OFITE, 11302 Steeplecrest Dr., Houston, TX 77065 USA / Tel: 832-320-7300 / Fax: 713-880-9886 / www.ofite.com
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The OFITE Roller Oven (U.S. Patent No. 4,677,843) is an effective aid in de-
termining the effects of temperature and pressure on drilling fluid as it circu
-
lates through the well bore. Aging the drilling fluid in pressurized containers
effectively demonstrates the thermal effects on drilling fluids in which a base
exchange reaction occurs and in determining the stability of mud additives
and emulsified fluids such as oil muds. Aging is done under conditions that
vary from static to dynamic and from ambient to highly elevated temperatures.
Many mud constituents degrade slowly at high temperatures. Such degrada-
tion occurs while circulating, but it is more severe when the mud is left in the
lower part of the hole when making a trip. When running laboratory tests,
aging temperatures are often selected to be near the anticipated circulating or
bottom-hole temperatures and pressures, and aging cells are typically rolled
in an oven for at least 16 hours.
Routine laboratory analysis using roller ovens would include:
a. Simulate chemical reactions taking place in freshly prepared muds.
b. Determine the time it takes reactions to reach equilibrium under tem-
perature and pressure.
c. Determine the Viscosity of the fluid prior to aging and after.
d. Determine filtration control properties prior to aging and after.
e. Determine the stability of drilling fluid additives and drilling fluids such
as oil muds.
f. Perform corrosion analysis.
The 4-roller oven can hold six 260-mL Aging Cells or three 500-mL Aging
Cells, while the 5-roller oven can hold twelve 260-mL Aging Cells or eight
500-mL Aging Cells. These are both ideal for laboratory use. OFITE rollers
are variable-speed controlled and constructed of stainless steel for longer life
and a cleaner environment inside the oven. Glass-impregnated Teflon
®
roller
bearings extend the life of the rollers and allow for longer maintenance-free
service.
All models feature a digital temperature controller that can be read directly
from outside the oven. The temperature is controlled by an electronic solid-
state thermostat and operates between 100°F and 450°F (38°C - 232.2°C).
The 4 and 5-roller ovens include a seven-day programmable timer as stan-
dard equipment. The timer may be preset to automatically start and stop the
heaters, allowing unattended operation. A circulating fan is included on all
models which greatly improves air circulation within the oven providing more
stable, consistent, and reliable uniform heating.
The Redundant Heat Control is available on select models and is a safety
feature for the heaters in the event one or more over-heat. Power to the
heaters will be shut down if the oven temperature exceeds a set maximum
temperature. The aging process due to the length of time required for com-
pletion of the test, is seldom monitored, so a heater failure may be serious.
Introduction
