ISSN:
1365-246X
Source:
Blackwell Publishing Journal Backfiles 1879-2005
Topics:
Geosciences
Notes:
The crucial problem of fracture detection and analysis has long challenged the capability of conventional logging. The electrical imaging technique is able to elegantly solve this problem. Electrical imaging of the borehole wall will take a growing part, with acoustical imaging, in exploration programmes. It can be expected that its applications will expand in the future with the constant improvement of the measurement devices.The present paper describes experience acquired with the Elias probe developed by BRGM Instruments. This probe is characterized by full coverage of the borehole wall, slim diameter of the probe and non-ambiguous depth matching between pads. After instrument design, data processing and enhancement is an important step before interpretation. Finally the visualization of fracture distribution and its statistical description provides a comprehensive tool for the analysis of borehole images and of structural data. The Elias probe, together with the processing and interpretation software, provides an integrated package for exploiting the full potential of high-resolution borehole investigations and the petrophysical sensitivity of formation resistivity.This paper describes the functioning of the tool, the processing of image data and the interactive curve matching used for the visual recognition of fracture surfaces. A field example from the Auriat well, located in the French Massif Central and drilled in a granitic intrusion, is used to validate the accuracy of the method and to define the spatial properties of a fracture network, by comparison with the complete sets of fracture observed along a full oriented coring of this borehole.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1111/j.1365-246X.1991.tb06335.x
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