BAKER HUGHES - Drilling Fluids Reference Manual

HORIZONTAL AND EXTENDED REACH DRILLING
Fluid Type Advantages Disadvantages
Oil Fluids
Co-Polymer
Gel / Water
Clear Water/
Polymer Sweeps
Sized Salt
Inhibitive
Lubricity
Formation damage
Somewhat inhibitive
Some lubricity
Some formation protection
Less expensive than Oil Fluid
Inexpensive
Environmentally safe
Simple
Inexpensive
Excellent under balanced
Minimum damage some
formations
Ultra simple
Lubricity
Minimal damage
Table 11 - 2
Environmental
Loss circulation
Expensive
(Not thixotropic, Solids removal difficult)
Moderately expensive
Must consider solids
Non-inhibitive
Can damage formation
Poor lubrication
(Limited by pore pressures)
Disposal
Solids removal
Cost
Comparison of Drilling Fluids
Originally, fears over anticipated torque and drag saw the use of oil fluids. In medium-radius wells,
this problem is not severe and oil fluids are not used as frequently as before for that purpose. Oil
fluids are frequently run where the source rock is shale, or where casing is not set through
troublesome formations.
Other fluids utilized are water-supplemented with occasional polymer sweeps such as partially
hydrolyzed polyacrylamides (PHPAs).These fluids are ideal in certain formations which don't react
to the water.
Water, as mentioned earlier, is kept in turbulence easily, provides optimum hole cleaning, is
relatively cheap, and requires only minimal sweeps to keep the hole clean.
Sized-salt fluids are super-saturated (where bottom hole temperature is not too high) and contain
salt crystals free to plug off the formation, thus reducing filtrate invasion. The salt is easily cleaned
up by pumping fresher water, thus dissolving the crystals.
BAKER HUGHES DRILLING FLUIDS
REFERENCE MANUAL
REVISION 2006. 11-25