CO 2 Geological storage - TOTAL Approach. SCA 2003 Symposium 14/12/2003

Transcription

1 CO 2 Geological storage - TOTAL Approach SCA 2003 Symposium

2 Presentation overview 1/ Context of CO 2 geological storage 2/ Subsurface technical issues 3/ Core Analysis issues 4/ Conclusions 2

3 Presentation overview 1/ Context of CO 2 geological storage 2/ Subsurface technical issues 3/ Core Analysis issues 4/ Conclusions 3

4 CO2 geological storage concepts CO2 injection in aquifers CO2 injection in depleted HC reservoirs CO2 injection in produced oil reservoirs (EOR) GEUS - CO 2 Storage - 4

5 Geological storage : capacity assessment type of storage capacity (in Gt CO2) in carbon cycle storage (1) year (2) forest aquatic biomass 10?? ocean coal bed aquifer? ,5 gas oil depleted oil EOR ,5 Large capacity available (1) compilation of MIT and IEA GHG figures (2) years equivalent for steady production of 20 GtCO 2 / y 5

6 Geological storage: not only a technical issue More and more operations Sleipner/Utsira project (North Sea) 6.2 Mt 1.0 Mt/yr Weyburn project (Canada) 2-3 Mt 1.3 Mt/yr Labarge -Salt Creek (USA) 0.0 Mt 2.6 Mt/yr Uncertainties on the legal framework EU GHG emission trading scheme from 2005 No specificities related to geological storage Risk analysis issue Public acceptability issue 6

7 Presentation overview 1/ Context of CO 2 geological storage 2/ Subsurface technical issues 3/ Core Analysis issues 4/ Conclusions 7

8 CO 2 Geological storage: three issues 1/ Injection of CO 2 into geological formations Wells and near well issues Short term (20 y): Injection period 2/ Storage of the CO 2 Equilibration of CO 2 within the formations Medium term (200 y): Stabilisation period 3/ Leakages of CO 2 What are the risks? What are the time scales? 8

9 Subsurface issues - CO 2 injection Pressure and temperature in the well CO 2 injected in a dense phase? Impact of CO 2 purity Corrosion issue water content of the CO 2 Near wellbore issues Matrix petrophysical alteration CO 2 -oil compatibility 9

10 Subsurface issues - CO 2 storage capacity What mass of injected CO 2 will be stored: in the oil (dissolution in the oil phase) in the aquifer (dissolution in water) in the solid phase (mineral trapping) left in the gas phase, resulting in a "gas cloud" What impact on the reservoir pressure: below initial pressure? below seal fracturation pressure? 10

11 Subsurface issues - Escape mechanisms Lateral escapes Fault Crossing Hydrodynamism Spill points Through cap rock Diffusion Fracturation Migration along fault Through wells Cements Corrosion SEAL RES. 11 RES. 2 FAULT FAULT CO 2 Oil HC gas Water 11

12 Lateral escapes Faults critical if leads to local pressure increase risks of hydrofracturing (faults or cap rock) Hydrodynamism CO2 circulation to larger areas difficulty to monitor CO2 moving to less dense areas buoyancy forces Stratigraphic traps Alteration of the trapping facies 12

13 Escape through cap rocks Diffusion of dissolved CO2 is a slow process Geochemical interactions have to be looked at Positive behaviour of CO2 - shales (?) Capillary entry pressure has to be investigated high CO2 column heights are obtained in aquifers Hydraulic fracturation is a critical issue mechanical models are difficult to set up pressure build up should be avoided 13

14 Escape through wells Leakage can result from Cement alteration Corrosion The CO2 injector can be designed to resist alteration still uncertainties on the long term Older wells (exploration & development wells) were not designed and abandoned to stand CO2 are the major concern 14

15 Presentation overview 1/ Context of CO 2 geological storage 2/ Subsurface technical issues 3/ Core Analysis issues 4/ Conclusions 15

16 CO 2 Geological storage: three technical issues 1/ Injection of CO 2 into geological formations Wells and near well issues Short term (20 y): Injection period 2/ Storage of the CO 2 Equilibration of CO 2 within the formations Medium term (200 y): Stabilisation period 3/ Leakages of CO 2 What are the risks? What are the time scales? 16

17 Core analysis issues - CO2 injection CO2 injected according to nominal rates Need to understand any CO2 induced process that will alter injectivity core floodings to mimic CO2 injection in reservoir at injection pressure and temperature to reproduce possible dissolution / precipitations 17

18 Core analysis issues - CO2 storage From reservoir cores Conventional CA needed Porosity, permeability, mineralogy residual water and oil saturations to CO2 SCAL critical for EOR projects cap pressure and relative permeability curves including oil - CO2 miscibility effects with a representative CO2 phase Residual water should be analysed to guide on reservoir water composition 18

19 Core analysis issues - Leakages Need of cap rock cores! Capillary entry pressure is critical to assess storage capacity porosity and permeability of the cap rocks are necessary to assess vertical migration of dissolved CO2 Long term stability of shales to CO2 need water composition and shales mineralogy In cases with significant fluid pressure changes, mechanical behaviour of the cap rock has to be assessed But drilling too close to the storage site can become a source of leakage 19

20 Presentation overview 1/ Context of CO 2 geological storage 2/ Subsurface technical issues 3/ Core Analysis issues 4/ Conclusions 20

21 Conclusions Proper core analysis is needed to evaluate a CO2 geological storage site The three main specific issues we see are cap rock core analysis analysis of residual water in cores two phase functions with a varying CO2 nature Geological storage is used for other gases 21