The GeoWell project has received funding from the European Union’s Horizon 2020

research and innovation programme under grant agreement No 654497

Corrosion testing of materials in geothermalsteamIngolfur Thorbjornsson, Gunnar S. Kaldal

Head of Geothermal Engineering Engineer

Iceland GeoSurvey Iceland GeoSurvey

Geothermal Well Materials and design!

2

Production casing

Geothermal Drilling experience

• Complex cemistry ➔ Complex

material problems

Microvoid in stainless steel

Chemical reaction between

geothermal gas and steel

surface gives:

H2S + M -> MS + 2H+ + 2e-

M (Fe, Mn)

Formation of Hydrogen

molecules in microvoids gives

pressure up to 2000 bar

resulting in cracks inside

material.

Cracks

Geothermal drilling experience.

• Testing of material after several years in service:

• Impact strength reduced significantly

• Material ability to take elongation under load reduced significantly

F

➔

F

Cracks forms under loading

Fractured surface of test specimen

Geothermal well K39 – Krafla Geothermal field

5

Krafla K-39 Depth 1600 m

6

Corrosion and Tensile testing K-39

7

Corrosion rate in the IDDP-1 well

8

-0,050

0,000

0,050

0,100

0,150

0,200

0,250

0,300

0,350

0,400

0,450

0,500

SAF 2507 254SMO SM2550 13Cr 316L K55 TN95 S235

mm/year 0,001 0,006 -0,005 0,248 0,006 0,419 0,371 0,478

Co

rro

sio

n r

ate

[m

m/y

ear

]

Materials tested: Cladded and stand alone

High temperature Autoclave testing

• Testing in 210° and 450°C at the same time in the same steam conditions

• Steam at 210°C from wellhead with 20 bar pressure through autoclave at well head conditions

• Temperature raised to 450°C with geothermal steam flowing through the autoclave

• Same set of materials at bothtemperatures

• Cladded noble material on carbon steelbase material

• Stand alone materials

Testing at well head temperature and pressure

Testing in Autoclave at 450°C and 20 bar

Geothermal steam wented through the autoclave

Temperature and pressure

Sample racks after testing

Samples from 450°C ready for analysing

Thank you for your attention!

17