|
Applications
Drilling fluids
Density modifying hollow spheres
Lost circulation control
Oil well cements
The drilling fluids used to drill petroleum
and gas wells perform the following functions:
Cool, clean, and lubricate the drilling bit and the drill string
Carry the rock cuttings to the surface
Control downhole pressure
Stabilize shale and clay formations
Sodium and potassium silicates are especially effective in stabilizing
shales that would otherwise disintegrate, or heave, upon contact with water.
Silicate provides a barrier to the detrimental effects of water. Drilling
problems are reduced because the hole is stable and more often in-gauge, and
because fluid loss and water infiltration are prevented.
Silicate-based
drilling fluids also have the following advantages:
Prevent bit balling
Prevent differential sticking
Prevent loss of circulation during drilling
Inhibit corrosion
Are relatively inexpensive
Meet legislative and environmental requirements around the world
Silicate-based fluids are characterized by high pH, but there are no
associated safety or health issues. Although contamination may deplete the
silicate, silicate levels can be monitored and replenished easily.
Silicate-based fluids may even be recycled for use at successive wells.
PQ’s Technical Service Group can provide formulations and other
technical information needed for successful drilling. Our expertise in silicate
chemistry keeps us at the forefront of developing enhanced silicate-based
drilling fluids.
Besides liquid silicate products, PQ’s
EXTENDOSPHERES™ hollow ceramic spheres may be used to modify the density of drilling
fluids. With compressive strengths of 2000-5000 psi and densities of 0.70 – 0.80
g/cc, EXTENDOSPHERES™ hollow ceramic spheres create a ball-bearing
effect that results in improved rheological properties in viscous fluids.
In addition, Potters Industries Inc., an affiliate of PQ Corporation, manufactures
Fine Grade
and Coarse Grade
glass beads which are designed for oil drilling mud applications to reduce
friction and torque within deviated holes. Potters solid glass spheres act as tiny ball bearings
to reduce friction and reduce differential pressure. The glass beads are a transparent,
solid soda lime glass, free of pits and air bubbles and have compressive strengths in excess of 10,000 psi. The
glass beads are chemically inert and do not affect the chemical characteristics of the
mud system.
In wells where lost circulation is an issue, sodium silicate may be used
to plug permeable formations and thereby prevent fluid loss or water
infiltration. Just as in grouting applications, the silicate is injected into
the formation along with a hardener or setting agent. Gel time can be controlled
from a few seconds to hundreds of hours or more by varying the type and the
amount of setting agent.
Another application for PQ products is in oil
well cements, which are used to glue the casing to the bore hole wall. (The
casing is a metal pipe installed in sections in the well.) Oil well cements must
be pumpable and must endure the temperatures and pressures of down-hole
conditions. For those reasons, they are specially formulated, normally with high
water content. Instead of setting, they thicken. PQ’s sodium metasilicates are
added to such cement slurries to help prevent segregation of solids from the
water phase.
|
