SIMULATION OF 3D DC BOREHOLE RESISTIVITY MEASUREMENTS WITH A GOAL-ORIENTED HP FINITE-ELEMENT METHOD
D. Pardo, M. Paszynski, C. Torres- Verdí, and L. Demkowicz (UDC: 004.922:621.317.33)
Abstract
We simulate and study the combined three-dimensional effects on resistivity logging
measurements due to dip angle (in deviated wells), different arrangements of three-dimensional
electrodes, and anisotropy effects. All results correspond to electrostatic (zero frequency)
measurements. Thus, we consider direct current (DC) electrodes. We simulate both laterolog
and logging-while-drilling (LWD) measurements.
goal-oriented hp-finite element (FE) method, and transferring these grids to a 3D hp-
FE software. Then, we perform 3D simulations (employing 2D optimal grids) using the 3D
software. Finally, an analysis of the error is performed by considering a finer (globally prefined)
grid.
Numerical results illustrate the accuracy of the simulations, and indicate that LWD-type
measurements (at zero frequency) are more sensitive to dip angle, different arrangements of
electrodes, and anisotropy effects than laterolog-type measurements. While vertical well
measurements may be insensitive to different electrode configurations and anisotropy effects,
for highly deviated wells, consideration of the exact electrode geometries and anisotropy effects
may become crucial for the correct interpretation of the results. Thus, all these 3D effects are
considered simultaneously, rather than as a superposition of individual effects.
