Simulation of Geological Storage of Carbon Dioxide in ... - CO2CRC

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the injection area (as well as spreading laterally). However the absence ofactual flow barriers probably underestimates the potential for trapping alongthe flow path, since the residual trapping mechanism will be more effectiveon a longer flow path.The second approach is that of object modelling, where one explicitly generatesstochastic realisations of shale distributions which meet the criterionof total shale fraction. The advantage of this technique is that it captures thelengthening of the flow path due to the tortuous vertical migration, allowingfor greater trapping at residual gas saturation.4.3 Relative permeabilityThe choice of relative permeability curves used to model two phase flow ofcarbon dioxide and water is known to have an important influence on thelong-term distribution of carbon dioxide, especially when vertical migrationoccurs. One of the critical parameters is the residual gas saturation on imbibition.Literature data (Suzanne et al., 2003) indicates a wide range ofvalues, between 5 % and 40 % can occur, depending on the local pore structure.No core flood measurements were available at this site, so guided bywork done in other basins, the base case used here is a residual gas saturationof 20 %, with one variant case using 30 %.4.4 Temperature, pressure and salinityUsing a mean surface temperature of 15 C, a fit to the temperature datayielded a gradient of 23.6 C/km. In the absence of extensive pressure data, atypical hydrostatic pressure gradient was assumed. Well completion reportsindicated a salinity of 30,000 ppm below 1340m depth, with a transitionbetween 1340m and 1160m depth to a salinity of 1000 ppm.4.5 Model parametersUsing the techniques discussed above for analysing the geological data, thefollowing model parameters were obtained for the simulation model. For thepurposes of this simulation, the formations are assumed to horizontal andof uniform thickness across the area of the injection site. Table 1 gives thedepth, the average porosity, and the ranges of permeability for each formation,while Table 2 gives the estimates of the ratio of vertical to horizontalpermeability, as this is used in the model with effective vertical permeabilityrather than explicit shale barriers.5
Table 1: Porosity, Permeability and depth for each formation in the modelFormation Depth (mSS) Porosity (% ) Perm. (mD) low/av./highYarragadee (Upper) 313-1019 26.8 238/814/1390Yarragadee (Lower) 1019-1725 20.5 7.7/58.5/109Cadda 1725-1914 18.5 119/526/932Cattamarra 1914- 20.7 1.0/8.5/24Table 2: Ratio of vertical to horizontal permeability for each formation inthe modelFormationk v /k h low/average/highYarragadee (Upper) 0.0038/0.018/0.045Yarragadee (Lower) 0.0031/0.016/0.039Cadda 0.0028/0.013/0.034Cattamarra 0.0092/0.026/0.075The injection rate in the base case is taken to be 1 million tonnes of carbondioxide per year for 20 years (about the scale of the Sleipner project), as amedium scale storage operation. The injection strategy is to inject as deepas possible, but with the constraint that adequate permeability is needed togive sufficient injectivity. Since the average permeability of the Cattamarrais too low for sufficient injectivity with a single well, the Cadda was chosenfor injection, at a depth of around 1760-1900m with a vertical well.The first model (with an effective vertical permeability) was carried outon a radial grid with 95 blocks in the radial direction and 110 blocks of 20mvertically (10450 blocks in all), extending down from 310m (the top of theYarragadee) down to 2510m, into the Cattamarra, and out to 3000m radially.The second model (with explicit flow barriers) was a 3D grid, with 31blocks of 100m in each lateral direction, and 100 blocks vertically, for a totalof 96100 blocks. The vertical extent was from 310m down to 2310m, againinto the Cattamarra.6
Page 1: Simulation of Geological Storage of
Page 4 and 5: Cooperative Research Centre for Gre
Page 6 and 7: List of Figures1 Vertical cross-sec
Page 8 and 9: 13 Vertical cross-section of gas sa
Page 10 and 11: 1 Executive SummaryNumerical simula
Page 12 and 13: 3 Simulation capabilitiesThe simula
Page 16 and 17: Figure 1: Vertical cross-section of
Page 24 and 25: Figure 11: Vertical cross-section o
Page 30 and 31: Figure 18: Horizontal cross-section
Page 32 and 33: Figure 20: Horizontal cross-section
Page 34 and 35: ReferencesBattistelli A, Calore C a

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