Page 81 - Well Control for Completions and Interventions

72 Well Control for Completions and Interventions

2.2.4 Cased and perforated completion
Cased and perforated completions are used extensively in a variety of res-
ervoir types. Wells can be completed with either a cemented production
liner or cemented production casing across the reservoir. Cased and per-
forated completions have many advantages over open hole completions.
These are summarized in Table 2.3: Cased and perforated completions
(Fig. 2.6).

2.2.5 Sand control completions
Although approximately 60% of the world’s hydrocarbon production
comes from carbonate reservoirs, almost 90% of the wells are in sandstone
1
formations. About 30% of these sandstone formations are unconsoli-
2
dated, and weak enough to be at risk of sand production. The type of
sand control completion used is dependent upon the consolidation of the

Table 2.3 Cased and perforated completions
Advantages Disadvantages
Selectivity in production/injection Perforating costs can be significant—
particularly for long horizontal wells
Ability to shut off water, gas, or sand Some risk of productivity impairment
production through relatively from “completion skins” depending
straightforward interventions—plugs, on how the well has been drilled
straddles, cement squeeze and completed
Good productivity—drilling related Adequate cement bond may be
formation damage can be by-passed difficult to obtain in wells with long
high angle liners
Zones can be added at a later date.
Poorly producing zones can be
re-perforated to by-pass damage
Suitable for fracturing/stimulation,
particularly where fracture
containment or multiple fracturing
is required
Reduced sanding through careful
perforating design
Ease of application of chemical
treatments—diversion
Easily adapted for “smart”
completions—single string multiple
zone with multiple packers and
inflow valves