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Table T14. Measurement performance specifications of the geoVISION tool. (See table notes.)

Measurements Vertical
resolution
(inch)		 Depth of
investigation
(inch)		 Diameter of investigation Horizontal resolution Midpoints of
extremes
Rt/Rxo = 10 Rt/Rxo = 0.1 [(Rt/Rxo = 10) * π]/56 [(Rt/Rxo = 0.1) * π]/56
Resistivity at the bit   12–24* 12 32 32      
Ring resistivity   2–3 7 22 25      
Button resistivity Shallow focused 2–3 1 19 24 1.07 1.35 1.2
Medium focused 2–3 3 15 21 0.84 1.18 1
Deep focused 2–3 5 11 16 0.62 0.9 0.75

Notes: * = depends on bit subs. Rt = true resistivity of formation. Rxo = resistivity of zone invaded by drilling fluid. Horizontal resolution for each of tools intermediate between extremes of Rt/Rxo in table above. Imaging tools record 56 times with each revolution of tool. Accuracy of segment location is ±1°.

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