Drilling fluids also known as drilling mud, are essential in the drilling of wells for oil, gas, water and other subsurface resources. The functions of drilling fluids are critical to ensuring sufficient safe and cost-effective drilling operations.

This course outline covers the fundamental aspects of drilling fluid functions providing a comprehensive introduction suitable for students, new industry professionals or anyone interested in the field.

The objective of a drilling operation is to drill, evaluate and complete a well that will produce oil and/or gas efficiently.

Drilling fluids perform numerous functions that help make this possible. Drilling fluid functions describe tasks, which the drilling fluid is capable of performing, although some may not be essential on every well. Removing cuttings from the well and controlling formation pressures are of primary importance on every well.

Recommending a drilling fluid system should be based on the ability of the fluid to achieve the essential functions and to minimize anticipated well problems. The responsibility for performing these functions is held jointly by the mud engineer and those who direct the drilling operation.

The duty of those charged with drilling the hole — including the oil company representative, drilling contractor and rig crew — is to make sure correct drilling procedures are conducted. The chief duty of the mud engineer is to assure that mud properties are correct for the specific drilling environment. The mud engineer should also recommend drilling practice changes that will help reach the drilling objectives

The functions discussed in this course may provide guidelines for mud selection, they should not be the sole basis for selecting a drilling fluid for a well. The selection process must be founded on a wide experience base, local knowledge and consideration of the best technology available.