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Dumitrescu C.C.,Sensor Geophysical Ltd. | Lines L.,University of Calgary
Journal of Seismic Exploration | Year: 2010

The focus of this study is the southern portion of the Long Lake lease located approximately 40 km southeast of Fort McMurray, Alberta, Canada. The lease area is roughly 25,000 hectares and contains over 8 billion barrels of bitumen in place. For heavy oil projects, the Vp/Vs ratio is a good lithology discriminator, and the objective of this paper is to predict a Vp/Vs ratio volume based on neural network analysis. Neural network estimation of reservoir properties has proven effective in significantly improving accuracy and vertical resolution in the interpretation of the reservoir. The strength of a neural network analysis is the ability to determine nonlinear relationships between logs and several seismic attributes. The result is a new lithology calibrated attribute that, when co-rendered with edge detector attributes, can predict the presence of muddy intervals responsible for impacting the propagation of steam through the reservoir, thereby allowing us to more effectively describe enhanced oil recovery in the reservoir. © 2010 Geophysical Press Ltd.

Zhang C.,Sensor Geophysical Ltd | Ulrych T.J.,University of British Columbia
Geophysics | Year: 2010

In seismic exploration, received seismic signals usually experience absorption during their propagation. However, seismic migration algorithms seldom take into account seismic absorption in their implementations. We have investigated the blurring effect in migrated images that occurs when using a regular migration algorithm to migrate those seismic data with absorption. The blurring functions can be calculated using a numerical method; and for layered media, a fast algorithm exists for updating the blurring function from one time step to another. The deblurring process is formulated as a problem of multidimensional nonstationary deconvolution. We use a least-squares inverse scheme to remove the absorption blurring effect and in turn refocus migrated images. The refocusing algorithm is stable, and convergence is achieved with a few iterations at each wavenumber. Experiments on synthetic and real data show that our refocusing technique is valid when compensating for seismic absorption after migration. © 2010 Society of Exploration Geophysicists.

Cary P.W.,Sensor Geophysical Ltd.
SEG Technical Program Expanded Abstracts | Year: 2011

5D interpolation with the MWNI algorithm has become a commonly used tool in the processing of land 3D seismic surveys because of its ability to regularize acquisition geometries before processes such as prestack time migration. Claims that it is able to overcome spatial sampling limitations in the original data are based upon 1) the fact that it includes data in four spatial dimensions at once during the interpolation process and 2) the fact that a procedure of applying filters and bootstrapping weights from low to high frequencies (Hermann et al., 2000) can overcome the effects of spatial aliasing when it occurs. These two claims are examined here. It is found that claim 1) is valid as long as the four coordinates are carefully chosen so that the poorly sampled coordinates appear to be randomly subsampled. Simple tests show that the procedure in claim 2) is able to overcome aliasing only in very simple situations, but it performs poorly in more realistic, complicated situations of spatial aliasing. © 2011 Society of Exploration Geophysicists.

White D.J.,Geological Survey of Canada | Secord D.,Sensor Geophysical Ltd. | Malinowski M.,Polish Academy of Sciences
Geophysics | Year: 2012

A 17-km 2 3D-3C seismic survey was conducted within the active Flin Flon mining camp located in Manitoba, Canada. The results for the vertical component data as obtained by conventional dip-moveout and prestack time-migration processing sequences and comparison of images from the 3D seismic volume with the subsurface location of known ore zones and the mine horizon generally showed a very good correlation. A well-defined diffraction response from the shallowest ore zone was observed in the unmigrated data with a corresponding phase reversal in the migrated data at the transition from intact ore to backfilled ore zone. The geometry of unmined and backfilled ore zones compared well with strong reflection amplitudes on corresponding cross sections to depths of ∼1000m. At greater depths, the ore zone had a weaker seismic signature due to a combination of effects, including imaging conditions, ore composition, and the increased presence of rhyolite within the mine horizon. In the case of the deeper ore zones that were characterized by low signal-to-noise levels, poststack migration was important in focusing weak ore-related reflections. The 3D data demonstrated the feasibility of detecting and accurately locating ore zones as small as a few million tons to depths of up to 1500 m. © 2012 Society of Exploration Geophysicists.

Cary P.W.,Sensor Geophysical Ltd. | Zhang A.,Sensor Geophysical Ltd.
73rd European Association of Geoscientists and Engineers Conference and Exhibition 2011: Unconventional Resources and the Role of Technology. Incorporating SPE EUROPEC 2011 | Year: 2011

Converted-wave pre-stack time migration is an important step in multicomponent seismic data processing not only for its ability to produce a better PS image, but also as a preparation of the data for further analysis such as joint PP, PS inversion. Technically, its implementation is similar to, but not the same as, P-wave migration because the down-going P-wave and up-going S-wave travel at different speeds and are affected by anisotropy differently. Some technical issues such as velocity and anisotropy parameterization, anti-aliasing, reflection amplitude preservation, random noise attenuation and 5D interpolation prior to converted wave (P-S) pre-stack time migration need to be handled appropriately in order to optimize the migrated image.

Zhang J.,University of Manitoba | Zhang J.,Sensor Geophysical Ltd. | Frederiksen A.W.,University of Manitoba
Tectonophysics | Year: 2013

A teleseismic data set from the POLARIS project is used to obtain 3-D images of southern Ontario using two imaging techniques: scattering tomography and common-conversion-point stacking. The resulting images reveal a layered crust, the layering being interrupted by discontinuities associated with major crustal-scale faulting. Breaks in crustal continuity and Moho deflections associated with the Ottawa-Bonnechère Graben indicate that the graben is associated with faulting on a whole crust scale. We also detect similar discontinuities across the Mississauga Domain, supporting the previous interpretation that the domain is bounded by crustal-scale faults. We locate discontinuous sub-lithospheric negative-polarity arrivals which indicate complex three-dimensional structures within the lithosphere and may be associated with subduction remnants or a mid-lithosphere discontinuity. © 2013 Elsevier B.V.

Dumitrescu C.,Sensor Geophysical Ltd. | Lines L.,University of Calgary
72nd European Association of Geoscientists and Engineers Conference and Exhibition 2010: A New Spring for Geoscience. Incorporating SPE EUROPEC 2010 | Year: 2010

Well logs are considered by geophysicists as hard data for seismic reservoir characterization. In the last few years, lots of wells have been drilled for heavy oil delineation in different fields. Also, many core samples were measured in the laboratory and a wide scattering of velocity within heavy oil sand was observed (Han et al., 2007). Some of the factors controlling the velocities in heavy oil sands are: rock texture, pore fluid properties and the interaction between pore fluids and the rock frame at different temperatures. All of these have been investigated by laboratory measurements. In this paper we analyze and investigate the effect of rock texture on Vp/Vs ratio from well logs in two different heavy oil reservoirs located in the Athabasca basin in northern Alberta, Canada. © 2010, European Association of Geoscientists and Engineers.

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