Microseismic Monitoring and Geomechanical Modelling of CO2 - bris

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CHAPTER 5. GEOMECHANICAL SIMULATION OF CO 2 INJECTION step the fluid flow and deformation are solved in an iterative manner, with data passed back and forth between the simulations until a stable solution is found. This is illustrated in Figure 5.4. At each time step the pore pressure and fluid properties are computed by the fluid flow simulator. These are passed to the geomechanical simulator to compute deformation (using a number of sub-steps). The changes in porosity are assessed for convergence, and if not yet converging, returned to the fluid flow simulation to repeat the iteration. This method is more computationally expensive than the explicit coupling, but produces more accurate results. Comparisons suggest that this method gives the same result as fully coupled simulations (e.g., Longuemare et al., 2002), highlighting the accuracy of this approach. The combination of accuracy with the ability to link successful commercial fluid flow and geomechanical simulation packages means that the iterative coupling method is the method that I will use. The computational speed of this approach has been greatly improved by Rockfield Software through the development of a high speed message passing interface (MPI) to link between MORE and ELFEN. 5.3.4 Workflow Using the iteratively coupled MORE-ELFEN simulation, the workflow for developing simple geomechanical models is as follows. The geomechanical mesh is constructed using the ELFEN pre-processing GUI. The model must include both the reservoir and the over, under and side burdens, as these will also be deformed by processes occurring in the reservoir. The GUI generates the input file for geomechanical modelling. The cells are populated with mechanical properties as selected by the user based on a large database of rock physics measurements. It is the geomechanical input file that controls the simulation timesteps, convergence conditions, end times, and how often results are written to file. The MORE input file is constructed by the user. The external dimensions of the reservoir in the MORE model must match the reservoir as defined in the geomechanical input. However, they need not have the same internal mesh, as ELFEN can interpolate between them. It is the MORE file that defines the well locations and injection/production rates. Internal calculation timesteps are computed by ELFEN are of a sub-day scale. However, to produce output files for each internal timestep would lead to data overload. Therefore output files are generated by ELFEN at user-defined timesteps. In my models I produce output files at 6 evenly spaced intervals during the simulations. 5.3.5 Simple representative models In order to assess the sensitivity of the stress path parameters during injection to reservoir geometry and material properties, I have developed a range of simple representative models, all consisting of cuboid reservoirs contained within non-pay rocks (Figure 5.5). In order to decrease the computational requirements, I simulate only a quarter of the system, relying on symmetry arguments to complete the model. The boundary conditions at the edges of the model are that there can be no movement perpendicular to the vertical bounding planes at the edges of the model (i.e., no movement in the x direction of the y − z plane) and no vertical movement at the base of the model. I include all of the overburden up 90
5.3. NUMERICAL MODELLING (a) (b) Figure 5.5: Geomechanical grid and material regions for the simple, rectangular reservoirs. The reservoir is marked in red, the over, side and under burdens are blue. In (b) the overburden has been removed to reveal the reservoir. To save computational time, only a quarter of the model is simulated, with symmetry used to complete the model. 91
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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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Page 59 and 60: 3.4. SWS MEASUREMENTS AT WEYBURN th
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Page 63 and 64: 3.4. SWS MEASUREMENTS AT WEYBURN ξ
Page 65 and 66: 3.4. SWS MEASUREMENTS AT WEYBURN da
Page 67 and 68: 4 2 2 3.4. SWS MEASUREMENTS AT WEYB
Page 69 and 70: 1 1 1 1 1 1 1 1 1 1 3.5. DISCUSSION
Page 71 and 72: 3.6. SUMMARY 3.6 Summary • I have
Page 73 and 74: 4 A comparison of microseismic moni
Page 75 and 76: 4.2. EVENT LOCATIONS 2400 Velocity
Page 77 and 78: 4.2. EVENT LOCATIONS 200 150 Northi
Page 79 and 80: 4.3. EVENT MAGNITUDES Pressure (MPa
Page 81 and 82: 4.3. EVENT MAGNITUDES 160 140 120 N
Page 83 and 84: 4.4. SHEAR WAVE SPLITTING 50 −3 E
Page 85 and 86: 4.5. INITIAL S-WAVE POLARISATION In
Page 87 and 88: 4.5. INITIAL S-WAVE POLARISATION 6
Page 89 and 90: 4.5. INITIAL S-WAVE POLARISATION of
Page 91 and 92: 4.6. INTERPRETATION OF SHEAR WAVE S
Page 93 and 94: 1 1 5 5 30 4.6. INTERPRETATION OF S
Page 95 and 96: 80 4.6. INTERPRETATION OF SHEAR WAV
Page 97 and 98: 2 3 3.5 4 5 2 1.8 1.4 4 4.6. INTERP
Page 99 and 100: 4.7. DISCUSSION 4.7 Discussion The
Page 101 and 102: pressure, P fl σ ′ ij = σ ij
Page 103 and 104: 5.2. EFFECTIVE STRESS AND STRESS PA
Page 105 and 106: 5.3. NUMERICAL MODELLING 5.3.1 Flui
Page 107: 5.3. NUMERICAL MODELLING MORE FLUID
Page 111 and 112: 5.4. RESULTS 0 500 1000 Depth (m) 1
Page 113 and 114: 5.4. RESULTS 1 0.9 0.8 Soft Med Sti
Page 115 and 116: 5.4. RESULTS Overburden Extension i
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
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7.3. RESULTS FROM SIMPLE GEOMECHANI
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7.3. RESULTS FROM SIMPLE GEOMECHANI
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7.4. SUMMARY 7.4 Summary • I have
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8 Linking geomechanical modelling a
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8.2. MODEL DESCRIPTION Layer Thickn
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8.2. MODEL DESCRIPTION Unit E (GPa)
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8.3. RESULTS Marl Vugg 0.8 0.8 Norm
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8.3. RESULTS 15 10 Injector Produce
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8.3. RESULTS 2000 15 2000 15 1500 1
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8.4. A SOFTER RESERVOIR 8.4 A softe
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8.4. A SOFTER RESERVOIR 2000 15 200
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8.4. A SOFTER RESERVOIR 2000 Max SW
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8.5. DISCUSSION pore-pressure being
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8.6. SUMMARY 8.6 Summary • I appl
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9 Conclusions Geological storage wi
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calibrate. This model has been cali
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9.1. NOVEL CONTRIBUTIONS techniques
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9.2. FUTURE WORK Finally, the compa
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Bibliography Abt, D. L., Fischer, K
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BIBLIOGRAPHY Gassmann, F., 1951. Ub
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BIBLIOGRAPHY Kendall, J.-M., Pilido
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BIBLIOGRAPHY Sayers, C. M., 2002. S
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BIBLIOGRAPHY White, D., 2009. Monit
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A List of Symbols The table below l
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B In Support of Carbon Capture and
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Both China and India are aggressive
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Utsira rock properties vary signifi
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