Which well log is used to determine the wellbore radius and may also be used to determine the location of permeable formations along the wellbore?

Which well log is used to determine the wellbore radius and may also be used to determine the location of permeable formations along the wellbore?

• A. Gamma ray log
• B. Caliper log
• C. Resistivity log
• D. Neutron log

Answer: (B)

Measuring the borehole diameter along depth is what the caliper log does. The tool contacts the borehole walls and records the diameter at each depth, producing a profile of the wellbore radius. When the rock is more permeable or weaker, the borehole walls can wash out and widen, so those sections appear as larger diameters on the log, helping you locate permeable formations along the wellbore. Other logs focus on lithology, porosity, or fluid content and do not directly measure hole size, so they wouldn’t give the borehole radius or indicate borehole enlargements in the same way.

Measuring the borehole diameter along depth is what the caliper log does. The tool contacts the borehole walls and records the diameter at each depth, producing a profile of the wellbore radius. When the rock is more permeable or weaker, the borehole walls can wash out and widen, so those sections appear as larger diameters on the log, helping you locate permeable formations along the wellbore. Other logs focus on lithology, porosity, or fluid content and do not directly measure hole size, so they wouldn’t give the borehole radius or indicate borehole enlargements in the same way.