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UNIVERSITY OF CALGARY Seismic modelling of CO2 in a sandstone aquifer, Priddis, Alberta by Virginia Cecilia Vera A THESIS SUBMITTED TO THE FACULTY OF GRADUATE STUDIES IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE DEPARTMENT OF GEOSCIENCE CALGARY, ALBERTA FEBRUARY, 2012 © Virginia Vera 2012 UNIVERSITY OF CALGARY FACULTY OF GRADUATE STUDIES The undersigned certify that they have read, and recommend to the Faculty of Graduate Studies for acceptance, a thesis entitled "Seismic modelling of CO2 in a sandstone aquifer, Priddis, Alberta" submitted by Virginia Cecilia Vera in partial fulfilment of the requirements of the degree of Master of Science. Supervisor, Dr. Donald C. Lawton, Department of Geoscience Dr. Laurence R. Lines, Department of Geoscience Dr. Ron K. Wong Department of Civil Engineering Date ii Abstract The CO2 storage potential of a shallow sandstone layer of the Paskapoo Formation, southwest of Calgary, was evaluated in this thesis. In order to assess the CO2 monitoring viability, Gassmann fluid substitution was undertaken, followed by 2D and 3D seismic modeling in the study area. From the Gassmann approach, considerable changes of velocity and density were found with increasing CO2 saturation. In addition, Amplitude versus offset (AVO) analysis proved to be sensitive for detecting saturation changes, especially through the evaluation of Shuey’s parameters. From the seismic modelled volumes, a difference in seismic amplitude was recognized. As well, time delays of the reflectors in the injection zone and below were measured. The reflectivity coefficient decreased approximately 30% and the time delay is about 1 ms. The changes caused by the presence of CO2 are identifiable by subtracting the monitor model data from the baseline model data. These models and simulations demonstrate the feasibility of using the Basal Paskapoo Fm. as a CO2 storage site, given its petrophysical, stratigraphic and geological characteristics. The proposed amount of CO2 injection is 3000 tonnes (5 injections of 600 tonnes each), a mass that can be resolved using the seismic method. Following volumetric calculations and seismic parameters it was possible to postulate that 300 tonnes of CO2 could be detected by time-lapse seismic analysis. iii Acknowledgements First I would like to thank my supervisor Dr. Don Lawton for giving me the opportunity of working in this project and under his advisory. Thanks for all the patience, support and knowledge. I thank to Carbon Management Canada (CMC), Natural Resources Canada (NRCan), Institute for Sustainable Energy, Environment and Economy (ISEEE) at the University of Calgary, Schlumberger Canada and CREWES project sponsors for making possible the development of this project. Thanks to Landmark Graphics Corporation for ProMax and Norsar for modelling software. Thanks also to CREWES students, staff and professors. Especial thanks to Helen Isaac for helping me through all this thesis process and collaborating in every step. Thanks to Kevin Hall and Rolf Maier for rescue me from my many technical problems. Thanks to Dr. Lines for his availability and sharing his knowledge in different stages of my thesis. Thanks to Malcolm Bertram, among other things for letting me drive the vibroseis and David Henley for the processing advices. Thanks to Laura Baird not only for her administrative support but for being there and caring about us. Thanks to my CREWES fellows Faranak, Hassan, Mahdi, Patricia, Diane, Melissa, Liliana, Vanja, Andrew and Akshay, that have helped me through this past couple years, and more than colleagues I consider them my friends. Finally, I want to thank all my family that, even when they are spread around the world, they always follow all my steps and support me unconditionally. iv Dedication To my mom, Belkys Gonzalez and my dad, Samuel Vera v Table of Contents Approval Page ..................................................................................................................... ii Abstract .............................................................................................................................. iii Acknowledgements ............................................................................................................ iv Dedication ............................................................................................................................v Table of Contents ............................................................................................................... vi List of Tables .......................................................................................................................x List of Figures and Illustrations ......................................................................................... xi List of Symbols, Abbreviations and Nomenclature ........................................................ xvii CHAPTER ONE: INTRODUCTION ..................................................................................1 1.1 CO2 Storage in Geological Formations and Seismic Monitoring ..............................1 1.1.1 Problem Overview .............................................................................................1 1.1.2 Injection in Sandstone Aquifers ........................................................................2 1.1.3 Alberta Carbon Capture and Storage (CCS) Potential ......................................3 1.1.4 Seismic Method for Monitoring CO2 Storage ...................................................4 1.2 Study Site ...................................................................................................................5 1.3 Well Data ...................................................................................................................6 1.4 Structure and Stratigraphy .........................................................................................9 1.4.1 Geological Framework ......................................................................................9 1.4.2 Stratigrapy .........................................................................................................9 1.4.3 Paskapoo Formation ........................................................................................10 1.4.4 Structural Characteristics .................................................................................12 1.5 Thesis Objectives .....................................................................................................13 1.6 Thesis Outline ..........................................................................................................13 1.7 Software ...................................................................................................................14 CHAPTER TWO: : REGIONAL GEOLOGICAL MODEL ...........................................15 2.1 Introduction ..............................................................................................................15 2.2 Seismic in the area ...................................................................................................15 2.3 2D Seismic Survey (August, 2010) .........................................................................16 2.3.1 Survey Design and Acquisition .......................................................................16 2.3.2 Data Processing ...............................................................................................18 2.4 3D Seismic Survey (May, 2010)..............................................................................20 2.4.1 Survey Design and Aqcuisition .......................................................................20 2.4.2 Data Processing ...............................................................................................21 2.4.2.1 Geometry set up: ....................................................................................23 2.4.2.2 First break picking: ................................................................................23 2.4.2.3 Elevation and Statics Correction: ..........................................................24 2.4.2.4 Noise attenuation ...................................................................................25 2.4.2.5 Deconvolution: .......................................................................................26 2.4.2.6 Velocity analysis ....................................................................................28 2.4.2.7 Common Depth Point Stack ..................................................................31 2.4.2.8 Post-stack time migration ......................................................................31 2.5 Seismic Interpretation ..............................................................................................33 2.6 Discussion ................................................................................................................35 vi CHAPTER THREE: PETROPHYSICS AND FLUID SUBSTITUTION ........................36 3.1 Introduction ..............................................................................................................36 3.2 Paskapoo Sandstone Aquifer ...................................................................................36