Drilling Fluid Mechanism:
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Drilling fluid or drilling mud:-
Is any fluist that is wood for the of drilling bonchoter into earthe surface. It is an carential component of drifting operations.
Major types of drilling mud include
* Water based mud (WBM).
* 0il based mud (OBM):
* Preumatic fluide (yal or foam)
Functions of drilling fluide :
1. Cuttings removal and transport.
2. Suspend solid particles.
3. Sealing of permeable formation.
4. stabilizing the wellbore
5. Transmitting hydraulic horsepower
6. Preventing formation damage
7. Cooling and lubricating the bit
8. Collection of formation data
9. Partial support of drill string and casing
10. Controlling corrosion
11. Surface pressure control.
* Surface Price control :-
Drillng fluid controls the formation pressure, ensuring safe operation.
A column of liquid, exerts a hydrostatic pressure equal to P = pgh .
in Psi P = pgh x 3°2808 x 0¹006944
where, h = Tuxe Vertionl Depth (metres) P = Density of the droitting fluid (in pcf)
The hydrostatic pressure of drilling fluid balances the pressure essented by the formation.
Removal of transport of cutting:
The fluid carries the cutting up through the annulus, and removed bysolid control units.
Adequate cutting removal ensures a clean wellbore, for smooth operation.
Factors effecting the cutting lifting property are :-
* Viscosity of fluid
* Velocity of fluid
* Density of fluid
* Rotation of the drill string.
Suspend and release cutting:-
-> Cutting that are yet to be removed should not to settle to the bottom when the fluid is in static conditions.
-> Due to thixotropic property of drilling fluid, un- removed cutting are suspended while static.
-> Suspended cutting are removed during circulation.
✴️ Suspended and release cutting:
# Cuttings that are yet to be removed should not to be settled to the bottom when the fluid is in static conditions.
# Dye to thixotropic property of drilling fluid, un- removed cutting are suspended while static.
# Suspended cutting are removed during circulation.
✴️ Sealing of permeable formation:
# During drilling, the liquid medium filters into the formation. Solids are deposited in the layers in a layer forming a filter cake or mud cake.
# The mud cake prevents further loss of fluid into the formation.
# The mud cake should be thin, compossible and should have low permeability.