Page 218 - Well Control for Completions and Interventions

Completion, Workover, and Intervention Fluids 211

Figure 5.7 Bulk calcium carbonate at the rig site.

Polymer breaking enzymes are often run in conjunction with the low
salinity wash, to aid in the removal of polymers in the filter cake.
Formation damage tests should be conducted to ensure that the high
salinity fluid is compatible with the reservoir.

5.9.3.3 Cellulose fibers
Cellulose fibers are plant material, for example, peanut (groundnut) husks,
or even sawdust. Cellulose fibers are more commonly used when circula-
tion is lost during drilling operations, and are rarely used during comple-
tion or workover operations unless losses are severe. In most cases,
CaCO 3 is equally as effective.
Cellulose fibers are removed by oxidizing with sodium hypochlorite
(diluted to make household bleach), however, this should only be consid-
ered after careful evaluation of potential formation damage and downhole
corrosion of tubulars.

5.9.3.4 Oil soluble resin
Oil soluble resins were developed in the 1970s as an alternative to calcium
10
carbonate. The aim was to develop a system that would develop a filter
cake that was completely soluble in oil, therefore eliminating the need to
use acid or low salinity water washing to remove residual particulates
from the formation. Experience has shown that in some cases a treatment
with an organic solvent has been required to remove soluble resin residue.