Functions of Drilling Fluids
- Remove cuttings from well
- Control formation pressure
- Suspend & release cuttings
- Seal permeable formations
- Maintain wellbore stability
- Minimize reservoir damage
- Cool, lubricate & support the bit and drilling ass.
- Transmit hydraulic energy to tools & bit
- Ensure adequate FE
- Control corrosion
- Facilitate cementing & completion
- Minimize impact on environment
- Prevent gas hydrate formation
Common types of drilling fluids
- WBM :
- Dispersed system
- Non dispersed system - Invert Emulsion DF (NADF)
- OBM
- SBM
- Ester based mud
What is Dispersed System?
Advantages & Disadvantages?
Allowing clay to be incorporated with the mud system to provide viscosity & fluid loss control
Advantages:
- Once dispersed clay from formation, will break cutting to smaller size
Disadvantages:
- In shallow area, clay dispersed and caused hole enlargement
- As we drill shale formation, shale dispersed
What is Non-Dispersed Polymer System?
Advantages & disadvantages?
As we drill clay, we want to prevent clay to be part of our drilling mud system
Advantages:
- Since it prevent clay to be part of the system, less solid in system - better control of solids - less frictional loss as we drill - overall circ system is better
Disadvantages:
- Cuttings will be bigger, hence challenging in hole cleaning
Drilling rig mud circulations systems
Mud pump (suck mud from active pit) - Standpipe manifold - TDS - Down to the drill string - out from bit - annulus - Flowline - Shale shaker - degasser - sandtrap - desilter - centrifuge - settling tank - active pit
