On the electromagnetic fields produced by marine frequency domain controlled sources
Chave, Alan D.
MetadataShow full item record
In recent years, marine controlled source electromagnetics (CSEM) has found increasing use in hydrocarbon exploration due to its ability to detect thin resistive zones beneath the seafloor. Although it must be recognized that the quantitative interpretation of marine CSEM data over petroleum-bearing formations will typically require 2-D surveys and 2-D or 3-D modelling, the use of the 1-D approximation is useful under some circumstances and provides considerable insight into the physics of marine CSEM. It is the purpose of this paper to thoroughly explore the 1-D solutions for all four fundamental source types—vertical and horizontal, electric and magnetic dipole (VED, HED, VMD and HMD)—using a set of canonical reservoir models that encompass brine to weak to strong hydrocarbon types. The paper introduces the formalism to solve the Maxwell equations for a 1-D structure in terms of independent and unique toroidal and poloidal magnetic modes that circumscribe the salient diffusion physics. Green's functions for the two modes from which solutions for arbitrary source current distributions can be constructed are derived and used to obtain the electromagnetic (EM) fields produced by finite VED, HED, VMD and HMD sources overlying an arbitrary 1-D electrical structure. Field behaviour is analysed using the Poynting vector that represents the time-averaged flow of energy through the structure and a polarization ellipse decomposition of the triaxial seafloor EM field that is a complete field description. The behaviour of the two EM modes using unimodal VED and VMD sources is presented. The paper closes by extending these results to the bimodal HED and HMD sources.
Author Posting. © The Author, 2009. This article is posted here by permission of John Wiley & Sons for personal use, not for redistribution. The definitive version was published in Geophysical Journal International 179 (2009): 1429-1457, doi:10.1111/j.1365-246X.2009.04367.x.
Showing items related by title, author, creator and subject.
Szpak, Michal T.; Monteys, Xavier; O'Reilly, S.; Simpson, A. J.; Garcia, Xavier; Evans, Rob L.; Allen, C. C. R.; McNally, D. J.; Courtier-Murias, D.; Kelleher, B. P. (American Geophysical Union, 2012-01-19)Marine pockmarks are a specific type of seabed geological setting resembling craters or pits and are considered seabed surface expressions of fluid flow in the subsurface. A large composite pockmark on the Malin Shelf, off ...
Chave, Alan D.; Lezaeta, Pamela F. (John Wiley & Sons, 2007-07-29)The marginal distributions for the magnetotelluric (MT) magnitude squared response function (and hence apparent resistivity) and phase are derived from the bivariate complex normal distribution that describes the distribution ...
Development and application of a field instrumentation system for the investigation of surf zone hydrodynamics Greer, Matthew Noble (Massachusetts Institute of Technology and Woods Hole Oceanographic Institution, 1979-02)The development and application of an autonomous field instrumentation system consisting of four current meters and four wave gauges, along with a field monitor and digital recorder, is documented. The flow sensors are ...