BAKER HUGHES - Drilling Fluids Reference Manual

GLOSSARY OF TERMS
complex structures with several types of sequestering chemicals. When held inside the complex, the
ions have a limited ability to react with other ions, clays or polymers.
Set Casing - The installation of pipe or casing in a well bore. Usually requires “mudding up”,
reconditioning or at least checking the drilling fluid properties.
Shale - Fine-grained clay rock with slate-like cleavage, sometimes containing an organic oil-yielding
substance.
Shale Shaker - Any of several mechanical devices for removing cuttings and other large solids from
the fluid. Typically a vibrating screen.
Shear (Shearing Stress) - An action, resulting from applied forces, which causes or tends to cause
two contiguous parts of a body to slide relatively to each other in a direction parallel to their plane of
contact.
Shearometer - A device used as an alternative method for measuring gel strengths. See API RP 13B
for specifications and procedure.
Shear Strength - A measure of the shear value of the fluid. The minimum shearing stress that will
produce permanent deformation. See Gel Strength.
Side Tracking - See Whipstock.
Sieve Analysis - See Screen Analysis.
Silica Gel - A porous substance consisting of SiO 2 . Used on occasion as a dehydrating agent in air or
gas drilling where small amount of water is encountered.
Silicate Mud - A type of shale-inhibitive water mud that contains sodium or potassium silicate as the
inhibitive component. High pH is a necessary characteristic of silicate muds to control the amount
and type of polysilicates that are formed. Mud pH is controlled by addition of NaOH (or KOH) and
the appropriate silicate solution. Silicate anions and colloidal silica gel combine to stabilize the
wellbore by sealing microfractures, forming a silica layer on shales and possibly acting as an osmotic
membrane, which can produce in-gauge holes through troublesome shale sections that otherwise
might require an oil mud. Good solids control practices are very important in the control of silicate
mud properties. Silicate muds are not recommended to be used while drilling the pay zone.
BAKER HUGHES DRILLING FLUIDS
REFERENCE MANUAL
REVISION 2006 15-41