BAKER HUGHES - Drilling Fluids Reference Manual

RESERVOIR APPLICATION FLUIDS
Under-reaming Operation
• Where a cased hole exists to the top of the pay zone and it is desired to drill and under-ream
for an open-hole completion, PERFFLOW DIF can be introduced to drill the pilot hole but
must be used before starting the under-reaming operation so that the final exposed producing
formation sees only the drill-in fluid. In most cases, it may be best to change to the drill-in
fluid while in the casing to avoid delay once the drilling operation has started. Displacement
would also be more efficient in the cased hole, and exposure of the formation to two different
fluids would be avoided.
• Where an old perforated cased hole exists through the pay zone and it is desired to cut a
section through the pay zone and to under-ream, the rheological properties and hole cleaning
capacity of the PERFFLOW DIF system can be adjusted to effectively carry steel cuttings
out of the hole; thus PERFFLOW DIF can be used as the cutting fluid. This adjustment,
however, will likely require treatment with additional W-306, W-307 or certain products such
as BIOZAN ® or XANVIS ® to obtain higher flow properties than are normally maintained.
Therefore, if the existing fluid in the casing is deemed adequate to do the milling operation,
then it may be more economical to use it and then change to PERFFLOW DIF before
initiating the under-reaming operation.
Drilling and Completing Horizontal Section
PERFFLOW DIF fluid can be used to cut a window and to drill the build section of the horizontal
well. Whether to use the PERFFLOW DIF fluid for this purpose depends upon the same reasoning
used in the under-reaming operation. If the existing fluid in the casing is deemed satisfactory for
the milling operation and will effectively stabilize the formation to be immediately drilled, then it
may be more economical to use that fluid. Where the existing fluid will require extensive treatment
or a complete change-out, then consideration should be given to using the PERFFLOW DIF fluid
for this purpose.
Extended Drilling Required from Casing Point/Kick-Off Point
Since PERFFLOW DIF is to be used as the drill-in fluid, it does not contain any highly active drill
solids such as clays. Therefore, using the PERFFLOW DIF to drill several thousand feet of hole
prior to encountering the producing formation may not be the best choice, unless the operator is
prepared to replace a significant volume with clean PERFFLOW DIF fluid prior to drilling into
the pay-zone.
Mixing Procedures
Ensure all pits, lines and pumps are clean and have been flushed with water/seawater prior to
mixing. Mixing sequence depends on the products being used. When mixing the W-306 or W-307
products, the following mixing order is recommended.
BAKER HUGHES DRILLING FLUIDS
REFERENCE MANUAL
REVISION 2006 6-26