Factors Affecting Mud Performance and Cost

A few basic items greatly influence the performance of the drilling fluid and ultimate cost of the drilling operations.

Pit Facilities


Pit Facilities should provide the necessary surface volume and should be arranged so the movement and conditioning of mud can be effectively accomplished.

Mixing Facilities

figure 2. Mud hopper with premix chamber.

Mixing Facilities should be capable of providing good mixing of mud additives. Adequate pumps, hoppers, and mud guns and mixers should be available.

Mechanical Mud Conditioning

Mechanical Mud Conditioning devices, such as fine screen shakers, degassers, desanders, desilters, mud cleaners and centrifuges are effective in reducing mud costs.

Materials Storage

Materials Storage under suitable cover eliminates spoilage or breakage caused by exposure to weather.

Mixing Water

Mixing Water greatly affects mud cost. The best available water should be chosen for the particular mud to be used. For fresh water muds, soft water having a low concentration of dissolved salts is desirable. Water to replace
that lost by surface evaporation and down-hole filtration should be added continuously while circulating. Add water below the shale shakers to avoid washing drill cuttings through the screen.


Hydraulics should be designed in such a way that available horsepower and pump facilities are effectively utilized.

Rig Personnel

Rig Personnel should be capable of carrying out mud treatment and should be vigilant to note any change in surface volume or properties of the mud.

Mud Type

Mud Type for best results will vary in different areas because of subsurface formations, availability of water or special requirements. The type of drilling fluid chosen should be based on efficiency and cost for the particular area.

The cost of the drilling fluid averages 10% of the total tangible costs of well construction; however, drilling-fluid performance can affect overall well-construction costs in several ways. A correctly formulated and well-maintained drilling system can contribute to cost containment throughout the drilling operation by enhancing the rate of penetration (ROP), protecting the reservoir from unnecessary damage, minimizing the potential for loss of circulation, stabilizing the wellbore during static intervals, and helping the operator remain in compliance with environmental and safety regulations. Many drilling-fluid systems can be reused from well to well, thereby reducing waste volumes and costs incurred for building new mud.