Water-rock-CO 2 interactions for CO 2 geological storage

Transcription

1 Water-rock-CO 2 interactions for CO 2 geological storage Prof. Dr. Pang Zhonghe Institute of Geology and Geophysics, Chinese Academy of Sciences,Beijing, Beijing, CHINA z.pang@mail.iggcas.ac.cn

2 Outline Purposes for water-rock-co 2 interaction study Typical water-rock-co 2 interactions for CO 2 geological storage Methods for water-rock-co 2 interaction study Future focuses

3 Purposes for water-rock-co2 interactions study determining CO 2 trapping mechanisms in saline formations understanding reservoir geochemical responses providing geochemical monitoring indicators assessing impact of CO2 storage on groundwater systems

4 CO 2 trapping mechanisms in saline formations Generally, four processes have been identified as the most important CO2 trapping mechanisms for CO2 sequestration in saline formations: With different time scales, the proportion of different forms of CO2 trapping mechanisms are varying and for different specific injection structural reservoir, and the stratigrafic proportions trapping of CO2 trapping mechanisms are specific residual due trapping to specific reservoir mineral compositions and formation water chemistry. solubility trapping mineral trapping (IPCC,2005) (Audigane P. et al., 2007)

5 Understanding reservoir geochemical responses initial solution mmol/l nco2=27.82mmol Ca+2 K+ Na+ Mg+2 F- Cl- SO4-2 HCO ph (Li et al., 2010) Generally speaking, after CO2 is injected into deep saline formations, ph of reservoir water will decrease by 1-2 units and concentrations of chemical components like Al, Si, and HCO 3 - increase significantly. And CO2 would be sequestrated (fixed) mainly by secondary carbonate minerals. 2 0 CO2(mmol)

6 (Xu et al., 2003) Minerals in the formation water show different evolution tendency due to specific rock compositions and water chemistry. In Xu s model, CO2 will be trapped by calcite, dolomite,siderite and dawsonite,which will occur in the presence of high pressure CO2.

7 (Palandri and Kharaka, 2009)

8 Providing geochemical monitoring indicators In order to understand the migration path of CO2 plume and what happens after large volume CO2 is injected into the reservoir, effective monitoring needs to be carried out. Although geophysical monitoring is very efficient, it s expensive and is difficult to apply. Geochemical monitoring is effective if appropriate monitoring indicators are identified.

9 Results from experiments, field tests and numerical simulation indicate that ph, ion concentrations of HCO3-, Fe, Mn will increase even by magnitudes and these geochemical constitutes can be effective monitoring targets. (Kharaka et al., 2006)

10 Isotopes of formation water can be chosen as geochemical indicators since great oxygen-shifts have been observed in CO2 injection due to isotope exchange between formation water, CO2 and reservoir minerals. (Myrttinen et al., 2010), Ketzin test (Kharaka et al., 2005), Frio test. (Johngon and Mayer, 2011)

11 Investigating impact of CO2 storage on groundwater systems Once injected, CO2 could accelerate water-rock interaction and cause ph decrease and mobilization of metals and hazardous inorganic and organic constituents which could lead to groundwater quality deterioration. When CO2 migrates from a deep saline formation, e.g. via local high-permeability pathways such as permeable faults or degraded wells, it will arrive in shallow groundwater systems and change the geochemical conditions in the aquifer and will cause secondary effects, contaminating shallow groundwater resources.

12 Ca, Mg, Na, K Concentration (mg/l) Ca Mg Na K Sr Ba Alkalinity, as HCO 3 (mg/l) Sr, Ba Concentration (mg/l) Concentrations of major cations in groundwater from the ZERT wells. Note the relatively constant concentrations of Na and K, but the general increases in the concentrations of divalent cations with water alkalinities, possibly indicating dissolution of carbonate minerals. Results from Research Project on CO2 Geological Storage and Groundwater Resources from Earth Sciences Division, LBNL.

13 Concentration (mg/l) Concentration (mg/l) B 2B 4B 5B A wells /7 7/10 7/13 7/16 7/19 7/22 7/25 7/28 7/31 8/3 8/6 8/9 8/12 8/ (a) Fe CO 2 start (b) Mn CO 2 start CO 2 stop CO 2 stop When CO2 is injected into groundwater, concentration of Fe and Mn show an increase. The low Fe and Mn concentrations during July 20 to July 26 could be attributing to the oxidizing conditions possibly caused by percolating oxygenated water from rainfall events /7 7/10 7/13 7/16 7/19 7/22 7/25 7/28 7/31 8/3 8/6 8/9 8/12 8/15 Results from Research Project on CO2 Geological Storage and Groundwater Resources from Earth Sciences Division, LBNL.

14 Typical water-rock-co 2 interactions for CO 2 geological storage CO2+H2O H2CO3 (aq) H2CO3 (aq) H++HCO3- Calcite + H+ Ca2++ HCO3- Dolomite+ 2H+ Ca2++ Mg2++2HCO3- Chlorite+ 16H+ 5Mg2++2Al3++3SiO2 (aq) +12H2O Albite + 4H+ Na++Al3++3SiO2 (aq) +2H2O Dawsonite + 4H+ Na++Al3++CO2 (aq) +3H2O Anorthite+ 8H+ Ca2++2Al3++2SiO2 (aq) +4H2O.

15 In the Frio test, the observed increases in concentrations of HCO3 and Ca likely result from the rapid dissolution of calcite (1); the increases of Fe are likely caused by dissolution of the observed iron oxyhydroxides (2),this is the same for Mn; another dominant reaction is aluminosilicate mineral dissolution. (Kharaka et al., 2006) Frio test

16 The following reactions are proposed to summarize the geochemical processes at Nagaoka during the early stage of CO2 storage at the reservoir (Mito et al., 2008).

17 The low ph and under-saturation of the solution promoted extensive calcite cement dissolution in all samples. The overall alterations after the initial acidification and dissolution of carbonates are represented by the following reactions (Ketzer et al., 2009):

18 Methods for water-rock-co 2 interaction study Experiments of Water-rock-CO 2 interactions in laboratory Numerical simulation of a specific site Field test and corresponding monitoring

19 Physical modeling of water-rock-co2 interaction for Nagaoka test site of Japan Reaction conditions: 50 and 10MPa; Reaction time: 15 days; Reactants: formation water stored for two years and 4g rock powers; (Mito S. et al., 2008)

20 K-feld kaolinite Water-rock-CO2 interaction study for Rio Bonito Formation (Permian), southern Brazil opal 200 and 10-15MPa; gypsite 100h; distilled water and round rock samples; (Ketzer J.M. et al.,2009)

21 Water-rock-CO2 interaction study for CO2 sequestration in the Guantao formation of the Bohai Bay Basin, NE China 200 and 20MPa; 15 days; Formation water and rock ;

22 Methods for water-rock-co 2 interactions study Experiments of Water-rock-CO 2 interactions in laboratory Numerical simulation based on specific site Field test and corresponding monitoring

23 Numerical simulations on specific site List of numerical codes (Study performed by Geogreen)

24 (Xu et al., 2006) Changes of different kinds of minerals over time scales due to waterrock-co2 interactions.

25 (Ketzer J.M. et al., 2009)

26 (Barbara et al., 2009)

27 Calcite Chlorite (Zhang et al., 2009)

28 Methods for water-rock-co 2 interaction study Experiments of Water-rock-CO 2 interactions in laboratory Numerical simulation based on specific site Field test and corresponding monitoring

29 (Mito et al., 2008) Ions changes and dissolution kinetics of K- feld from the field test of CO2 injection in Nagaoka site.

30 HCO3 (mg/l) Fe (mg/l) D H 2 O (per mil) Fe injection C Fe observation C Fe observation B Mn injection C Mn observation C Mn observation B Frio baseline brines Brines after injection Meteoric water line HCO3 injection HCO3 MDT injection HCO3 observation C-sand HCO3 observation B-sand EC injection EC MDT injection EC observation C-sand EC observation B-sand Jun Oct Feb Jun Oct-05 Feb-06 6/04 8/04 Cl (mg/l) Ca (mg/l) Cl injection well Cl MDT injection well Cl observation well C-sand Cl observation well B-sand Ca injection well Ca MDT injection well Ca observation well C-sand Ca observation well B-sand /5 10/6 10/7 10/8 Jun-04 Aug-04 Oct-04 Dec-04 Jan-05 Apr-05 10/5/04 18 O H 2 O (per 10/6/04 mil) 10/7/ /04 2/05 4/ Ca (mg/l) Mn (mg/l) E. Conductance ( S/cm) (Kharaka et al., 2006)

31 (Myrttinen et al., 2010) Isotope changes results from Ketzin injection site of Germany.

32 40 Cl + SO4=> E 60 <=Ca + Mg 40 A Nm D Ng E O H Jxw Mg 40 E 20 E DH A E A H H D A H E DA H EH AD D H D D D D A A A A A A 20 SO4 80 E A H AD H HH D D E D D Ca Na+K HCO3 Cl Geochemical background of formation water from Guantao formation, Bohai Bay Basin.

33 Future focuses Water-rock-CO2 interaction for specific reservoir conditions Influences of water-rock-co2 interactions on CO2 storage capacity Minerals kinetics in water-rock-co2 interaction and corresponding influences on reservoir physical properties

34 Different sedimentary environments can lead to different reservoir and caprock conditions, e.g., continental and marine sedimentary environments. Different reservoir minerals and formation water chemistry may have great influences on water-rock-co2 interactions. Therefore, water-rock-co2 interaction should be studied for each specific testing site.

35 CO2 storage capacity is variable and is mainly controlled by the capacities of mineral, solubility, structural and stratigraphic and residual trappings. The proportion of different trapping forms is changes with time and so does the total capacity. Attention should be paid to CO2 storage capacity at specific time scales. (Audigane et al., 2007)

36 Minerals kinetics in water-rock-co2 interaction The general rate equation is adopted from Lasaga et al., 1995 and in general, the most well-studied mechanisms are those in pure H2O( neutral ph) and those catalyzed by H+( acid) and OH-(base). For many minerals, the full equations includes a terms for each of these the three water-rock mechanisms. interaction kinetic equation basic theory the competence of minerals kinetics database the accurate definition of reactive surface area scale effects of mineral data from laboratory testing other factors affecting water-rock interactions especially microorganisms processes (Transitionary theory by Lasaga et al., 1995)

37 谢谢! Thanks!