Modelling and Simulation of Leakage-Induced Pressure Drops Along Oil and Gas Pipelines

ABSTRACT

This work on “Modelling and of Leakage-Induced Pressure drops along oil and gas tends to develop flow equations that can detect and localize leakages in oil and gas pipelines by modifying the Darcy-weisbach equation for liquid/oil flow, and the Panhandle B equation for natural gas flow in pipelines.

These modified were simulated using matlab to show how flow rate for the oil and gas pipelines vary when; the pipeline is working at full capacity, ie no leak, when the pipe is opened, ie with leak, at different leak diameters, and when a host is inserted into the pipeline  for  oil/gas bunkering.

The natural gas used is methane while the oil is gasoline. This research work was necessitated by the reports that the United States of America lost approximately $6.75B to pipeline incidences between 1986-2012.

Nigeria also lost $10.9bn to oil theft(bunkering) and vandalism between 1999 to 2011.

Thus, owing to the fact that there is increasing demands for oil and gas products, and their bye products all over the world cum the climatic changes, distortion of aquatic ecosystems, the environmental degradation, property damages and the billions of dollars spent in cleaning up these spill.

There is great need for all hands to be on deck to checkmate this ugly trend. Hence, the need for leakage detection and localization cannot be over-emphasized.

The materials used in this work were obtained from the databases of oil companies in Nigeria, oil spill intelligence report, shell, oil and gas journals, U.S institute of standards and safety, etc.

The simulation results for oil and gas follow similar trend and shows that; the flow rate is inversely proportional to pipeline lengths, the flow rate decreases as leak diameter increases.

Above all, this project discovered from the simulation result that if a long and wide host is inserted into a pipeline for oil bunkering, the difference in flow rates is infinitesimal that control room engineers term it “small leak”when huge quantities of oil or gas is being taken away from the pipeline.

It is recommended that pipeline engineers should treat small variations in flow parameters with all urgency and alacrity instead of terming it small leak.

TABLE OF CONTENTS

Title page i
Approval page ii
Certification page iii
Dedication iv
Acknowledgement v
Abstract vi
Table of contents vii
List of Figures xii
List of Tables xiv
List of Graphs xv
List of Abbreviations xvi
Appendixes xviii

CHAPTER ONE INTRODUCTION

1.1 Background of the study 1
1.2 Significance of the study 5
1.3 Problem statement 5
1.4 Objectives of the project 5
1.5 Scope of the study 6
1.6 Thesis structure or organisation 6

CHAPTER TWO LITERATURE REVIEW

2.0 Oil exploration and production in Nigeria 7
2.0.1 Natural gas exploration and production 9
2.0.2 Downstream operations 10
2.0.3 Upstream operations 10
2.0.4 Production capacity and supply 11
2.1 Pipelines for oil and gas 12
2.1.1 Pipeline operations 13
2.1.2 Components of a pipeline 14
2.1.3 Maintenance of pipeline 18
2.2 Pipeline failures in the oil and gas industries in the Niger Delta area of Nigeria. 18
2.3 Pipeline Leak detection techniques 20
2.3.1 Biological methods 21
2.3.2 Hardware-based methods 21
2.3.3 Software-based method 22
2.3.4 Comparison of key attributes of different methods 23
2.4 Communication systems for pipeline protection 25
2.4.1 Fibre optical cable 25
2.4.2 Scada system 27
2.4.3 Monitoring of gas leak detection 30
2.5 Basic fluid analysis and properties 31
2.6 Newton’s law of viscosity 31
2.7 Newtonian / non-newtonian fluids 33
2.8 Pressure 35
2.9 Uniform flow, steady flow 35
2.10 Compressible or incompressible 37
2.11 Three-dimensional flow 37
2.12 Mass flow rate 38
2.13 Volume flow rate – discharge 38
2.14 Bernoulli’s equation 38
2.15 Real fluids 40
2.16 Laminar and turbulent flow 41
2.17 Pressure loss due to friction in a pipeline 44
2.18 Pressure loss during laminar flow in a pipe 46
2.19 Pressure loss during turbulent flow in a pipe 47
2.20 The value of f for laminar flow 48
2.21 Colebrook- white equation for frictional factor f 48
2.22 Moody equation and diagram/chart 48
2.23 Density and specific gravity of liquids 51
2.24 Specific gravity and compressibility factor of gas 52

CHAPTER THREE RESEARCH METHODOLOGY PIPELINE DESIGN AND MODELLING

3.1 Pipeline design,equation and modeling 53
3.2 Pressure drop for gas flow in pipes 54
3.3 Practical equation for gas flows in pipeline 55
3.4 The Weymouth equation 57
3.5 Panhandle A equation 57
3.6 Panhandle B equation 58
3.7 Application of the formulas 59
3.8 Modification of panhandle B equation for leak detection in gas pipeline 60
3.9 Materials and method 61
3.10 Matlab simulation parameters and programs for natural gas(methane) 63
3.11 Pressure drop for liquid (oil) flow in pipes 69
3.12 Modification of the Darcy- weisbach equation for leakage detection in oil pipeline 63
3.13 Matlab simulation of the modified liquid (gasoline) flow in pipeline 71

CHAPTER FOUR DATA PRESENTATION AND ANALYSIS

4.1 Results and Analysis 75

CHAPTER FIVE CONCLUSION AND RECOMMENDATION

5.1 Conclusion 86
5.2 Recommendations 87
REFERENCES 88
APPENDIXES 95

INTRODUCTION

1.1 Background of the Study

Pipeline networks are the most economic and safest mode of transportation for oil, gases and other fluid products. As a means of long-distance transport, pipelines have to fulfill high demands of safety, reliability and efficiency. If properly maintained, pipelines can last indefinitely without leaks.

Most significant leaks that do occur are
caused by damage from nearby excavation equipment. Therefore, it is critical to call authorities prior to excavation to assure that there are no buried pipelines in the vicinity.

If a pipeline is not properly maintained, it can begin to corrode slowly, particularly at construction joints, low points where moisture collects, or locations with imperfections in the pipe.

However,these defects can be identified by inspection tools and corrected before they progress to a leak. Other reasons for leaks include accidents, terrorism,or earth movement ,or sabotage[1].

In Nigeria, the Department of Petroleum Resources(DPR) estimated 1.89 million barrels of petroleum were spilled into the Niger Delta region of Nigeria between 1976 and 1996 out of a total of 2.4 million barrels spilled in 4,835 incidents(approximately 220 thousand cubic metres)[2].

A UNDP(United nations Development programme) report  states that there have  been a total of 6,817 oil spills between 1976 and 2001, which account for a loss of three million barrels of oil, of which more than 70% was not recovered[3].

Most of these spills occurred off- shore (69%), a quarter was in swamps and 6% spilled on land. Some spills are caused by sabotage and thieves, however most are due to poor maintenance by oil companies (4).

REFERENCES

http://www.ingaa.org/File.aspx?id=1228

Environmental impacts of oil spills in Niger-Delta: Department of petroleum resources report, 1997.
Niger Delta Human Development Report.”2006.p.76.Retrieved 19 june 2011.

Shell International Petroleum Company,Development,in Nigeria(London :march 1995) Quoted in Greenpeace International, Shell Shocked,11(Greenpeace 2013).

Anderson.I:Niger River Basin: A Vision for Sustainable Development pp.1-131,The World Bank, 2005.

StudentsandScholarship Team