STANDARD HANDBOOK OF PETROLEUM & NATURAL GAS ...

Drilling Muds and Completion Fluids 701
Problem Symptoms Treatment
in aerated muds Severe pitting, black to red 1. Keep pH above 11 with
rust
caustic soda on line;
2. Use cationic-type
inhibition. 3. Identify type
of corrosion contaminant.
4. Treat with specific
corrosion inhibition.
8. High temperature
High temperature gelatin Difficult to start circulation. Dilute with water and add
High viscosity and gel bentonite. Treat with
strength of mud off
thinner. Spot a slurry of
bottom. Deceased
mud treated with 1-2 ppb
alkalinity and increased
water loss.
Adapted from IADC Drilling Manual, 10th edition, 1982; Courtesy IADC.
sodium chromate in the
high-temperature section
of the hole.
(text continued from page 695)
Completion and Workover Fluids
Completion and workover fluids are those placed against the formation while
killing well, cleaning out, plugging back, stimulating, or perforating. Their
primary functions are (1) to transfer treating fluid to a particular zone in the
borehole, (2) to protect the producing formation from damage, (3) to control
the well pressure during servicing operations, (4) to clean the well, and (5) to
displace other fluids or cement.
Design Considerations for CompletionMlorkover Fluids
While designing completion/workover fluids the main consideration is given
to the effect of the fluids on well’s productivity. Low production rates can be
due to factors that are unrelated to the fluids introduced to the production zone.
These would include poor or shallow perforations, cement filtrate invasion,
paraffin wax deposition from crude oil, or movement of formation sand to block
the well-bore.
Productivity damage attributable to drilling or completion fluids results from
three mechanisms:
Particulate invasion which blocks the formation pores.
Filtercake can fill up and plug large cracks, fractures or perforations. This
is difficult to remove by flowing the well or acidisation.
Filtrate invasion can interact in various ways with solids or liquids in the
pores to cause a reduction in flow.