| Drilling Fluids are key to any drilling operation.
Without a proper mud program the drilling process would be very slow and
dangerous. In order to optimize your drilling mud it is necessary
to change the mud properties when drilling deep and hot holes where you
could encounter reactive shales.
There are many drilling fluids today which are classed
among the "widely used." The three main types are water base fluids,
oil base fluids and the air or gas. Each of these can be subdivided
into several subtypes. Oil based fluids are used regularly, air and
gas are used to a lesser extent, and water based muds are used most often.
The control of drilling fluids always presents two problems:
-
Determination of what properties are needed for the
drilling mud to satisfactorily handle the drilling operation i.e., weight,
viscosity, gel strength and filtration.
-
The selection of the type of mud and the materials and chemicals
which will give the desired mud properties.
The properties of drilling muds can be adjusted to meet any
reasonable set of conditions, and therefore overcome most drilling problems,
such as abnormal pressure, lost circulation and sloughing shale.
The selection of the proper mud additive for certain conditions is sometimes
confusing because of the large number of mud dealers and the wide variety
of trade names. To simplify this problem it is helpful to think of
mud additives according to their application or specific performance requirements:
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Barite weight materials for preparing muds in excess of
10 lb/gal.
-
Bentonite, premium clays and asbestos fibers for viscosity,
suspension, and wall building properties.
-
Thinners or deflocculants primarily for viscosity and gel
strength control and secondarily for water loss control and as emulsifiers.
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Filtration control agents for reduction of water loss.
-
Lost circulation materials for preventing loss of circulation
or restoring circulation.
-
Special chemicals and products for control of specific mud
characteristics such as emulsification, lubrication, foaming, fermentation
and inhibition.
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