BAKER HUGHES - Drilling Fluids Reference Manual

RESERVOIR APPLICATION FLUIDS
• Pump pressures
• Deepwater application
Spacers
• User can choose one spacer or multiple spacer fluids.
• If “multiple spacer fluids” option is selected:
• In annulus - up to 9 different fluids with fluid interface locations and their individual
rheological properties
• Inside pipe - up to 9 different fluids with fluid interface locations and their individual
rheological properties
• Inside choke/kill/boost lines – 1 fluid and its rheological properties
DISPLEX Simulation for UNOCAL INDONESIA
The attached DISPLEX simulation was executed for UNOCAL INDONESIA for the purpose of
demonstrating its benefits with respect to wellbore clean-up and cost savings from proper spacer
selection, optimized contact time, proper displacement rates and reduced circulation time.
For this simulation, some pipe size selections were estimated but this does not reduce the value of
the output. There are several scenarios available to choose from with respect to the rig and
location. The example illustrated below is a deepwater scenario where the 2-step method has been
used. The 2-step method for deepwater applications uses the DISPLEX program to clean the
bottom casing strings up to the top of the riser through the coke and kill lines. Once the clean-up
spacers and brine have reached the surface (Stage 1 completed), then an additional clean up spacer
system is pumped back down the choke and kill lines to clean the riser (Stage 2).
Because of field success in deepwater clean up applications, the following spacer sequence has
been selected:
• Base oil spacer – begins the cleaning and is recycled into the used oil-based mud. DISPLEX
calculated the flow rate for this spacer to be in turbulent flow for best cleaning.
• Viscosified mud spacer – pushes debris up the hole dislodged by the turbulent base-oil
spacer.
• Lead solvent cleaner (Viscosified and Weighted FLOW-CLEAN) – continues the cleaning
process. This pill is non-aqueous.
• Second solvent cleaner (neat FLOW-CLEAN) – continues the cleaning process. To this
point the wellbore has not seen any aqueous solution which is the key to using small pill
volumes.
• Water-wetting spacer (FLOW-SURF or CASING WASH 300) – water-wets the casing.
This spacer represents the first time the wellbore is contacted with water (brine).
• Final viscous sweep (HEC viscosified brine) – sweeps any remaining solids up the hole
• Completion brine
As mentioned for Stage 1, the spacer system will be circulated to the surface via the kill and choke
lines. Stage 2 of the displacement is for riser cleaning, and in this case, the riser cleaning pill is
circulated down the kill line, choke and booster lines and finally up the riser, isolating the
previously cleaned casing. DISPLEX will calculate the time, strokes, pump pressure and pump
rate required circulate the various pills to surface so that the various spacers are in the proper flow
BAKER HUGHES DRILLING FLUIDS
REFERENCE MANUAL
REVISION 2006 6-110