Page 80 - Basic Well Log Analysis for Geologist

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RESISTIVITY LOGS

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Figure 25. Example of a Proximity Log* with a Microlog*® and caliper. The Proximity Log* is designed to read the resistivity of
the flushed zone (R,,,). This particular log package includes: a Proximity Log* to read R,,, a Microlog® to determine
permeable zones, and a caliper to determine the size of the borehole.
Examine the log curves at the sample depth of 4.144 ft.
Track #1—Track #1 depicts both a Microlog* and a caliper log. At the sampie depth of 4,144 ft note that micro normal
(shown by the dashed line) shows higher resistivity than micro inverse (shown by the solid line). Note: on this
example. the resistivity values for micro normal and micro inverse increase from right-to-lefi. Micro inverse has a
value of about 1.5, and micro normal has a value of about 3.0; the Microlog™ indicates a permeable zone. The
caliper log indicates a borehole slightly Iess than 9 inches.
Tracks #2 and #3—The Proximity Log* measures resistivity of the flushed zone (R,,). In this example the scale is
logarithmic, reading from left-to-right. At the sample depth of 4,144 ft we read a proximity curve value (R,,,) of
{8 ohm-meters.