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INDUCTION LOGGING

“Induction logging tools have

become increasingly difficult
to characterize using simple
models. Similarly, with the
advent of directional drilling,
it has become imperative to
model fully 3D formations”

–DR. SUSHANT DUTTA, RESEARCHER AT

 BAKER HUGHES

borehole fluid. The borehole makes           FIGURE 3. Simulation result snapshot when the inductive logging tool’s Z-transmitter is
a high angle with the vertical, which        active at a depth of 8 feet. The subdomain colormap shows the magnitude of induced
represents a realistic directional           current density in the formation, while the arrows show the direction of flow of the
drilling scenario. The induction tool        induced currents. The colormap is log10 scaled for clarity.
may or may not be centered inside the
borehole. Furthermore, the induction
tool transmitters and receivers are
triaxial, which makes them capable of
transmitting and measuring magnetic
fields in each of three orthogonal
directions, although they are modeled as
simple wire loops.
	 The induction tool operates at multiple
frequencies. The results , an example
of which are shown in Figure 2, show
the direct magnetic fields in all three
directions (imaginary parts) logged by
the tool as a function of true vertical
depth. The imaginary magnetic fields
represent the voltage signals generated
in the receivers that are in phase with
the transmitter currents. A 3D simulation
shows the induced currents in the
formation when the Z-transmitter is active
(see Figure 3).

èLOOKING FORWARD                             Dr. Fei Le (left) and Dr. Sushant M. Dutta (right), scientists in the Drilling and Evaluation
                                             product line group at Baker Hughes.
Dutta continues to use COMSOL for
sensor design, solving forward problems,
validating experiments, and testing new
design ideas. “Using simulations for sensor
design reduces prototyping costs. Solving
forward problems helps us characterize
new tools and build confidence in fast
forward models for inversion,” he said.
	 And since directional drilling, reservoir
navigation, and formation evaluation are
areas of the oil and gas industry that use
some of the most advanced technology
in the world, “Baker Hughes’ expertise in
these areas often saves customers millions
of dollars in improved productivity and
time saved. The ability to accurately
characterize induction-logging scenarios
and to evaluate ideas for new and
improved induction logging tools helps us
keep that competitive edge.” v

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