Microseismic Monitoring and Geomechanical Modelling of CO2 - bris

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7 6 5 4 3 2 1 0 CHAPTER 8. LINKING GEOMECHANICAL MODELLING AND MICROSEISMIC OBSERVATIONS AT WEYBURN in order to calibrate and refine the models. Figure 8.1: Workflow demonstrating how the predictions from coupled geomechanical models can be compared with microseismic observations 0 6 8 10 12 14 16 18 20 Normal Stress (MPa) 1500 2000 2500 3000 X (m) 500 Shear Stress (MPa) Y (m) 1000 1500 Comparison between model and observations Max SWS =0.22263% Event locations Microseismicity predictions 2000 Anisotropy modelling 180° 210° 150° 240° 120° 270° 90° 1500 0 10 20 30 40 Pressure (MPa) 300° 60° 2000 Stress dependent velocity models 330° 30° 0° Velocity (m/s) 2500 3000 Splitting observations 3500 Stress map 4000 1788 Core sample measurements Fluid-flow model Geomechanical model Recalibrate geomechanical model 148
8.2. MODEL DESCRIPTION Layer Thickness Φ κ x κ z Marly 13m 0.25 5mD 4mD Vuggy 27m 0.15 10mD 7mD Table 8.1: Flow properties used to simulate the Weyburn reservoir. the reservoir are bounded by impermeable and stiff evaporites (the Midale and Frobisher evaporites, respectively), and overlying the Midale evaporite is a secondary seal of Mesozoic shale (the Watrous). Above these layers are further overburden rocks that will not be modelled directly in this work. 8.2.1 Fluid flow simulation The fluid flow simulation only has to simulate the reservoir. Because the reservoir is laterally extensive with little topography, it is appropriate to model it as a flat layer with a structured mesh. I set up the injection and production wells to approximate the pattern at Weyburn where microseismic monitoring has been deployed. 4 horizontal wells are modelled, trending parallel to the y axis. In between the production wells are 3 vertical injection wells with a spacing in the y direction of 500m. The horizontal wells are completed over a length of 1400m in the reservoir. To reduce computational requirements I model only half of the reservoir, and complete the simulation by assuming that the model is symmetrical about the x axis. Therefore the figures in this chapter show only the half of the model that has been simulated. The region enclosed by the wells is approximately 1.5×1.5km. However, I extend the model to 4.4km in the x direction and 4km in the y direction in order to reduce the influence of edge effects. The reservoir is 40m thick, and for the purpose of fluid flow simulation is split into upper Marly and lower Vuggy layers, whose flow properties are given in Table 8.1. Although these properties differ slightly from the values given in Chapter 2, discussion with the field operators (D. Cooper, pers. comm., 2009 ) suggests that these values provide the best match with observed pressures and gas saturation. The mesh through the well region has a minimum spacing of 60×50×4m (x × y × z), with an increasingly coarse mesh used laterally away from the wells (up to 240×275m). The flow simulation mesh is depicted in Figure 8.2. The flow regime is as follows: For one year there is no injection in order to ensure that the model has stabilised; after this the field is produced for two years through all the wells, drawing the pressure down from 15 to 10MPa; then the three vertical wells are switched to inject CO 2 for 1 year, increasing the pressure to ∼18MPa, while the pressure is still below 15MPa at the producers. This provides an approximation of the state of the field after 1 year of injection (i.e., by the end of 2004, the end of Phase IB). The gas injection rate at each well is 100MSCM/day. The pore pressures and gas saturations at the end of the simulation are plotted in Figure 8.2. 8.2.2 Geomechanical model The geometry of the reservoir in the geomechanical model must be the same as for the fluid flow modelling. For the geomechanics I use a mesh spacing of 60×50×20m (x × y × z) in the reservoir, 149
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Microseismic Monitoring and Geomech
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Abstract Capture of CO 2 produced a
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Author’s Declaration I declare th
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Acknowledgments There are many thin
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Table of Contents Abstract Author
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TABLE OF CONTENTS 5.4 Results . . .
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Preface ‘Research is not an end i
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6. D. Angus, J-M. Kendall, J.P. Ver
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1 Introduction A technology push ap
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1.2. CCS OVERVIEW Figure 1.2: CCS s
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1.3. THESIS OVERVIEW for CO 2 to be
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1.3. THESIS OVERVIEW as microseismi
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2 The Weyburn CO 2 injection projec
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2.2. WEYBURN GEOLOGICAL SETTING Fig
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2.2. WEYBURN GEOLOGICAL SETTING N F
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2.4. EVENT TIMING AND LOCATIONS 500
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2.4. EVENT TIMING AND LOCATIONS 500
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2.4. EVENT TIMING AND LOCATIONS Nor
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2.4. EVENT TIMING AND LOCATIONS Fig
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2.5. DISCUSSION 500 1000 1100 North
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2.6. SUMMARY 2.6 Summary • CO 2 s
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3 Inverting shear-wave splitting me
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3.2. INVERSION METHOD the additiona
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3.2. INVERSION METHOD 1. P-wave inc
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3.2. INVERSION METHOD 180 160 140 C
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3.2. INVERSION METHOD 2800 2800 260
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3.2. INVERSION METHOD Loop over γ,
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20 10 5 5 1 20 30 40 80 100 60 40 1
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3.4. SWS MEASUREMENTS AT WEYBURN th
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3.4. SWS MEASUREMENTS AT WEYBURN ei
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3.4. SWS MEASUREMENTS AT WEYBURN ξ
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3.4. SWS MEASUREMENTS AT WEYBURN da
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4 2 2 3.4. SWS MEASUREMENTS AT WEYB
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1 1 1 1 1 1 1 1 1 1 3.5. DISCUSSION
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3.6. SUMMARY 3.6 Summary • I have
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4 A comparison of microseismic moni
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4.2. EVENT LOCATIONS 2400 Velocity
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4.2. EVENT LOCATIONS 200 150 Northi
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4.3. EVENT MAGNITUDES Pressure (MPa
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4.3. EVENT MAGNITUDES 160 140 120 N
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4.4. SHEAR WAVE SPLITTING 50 −3 E
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4.5. INITIAL S-WAVE POLARISATION In
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4.5. INITIAL S-WAVE POLARISATION 6
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4.5. INITIAL S-WAVE POLARISATION of
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4.6. INTERPRETATION OF SHEAR WAVE S
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1 1 5 5 30 4.6. INTERPRETATION OF S
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80 4.6. INTERPRETATION OF SHEAR WAV
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2 3 3.5 4 5 2 1.8 1.4 4 4.6. INTERP
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4.7. DISCUSSION 4.7 Discussion The
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pressure, P fl σ ′ ij = σ ij
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5.2. EFFECTIVE STRESS AND STRESS PA
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5.3. NUMERICAL MODELLING 5.3.1 Flui
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5.3. NUMERICAL MODELLING MORE FLUID
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5.3. NUMERICAL MODELLING (a) (b) Fi
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5.4. RESULTS 0 500 1000 Depth (m) 1
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5.4. RESULTS 1 0.9 0.8 Soft Med Sti
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Page 117 and 118: 5.4. RESULTS 1z:100x:100y 1z:100x:5
Page 119 and 120: 5.5. SURFACE UPLIFT 1 0.9 0.8 Soft
Page 121 and 122: 5.5. SURFACE UPLIFT Figure 5.17: Ma
Page 123 and 124: 6 Generating anisotropic seismic mo
Page 125 and 126: 6.2. STRESS-SENSITIVE ROCK PHYSICS
Page 127 and 128: 6.3. A MICRO-STRUCTURAL MODEL FOR N
Page 145 and 146: 6.4. CALIBRATION WITH LITERATURE DA
Page 147 and 148: 6.4. CALIBRATION WITH LITERATURE DA
Page 149 and 150: 6.5. COMPARISON OF ROCK PHYSICS MOD
Page 151 and 152: 6.5. COMPARISON OF ROCK PHYSICS MOD
Page 153 and 154: 7 Forward modelling of seismic prop
Page 155 and 156: 7.2. SEISMODEL c⃝ WORKFLOW time s
Page 157 and 158: 7.3. RESULTS FROM SIMPLE GEOMECHANI
Page 163 and 164: 7.4. SUMMARY 7.4 Summary • I have
Page 165: 8 Linking geomechanical modelling a
Page 169 and 170: 8.2. MODEL DESCRIPTION Unit E (GPa)
Page 171 and 172: 8.3. RESULTS Marl Vugg 0.8 0.8 Norm
Page 173 and 174: 8.3. RESULTS 15 10 Injector Produce
Page 175 and 176: 8.3. RESULTS 2000 15 2000 15 1500 1
Page 177 and 178: 8.4. A SOFTER RESERVOIR 8.4 A softe
Page 179 and 180: 8.4. A SOFTER RESERVOIR 2000 15 200
Page 181 and 182: 8.4. A SOFTER RESERVOIR 2000 Max SW
Page 183 and 184: 8.5. DISCUSSION pore-pressure being
Page 185 and 186: 8.6. SUMMARY 8.6 Summary • I appl
Page 187 and 188: 9 Conclusions Geological storage wi
Page 189 and 190: calibrate. This model has been cali
Page 191 and 192: 9.1. NOVEL CONTRIBUTIONS techniques
Page 193 and 194: 9.2. FUTURE WORK Finally, the compa
Page 195 and 196: Bibliography Abt, D. L., Fischer, K
Page 197 and 198: BIBLIOGRAPHY Gassmann, F., 1951. Ub
Page 199 and 200: BIBLIOGRAPHY Kendall, J.-M., Pilido
Page 201 and 202: BIBLIOGRAPHY Sayers, C. M., 2002. S
Page 203 and 204: BIBLIOGRAPHY White, D., 2009. Monit
Page 205 and 206: A List of Symbols The table below l
Page 207 and 208: B In Support of Carbon Capture and
Page 209 and 210: Both China and India are aggressive
Page 211 and 212: Utsira rock properties vary signifi
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