Cylindrical FDTD Analysis of LWD Tools Through Anisotropic Dipping-Layered Earth Media

• Published in: IEEE transactions on geoscience and remote sensing Vol. 45; no. 2; pp. 383 - 388
• Main Authors: Hwa Ok Lee, Teixeira, F.L.
• Format: Journal Article
• Language: English
• Published: New York, NY IEEE 01.02.2007; Institute of Electrical and Electronics Engineers; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Algorithm design and analysis; Algorithms; Anisotropic magnetoresistance; Anisotropy; Applied geophysics; borehole problems; Conductivity; Dipping; Drilling; Earth; Earth sciences; Earth, ocean, space; Exact sciences and technology; Finite difference methods; Finite difference time domain method; finite-difference time-domain (FDTD) method; Internal geophysics; logging-while-drilling (LWD) tools; Mathematical analysis; Media; Perfectly matched layers; Petroleum; Resistivity; Tensile stress; Time domain analysis; well logging; algorithms; models; exploration; electrical logging; finite difference analysis; layered media; anisotropy; logging-while-drilling (LWD) tools; exhibits; tensor; time domain analysis; boreholes; horizontal drilling; conductive media; well logging; electrical conductivity; finite-difference time-domain (FDTD) method; borehole problems
• ISSN: 0196-2892; 1558-0644
• DOI: 10.1109/TGRS.2006.888139

Electrical logging-while-drilling (LWD) tools are commonly used in oil and gas exploration to estimate the conductivity (resistivity) of adjacent Earth media. In general, Earth media exhibit anisotropic conductivities. This implies that when LWD tools are used for deviated and horizontal drilling, the resulting borehole problem may include dipping-layered media with dipping beds having full 3 times 3 conductivity tensors. To model this problem, we describe a 3-D cylindrical finite-difference time-domain (FDTD) algorithm extended to fully anisotropic conductive media and implemented with cylindrical perfectly matched layers to mimic open-domain problems. The 3-D FDTD algorithm is validated against analytical results in simple formations, showing good agreement, and used to simulate the response of LWD tools through anisotropic dipping beds for various values of anisotropic conductivities and dipping angles