Introduction to the High Resolution Induction Tool


Robert Strickland, Paul Sinclair, James Harber, and John DeBrecht
Gearhart Industries, Inc


The High Resolution Induction Tool (HRI*) is a dual induction tool that offers superior vertical resolution and significantly greater depth of penetration than conven- tional induction tools. The HRd can resolve beds as thin as two feet and is accurate in beds thicker than three feet while reading 40% deeper than the ILd. New coil arrays with matched vertical resolution and a new signal processing scheme ensure that the HRd and HRm will overlay in the absence of invasion. This matched response makes it easier for the analyst to interpret invasion than with the unmatched vertical responses of the conventional ILm and ILd. The HRd has much less borehole effect than the ILd and is less sensitive to variations in eccentering. The signal processing scheme uses both the R- and X-components of the received signals to produce logs that are fully corrected for adjacent bed effect and skin effect. The results of extensive computer modeling demonstrate the superiority of the HRI.