Geomechanical Assessment of the Cincinnati Group as a Caprock Thesis Presented in partial fulfillment of the requirements for the degree Master of Science in the Graduate School of The Ohio State University Matthew R. Hawrylak, B.S. Graduate Program in Earth Sciences 2013 Thesis committee Dr. Jeffrey Daniels, adviser Dr. Ann Cook Dr. E. Scott Bair i Copyright by Matthew R. Hawrylak 2013 ii Abstract In this study, the Cincinnati Group, was investigated for its potential as a confining layer (caprock.) The Cincinnati Group is a thick layer of late–Ordovician calcareous shale that directly overlies the Utica/Point Pleasant throughout the Appalachian Basin as a potential seal for fluid injection and CO2 sequestration. The Cincinnati Group was deposited in a shallow sea environment in Late–Ordovician Laurentia in multiple transgressive–to–regressive sequences. The viability of the Cincinnati Group as a caprock was studied using petrophysical and geomechanical methods, including well log analysis and laboratory evaluation of lithology, permeability, and tensile strength. Core samples of the Cincinnati Group were taken from the Aristech Well in Scioto County. Logs were obtained from many locations across the state of Ohio. I use permeability and Poisson’s ratio measurements from the core, and traveltime, density, and porosity data from logs to calculate both multiphase fluid flow times and fracture initiation pressures for the Cincinnati Group at the location of each well log. I compare results to mineralogical data obtained via energy dispersive x–ray spectroscopy, which demonstrates that increasing shale content decreases permeability and increases fracture resistance. ii At the location in Scioto County, the intrinsic permeabilities of core samples from a well were measured to be in the range of 0.001 to 0.705 mD, with an average value of 0.111 mD. These values resulted in calculated migration times of 3,700 years and 900 years for water and CO2–water mixture through the entire Cincinnati Group, which has a thickness of 795 at this location. Fracture gradient calculations predict an injection pressure of at least 0.81 psi per foot is required to induce a fracture at the base of the Cincinnati Group rocks. Individual fluid migration time (0.215 feet/year at Scioto County site) and the prediction of the formation of fractures from each location were compared to values from similar studies in the literature and from communications with current operators in the Utica/Point Pleasant of Ohio for context. It was found that lower– bound calculations predict the physical characteristics of the Cincinnati Group are those of an excellent caprock capable of containing water injected under pressure, but the Cincinnati Group requires further investigation to determine its potential for CO2 sequestration. iii Acknowledgments I would like to thank my advisers, Jeff Daniels, Ann Cook, and E. Scott Bair. This research was made possible through funding from the Ohio Coal Development Office and the U.S. Department of Energy. I would also like to thank Julie Sheets, Sue Welch, Alex Swift, Mike Murphy, Kyle Shalek, Tingting Liu, and Nick Leeper of OSU Earth Sciences; Chris Perry, Jim McDonald, Joe Wells , Mark Baronoski, Ron Riley, and Greg Schumacher of the Ohio Geological Survey; and Brian Mott of DLZ Engineering. iv Vita May 2007……………………………………..………………St. Edward College Preparatory High School May 2011…………………………….........................……..B.S., Geology, The Ohio State University September 2011...........Graduate Research Associate, Geology, The Ohio State University June 2012.....................Intern, the US Army Engineer Research and Development Center January 2013................Graduate Teaching Associate, Geology, The Ohio State University April 2013.............Distinguished Teaching Award, The Ohio State School of Earth Science June 2013...............Intern, Chevron North America Exploration and Production Company December 2013...................................................M.S., Geology, The Ohio State University Fields of Study Major Field: Earth Sciences v Table of Contents Abstract ..............................................................................................................................ii Acknowledgments..............................................................................................................iv Vita .....................................................................................................................................v List of Tables .....................................................................................................................vii List of Figures ...................................................................................................................viii Chapter 1: Introduction…………………...................................................................................1 Chapter 2: Geologic Setting…………………………………………………............................................6 Chapter 3: Methods……………………………………………………………………………………………………..12 Chapter 4: Results and Discussion………………………………………………………………………………..19 Chapter 5: Conclusions…………………………………………………………………………………………………28 References .......................................................................................................................31 Appendix A: Cincinnati Group Picks from Gamma Ray Logs………………………………………….36 Appendix B: Laboratory Measurements…………………………………………..…………………………..48 Appendix C: Scioto County Fracture Gradient Calculations..………………………………………...53 Appendix D: Belmont County Fracture Gradient Calculations ……………………………………...60 Appendix E: Gallia County Fracture Gradient Calculations ……………………………………….....69 vi List of Tables Table 1: Cincinnati Group Fluid Migration Times………………………………………………………….23 vii List of Figures Figure 1: Generalized stratigraphic column for east–central Ohio....………………………….....2 Figure 2: Sites used in this study.……......................………………………………………...................3 Figure 3: Map of horizontal Utica wells in Ohio ………………………........................................4 Figure 4: Paleogeographic map of Laurentia during the late Ordovician...........................7 Figure 5: Generalized stratigraphic column of Ohio……………………………………………............8 Figure 6: Relation between shale acoustic parameter and reservoir fluid pressure gradient…………………………………………….……………………………………………................16 Figure 7: Allen County well gamma ray curve…………………………………………….…………………37 Figure 8: Ashtabula County well gamma ray curve……………………………………………............38 Figure 9: Belmont County well gamma ray curve……………………………………………..............39 Figure 10: Columbiana County well gamma ray curve…………………………………………….......40 Figure 11: Fairfield County well gamma ray curve…………………………………………….............41 Figure 12: Gallia County well gamma ray curve…………………………………………….................42 Figure 13: Henry County well gamma ray curve……………………………………………................43 Figure 14: Marion County well gamma ray curve……………………………………………..............44 Figure 15: Medina County well gamma ray curve……………………………………………..............45 Figure 16: Sandusky County well gamma ray curve……………………………………………...........46 Figure 17: Scioto County well gamma ray curve……………………………………………................47 Figure 18: Warren County well gamma ray curve……………………………………………..............48 Figure 19: Scioto County Intrinsic Permeability Measurements………………………………......50 Figure 20: Scioto County SEM/QEMSCAN Results……………………………………………..............51 viii Figure 21: Scioto County AR2–15 unconfined compression test……………………………….....52 Figure 22: Scioto County AR2–16 unconfined compression test……………………………........53 Figure 23: Scioto County P–wave curve: compressional trend and deviation………….......55 Figure 24: Scioto County density log………………………………………………………………...............56 Figure 25: Scioto County reservoir fluid pressure gradient……………………………….............57 Figure 26: Scioto County reservoir fluid pressure………………………………………………………...58 Figure 27: Scioto County fracture gradient……………………………………………………………….....59 Figure 28: Scioto County fracturing pressure………………………………………………………………..60 Figure 29: Belmont County dipole sonic logs………………………………………………………………..62 Figure 30: Belmont County P–wave curve: compressional trend and deviation……………63 Figure 31: Belmont County density log………………………………………………………………...........64 Figure 32: Belmont County reservoir fluid pressure gradient………………………………..........65 Figure 33: Belmont County reservoir fluid pressure………………………………………………….....66 Figure 34: Belmont County Poisson’s ratio……………………………………………………………….....67 Figure 35: Belmont County fracture gradient……………………………………………………………….68 Figure 36: Belmont County fracturing pressure…………………………………………………………...69 Figure 37: Gallia County dipole sonic logs……………………………………………………………….......71 Figure 38: Gallia County P–wave curve: compressional trend and deviation...................72 Figure 39: Gallia County reservoir fluid pressure………………………………………………………....73 Figure 40: Gallia County reservoir fluid pressure gradient………………………………..............74 Figure 41: Gallia County density log………………………………………………………………................75 Figure 42: Gallia County Poisson’s ratio………………………………………………………………..........76 Figure 43: Gallia County fracture gradient………………………………………………………………......77 Figure 44: Gallia County fracturing pressure ………………………………………………………………..78 ix Chapter 1: Introduction Fluids are currently being injected into deep formations for the purposes of the production of hydrocarbons and the storage and sequestration of