This paper presents the formulations for calculating electromagnetic (EM) fields in multilayered generalized anisotropic media. Maxwell's equations are written into a first-order differential (in <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$z$ </tex-math></inline-formula> ) equation concerning transverse electric and magnetic field components spectral domain. The can be solved to obtain EM homogeneous...

Evaluation of hydraulic fractures has been under intensive study since the last decade. Among published works, only a few have included casing effects. This paper focuses on through-casing electromagnetic (EM) induction imaging method that evaluates with enhanced contrasts. An experimental system and an inverse scattering algorithm are presented. The laboratory scaled is built for feasibility EM fracture evaluation. To develop algorithm, outside boreholes metallic modeled by novel hybrid...

Abstract The goal of this project is to develop techniques for monitoring hydraulic fractures in reservoirs by injecting electrically conductive, dielectric, or magnetically permeable proppants. contrasts between the properties proppants and subsurface provided basis imaging using geophysical methods. initial experiments focused on a series small, shallow fractures; however, methods applicable oil-field fractures. began screening different proppant types laboratory numerical analyses that...

Abstract In April 2017, the Advanced Energy Consortium (AEC) successfully completed data collection for a proof-of-concept demonstration of remote mapping hydraulically fractured networks using electromagnetic (EM) proppant additives and variety EM tools configurations. This field-pilot was conducted at Devine Test Site, located approximately 50 miles southwest San Antonio, Texas, managed by Bureau Economic Geology (Bureau) The University Texas Austin. objective ongoing integrated research...

Hydraulic fracturing is a technique to fracture rocks by pumping high-pressure fluid into segment of well. The created fractures help release hydrocarbon resource such as oil or natural gas from the rock. A group small-scaled field tests are performed Advanced Energy Consortium investigate feasibility using galvanic electromagnetic (EM) method map fractures. injected proppants designed with high EM contrasts (e.g., conductivity and permittivity) generate detectable signals at electrode-type...

Nanoparticles designed with high electric conductivity and magnetic permeability are injected into oil reservoirs to enhance fluid flow monitoring. The movement of nanoparticles the in a porous medium can be modeled by solving transport equation. In this research, three-dimensional spectral-element time-domain method based on Gauss-Lobatto-Legendre polynomials is employed solve equation obtain nanoparticle (NP) concentration distribution reservoirs. This shows spectral accuracy, as error...

This letter extends the axisymmetric version of efficient forward and inverse algorithms to characterize reconstruct arbitrary 3-D fractures in a cased borehole environment. We improve our previous hybrid distorted Born approximation stabilized biconjugate gradient fast Fourier transform method as modeling algorithm that can significantly reduce computational cost modeling. The bounding constraints model parameter transformation functions are introduced variational iterative effectively...

To further improve the computational efficiency of existing wave equation-based discontinuous Galerkin time-domain (DGTD) method for modeling electrically small structures, weighted Laguerre polynomials are incorporated to span fields in temporal domain, which finally results a set recursive linear equations related be solved. Compared with conventional time integration methods, proposed approach requires much fewer iterations and thus shows considerable improvement terms efficiency. With...

As one of the most important nondestructive characterization techniques, electromagnetic (EM) methods can be used in subsurface fracture detection, especially for hydraulic evaluation unconventional petroleum exploration and development. The multiscale nature long but extremely thin 3-D fractures is difficult conventional EM modeling such as finite element method (FEM) numerical simulation. problem becomes even more challenging when effects tilted borehole, casing, planar stratified media...

This article presents an efficient method for calculating the scattered electromagnetic (EM) fields from anisotropic objects embedded in general multilayers, both with arbitrary anisotropy. The electric field integral equation (EFIE) is derived based on dyadic Green's functions multilayers. volume (VIE) involves a convolution form between function and equivalent sources. To accelerate computation, fast Fourier transform technique (FFT) adopted which reduces computational cost O(N <sup...

The discontinuous Galerkin finite-element time-domain (DG-FETD) method with implicit time integration has an advantage in modeling electrically fine-scale electromagnetic problems. Based on domain decomposition methods, it avoids the direct inversion of a large system matrix as conventional FETD method; by employing integration, obviates extremely small time-step interval to maintain stability explicit schemes. curl-conforming basis functions for electric field intensity E and...

In many applications, electromagnetic scattering from inhomogeneous objects embedded in multiple layers needs to be simulated numerically. The straightforward solution by the method of moments (MoM) for volume integral equation is computationally expensive. Due shift-invariance and correlation properties layered-medium Green's functions, stabilized-biconjugate gradient fast Fourier transform (BCGS-FFT) has been developed greatly reduce computational complexity MoM, but so far this limited...

Triaxial induction logging tools have been widely applied to formation characterization due their sensitivity electric anisotropy. To model triaxial logs in multilayered general anisotropic formations, where the anisotropy can be arbitrary, an analytical method is compute tool responses. For method, Maxwell’s equations spectral domain are written into a compact first-order differential equation. The equation solved obtain spectral-domain fields, which transformed spatial through inverse...

Formation anisotropy in complicated geophysical environments can have a significant impact on data interpretation of electromagnetic surveys. To facilitate full 3D modeling arbitrary anisotropy, we adopted an [Formula: see text]-version geometric multigrid preconditioned finite-element method (FEM) based vector basis functions. By using structured mesh, instead unstructured one, our conveniently construct the restriction and prolongation operators for implementation, then recursively coarsen...

This letter extends the discontinuous Galerkin frequency domain (DGFD)-based decomposition method (DDM) to model open borehole environment accurately with a newly developed hierarchical sudoku mesh. Both and mud invasion effects can be modeled by this framework efficiently. Furthermore, deep reading measurements conveniently inserting arbitrarily shaped objects into mesh; capability distinguish cavity saturated either oil or water different borehole-object distances are then studied for tool...

Hydraulic fracturing is critical for unconventional oil and gas production. Recently, galvanic methods, including borehole-to-surface surface-to-borehole electromagnetic have been applied in hydraulic fracture evaluation. However, conventional computational methods require huge cost to simulate the common model, which consists of a long cased borehole, 3-D thin fractures, an underground stratified medium. More seriously, modeling both vertical horizontal energized boreholes layered media...

Mud-filtrate invasion happens commonly during the drilling and has a great effect on triaxial induction logging data. A good description of can help achieve better understanding formation. mud-filtrate constrained inversion approach is thus introduced to simultaneously invert for sand fraction (F <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">sand</sub> ), irreducible water saturation (S xmlns:xlink="http://www.w3.org/1999/xlink">wr</sub>...

With the ever increasing number of research on hydraulic fracture aiming at improved oil production, forward and inverse solvers based electromagnetic method to detect reveal properties have become an important subject research. Most existing methods are developed simulate well logging model, such as Method Moments (MoM) Born Approximation. Those advantages reconstruct geometrical information formation. However, they not fast enough memory cost large. Moreover, when those used fractures,...