Cézac, Pierre

Dupin, Jean-Charles

Martinez, Hervé

Poulain, Marie

Serin, Jean-Paul

English

Archive Ouverte en Sciences de l'Information et de la Communication

HAL Id: hal-02378687
https://hal-univ-pau.archives-ouvertes.fr/hal-02378687
Submitted on 25 Nov 2019
HAL is a multi-disciplinary open access
archive for the deposit and dissemination of sci-
entific research documents, whether they are pub-
lished or not. The documents may come from
teaching and research institutions in France or
abroad, or from public or private research centers.
L’archive ouverte pluridisciplinaire HAL, est
destinée au dépôt et à la diffusion de documents
scientifiques de niveau recherche, publiés ou non,
émanant des établissements d’enseignement et de
recherche français ou étrangers, des laboratoires
publics ou privés.
Experimental determination of CO2 solubility in brines
at high temperatures and high pressures and induced
corrosion of materials in geothermal equipment
Marie Poulain, Jean-Charles Dupin, Hervé Martinez, Jean-Paul Serin, Pierre
Cézac
To cite this version:
Marie Poulain, Jean-Charles Dupin, Hervé Martinez, Jean-Paul Serin, Pierre Cézac. Experimental
determination of CO2 solubility in brines at high temperatures and high pressures and induced corro-
sion of materials in geothermal equipment. AGIS VIII : 8th International Acid Gas Symposium, Jul
2019, Calgary, Canada. ￿hal-02378687￿
Experimental determination of CO2 solubility in brines at high 
temperatures and high pressures and induced corrosion of materials 
in geothermal equipment 
 
Marie Poulain1,2, Jean-Charles Dupin1, Hervé Martinez1, Jean-Paul Serin2, Pierre Cézac2 
1Univ Pau & Pays Adour / E2S UPPA, IPREM – CNRS, UMR 5234, 64000, Pau, France 
2Univ Pau & Pays Adour / E2S UPPA, Laboratoire de Thermique, Energétique et Procédés – 
IPRA, EA1932, 64000, Pau, France 
 
Global warming has been observed for many years and has brought about important 
climate change. A major cause of global warming is the steady increase of greenhouse gases 
emissions and particularly CO2. One of the objectives of the Paris agreement, whose purpose is 
to fight against global warming, is to keep the increase of the general temperature below 2°C 
by 2100 [1].  
To lessen the emissions of this greenhouse gas and thus reduce global warming, the 
capture, recovery and storage of carbon dioxide is an increasingly studied option. Carbon 
dioxide can be stored in deep saline formations which have a large capacity. Nevertherless, the 
amount of carbon dioxide dissolved in the water depends on the pressure, temperature and 
composition of the water.  
Another studied option to reduce global warming is to develop renewable energy. The use 
of geothermal energy in the world is still in development, both for the production of electricity 
and heat. In 2015, the total energy produced by geothermal power throughout the world was 
around 74,000 GWh [2]. The deep geothermal energy to produce electricity or heat for large 
complexes is under development. In France, more precisely in the Upper Rhine Graben region, 
several projects have been carried out, in Soultz-sous-Forêts for instance. The aim is to recover 
a hot fluid from deep subsoil. This fluid passes through a heat exchanger where the energy is 
released to a secondary fluid. The cooled geothermal fluid is then re-injected into a second well 
[3]. It is very important to have a good knowledge of the fluid behaviour to better design 
equipment and reduce the cost of the installations. Another crucial point is to prevent 
installations from corrosion. Material choice remains difficult due to the fluid composition, the 
operating temperatures and pressures and the presence of acid gas dissolved. 
A good knowledge of the liquid-vapour equilibrium, particularly gas solubility, for these 
two different applications is essential. Models allowing the prediction of carbon dioxide 
solubility in brines have been previously developed. However, they are fitted from experimental 
data. Experimental measurements of carbon dioxide in brines are therefore needed. The 
determination of gas solubility at high temperatures and pressures is quite complex. Although 
many data are available in the literature for the CO2 solubility in pure water or single salt 
solutions, data for carbon dioxide solubility in mixed-salt solutions are still missing. The aim 
of this study was to use a simple method developed in previous papers [4, 5] to determine the 
carbon dioxide solubility in brines at high temperatures and high pressures. 
CO2 solubility has been measured in two synthetic brines. The composition of the brines 
was based on the Soultz-sous-Forêts (Upper Rhine Graben) water. The fluid of Soultz is 
classified as Na-Ca-Cl type with a TDS (Total Dissolved Solids) around 90 g/L. The first brine 
consists in a mixture of NaCl and CaCl2 salts, respectively at concentration of 1.2 mol/kgw and 
0.2 mol/kgw. The second brine is made of 1.2 mol/kgw of NaCl, 0.2 mol/kgw of CaCl2 and 0.1 
mol/kgw of KCl. Both CO2-H2O-NaCl-CaCl2 and CO2-H2O-NaCl-CaCl2-KCl systems have 
been studied at three temperatures: 323, 373 and 423 K and up to 20 MPa. 
A high pressure and high temperature apparatus has been used to reproduce the subsoil 
conditions and obtain the thermodynamic equilibrium. The sampling process is based on the 
trapping method. It consists in withdrawing an aqueous sample of the equilibrium cell in a 
syringe containing soda. Then, carbon dioxide measurements have been carried out by 
conductimetric titration coupled with pH measurements. 
48 experimental solubility data have been obtained. The results show that the carbon 
dioxide solubility increase when the pressure increase. On the other hand, an increase in 
temperature or salinity implies a decrease of the gas solubility. Experimental results have been 
compared with two different models (PhreeSCALE and PSUCO2). This comparison between 
measured and calculated values show a good agreement (Figure 1). 
The second part of this work consists in studying the material corrosion in these particular 
environments (high temperature, high pressure, brines). The aim of this study is to observe if 
the corrosion process induced by geothermal fluid occurs on several materials. In such case, the 
next step is to better understand the corrosion phenomena. Previous studies conducted at the 
Figure 1: Comparison between experimental data obtained in the two synthetic brines at 323 
(●), 373 (■) and 423 K (▲) up to 20 MPa and predicted CO2 solubility obtained with 
PhreeSCALE (solid line) and PSUCO2 model (dashed line) 
Soultz-sous-Forêts geothermal power plant have allowed a first step towards the understanding 
of corrosion processes and mechanisms [6, 7, 8].  
In this study, a corrosion pilot (Figure 2) has been developed to conduct investigations on 
materials. Four autoclaves made of titanium are divided two by two in ovens. The autoclave 
can operate until 473 K and 20 MPa. An inert insert is placed in the cell to avoid the contact 
between the titanium and the fluid or the exposed materials. Temperature probes and pressure 
sensor enable the monitoring of experimental conditions. 
In this work, two materials were studied: a carbon steel (DC01) and a stainless steel (304L). 
First, the microstructure of the materials were determined. Before exposition, material coupons 
were prepared according to the ASTM G1-03 [9]. Then, these coupons were placed into an 
autoclave containing brine at a given temperature and pressure. The coupons can be placed 
either in the gas phase or in the aqueous phase or at the gas/liquid interface. After different 
exposure times, the coupons were analysed.  
First, a study of the weight loss allows the determination of the corrosion rate, which can 
be compared to the corrosion rate obtained by electrochemical measurements. The originality 
of this work is to associate surface analysis by XPS to the previous information. This technic 
enables the identification of corrosion products and their composition. By coupling the 
electrochemical and the surface analysis data, the comprehension of the corrosion mechanism 
and process can be improved. This leads to the determination of the most appropriate material 
from a technico-economic point of view: resistance to corrosive medium vs. cost of material. 
Further investigations could be led using inhibitors in the geothermal fluid in order to observe 
their impact on the reduction of the corrosion phenomena. 
Figure 2: Photograph of the corrosion pilot 
References 
[1] Rogelj,J.; den Elzen, M.; Höhne, N.; Fransen, T.; Fekete, H.; Winkler, H.; Schaeffer, R.; 
Sha, F.; Riahi, K.; Meinshausen, M. Paris Agreement climate proposals need a boost to keep 
warming well below 2°C. Nature 2016, 534, 631-639. 
[2] Bertani, R. Geothermal Power Generation in the World 2010-2015 Update Report. 
Melbourne, WGC 2015. 
[3] Agemar, T.; Weber, J.; Schulz, R. Deep Geothermal Energy Production in Germany. 
Energies 2014, 7, 4397-4416. 
[4] Messabeb, H.; Contamine, F.; Cézac, P.; Serin, J. P.; Gaucher, E. C. Experimental 
Measurement of CO2 Solubility in Aqueous NaCl Solution at Temperature from 323.15 to 
423.15 K and Pressure of up to 20 MPa. J. Chem. Eng. Data 2016, 61, 3573−3584. 
[5] Messabeb, H.; Contamine, F.; Cézac, P.; Serin, J. P.; Pouget, C.; Gaucher, E. C. 
Experimental Measurement of CO2 Solubility in Aqueous CaCl2 Solution at Temperature from 
323.15 to 423.15 K and Pressure of up to 20 MPa Using the Conductimetric Titration. J. Chem. 
Eng. Data 2017,62, 4228−4234.  
[6] Mundhenk, N. et al. Corrosion and scaling as interrelated phenomena in an operating 
geothermal power plant. Corros. Sci. 70, 17–28 (2013). 
[7] Mundhenk, N.; Huttenloch, P.; Kohl, T.; Steger, H.;  Zorn, R. Metal corrosion in geothermal 
brine environments of the Upper Rhine graben – Laboratory and on-site studies. Geothermics 
46, 14–21 (2013). 
[8] Mundhenk, N. et al. Electrochemical study of the corrosion of different alloys exposed to 
deaerated 80°C geothermal brines containing CO2. Corros. Sci. 84, 180–188 (2014).  
[9] ASTM G1-03. Standard practice for preparing, cleaning, and evaluating corrosion test 
specimens, ASTM International, West Conshohocken, PA, 2018, www.astm.org 


Experimental determination of CO2 solubility in brines at high temperatures and high pressures and induced corrosion of materials in geothermal equipment

https://hal-univ-pau.archives-ouvertes.fr/hal-02378687/file/Extended_abstract_AGISVIII_Poulain.pdf

Experimental determination of CO2 solubility in brines at high temperatures and high pressures and induced corrosion of materials in geothermal equipment

Abstract

Similar works

Full text

Available Versions

Archive Ouverte en Sciences de l'Information et de la Communication