Instructional

Introduction

In mud rotary drilling, drilling fluids (or “mud”) are engineered liquids (usually water mixed with bentonite clay and additives) circulated down the drill pipe to clean the hole, cool the bit, stabilize walls, and carry rock cuttings to the surface, functioning as the workhorse that makes drilling possible, especially in unstable formations.

A good drilling fluid will assist the driller by performing functions in five main areas:

1. Hole making
2. Hole clearing
3. Hole stabilizing and control
4. Sample transport and logging
5. Self care, that is, should be stable, easy to treat and testable.

The ability of the drilling mud to carry out all these functions depends on specific parameters of the fluid namely:

• Viscosity
• Density
• Sand content