon exploration (). Data are collected over a long (weeks or months) time period (). Segments of the data () are identified with known events from earthquake catalogs (). Those data segments are analyzed using techniques such as traveltime delay measurements () or receiver function calculations () and then are combined with one or more other types of geophysical data acquired from the target region, using joint inversion (-) in some embodiments of the method, to infer physical features of the subsurface indicative of hydrocarbon potential or lack thereof ().

Hydrocarbon detection with passive seismic data

There is provided a system and method for creating a physical property model representative of a physical property of a region. An exemplary method comprises transforming information from a model domain that represents the physical property model into simulated data in a data domain, the data domain comprising simulated data and measured data representative of a plurality of observations of the region. The exemplary method also comprises determining an areal misfit between the simulated data and the measured data representative of the plurality of observations of the region. The exemplary method additionally comprises performing an evaluation of the areal misfit based on known criteria. The exemplary method comprises adjusting data in the data domain or information in the model domain corresponding to a region in the model domain based on the evaluation of the areal misfit.

System and method for providing a physical property model

Method for rapid inversion of data from a controlled-source electromagnetic survey of a subterranean region. Selected () common-receiver or common-source gathers of the data are reformed into composite gathers () by summing their data. Each composite gather is forward modeled (in the inversion process) with multiple active source locations (). Computer time is reduced in proportion to the ratio of the total number of composite gathers to the total number of original common-receiver or common-source gathers. The data may be phase encoded to prevent data cancellation. Methods for mitigating loss of far offset information by data overlap in the summing process are disclosed.

Rapid inversion of electromagnetic reconnaissance survey data

Method for transforming electromagnetic survey data acquired from a subsurface region to a subsurface resistivity model indicative of hydrocarbon accumulations or lack thereof. In one embodiment, data are selected for two or more non-zero frequencies (), and a structural model of the region is developed based on available geological or geophysical information. An initial resistivity model of the region is developed based on the structural model (), and the selected data are inverted to update the resistivity model () by iterative forward modeling () and minimizing an objective function () including a term measuring mismatch between model synthesized data and measured survey data, and another term being a diffusive regularization term that smoothes the resistivity model (). The regularization term can involve a structure or geology constraint, such as an anisotropic resistivity symmetry axis or a structure axis, determined from the a priori information ().

Method for geophysical imaging

Method for determining receiver orientation angles in a controlled source electromagnetic survey, by analyzing the survey data. For a given survey receiver, two data subsets are selected. (). The two subsets may be from two offset ranges that are geometrically symmetrical relative to the receiver location. Alternatively, the second subset may be a computer simulation of actual survey data. In either instance, an orientation is assumed for the receiver (), and that orientation is used to compare component data from the two subsets that can be expected to match if the assumed orientation angle(s) is (are) correct (). The mismatch is ascertained, and the assumed orientation is adjusted () and the process is repeated.

Method for determining orientation of electromagnetic receivers

Method for reducing the time needed to perform geophysical inversion by using simultaneous encoded sources in the simulation steps of the inversion process. The geophysical survey data are prepared by encoding () a group of source gathers (), using for each gather a different encoding signature selected from a set () of non-equivalent encoding signatures. Then, the encoded gathers are summed () by summing all traces corresponding to the same receiver from each gather, resulting in a simultaneous encoded gather. (Alternatively, the geophysical data are acquired from simultaneously encoded sources.) The simulation steps needed for inversion are then calculated using a particular assumed velocity (or other physical property) model () and simultaneously activated encoded sources using the same encoding scheme used on the measured data. The result is an updated physical properties model () that may be further updated () by additional iterations.

Iterative inversion of data from simultaneous geophysical sources

A method for suppressing measurement system signature, or artifacts, that arise when controlled source electromagnetic survey data are inverted to obtain a resistivity image of a subsurface region. The method involves identifying regions () where the image has low or rapidly varying sensitivity to data acquired by a given receiver, typically regions close to and under the given receiver. Then, in the iterative inversion process where a resistivity model is updated to minimize an objective function, the model update is modified () to reduce the impact of such low sensitivity regions on the update.

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Houston, TX, United States of America

Charlie Jing