Drilling FluidsDrilling Fluids are required in large quantities to successfully complete drilling operations. A good drilling fluid will assist the driller by performing functions in five main areas. It will perform all these functions in a safe way without providing any hazards to the crew or to the environment or causing any damage to the drilling tools and the equipment.
The main functions of the drilling fluids have been listed below
1. Hole making function
- Cool the Bit
- Clear the bit and the bottom of the hole
- Lubricate the rods/ pipes and the bit
- Transmit hydraulic energy to the chip making and clearing process
- Inhibit corrosion of down-hole tools and casing
- Assist in running casing, reduce costs of placing casing and in deep holes, support the weight of the casing
2. Hole clearing functions
- Remove cuttings from the hole
- Deposit cutting at the surface
- Hold cuttings in suspension when the flow has stopped
3. Hole stabilising and control functions
- Control down-hole pressure and temperature
- Provide support for unconsolidated formations, consolidate caving formation
- Protect target formations or ore bodies against invasion or contamination
- Restrict wall cake build up
- Control circulation loss
- Inhibit formation deterioration
4. Sample Transport and Logging functions
- Communicate accurately about what is happening down the hole. (Changes in colour, smell, feel appearance, flow and chip content all help to convey the message. Message carried quickly are better managed.
- Preserve the core and the chip sample
- Deliver the sample rapidly without breaking or loss
- Facilitate electric or geophysical logging
5. Self care functions
- Testable- The fluid needs to be testable. Test and Testing equipment should be able to identify fluid properties and indicate any treatment required.
- Easy to treat - If the desired properties are lost, treatment should be available to restore or adjust them.
- Stable - The desired properties of the fluid once established, should be stable under normal drilling conditions.