Neftegaz.RU #3-17 ENG

OFS
TABLE 1. Criteria of applicability of different methods of corrosion protection
No. Protection method Criteria of applicability
1
Application of low and medium alloy
steel, high chrome steels (5%)
Corrosion ratio (medium corrosion activity) 2.0 mm/h
2
Application of stainless steels (chrome
content 13% and higher)
No limitations
3 Application of fiberglass tubing
Performance of tripping at T not lower than -30°С,
Abrasive wear susceptibility
Special storage conditions (without exposure to sunlight)
Necessity to use special tools and substitutes for mounting/dismounting
Coupling large diameter – 95.4mm
Working temperature 110°С
4 Neozinc Thermodiffusion Zinc Coating No resistance in acid and alkaline mediums
5 Silicate enamel coating
Brittleness, susceptibility to spalling at deformations of tubing metal during
tripping, especially in male section
6 Epoxy coating Upper temperature limit +90°С
7 Argof Polyester Coating Abrasive wear susceptibility
8 PoiyPlex-P Polyurethane Coating No limitations *
9 Polyphenylene Sulfide (PPS) Coating No limitations *
10 Periodic inhibition through annulus
At suspended solids of 100 mg/l, liquid-gas mixture speed on top is 3 m/s
At suspended solids of 500 g/l, liquid-gas mixture speed on top is 1 m/s
At suspended solids of >500 mg/l not applicable
No protection for downhole motor case
Not applicable at well performance through annulus
Risk of electrocorrosion
11 Constant inhibition through annulus
At suspended solids of 100 mg/l, liquid-gas mixture speed is 5 m/s
At suspended solids of 500 mg/l, liquid-gas mixture speed is 2 m/s
At suspended solids of 1,000 mg/l, liquid-gas mixture speed is 1 m/s
No protection for downhole motor case
Not applicable at well performance through annulus
Risk of electrocorrosion
No protection for downhole motor case
12 Constant dosing through capillary tube
At suspended solids of 100 mg/l, liquid-gas mixture speed is 5 m/s
At suspended solids of 500 mg/l, liquid-gas mixture speed is 2 m/s
At suspended solids of 1,000 mg/l, liquid-gas mixture speed is 1 m/s
Necessity of well service / workover for technology launching
Possibility of targeted protection (including downhole motor case)
13 Inhibitor squeezing into the formation
Mass flow rate 200 m 3 /d
Inhibitor thermal stability
Necessity of well service / workover for technology launching
14 Use of spring measuring container
Mass flow rate 50 m 3 /d
Necessity of well service / workover for technology launching, dibhole availability
15
CP with use of cathodic protection
station
16 Ground protection
17 High velocity oxygen fuel For ESCP protection
* – as reported by manufacturer
For protection of casing pipe external surface
When used for ESCP protection, running of additional cable or four-core cable is
required
No protection for tubing internal surface
Applicable for ESCP protection
Watercut 60%
Efficiency of corrosion inhibitor
from downhole container is
determined based on the run
time increase. It should be noted
that the downhole container
volume is limited and not all
suppliers provide the procedure
for determination of residual
content of corrosion inhibitor.
Therefore, it is practically
impossible to determine the
control of protection period. Table
1 gives criteria of applicability of
different methods of corrosion
protection.
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