Page 503 - Practical Well Planning and Drilling Manual

Appendix NEW! revised 11/00/bc 1/30/01 3:30 PM Page 479

[ ]
Glossary

Gel. A state of a colloidal suspension in which shearing stresses
below a certain finite value fail to produce permanent deformation.
The minimum shearing stress that will produce permanent deforma-
tion is known as the shear or gel strength of the gel. Gels commonly
occur when the dispersed colloidal particles have a great affinity for
the dispersing medium. Thus gels commonly occur with bentonite in
water. See also Gel Strength, Initial and 10-min.

Gel. A term used to designate highly colloidal, high-yielding, viscosi-
ty-building commercial clays, such as bentonite and attapulgite clays.

Gel Strength, 10-Min. The measured 10-min gel strength of a fluid is
the maximum reading taken from a direct-reading viscometer after the
2
fluid has been quiescent for 10 min. The reading is reported in lb/100 ft .

Gel Strength, Initial. The measured initial gel strength of a fluid is
the maximum reading taken from a direct-reading viscometer after
2
the fluid has been quiescent for 10 sec. It is reported in lb/100 ft .

Gel Strength. The ability or the measure of the ability of a colloid to
form gels. Gel strength is a pressure unit usually reported in lb/100
ft2. It is a measure of the same interparticle forces of a fluid as deter-
mined ,by the yield point except that gel strength is measured under
static conditions, yield point under dynamic conditions. The common
gel-strength measurements are initial (10 second) and the 10-min gels.

Gelation. Association of particles to form a continuous structure.

Gelled Up. Oil-field jargon usually referring to any fluid with high
gel strength and/or highly viscous properties. Often a state of severe
flocculation.

Geochemical Logging Tool. Schlumberger wireline tool that measures
concentrations of 12 elements. The processing quantifies mineral
analysis to allow formation analysis in complex lithologies, clay vol-
ume and typing, porosity, permeability evaluation, sandstone classifi-
cation, grain density determination, well to well correlation, dielectric
log correlation, and Cation Exchange Capacity study.

479