Spectral-Domain Computation of Fields Radiated by Sources in Non-Birefringent Anisotropic Media

Sainath, Kamalesh; Teixeira, F.L.

doi:10.1109/lawp.2015.2444099

Cited by 7 publications

(1 citation statement)

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“…Why this recommendation? Although pseudo-analytical techniques are available to compute fields when the receiver and/or transmitter are located in such layers [66], the main reason is to eliminate spurious discontinuities of the normal (z in our case) electric and magnetic field components manifest when the source (or, as can be anticipated from EM reciprocity, the receiver) traverse a boundary separating a true formation layer and a coating slab [47]. Second, the thickness d of the coating slabs must also be adjusted to ensure the coating layer just beneath the mth interface does not cross over into the coating layer just above the (m + 1)st interface.…”

Section: Tilted Layer Modelingmentioning

confidence: 99%

Full-wave algorithm to model effects of bedding slopes on the response of subsurface electromagnetic geophysical sensors near unconformities

Sainath

Teixeira

2016

Journal of Computational Physics

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We propose a full-wave pseudo-analytical numerical electromagnetic (EM) algorithm to model subsurface induction sensors, traversing planar-layered geological formations of arbitrary EM material anisotropy and loss, which are used, for example, in the exploration of hydrocarbon reserves. Unlike past pseudo-analytical planar-layered modeling algorithms that impose parallelism between the formation's bed junctions however, our method involves judicious employment of Transformation Optics techniques to address challenges related to modeling relative slope (i.e., tilting) between said junctions (including arbitrary azimuth orientation of each junction). The algorithm exhibits this flexibility, both with respect to loss and anisotropy in the formation layers as well as junction tilting, via employing special planar slabs that coat each "flattened" (i.e., originally tilted) planar interface, locally redirecting the incident wave within the coating slabs to cause wave fronts to interact with the flattened interfaces as if they were still tilted with a specific, user-defined orientation. Moreover, since the coating layers are homogeneous rather than exhibiting continuous material variation, a minimal number of these layers must be inserted and hence reduces added simulation time and computational expense. As said coating layers are not reflectionless however, they do induce artificial field scattering that corrupts legitimate field signatures due to the (effective) interface tilting. Numerical results, for two half-spaces separated by a tilted interface, quantify error trends versus effective interface tilting, material properties, transmitter/receiver spacing, sensor position, coating slab thickness, and transmitter and receiver orientation, helping understand the spurious scattering's effect on reliable (effective) tilting this algorithm can model. Under the effective tilting constraints suggested by the results of said error study, we finally exhibit responses of sensors traversing threelayered media, where we vary the anisotropy, loss, and relative tilting of the formations and explore the sensitivity of the sensor's complex-valued measurements to both the magnitude of effective relative interface tilting (polar rotation) as well as azimuthal orientation of the effectively tilted interfaces.

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Section: Tilted Layer Modelingmentioning

confidence: 99%