Composition of WaterBase Drilling Muds

• Spud Muds

• Petroleum Extension

• Natural Muds

Water-base muds are the most widely used drilling fluid

Because either fresh water or salt water is available in most

of the world’s drilling areas, water-base muds are easier to use a
less expensive than oil-base muds or compressed air.
The quality of water used to make up and maintain water-base
muds affects the way mud additives perform. For example, clays work
best in distilled water. Hard water—water that contains large amounts
of calcium and magnesium salts—and salt water reduce a clay’s effect.
The composition of the mud used to start a well, or spud in, varies
with drilling practices around the world. Sometimes the operator uses
water alone from a nearby source such as a well, stream, or lake. The
ideal situation is when the makeup water is soft and the formations
near the surface make a good natural mud. If this is not the case, the
operator may mix clay, lime, and soda ash into the mud. Lime thickens
the mud and allows the operator to use less clay to build viscosity.
Sometimes the formations near the surface contain enough clay
to make up a good natural mud when mixed with water. Natural
muds that have low weight and viscosity, because they either do
not hydrate well or need a lot of water to keep the weight and
viscosity down, are useful at shallow depths, such as for surface
drilling and for making hole below the conductor casing. In shallow holes,

the formation pressures are usually normal, and mud
does not need to be heavy to prevent kicks. These low-weight,
low-viscosity muds provide a high rate of penetration and decrease
the risk of stuck pipe and lost circulation.