ENGINEERING DESIGN AND PREDICTION OF HYDRATE FORMATION FOR A GAS PIPELINE

ABSTRACT

This research is focused on the difficulties that gas producers usually face with Hydrate formation during transportation. Hydrate build up in gas transportation flowlines is one of the major tasks for gas operators to deal with as it may cease gas flow through the pipeline, reduce well head measured flow rate, equipment damages e.t.c Two kinds of Engineering designs were developed to help transport gases of different pressures to an extension facility whose inlet pressures was designed at 8 barg. HYSYS VERSION 2006 was used for the simulation of these designs to check for the possibilities of Hydrate formation and recommendations were made based on the outputs.
Flow velocity is a very important criterion in determining the possibilities of noise in a gas transporting pipeline. There is a possibility of noise in a gas pipeline if the fluid mean velocity exceeds 60 ft/sec. Also, one of the objectives of this project is to verify the suitability of pipe lines sizes for the 8 barg pressure to transport gas over a distance of 120 km. For this project, a default pipe line size of 10” SCH 40 was selected and other pipe sizes lesser and greater than it were also used to pick the most suitable, simultaneously considering cost. PIPESIM VERSION 2009.1 was used for these analyses and the best pipeline size was determined.
The simulations reveal that both designs are efficient enough and at standard conditions, there will be no possibilities of hydrate formations but the possibilities of establishing design A will be recommended because it entails lower cost and less space is required. Also, a pipeline size of 10” SCH 40 will be sufficient for the given flow conditions but a pipe line size of 8” SCH 40 can also be used.

• TABLE OF CONTENTS

• CERTIFICATION ii

• DEDICATION iii

• ACKNOWLEDGEMENT iv

• ABSTRACT v

• LIST OF TABLES viii

• LIST OF FIGURES ix

• CHAPTER ONE 1

• 1.0 INTRODUCTION 1

• 1.1 Background Knowledge 2

• 1.2 Aims and Objectives of the Project 3

• 1.3 Justification 3

• 1.4 Scope of work 4

• 1.5 Problem Statement 4

• 1.6 Facilities Schematics 5

• CHAPTER TWO 7

• 2.0 LITERATURE REVIEW 7

• 2.1 Natural Gas Transportation through Pipelines 7

• 2.2 Single Phase Pipe Flow 8

• 2.2.1 General Pressure Drop Equations in Gas Flow 8

• 2.2.2 Simplified Equation 9

• 2.2.4 Panhandle Equation 11

• 2.2.5 The Spitzglass Equation 12

• 2.3 Flow Assurance 12

• 2.4 Natural Gas Hydrates 14

• 2.4.1 History of Natural Gas Hydrates 14

• 2.4.2 Structure of Natural Gas Hydrate 15

• 2.5 Flow Assurance Challenges and Control 18

• CHAPTER THREE 21

• 3.0 METHODOLOGY 21

• 3.1 System Description and Simulation Model 21

• 3.2 Basis of Design 23

• 3.2.1 Design Basis Feed Composition 23

• 3.2.2 Basis of Analysis 24

• 3.2.3 Bulkline 24 vii

• 3.2.4 Pipeline Hydraulic Profile 24

• 3.3 HYSYS Simulation Modelling 24

• 3.3.1 Hysys Compositional Modelling 25

• 3.4 PIPESIM Simulation Modelling 25

• 3.4.1 Pipesim Compositional Modelling 26

• 3.5 Pipe Flow Models and Flowsheets 27

• CHAPTER FOUR 30

• 4.0 Analysis of Results 30

• 4.1 Results achieved with the HYSYS simulation 30

• 4.1.1 HYSYS simulation results for design A 30

• 4.1.2 HYSYS simulation results for design B 33

• 4.1.3 Comparison of Designs A and B from HYSYS Outputs 35

• 4.2 Results achieved with the PIPESIM simulation 36

• 4.2.1 Suitability of pipe various pipe sizes 36

• 4.2.2 Outlet pressure analysis for design A & B 37

• 4.2.3 Fluid Mean Velocity for 10 inches sch 40 pipe size 38

• 4.2.4 Fluid Mean Velocity for 8 and 24 inches sch 40 pipe size 39

• 5.0 CONCLUSION AND RECOMMENDATION 41

• 5.1 Conclusion 41

• 5.2 Recommendation 43

• REFERENCES