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Gas Viscosity at High Pressure and High Temperature

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GAS VISCOSITY AT HIGH PRESSURE AND HIGH TEMPERATURE A Dissertation by KEGANG LING Submitted to the Office of Graduate Studies of Texas A&M University in partial fulfillment of the requirements for the degree of DOCTOR OF PHILOSOPHY December 2010 Major Subject: Petroleum Engineering GAS VISCOSITY AT HIGH PRESSURE AND HIGH TEMPERATURE A Dissertation by KEGANG LING Submitted to the Office of Graduate Studies of Texas A&M University in partial fulfillment of the requirements for the degree of DOCTOR OF PHILOSOPHY Approved by: Co-Chairs of Committee, Gioia Falcone Catalin Teodoriu Committee Members, William D. McCain Jr. Yuefeng Sun Head of Department, Stephen A. Holditch December 2010 Major Subject: Petroleum Engineering iii ABSTRACT Gas Viscosity at High Pressure and High Temperature. (December 2010) Kegang Ling, B. S., University of Petroleum, China; M. S., University of Louisiana at Lafayette Chair of Advisory Committee: Dr. Gioia Falcone Gas viscosity is one of the gas properties that is vital to petroleum engineering. Its role in the oil and gas production and transportation is indicated by its contribution in the resistance to the flow of a fluid both in porous media and pipes. Although viscosity of some pure components such as methane, ethane, propane, butane, nitrogen, carbon dioxide and binary mixtures of these components at low-intermediate pressure and temperature had been studied intensively and been understood thoroughly, very few investigations were performed on viscosity of naturally occurring gases, especially gas condensates at low-intermediate pressure and temperature, even fewer lab data were published. No gas viscosity data at high pressures and high temperatures (HPHT) is available. Therefore this gap in the oil industry still needs to be filled. Gas viscosity at HPHT becomes crucial to modern oil industry as exploration and production move to deep formation or deep water where HPHT is not uncommon. Therefore, any hydrocarbon encountered there is more gas than oil due to the chemical reaction causing oil to transfer to gas as temperature increases. We need gas viscosity to optimize production rate for production system, estimate reserves, model gas injection, design drilling fluid, and monitor gas movement in well control. Current gas viscosity correlations are derived using measured data at low-moderate pressures and temperatures, and then extrapolated to HPHT. No measured gas viscosities at HPHT are iv available so far. The validities of these correlations for gas viscosity at HPHT are doubted due to lack of experimental data. In this study, four types of viscometers are evaluated and their advantages and disadvantages are listed. The falling body viscometer is used to measure gas viscosity at a pressure range of 3000 to 25000 psi and a temperature range of 100 to 415 oF. Nitrogen viscosity is measured to take into account of the fact that the concentration of nonhydrocarbons increase drastically in HPHT reservoir. More nitrogen is found as we move to HPHT reservoirs. High concentration nitrogen in natural gas affects not only the heat value of natural gas, but also gas viscosity which is critical to petroleum engineering. Nitrogen is also one of common inject gases in gas injection projects, thus an accurate estimation of its viscosity is vital to analyze reservoir performance. Then methane viscosity is measured to honor that hydrocarbon in HPHT which is almost pure methane. From our experiments, we found that while the Lee-Gonzalez-Eakin correlation estimates gas viscosity at a low-moderate pressure and temperature accurately, it cannot give good match of gas viscosity at HPHT. Apparently, current correlations need to be modified to predict gas viscosity at HPHT. New correlations constructed for HPHT conditions based on our experiment data give more confidence on gas viscosity. v DEDICATION To my family for their love and support vi ACKNOWLEDGMENTS During these four years at Texas A&M University I have tried my best to adhere to the requirements of being a qualified graduate student. I got tons of help in the process of pursuing my Ph.D. degree. I want to acknowledge these people for their generosity and kindness. First of all, my gratitude goes to my advisors, Dr. Gioia Falcone and Dr. Catalin Teodoriu, for their veritable academic advice to me in these years, and in years to come. Their inspiration, encouragement, guardianship, and patience were essential for my research and study. I would also like to express my sincere appreciation to my committee member, Dr. William D. McCain Jr., for his advice, knowledge, and priceless assistance during these years. Thanks are also extended to a member of my supervising committee, Dr. Yuefeng Sun, of the Department of Geology and Geophysics, for managing time out of his busy schedule to provide valuable comments and suggestions. Furthermore, I appreciate Dr. Catalin Teodoriu, Dr. William D. McCain Jr., and Mr. Anup Viswanathan for setting up the High Pressure High Temperature laboratory for this project, and Mr. John Maldonado, Sr. for supplying gas resources. I am grateful to the sponsors of the Crisman Petroleum Research Institute at Texas A&M University for providing funding for this project. I wish to express my appreciation to the faculty and staff of the Department of Petroleum vii Engineering at Texas A&M University. I am indebted to my colleagues because they made the whole study more enjoyable. I truly appreciate my family, without their support I would not have realized my dream. viii TABLE OF CONTENTS Page ABSTRACT...................................................................................................................iii DEDICATION ...............................................................................................................v ACKNOWLEDGMENTS..............................................................................................vi TABLE OF CONTENTS...............................................................................................viii LIST OF TABLES .........................................................................................................x LIST OF FIGURES........................................................................................................xii CHAPTER I INTRODUCTION .............................................................................1 1.1 Viscosity.............................................................................................................1 1.2 Role of Gas Viscosity in Petroleum Engineering...............................................4 1.3 Methods to Get Gas Viscosity............................................................................5 CHAPTER II LITERATURE REVIEW...................................................................7 2.1 Gas Viscosity Measuring Instrument .................................................................7 2.2 Gas Viscosity Experimental Data ......................................................................29 2.3 Available Gas Viscosity Correlations ................................................................47 CHAPTER III OBJECTIVE .......................................................................................77 CHAPTER IV METHODOLOGY .............................................................................78 4.1 Experiment Facility............................................................................................78 4.2 Experiment Procedure ........................................................................................86 4.3 Measurement Principle of Viscometer in This Study ........................................89 4.4 Calibration of Experimental Data ......................................................................109 CHAPTER V EXPERIMENTAL RESULTS............................................................125 5.1 Nitrogen Viscosity Measurement.......................................................................125 ix Page 5.2 Nitrogen Viscosity Analysis...............................................................................126 5.3 Methane Viscosity Measurement.......................................................................134 5.4 Methane Viscosity Analysis...............................................................................136 CHAPTER VI NEW GAS VISCOSITY CORRELATIONS.....................................141 6.1 Nitrogen Viscosity Correlation ..........................................................................141 6.2 Methane Viscosity Correlation...........................................................................154 CHAPTER VII CONCLUSIONS AND RECOMMENDATIONS..............................176 7.1 Conclusions ........................................................................................................176 7.2 Recommendations ..............................................................................................176 NOMENCLATURE.......................................................................................................177 REFERENCES...............................................................................................................183 APPENDIX A ................................................................................................................191 APPENDIX B ................................................................................................................205 VITA ..............................................................................................................................224
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