Density and Viscosity of Hydrocarbons at Extreme Conditions Associated with Ultra-Deep Reservoirs-Measurements and Modeling
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DENSITY AND VISCOSITY OF HYDROCARBONS AT EXTREME CONDITIONS ASSOCIATED WITH ULTRA-DEEP RESERVOIRS-MEASUREMENTS AND MODELING by Hseen O. Baled Dipl.-Ing., RWTH Aachen, 2003 Submitted to the Graduate Faculty of Swanson School of Engineering in partial fulfillment of the requirements for the degree of Doctor of Philosophy University of Pittsburgh 2012 i UNIVERSITY OF PITTSBURGH SWANSON SCHOOL OF ENGINEERING This dissertation was presented by Hseen O. Baled It was defended on November 26th, 2012 and approved by Badie I. Morsi, Ph.D., Professor, Department of Chemical and Petroleum Engineering Sachin Velankar, Ph.D., Associate Professor, Department of Chemical and Petroleum Engineering Yee Soong, Ph.D., Acting Division Director, National Energy Technology Laboratory Dissertation Director: Robert M. Enick, Ph.D., Professor, Department of Chemical and Petroleum Engineering ii Copyright © by Hseen O. Baled 2012 iii DENSITY AND VISCOSITY OF HYDROCARBONS AT EXTREME CONDITIONS ASSOCIATED WITH ULTRA-DEEP RESERVOIRS-MEASUREMENTS AND MODELING Hseen O. Baled, PhD University of Pittsburgh, 2012 There is a lack of experimental density and viscosity data particularly at extremely high temperature, high pressure (HTHP) conditions associated with ultra-deep petroleum formations found at depths of approximately 20000 ft or more, where the pressure and temperature can reach as high as 35000 psia and 500oF, respectively. In many applications, such as the simulation of oil reservoirs and the design of transport equipment, it is more convenient to use models to obtain such properties. However, development of reliable models requires sufficient experimental data that cover the entire temperature and pressure ranges of interest. A HTHP density prediction model has been developed by utilizing the concept of volume- translation (VT) in the SRK and PR equations of state. The new proposed model provides very accurate density predictions over a wide range of temperature and pressure. The overall mean absolute percentage deviation (MAPD) of 1-2% obtained with the new model is substantially lower than those calculated with other models considered in this study. A novel windowed, high temperature, high pressure rolling ball viscometer was designed and constructed specifically for this project. The viscometer has been calibrated with n-decane and used to measure the viscosity of n-octane for temperatures to 500oF and pressures to 35000 psia. A literature review of different viscosity models has shown that the friction theory and free iv volume theory models are superior to many other viscosity models. A correction term added to the friction theory model has been proposed to get more accurate predictions. In the oil industry, there is a need to identify a viscosity standard that is representative of light oils produced from ultra-deep formations found beneath the deep waters of the Gulf of Mexico. Deepwater viscosity standard (DVS) is a liquid that would exhibit a viscosity of roughly 20 cP at 500oF and 35000 psia. This work suggests Krytox® GPL 102 as a promising candidate for a HTHP DVS. The windowed rolling ball viscometer calibrated with dioctyl phthalate were used to determine the viscosity of Krytox® GPL 102, and all of the results were modeled with scaling theory and surface fitting. v TABLE OF CONTENTS TABLE OF CONTENTS ...................................................................................................... XVII LIST OF TABLES ...................................................................................................................... IX LIST OF FIGURES .................................................................................................................... XI LIST OF SYMBOLS ............................................................................................................. XVII PREFACE ............................................................................................................................... XVII 1.0 INTRODUCTION ........................................................................................................ 1 1.1 DENSITY PREDICTION OF HYDROCARBONS .......................................... 1 1.2 VISCOSITY OF HYDROCARBONS................................................................. 5 2.0 PREDICTION OF HYDROCARBON VOLUMETRIC PROPERTIES ............... 7 2.1 DEVELOPMENT OF A HIGH-TEMPERATURE-HIGH PRESSURE (HTHP) VOLUME-TRANSLATED (VT) EOS ................................................. 9 2.2 CALCULATION RESULTS FOR PURE COMPONENTS .......................... 15 2.3 EXTENSION TO MIXTURES .......................................................................... 23 2.4 EXTENSION TO LOW PRESSURE CONDITIONS ..................................... 25 2.5 EXTENSION TO DERIVATIVE PROPERTIES ........................................... 29 2.6 VALIDATION OF THE HTHP VT EQUATIONS OF STATE .................... 31 2.7 CONCLUSIONS ................................................................................................. 32 3.0 VISCOSITY OF HYDROCARBONS AT ULTRA-DEEP RESERVOIR CONDITIONS ............................................................................................................ 34 vi 3.1 ROLLING BALL VISCOMETER ................................................................... 35 3.2 WINDOWED VOLUME-VARIABLE HTHP ROLLING BALL VISCOMETER ................................................................................................... 43 3.3 CALIBRATION OF THE ROLLING BALL VISCOMETER ...................... 46 3.4 VISCOSITY RESULTS OF N-OCTANE ........................................................ 50 3.5 CONCLUSIONS ................................................................................................. 53 4.0 VISCOSITY MODELING ........................................................................................ 54 4.1 FRICTION THEORY VISCOSITY MODEL (F-THEORY) ........................ 54 4.2 FREE VOLUME THEORY VISCOSITY MODEL (FV-THEORY) ............ 59 4.3 CONCLUSIONS ................................................................................................. 61 5.0 DEEPWATER VISCOSITY STANDARD (DVS) .................................................. 62 5.1 MATERIALS ...................................................................................................... 64 5.2 EXPERIMENTAL RESULTS ........................................................................... 66 5.2.1 Rolling ball viscometer calibration with DEHP ....................................... 66 5.2.2 Rolling ball viscometer measurements of the viscosity of Krytox® GPL 102................................................................................................................. 71 5.3 ALTERNATIVE KRYTOX-BASED DVS CANDIDATES ........................... 75 5.4 VISCOSITY MODELING RESULTS .............................................................. 77 5.5 CONCLUSIONS ................................................................................................. 81 6.0 CONCLUSIONS AND RECOMMENDATIONS ................................................... 82 6.1 PROJECT SUMMARY...................................................................................... 82 6.2 SUGGESTIONS AND RECOMMENDATIONS ............................................ 84 APPENDIX A .............................................................................................................................. 86 APPENDIX B .............................................................................................................................. 88 APPENDIX C .............................................................................................................................. 96 vii APPENDIX D .............................................................................................................................. 98 BIBLIOGRAPHY ....................................................................................................................... 99 viii LIST OF TABLES Table 1. Optimized values of the volume translation parameters A and B based on literature data in the ~(7-276) MPa and ~(278-533) K ranges ........................................................... 11 Table 2. Parameters of Equation 14 .............................................................................................. 15 Table 3. Mean absolute percentage deviation (MAPD) and standard deviation (SD) for all compounds and equations of state studied in this work ................................................. 21 Table 4. Some references for rolling ball viscometer ................................................................... 36 Table 5. Summary of calibration conditions and references used for the calibration ................... 47 Table 6. Linear correlations of the calibration results with n-decane ........................................... 49 Table 7. Viscosity of n-octane ...................................................................................................... 50 Table 8. Coefficients of polynomial fit Equation 46 and MAPD values ...................................... 52 Table 9. Values for the F-theory correction parameters k, m, and n for selected compounds; comparison of MAPD and SD values for predictions with the original and corrected F- theory .............................................................................................................................. 59 Table 10. Values for the FV-theory parameters L, α, and B for selected compounds; MAPD and SD values for predictions