Exxonmobil Upstream Research Company

Exxon Production Research Company

Exxon Upstream Research Co.

Dennis E Willen

Charlie Jing

Xinyou Lu

Thomas A Dickens

Dmitriy A Pavlov

Scott C Hornbostel

Rebecca L Saltzer

James J Carazzone

James W Juszczak

Leonard J Srnka

William A Schneider

Partha Sarathi Routh

Pavel Dimitrov

Leslie A Wahrmund

James A Rice

Yaxun Tang

Anoop A Mullur

Olivier M Burtz

Young Ho Cha

William Curry

Martin J Terrell

Philip J Summerfield

Louis M Houston

Kenneth E Green

William A Burnett

Roel Arevalo

David Y Wang

Adrian Ciucivara

Charles A Rendleman

Louis J Maher

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 and apparatus for hydrocarbon management including generating an image of a subsurface formation by: obtaining simultaneous-source survey data, an earth model, and a first and a second velocity model of the subsurface formation; generating synthetic survey data with at least one of the earth model, the first velocity model, and the second velocity model. The method and apparatus may include directly migrating the simultaneous-source survey data; migrating the synthetic survey data; and subtracting the migrated synthetic survey data from the migrated simultaneous-source survey data. The method and apparatus may include subtracting the synthetic survey data from the simultaneous-source survey data; and directly migrating the result of the subtraction. The method and apparatus may include generating an artifact-reduced image.

Direct migration of simultaneous-source survey data

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 estimating uncertainty in a physical property model generated by inverting measured geophysical data, for example, a resistivity model inferred from electromagnetic field data. The method involves as few as one data inversion coupled with a number of forward simulation. Alternative solutions (models) are generated by probing a perturbation space defined from a reduced model space, resulting from a principal component decomposition of the inverted model, and selecting some of the larger components. Statistical analysis techniques may be applied (to those alternative solutions remaining after thresholding) to generate quantitative uncertainty estimates applicable to the inverted model.

Uncertainty estimation of subsurface resistivity solutions

Embodiments described herein use stochastic inversion () in lower dimensions to form an initial model () that is to be used in higher-dimensional gradient-based inversion (). For example, an initial model may be formed from 1.5-D stochastic inversions, which is then processed () to form a 3-D model. Stochastic inversions reduce or avoid local minima and may provide an initial result that is near the global minimum.

Constructing resistivity models from stochastic inversion

Method for reducing a 3D joint inversion of at least two different types of geophysical data acquired by 3-D surveys to an equivalent set of 1D inversions. First, a 3D inversion is performed on each data type separately to the yield a 3-D model of a physical property corresponding to the data type. Next, a 1D model of the physical property is extracted at selected (x,y) locations. A 1D simulator and the 1D model of the physical property is then used at each of the selected locations to create a synthetic 1D data set at each location. Finally, the 1D synthetic data sets for each different type of geophysical data are jointly inverted at each of the selected locations, yielding improved values of the physical properties. Because the joint inversion is a 1D inversion, the method is computationally advantageous, while recognizing the impact of 3-D effects.

Reducing the dimensionality of the joint inversion problem

Systems and methods which provide electromagnetic subsurface mapping to derive information with respect to subsurface features whose sizes are near to or below the resolution of electromagnetic data characterizing the subsurface are shown. Embodiments operate to identify a region of interest () in a resistivity image generated () using electromagnetic data (). One or more scenarios may be identified for the areas of interest, wherein the various scenarios comprise representations of features whose sizes are near to or below the resolution of the electromagnetic data (). According to embodiments, the scenarios are evaluated (), such as using forward or inverse modeling, to determine each scenarios' fit to the available data and further to determine their geologic reasonableness (). Resulting scenarios may be utilized in a number of ways, such as to be substituted in a resistivity image for a corresponding region of anomalous resistivity for enhancing the resistivity image ().

Systems and methods for subsurface electromagnetic mapping

A method and apparatus of constructing a signal for a controlled source electromagnetic survey is described. In one embodiment, a method is described that includes determining a first waveform and a second waveform, the first waveform and second waveform related to a combined frequency spectrum and bandwidth associated with a geophysical survey line. Then, a signal is constructed by sequencing the first waveform with the second waveform. This signal may be utilized in a transmitter, which may be pulled by a vessel along the geophysical survey line.

Method and apparatus for utilizing time division multiple waveform transmitting

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

The invention is a method for suppressing noise in controlled source electromagnetic survey data based on the frequency content of the noise. The invention recognizes that some data variations across bins cannot be attributed to resistivity variations within the earth. This variation across bins constitutes a model of noise in such surveys, and the invention mitigates noises that obey this model. Noise varying rapidly in either space or time is removed by filtering temporal frequency domain data () with a low-pass filter () having a selected cutoff frequency ().

Method for spatial filtering of electromagnetic survey data

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.

Inversion of CSEM data with measurement system signature suppression

Method for identifying, determining and correcting source-related phase errors in data from a controlled source electromagnetic survey by using data from ordinary survey receivers, i.e. without benefit of source monitoring data. Abrupt anomalies indicating source malfunctions are identified () in the time domain by plotting time intervals between neighboring zero crossings or by zero-lag cross correlation between consecutive bins of receiver data, and the amount of the time error () can be determined by performing cross correlation between two bins on either side of an anomaly. In the frequency domain, transmitter anomalies can be identified by looking for discontinuities in plots of phase vs. offset, and the corrective phase shift can be determined by matching the phase on one side of the anomaly to that on the other side. A global time/phase shift () can be determined by using phase frequency-scaling behavior at near offsets.

Method for correcting the phase of electromagnetic data

The method for suppressing noise in the controlled seismic source electromagnetic survey data based on the frequency content of the noise () contained in the data. The invention recognizes that some data variations across bins cannot be attributed to resistivity variations within the earth. This variation across the bins constitutes a model of noise in such surveys, and the invention mitigates noise that obeys this model.

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Houston, TX, United States of America

Dennis E Willen