A New
Micro-Resistivity Imaging
Device for Use in Wells Drilled with Non-Conductive Mud System
By
Mitch Pavlovic1
(1) Baker Atlas, Houston, TX
The use of micro-resistivity imaging
logs is an increasingly critical
component in evaluating the full potential of a field prior the initiation of
the development phase. Over the years, a number of technological advances have
significantly improved quality of the acquired micro-resistivity images in
conductive mud system. Borehole image data collected today are well-established
tool of geologists and reservoir engineers used for detailed reservoir
description, providing high-resolution structural, stratigraphic, and
sedimentological data. In addition, micro-resistivity images are used to help
choose intervals for formation testing and perforation zone selection.
The increasing use of oil and synthetic base mud systems to limit drilling
risks and improve efficiency have provided an environment that precluded the use
of conventional micro-resistivity imaging
devices. Oil-base mud could be
displaced with water-base mud at considerable expense, but there is no guarantee
that acquired data will be of an acceptable quality. Furthermore, borehole
images of limited quality have sometimes been obtained in oil-based mud system
when the mud conductivity has had a high but finite value. This, it was
imperative to develop a new micro-resistivity
imaging
technology that works well
in oil-based mud systems.
This paper introduces the development and successful application of a new
micro-resistivity imager (EARTH
ImagerSM) that brings well-accepted resolution
and formation response characteristics of conventional micro-resistivity
imaging
technology to the non-conductive mud systems, such as oil or synthetic based
muds. We will present several field examples to demonstrate the instrument’s
functionality and applications throughout a range of geological environments and
borehole conditions.