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Tore R. AndersenHydro O&E Operations2007-09-10

Current Status and Need for Future Research

Corrosion in water injection

Date: 2007-09-10 • Page: 2

Water injection modes - I

Seawater

For EOR

Corrosion by oxygen, chlorine and bacteria

Corrosion control by deoxygenation, biocide, nitrate and cleaning pigging

Date: 2007-09-10 • Page: 3

Water injection modes - I

Seawater

For EOR

Corrosion by oxygen, chlorine and bacteria

Corrosion control by deoxygenation, biocide, nitrate and cleaning pigging

Aquifier water

EOR

Corrosion CO2 and bacteria

Corrosion control by materials selection, inhibition, biocide

Date: 2007-09-10 • Page: 4

Water Injection Modes - 2

Produced water

For EOR

Reduce discharge of produced water

UK

Norway

DenmarkNetherlands

Discharge of produced water1993-2004MSm3/year

Date: 2007-09-10 • Page: 5

Produced water characteristics

Low CO2 partial pressure

H2S from wells and SRBs in process system

Traces of oxygen

Bacteria

Deposits

CaCO3

BaSO4

Iron oxides

Elemental sulphur

Soft scales (schmoo)

Date: 2007-09-10 • Page: 6

Experiences

Crevice corrosion and SCC of AISI 304 filters

Corrosion of 13%Cr steel

0

1

2

3

4

5

Cor

rosi

on d

epth

[mm

]

20032006

Corrosion in PWRI pipeline

Replacement of carbon steel piping and wells

Date: 2007-09-10 • Page: 7

Replacement of carbon steel piping and wells

After 3.5 years produced water + some aquifier injection:

Local corrosion with depth 1-11 mm in piping

Remaining wall thickness 8 mm in manifold weld,nominal thickness 40 mm

Thick deposits of iron oxides, some iron sulphide

Elemental sulphide has been identified

MIC nodules were identified

Extensive deposition and corrosion in wells

Date: 2007-09-10 • Page: 8

Mitigation

Corrrosion inhibition

Biocide treatment

Cleaning pigging

Materials selection

Stainless steel

Lined carbon steel

Date: 2007-09-10 • Page: 9

The influence of nitrate on corrosion - I

Side stream test Laboratory test

No nitrate

Nitrate

Date: 2007-09-10 • Page: 10

The influence of nitrate on corrosion - II

Addition of nitrate to produced water with CO2 can cause a large increase in corrosion rate on carbon steel.

Nitrate should not be added to produced water containing CO2.

Different microorganisms able to utilize hydrogen were detected. This microbial hydrogen consumption can stimulate corrosion.

Date: 2007-09-10 • Page: 11

Future research

Estimation of corrosivity

Characterisation of produced water properties

Corrosion mechanisms

MIC

Tools for corrosivity assessment

Deposition mechanism

Chemical treatment

Date: 2007-09-10 • Page: 12

Thank you