8027504 AHMED, Tarek Hussein AN EXPERIMENTAL STUDY OF CRUDE OIL RECOVERY BY HIGH PRESSURE NITROGEN INJECTION The University of Oklahoma PH.D. 1980 University Microfilms I nternétions! 300 N. Zeeb Road, Ann Arbor, MI 48106 18 Bedford Row, London WCIR 4EJ, England Copyright 1980 by Ahmed, Tarek Hussein All Rights Reserved PLEASE NOTE: In all cases this material has been filmed in the best possible way from the available copy. Problems encountered with this document have been identified here with a check mark . 1. Glossy photographs 2. Colored illustrations 3. Photographs with dark background s/ 4. Illustrations are poor copy 5. °rint shows through as there is text on both sides of page 6. Indistinct, broken or small print on several pages \/ 7. Tightly bound copy with print lost in spine 8. Computer printout pages with indistinct print 9. Page(s) lacking when material received, and not available frwn school or author 10. Page(s) ________seem to be missing in numbering only as text follows n. Poor carbon copy________ 12. Not original copy, several pages with blurred type 13. Appendix pages are poor copy ________ 14. Original copy with light type ________ 15. Curling and wrinkled pages ________ 16. Other Universiw MioOTims intemarionai 300 \ ZE = = RD. ANNAR30R Ml ^8106'313) 761-4700 THE UNIVERSITY OF 0KLAH0Î1A GRADUATE COLLEGE AN EXPERIMENTAI. STUDY OF CRUDE OIL RECOVERY BY HIGH PRESSURE NITROGEN INJECTION A DISSERTATION SUBMITTED TO THE GRADUATE FACULTY in partial fulfillment of the requirements for the degree of DOCTOR OF PHILOSOPHY BY TAREK H. AHMED Norman, Oklahoma 1980 AN EXPERIMENTAL STUDY OF CRUDE OIL RECOVERY BY HIGH PRESSURE NITROGEN INJECTION APPROVED BY '^/lA DISSERTATION COMMITTEE AN EXPERIMENTAL STUDY OF CRUDE OIL RECOVERY BY HIGH PRESSURE NITROGEN INJECTION BY; Tarek H. Ahmed MAJOR PROFESSOR: Dr. Donald E. Menzie ABSTRACT AN EXPERIMENTAL STUDY OF CRUDE OIL RECOVERY BY HIGH PRESSURE NITROGEN INJECTION The objectives of this study were to investigate the: 1. Compositional changes taking place during the displacing of crude oil by continuous high pressure nitrogen injection. 2. Changes in the properties of the liquid and vapor phases. 3. Miscible pressures for nitrogen displacement. 4. Distance from the injection point at which the miscibility will be achieved. The experiments were conducted in a low permeability, consolidated, sand-packed, stainless steel tube 125 feet long and 0.45 inches in diameter. Five sampling points were located at equal intervals along the length of the linear core. Vapor samples were collected periodically from the sampling valves and analyzed by the gas chromatograph. The results of this experimental investigation showed the compositional distribution of the vapor phase throughout the core during the nitrogen injection process. The mechanism of the nitrogen displacement process was analyzed and the fronts formed during the oil recovery experiments were recorded and studied in order to better understand the overall recovery mechanism. Ill ACKNOWLEDGEMENTS The author wishes to express his sincere appreciation to the many people who helped make this work possible. Special appreciation is given to Dr. D. E. Menzie, who served as an advisor in this research, for his continued support,i nterest and guidance in the completion of this effort. Appreciation is also extended to the members of my doctoral committee; Dr. H. B. Crichlow, Dr. F. M. Townsend, Dr. B. Foote, and Dr. A. W. McCray. Special thanks is extended to Mr. N. S. Knight for his help and superb craftsmanship in the design and construction of certain specialized equipment. I also wish to express my thanks to Mrs. Carol Wedel for her superb typing ability. Thanks is given to Patrick, Susan and Shanna for their help, and appreciation is also expressed to the Egyptian Government, Tenneco Oil Company, and the E.R.C. Finally, and most importantly, I would like to express my appreciation to my Father, General Hussein Ahmed, for*h±s continued encouragement, understanding and support throughout the entire program of advanced study leading to this work. IV TABLE OF CONTENTS Page LIST OF TABLES.........................................viii LIST OF FIGURES...........................................ix Chapter I. INTRODUCTION ..................................... 1 II. STATEMENT OF THE PROBLEM......................... 5 III. LITERATURE REVIEW ................................. 7 High Pressure Gas Injection ...................... 7 Laboratory Studies ............................ 7 High Pressure Projects.................. . . . 10 Condensing Gas-Drive Process (Enriched Gas Drive) . 11 Laboratory Studies ............................ 11 Condensing Gas-Drive Projects ................ 14 Liquid Petroleum Gas (LPG) Slug Drive.............. 15 Laboratory Studies ............................ 15 LPG Slug Drive Projects.........................16 Carbon Dioxide Injection ........................ 16 Laboratory Studies ............................ 16 Carbon Dioxide Injection Projects ............ 13 IV. MISCIBILITY RELATIONSHIPS IN THE DISPLACEMENT OF OIL. BY NITROGEN.................................19 Representation of Miscible Displacement by Nitrogen on Triangular Diagram .................. 19 V. CALCULATION OF FLUID PROPERTIES ................... 32 Densities of Gas and O i l ...........................32 Gas Density.....................................32 Liquid Density ................................ 34 Molecular Weight of Liquid Hydrocarbon Mixture . . 35 Surface Tension .................................. 39 Physical and Critical Properties of Hexane and Heavier Fraction ................................ 42 V TABLE OF CONTENTS (continued) Chapter Page Viscosities of Gas and O i l ........................ 45 Gas Viscosity.................................. 45 Liquid Viscosity .............................. 47 K-Values and Convergence Pressure in Equilibrium Calculations .................................... 49 Convergence Pressure .......................... 50 VI. TECHNIQUES OF CHROMATOGRAPHIC ANALYSES .......... 5 3 Apparatus...........................................54 Flow System.................................... 54 Columns........................................ 54 Detectors...................................... 56 Calibration of Gas Chromatograph ................ 6 3 Gas Analysis...................................... 64 VII. EXPERIMENTAL APPARATUS AND MATERIALS ............ 67 Apparatus.......................................... 67 Injection System .............................. 67 Laboratory Oil Reservoir Model ................ 71 Materials.......................................... 76 VIII. EXPERIMENTAL PROCEDURE............................. 84 Recombination Process..............................' 84 Saturating and Displacing Process ................ 86 Saturation Process ............................ 86 Displacement Process .......................... 87 Recording and Sampling Analysis Process .......... 89 IX. PRESENTATION AND DISCUSSION OF RESULTS ........... 91 First Ru n.......................................... 91 Second R u n ....................................... 124 Third Run......................................... 145 Fourth R u n ....................................... 145 Fifth and Sixth Run............................... 156 Seventh Ru n ....................................... 168 Recoveries....................................... 16 8 X. CONCLUSIONS........................................ 179 XI. RECOMMENDATIONS FOR FURTHER WORK.................... 181 NOMENCLATURE .......................................... 183 BIBLIOGRAPHY .......................................... 185 VI TABLE OF CONTENTS (continued) Chapter Page APPENDICES.............................................. 191 A. Data and Results of Run No. 1 ...................... 192 B. Data and Results of Run No. 2 ......................257 C. Data and Results of Run No. 4 ...................... 292 D. Oil Displacements Tests........................... 341 VIX LIST OF TABLES Table Page 5-1 Parachors of Pure Substance........................ 40 5-2 Values for b-Function for Pure Hydrocarbon Components......................................... 44 6-1 Samples Volumes for Different Columns.............. 53 7-1 Properties of Oil................................ 81 7-2 Analysis of Natural G a s .......................... 8 3 9-1 Results of Oil Displacement by Nitrogena nd Water Injection.....................................92 9-2 Molar Composition of the Collected Samples . . . . 93 9-3 Molar Composition of the Generated Slug............. 99 9-4 Calculated Liquid and Gas Viscosity................118 9-5 Molar Composition of the Collected Samples . . . . 132 9-6 Summary of the Results of the First and Second R u n ........................................ 133 9-7 Oil Displacement Recovery - Run Numbers 5a nd 6 . .170 9-8 Data and Results of the Conducted R u n s ........... 171 Vlll