Page 518 - Practical Well Planning and Drilling Manual

Appendix NEW! revised 11/00/bc 1/30/01 3:30 PM Page 494

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Glossary

Protection Casing. A string of casing set to protect a section of the
hole and to permit drilling to continue to a greater depth. Sometimes
called “protection string” and “intermediate string.”

Quiesence. The state of being quiet or at rest (being still). Static.

Rathole.
1. A 30 to 35 ft. cased hole drilled at one corner of the derrick floor
used to store the swivel and kelly while making a trip.
2. Sometimes refers to a hole of reduced size in the bottom of the
regular well bore. In some cases the driller “ratholes ahead” to
facilitate the taking of a drill stem test when it appears such a test
will be desirable.

Rate of Shear or Shear Rate. The rate at which an action, resulting
from applied forces, causes or tends to cause two adjacent parts of a
body to slide relatively to each other in a direction parallel to their
plane of contact. Commonly given in rpm.

Reaming. The operations of smoothing the well bore or enlarging
the hole to the desired size, straightening doglegs and assist in direc-
tional drilling.

Repeat Formation Tester. Schlumberger wireline tool that can take
multiple pressure readings and up to two formation fluid samples on
one trip.

Reservoir Saturation Tool. Schlumberger wireline tool that uses a
neutron induced GR spectroscopy principle to determine oil satura-
tion in unknown or fresh formation water, borehole oil fraction,
and Sigma.

Resistivity At the Bit. Anadril LWD tool.

Resistivity. The electrical resistance offered to the passage of a cur-
rent, expressed in ohmmeters; the reciprocal of conductivity. Fresh-
water muds are usually characterized by high resistivity, saltwater
muds by a low resistivity.

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