BAKER HUGHES - Drilling Fluids Reference Manual

GLOSSARY OF TERMS
Resistivity - The electrical resistance offered to the passage of a current; expressed in ohm-meters;
the reciprocal of conductivity. Freshwater fluids are usually characterized by high resistivity,
saltwater fluids by a low resistivity.
Resistivity Meter - An instrument for measuring the resistivity of drilling fluids and their filter
cakes.
Reverse Circulate - The method by which the normal flow of a drilling fluid is reversed by
circulating down the annulus and up and out the drillstring.
Reynolds Number - A dimensionless number (Re) that occurs in the theory of fluid dynamics. The
diameter, velocity, density and viscosity (consistent units) for a fluid flowing through a cylindrical
conductor are related as follows:
Re = (Diameter)(Velocity)(Density)/(Viscosity)
or
Re = (D) (V)p/u
The number is important in fluid hydraulics calculations for determining the type of fluid flow, i.e.,
whether laminar or turbulent. The transitional range occurs approximately from 2000 to 3000; below
2000 the flow is laminar, above 3000 the flow is turbulent.
Rheology - The science that deals with deformation and flow of water.
Rotary Drilling - The method of drilling wells that depends on the rotation of a column of drillpipe
to the bottom of which is attached a bit. A fluid is circulated to remove the cuttings.
Salt - In fluid terminology, the term salt is applied to sodium chloride, NaCI. Chemically, the term
salt is also applied to anyone of a class of similar compounds formed when the acid hydrogen of an
acid is partly or wholly replaced by a metal or a metallic radical. Salts are formed by the action of
acids on metals, or oxides and hydroxides, directly with ammonia, and in other ways.
Saltwater Clay - See Attapulgite Clay.
Saltwater Fluids - A drilling fluid containing dissolved salt (brackish to saturated). These fluids
may also include native solids, oil, and/or such commercial additives as clays, starch, etc.
BAKER HUGHES DRILLING FLUIDS
REFERENCE MANUAL
REVISION 2006 15-39