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Michael W Dunham - One of the best experts on this subject based on the ideXlab platform.
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application of 3d marine controlled source electromagnetic finite element Forward Modeling to hydrocarbon exploration in the flemish pass basin offshore newfoundland canada
Geophysics, 2018Co-Authors: Michael W Dunham, Seyedmasoud Ansari, Colin G FarquharsonAbstract:In recent years, marine controlled-source electromagnetic (CSEM) surveying has become an effective supplemental interpretation tool to the seismic reflection method to help mitigate risk in an offshore exploration setting. Interpretation of marine CSEM data is commonly achieved via finite-difference inversions on rectilinear meshes, which has its merits, but the results are typically very low resolution. The alternative is Forward Modeling, which requires a model to be known a priori, but the detail of the model can be created to reflect realistic geologic conditions. What is typically seen in the literature are applications of EM Forward Modeling codes to synthetic, and sometimes complex synthetic models. However, what the literature is missing is an application that overcomes the challenges of applying a 3D Forward Modeling method to real models constructed from real information. We present an application of a 3D marine CSEM finite-element Forward Modeling method to the Bay du Nord prospect in the Flemi...
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application of 3d marine controlled source electromagnetic finite element Forward modelling to hydrocarbon exploration in the flemish pass basin offshore newfoundland and labrador canada
Geophysics, 2018Co-Authors: Michael W DunhamAbstract:The Flemish Pass Basin located 450 km east offshore St. John’s, Newfoundland, Canada has seen an increase in exploration activity over the past decade. Risk mitigation is important for deepwater drilling, and marine CSEM interpretation techniques have the potential help de-risk reservoirs in an offshore exploration setting. This thesis uses 3D marine CSEM finite-element Forward Modeling with comparisons to measured data to (1) show the finite-element Forward Modeling code can synthesize data from real complex models built using unstructured grids, and (2) use this Forward Modeling technique to provide additional support and interpretations for two offshore exploration fields in the Flemish Pass Basin: Mizzen and Bay du Nord. In summary, the finite-element Forward Modeling code was able to synthesize good quality results from complex models built from real data. Sensitivity to the Mizzen reservoir was found, but it is likely below the detectability threshold. This is likely a result of the reservoir being too small and containing uneconomic volumes of hydrocarbons. However, the Bay du Nord reservoir is much larger and is predicted to contain much higher volumes of hydrocarbons. Numerical analysis confirmed a much greater sensitivity to the Bay du Nord reservoir exists.
Steven Constable - One of the best experts on this subject based on the ideXlab platform.
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marine controlled source electromagnetic sounding 1 Modeling and experimental design
Journal of Geophysical Research, 1996Co-Authors: A H Flosadottir, Steven ConstableAbstract:Numerical Forward Modeling, predicting an observable response given a mathematical representation of the Earth, is an important component of practical exploration work. In addition, derivatives which relate changes in response to changes in the Earth model are useful for experimental design and are a crucial element of linearized inversion techniques. Differentiation of kernels followed by numerical integration using a fast Hankel transform provides an efficient combination of Forward and sensitivity Modeling for frequency-domain horizontal electric dipole-dipole sounding over a layered seafloor. Our code is validated against an independent Forward Modeling technique using a mode analysis and against central difference derivatives. Efficiency is important in the application of regularized inversion to large data sets; we give an example from the East Pacific Rise, requiring 2000 elements in the Jacobian matrix. We illustrate the use of Forward Modeling and discrete analogs of the Frechet kernels to provide aid to physical intuition and experimental design in the context of the electrical conductivity of the oceanic lithosphere. By using the most favorable parts of range-frequency space, experiments using current technology should be capable of distinguishing a thicker, less resistive, from a thinner, more resistive “lithospheric resistor” layer.
A H Flosadottir - One of the best experts on this subject based on the ideXlab platform.
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marine controlled source electromagnetic sounding 1 Modeling and experimental design
Journal of Geophysical Research, 1996Co-Authors: A H Flosadottir, Steven ConstableAbstract:Numerical Forward Modeling, predicting an observable response given a mathematical representation of the Earth, is an important component of practical exploration work. In addition, derivatives which relate changes in response to changes in the Earth model are useful for experimental design and are a crucial element of linearized inversion techniques. Differentiation of kernels followed by numerical integration using a fast Hankel transform provides an efficient combination of Forward and sensitivity Modeling for frequency-domain horizontal electric dipole-dipole sounding over a layered seafloor. Our code is validated against an independent Forward Modeling technique using a mode analysis and against central difference derivatives. Efficiency is important in the application of regularized inversion to large data sets; we give an example from the East Pacific Rise, requiring 2000 elements in the Jacobian matrix. We illustrate the use of Forward Modeling and discrete analogs of the Frechet kernels to provide aid to physical intuition and experimental design in the context of the electrical conductivity of the oceanic lithosphere. By using the most favorable parts of range-frequency space, experiments using current technology should be capable of distinguishing a thicker, less resistive, from a thinner, more resistive “lithospheric resistor” layer.
Motohide Tamura - One of the best experts on this subject based on the ideXlab platform.
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precision radial velocity measurements by the Forward Modeling technique in the near infrared
arXiv: Earth and Planetary Astrophysics, 2020Co-Authors: Teruyuki Hirano, Masayuki Kuzuhara, Takayuki Kotani, Masashi Omiya, Tomoyuki Kudo, Hiroki Harakawa, Sebastien Vievard, Takashi Kurokawa, Jun Nishikawa, Motohide TamuraAbstract:Precision radial velocity (RV) measurements in the near infrared are a powerful tool to detect and characterize exoplanets around low-mass stars or young stars with higher magnetic activity. However, the presence of strong telluric absorption lines and emission lines in the near infrared that significantly vary in time can prevent extraction of RV information from these spectra by classical techniques, which ignore or mask the telluric lines. We present a methodology and pipeline to derive precision RVs from near-infrared spectra using a Forward Modeling technique. We applied this to spectra with a wide wavelength coverage (Y, J, and H bands, simultaneously), taken by the InfraRed Doppler (IRD) spectrograph on the Subaru 8.2-m telescope. Our pipeline extracts the instantaneous instrumental profile of the spectrograph for each spectral segment, based on a reference spectrum of the laser-frequency comb that is injected into the spectrograph simultaneously with the stellar light. These profiles are used to derive the intrinsic stellar template spectrum, which is free from instrumental broadening and telluric features, as well as model and fit individual observed spectra in the RV analysis. Implementing a series of numerical simulations using theoretical spectra that mimic IRD data, we test the pipeline and show that IRD can achieve 100$ per pixel at 1000 nm. Dependences of RV precision on various stellar parameters (e.g., $T_{\rm eff}$, $v\sin i$, [Fe/H]) and the impact of telluric-line blendings on the RV accuracy are discussed through the mock spectra analyses. We also apply the RV-analysis pipeline to the observed spectra of GJ 699 and TRAPPIST-1, demonstrating that the spectrograph and the pipeline are capable of an RV accuracy of <3 m s$^{-1}$ at least on a time scale of a few months.
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scexao charis near infrared direct imaging spectroscopy and Forward Modeling of κ and b a likely young low gravity superjovian companion
The Astronomical Journal, 2018Co-Authors: Motohide Tamura, Thayne Currie, Timothy D Brandt, Taichi Uyama, Eric L Nielsen, Sarah Blunt, Olivier Guyon, Christian MaroisAbstract:We present SCExAO/CHARIS high-contrast imaging/JHK integral field spectroscopy of κ And b, a directly imaged low-mass companion orbiting a nearby B9V star. We detect κ And b at a high signal-to-noise ratio and extract high-precision spectrophotometry using a new Forward-Modeling algorithm for (A-)LOCI complementary to KLIP-FM developed by Pueyo et al. κ And b's spectrum best resembles that of a low-gravity L0–L1 dwarf (L0–L1γ). Its spectrum and luminosity are very well matched by 2MASS J0141-4633 and several other 12.5–15 M_J free-floating members of the 40 Myr old Tuc–Hor Association, consistent with a system age derived from recent interferometric results for the primary, a companion mass at/near the deuterium-burning limit (13_(-2)^(+12) M_J), and a companion-to-primary mass ratio characteristic of other directly imaged planets (q ~ 0.005_(-0.001)^(+0.005)). We did not unambiguously identify additional, more closely orbiting companions brighter and more massive than κ And b down to ρ ~ 0farcs3 (15 au). SCExAO/CHARIS and complementary Keck/NIRC2 astrometric points reveal clockwise orbital motion. Modeling points toward a likely eccentric orbit: a subset of acceptable orbits include those that are aligned with the star's rotation axis. However, κ And b's semimajor axis is plausibly larger than 55 au and in a region where disk instability could form massive companions. Deeper high-contrast imaging of κ And and low-resolution spectroscopy from extreme adaptive optics systems such as SCExAO/CHARIS and higher-resolution spectroscopy from Keck/OSIRIS or, later, IRIS on the Thirty Meter Telescope could help to clarify κ And b's chemistry and whether its spectrum provides an insight into its formation environment.
Colin G Farquharson - One of the best experts on this subject based on the ideXlab platform.
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application of 3d marine controlled source electromagnetic finite element Forward Modeling to hydrocarbon exploration in the flemish pass basin offshore newfoundland canada
Geophysics, 2018Co-Authors: Michael W Dunham, Seyedmasoud Ansari, Colin G FarquharsonAbstract:In recent years, marine controlled-source electromagnetic (CSEM) surveying has become an effective supplemental interpretation tool to the seismic reflection method to help mitigate risk in an offshore exploration setting. Interpretation of marine CSEM data is commonly achieved via finite-difference inversions on rectilinear meshes, which has its merits, but the results are typically very low resolution. The alternative is Forward Modeling, which requires a model to be known a priori, but the detail of the model can be created to reflect realistic geologic conditions. What is typically seen in the literature are applications of EM Forward Modeling codes to synthetic, and sometimes complex synthetic models. However, what the literature is missing is an application that overcomes the challenges of applying a 3D Forward Modeling method to real models constructed from real information. We present an application of a 3D marine CSEM finite-element Forward Modeling method to the Bay du Nord prospect in the Flemi...