.,0",

FLOW ASSURANCE IN OIL AND GA,S PIPELINES

[MATHEMATICAL MODELLING AND'!SIMULATION

OF HYDRATE FORMATION'CONi:DITIONS]

BY

OKPATAKU CELESTINE

99t8302EH

DEPARTMENT OF C'HEMICAL ENGINEERING

SCHOOL OF ENGINEERING AND ENGINEERING , .

TECI+INOLOGY

FEDERAL,UNIVERSITY OF TECHNOLOGY

MINNA--NIGER STATE

NOVEMBER, 2005. ~ " d'" -

. FLOW ASSURANCE IN OIL AND GAS PIPELINES

[MATHEMATICAL MODELLING AND SIMULATION

OF HYD·RATE FORMATION CONDITIONS]

,,". OKPATAKU CELESTINE

99/8302EH

DEPARTMENT OF CHEMICAL ENG'INEERING SCHOOL OF ENGINEERING AND ENGINEERING

TECHNOLOGY FEDERAL UNIVERSITY OF TECH'NOLOGY

MINNA--NIGER STATE

IN PARTIAL FULFILLMENT OF THE REQUIREMENTS 'FOR THE AWARD OF

BACHELOR OF ENGINEERING DEGREE (B.ENG.) IN CHEMICAL ENGINEERING

NOVE~BER, 2005. ,.,

DECLARATION

I, Ol{pataku Ceiestine, declare that this research work is solely the result of my work

and has never been submitted anywhere for any degree. All literature cited have been

fuliy acknowledged in the reference.

Okpataku.C.

iii

CERTIFICAtION

This project titled "Flow Assurance in Oil and Gas Pipelines" meets the regulations

governing the award of the degree of Bachelor of Engineering of the federal university

ofteclmology, Minna and is approved fot its contributions to scientific knowledge and

literary presentation.

Engr. A.S Kovo

(Supervisor)

Dr. F. Aberuagba

(Head of department/chief internal examiner)

External examiner

Date

Date

Date

iv

DEDICATION

This project is dedicated first and foremost to the Almighty God for giving me the

inspiration to carry out all the research and to put down this report; I thank him for his

special grace. Also I dedicate this project to the less privileged in the society who do

not have the opportunity to acquire formal education.

v

ACKNOWLEDGEMENT

I would like to acknowledge the following people; My supervisors, Engr A.S Kovo

and EngrA.S Abdulkareem for the guardianssupport and encouragement throughout

the period of this research. My parents, Mr. and Mrs. Okpataku, for their love, support

and prayers in my career. My beloved brothers and sisters; Johnson, Christy, ken,

Rose,Blessing, Gladys, Charles; Uchechi and·Charity you are all a blessing to me and

your various contributions, guide and advices made this work to be varried out

successfully. Finally not forgetting all my friends and well wishers who were a form

of encouragement to me.

VI

ABSTRACT -

The transportation of production and processing of petroleum fluids in pipe lines and

other transport lines can be significantly affected by flocculation, deposition and

plugging(i.e. by hydrates, paraffin waxes, asphaltenes and other solids). The economic

implications of this proble:m are tremendous. Flow Assurance strategies are being used to

reduce this problem to minimum. Flow assurance includes the following aspects such as

hydraulic analysis, thermal behaviour, operability investigations, and the investigation of

potential blockages. In this project more emphases are laid on the investigation of

potential blockages in pipelines. The flow assurance strategies that are being highlighted

in this project includes the prevention, mitigation and remediation of hydrate as hydrate

constitute the major problems in the transportation and processing of hydrocarbons. A

mathematical model for predicting the equilibrium conditions for hydrate formation is

generated in this project and simulations carried out to compare with experimental data.

l~ .

vii

" ~

TABLE OF CONTENT

Title page 11

Declaration 111

Certification IV

Dedication V

Acknowledgement VI

.. Abstract Vll

Table of contents Vlll

.. List of tables ix

List of figures x

List of graphs Xl

CHAptER ONE

to Introduction 1

1.1 Objective of study 3

1.2 Scope of work . 3

1.3 Justification 3

CHAPTER twO

2.1 What is flow Assurance 4

2.1.1 Aspect of Flow Assurance 5

2.2 'Investigation of potential blockages in pipelines and other

transpoi't facilities 6

2.2.1 Wax (Paraffins ) 7

2.2.2 Aspaltenes 7

2.2.3 Hydrates 9

2.3.3.1 History 9

2.2.3.2 The Hydrate structure· lO·

2.2.3.3 Molecules identified as Hydrate formers 11

2.2.3.4 Factots governing Hydrate formation 12

2.2.3.5 Nucleation growth and deposition 15 .

viii

2.2.3.6 Importance of Hydrate formation during oil and gas operation

2.2.3.7 Effect of Hydrate formation during oil and gas operation

2.2.3.8

2.2.3.9

2.2.3.10

2.2.3.11

2.2.3.12

2.2.3.13

Hydrate prevention strategies

Operability strategies Hydrate prevention

Hydrate prevention with chemical inhibitors

Hydrate mitigation strategies

Hydrate remediation strategies

Selection of hydrate prevention, mitigation and remediation

Strategies

CHAPTER tlIREE

3.0 Mathematical modeling

·3 .. 2 Types ofnl0dels

3.2.1 Iconic models

3.1.2 Analogue models

3.2.3 Theoretical (physical) models

3.2.4 Mathematical (symbolic/empirical) model

16

17

18

19

20

21

24

26

26

26

27

27

27

3.3 Modellling methodology 27

3.4 Modelling ofEquilibdum Condition for Hydrate Formatiotl 29

Diagram

Assumptions

Development of the model equation

FOUR

Experimental Results .

Simulated Results

C~)lnparism of Experimental and Simulated results

IX

29

29

29

33

33

37

CHAPTER FIVE 39

5.1 Discussion of Results 41

-' 5.2 Conclusion 41

5.3 Recommendation 42

Refrences 44

Appendix 45

Graph

x

LIST OF TABLES

1 . List of hydrate forming molecules which have been identified to date 11

2 Summery of application, benefits and limitations of chemical inhibitors 24

4.1 Experimental results for pure water 33

4.2 Experimental results for seawater 34

4.3 Simulated results for pure water 35

4.4 Simulated results for sea water 36

4.5 Experimental and simulated results with percentage errors for pure 37

4~6 Experimental and simulated results with percentage error fot sea water 38

xi

LIST OF FIGURES

Figure

1 Deposition and plugging of petroleum flow conduit due to streamipg potential of

generated and sticking asphaltene particles to the walls of a pipeline

2. The Hydrate Structure

·3. Typical Hydrate formatioil diagram

4

5

6

Typical experimental hydrate formatibnldissociationresults

The addition of 25% of st-I former to methane

Hydrate plug formation in pipeline

7 The use of Anti-Agglomerant in pipeline

3.4 Modelling of Equilibrium Condition for Hydrate Formation

xii

8

10

13

14

15

16

22

29