Page 53 - Petroleum and Gas Field Processing

Chemical or plastic consolidation involves the injection of the
polymer and catalyst solution into the formation to coat the sand grains
around the wellbore with the polymer. The polymer is then cured to
harden and bonds the sand grains together and thus consolidates the sand
around the wellbore.
Each sand control method has its limitations and care should be
taken to select the most suitable method for the situation in hand. All
methods of sand control result in loss of productivity; this, however, is
acceptable in comparison to the problems associated with sand
production.

Remedial Cementing
Remedial cementing refers to any cementing operation performed on the
well after placing it in production. These are basically repair jobs executed
to resolve specific problems in the well. The most common applications of
remedial cementing are the following:
1. Control of GOR and WOR. Squeezing cement into the
perforations producing gas or water can stop excessive gas or
water production with the oil and thus reduce an undesired high
gas–oil ratio (GOR) or water–oil ratio (WOR).
2. Channel Repair. A channel is a void or crack that developed
during the primary cementing of the production casing string.
When the channel behind the casing communicates two or more
zones, unwanted fluids (such as water) may flow through the
channel into the formation and be produced with the oil.
Alternatively, the oil may flow through the channel and be lost
into another lower-pressure formation. A channel is repaired by
creating a few perforations at the top and bottom of the channel
and squeezing cement into the channel to seal if off.
3. Recompletion. When one well is used to produce from multiple-
reservoir or multiple zones with one reservoir or zone produced
at a time, the depleted zone must be plugged off before
producing the next zone. Cement is squeezed into the old
perforations to seal the depleted zone completely; then, the new
zone is perforated.
4. Casing Leak Repair. Depending on the nature of the leak,
cement may be used to seal parts of the casing, leaking unwanted
fluids into the well or allowing produced oil to leak into other
formations.
5. Setting Liners. Cementing liners to convert an open hole
completion into a perforated liner completion.

Copyright 2003 by Marcel Dekker, Inc. All Rights Reserved.