University Microfilms Copyright 1980 by Ahmed, Tarek Hussein All

364 Pages·2013·5.88 MB·English

8027504
AHMED, Tarek Hussein
AN EXPERIMENTAL STUDY OF CRUDE OIL RECOVERY BY HIGH
PRESSURE NITROGEN INJECTION
The University of Oklahoma PH.D. 1980
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Ahmed, Tarek Hussein
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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