This article presents some tips for running drilling fluid systems.
PV and YP
For optimum hydraulic parameters the values of PV and YP should be as low as hole cleaning efficiency and suspension of solids will allow. Low viscosities result in turbulent flow at any given pump rate.
Gel Strength
A ‘ten minute’ gel strength of 25 lbs/100 ft2 shall be considered the absolute maximum for all muds under all conditions.
ECD
ECD should be kept to a minimum at all times. At laminar flow the frictional pressure drop is lower than at turbulent flow.
Borehole Stability
To minimise borehole deterioration in water-sensitive formations (eg., shales and loose sandstones) the erosional forces on the formation are lower at laminar flow than at turbulent flow.
Milling Fluid Rheology
Milling fluid should have a rheology similar to values shown below
PV = 14 cp
YP = 76 lb/100ft2
GELS = 30/40 lb/100ft2
Viscosity = 120 s/qt
Inhibition
The pH of the drilling fluid shall be maintained between 9.5 and 10.5 with caustic.
Corrosion Inhibitor
Corrosion inhibitors shall be used in packer fluids.
Well Control
Barite should not be used as weighting material for well control purposes in reservoir sections. Salt and CaCO3 should be used for this purpose.
Lubricating Fluid
Lubraglide or oil seed rape oil is used as a lubricating fluid or for sliding assistance.