VIETNAM NATIONAL UNIVERSITY HO CHI MINH CITY HO CHI MINH CITY UNIVERSITY OF TECHNOLOGY FALCUTY OF GEOLOGY AND PETROLEUM ENGINEERING DEPARTMENT OF DRILLING AND PRODUCING PETROLEUM ENGINEERING OFFICE OF INTERNATIONAL STUDY PROGRAM A thesis submitted in accordance with the requirement for the degree of BACHELOR OF ENGINEERING (Petroleum Engineering) Mechanistic Modeling of Multiphase Flow in Subsea Pipeline of Oil Field X for Wax Deposition Prediction INSTRUCTOR: Dr. MAI CAO LAN Mr. NGUYEN VIET VAN STUDENT’S NAME: VO NHAT LINH CLASS: CC17DK11 STUDENT ID: 1652347 HO CHI MINH CITY September, 2021 HO CHI MINH UNIVERSITY OF TECHNOLOGY SOCIALIST REPUBLIC OF VIETNAM Faculty of Geology and Petroleum Engineering Independence – Freedom – Happiness Department of Drilling and Producing Petroleum Engineering No. _____________/BKĐT FINAL YEAR PROJECT PROPOSAL (This form must be appeared at the first page of the final report of the final year project) Faculty: Geology and Petroleum Engineering Department: Drilling and Producing Petroleum Engineering Student name: VÕ NHẬT LINH Student ID: 1652347 Program: Petroleum Engineering Class: CC17DK11 Topic: “Mechanistic Modeling of Multiphase Flow in Subsea Pipeline of Oil Field X for Wax Deposition Prediction” Expected outcome: • Definition and characteristic of multiphase flow in pipeline • Determining criteria for evaluation, selection of pipeline diameter • Mathematical calculating the thickness of insulation • Establishing model and principle for calculating the wax deposition in pipeline.
Start date: 01/03/2021 End date: 18/09/2021 Adviser Affiliation Responsibility Dr. Mai Cao Lan Department of Drilling and Production Petroleum 100% Engineering Mr. Nguyen Viet Van Hoang Long – Hoan Vu Joint Operating Company 100% The proposal has been screened by the Head/Deputy Head of the Department. Ho Chi Minh City, ……………………… 2021 Head of Department Advisor Advisor Ph.
Mai Cao Lan M. Nguyen Viet Van FOR OFFICIAL USE ONLY Faculty:. Date of defense:. ACKNOWNLEDGE I wish to express sincere appreciation to Dr.
Mai Cao Lan for allowing to pursue this thesis in the “Mechanistic Modeling and Wax Deposition in Multiphase Transportation Pipeline”. I am extremely thankful for his personal guidance, assistant and supervision I am most grateful to M. Nguyen Viet Van and his friendly colleague in Hoan Long – Hoang Vu JOC for their unwavering support and understanding throughout this work. Their continued support and understanding were instrumental to the success of this wok and greatly appreciated.
Furthermore, I will like to show gratitude to all petroleum engineers in “Tôi là Người Dầu Khí” community for their advice throughout the evaluation and correction for calculation tools. Additionally, I will like to show gratitude to Nguyen Huu Nhan, Nguyen Hoai Vu and Nga Duong for their personal guidance and advices over the course of study. Finally, my warmest thanks go to my family, who constantly supported me during five years. i DECLARATION I declare that the thesis has been composed by myself.
The thesis is submitted for examination in consideration of graduation of bachelor degree of petroleum engineer in Ho Chi Minh City University of Technology. Furthermore, I took reasonable care to ensure that the work is original, and to the best of my knowledge, and has not been taken from other sources except where such work, investigated data have been cited and acknowledge within the text. ii ABSTRACT Oil and gas are currently produced through wells and pipelines. The far reservoirs are, the restricted in production is.
Transportation of hydrocarbon components tens of kilometers away or even hundreds of kilometers would rise varieties of situation that a production engineer must concerned. Those restrictions may happen in a reservoir, in a production tubing or gathering pipeline. One of the main issues is prevent paraffin wax deposition in pipe walls which causes the instabilities, interrupted supply of hydrocarbons to processing platforms and damages of downstream facilities. Therefore, it is necessary to develop a flow-assurance model to analyze and calculate optimal conditions for a stable production of gas and hydrocarbon liquids with water in which pressure and temperature profiles are two key factors.
There are two ways in which are commonly used. They are 1) experimentally, through laboratory-sized investigation with appropriate instrumentation to address relative method applied for specific cases (normally called empirical correlation methods) 2) and theoretically, using mathematical equations and models for the flow which is known as mechanistic models. Poettmann and Carpenter’s method which is a semi-empirical correlation are quietly used because its reliable and is generally accepted. However, a limited range of flow rates and gas-liquid ratios have made this method less used in many cases.
Furthermore, many empirical models exhibit large discontinuities at flow pattern transitions which may cause convergence problem when are used for the simulation of practical cases. Mechanistic models, on the other hands, have become a perfect adjustment due to using mathematical equations based on fundamental laws which can be applied in full range of data with more accurate. OLGA, a dynamic multiphase flow simulator, is one of well-known software which is widely used in oil and gas field. And in this thesis, a computation program developed in VBA (a coding method created by Microsoft) applied those impressive models to predict the pressure and temperature distribution in seabed pipeline.
The program was compared with OLGA to correct the workflow and check its validation before it is applied in practical cases. In 2014, Thap Minh Thu introduced a model simulating oil and gas transportation pipeline from W2-WHP to X1- CPP who applied on fundamental theory of flow assurance and OLGA to propose a suitable inner diameter, insulation materials and analyze factors relating to flow-assurance problems. However, Thap Minh Thu only used OLGA to develop model, therefore, a gap between applicability of theorem proposed and practicality was created which might not well understand the fundamental background of OLGA software. Hence, in order to overcome this disadvantage, this thesis proposes a comprehensive model based on fundamental theorem for predicting pressure and temperature profiles.
To do this, VBA, a programing language for Excel is used due to its simple and ease of access. The program is then compared with OLGA’s sample results to verify the model which would be used to apply in a practical case collected from Thap Minh Thu’s master thesis and shows an impressive accurate. Wax deposition problem is one of critical issues that Thap Minh Thu did not mention in his Master thesis. To consolidate his contribution, the OLGA software is then used to investigate wax deposition in X field pipelines system by using wax deposition module and his data set.
The task of this section is determining the paraffin wax thickness consider the maximum allowed inlet pressure to propose a necessary time of pigging operation to prevent blockages. All necessary data such as pressure and temperature profiles, wax deposition rate and effects of surrounding environment are also a primary concern to confirm the objective of this section. iii TABLE OF CONTENTS ACKNOWNLEDGE. iii TABLE OF CONTENTS.
iv TABLE OF FIGURES. vi TABLE OF TABLES. Purpose and Scope. Motivation of Study.
PVT Properties Of Oil And Gas. Pseudo-Critical Quantities. Direct Calculation of Compressibility Factor. Gas Formation Volume Factor.
The Bubble-point Pressure. Oil Formation Volume Factor. Isothermal Compressibility Coefficient of Crude Oil. Multiphase-Flow In Subsea Pipeline.
The Main Parameter of Multiphase-Flow. Flow Regimes in Pipeline. Pressure Drop Along Multiphase Flow Pipeline. Mechanistic Model for Predicting Flow Regimes and Pressure Distribution.
Heat Transfer in Pipes. Temperature Prediction Along Multiphase-Flow Pipeline. Basic Concepts of Wax Deposition and Wax Deposition Mechanisms. Cloud Point or Wax Appearance Temperature (WAT).
41 iv TABLE OF CONTENTS 2. Mechanisms of Wax Deposition. PREDICTING TEMPERATURE AND PRESSURE FOR SEABED PIPELINE IN X FIELD. Computational Workflow for Pressure and Temperature Prediction.
Validation of Computational Workflow. Results and Discussions. Application of The Computational Workflow for The Gathering Pipeline in Field X. Results and Discussion.
WAX DEPOSITION MODELING FOR SEABED PIPELINE IN X FIELD. Factors Affecting The Wax Deposition. Temperature Difference And Cooling Rate. Crude Oil Composition.
Pipe Surface Properties. Wax Control Strategies For The Field. Computational Workflow for Deposited Wax Prediction. Application of OLGA for Wax Thickness Prediction in The Gathering Pipeline, Field X.
Construction of OLGA Wax Module for Wax Thickness Prediction. Methodology of Wax Deposition Simulation. Results and Discussions. 63 CONCLUSIONS AND RECOMMENDATIONS.
Newton-Raphson Iterative Procedure and the Existence of the Solution For Slug Flow Model. Stratified Flow Model. The Derivation Of Equations For Temperature Prediction. 75 v TABLE OF FIGURES Figure 2-1.
Gas-solubility pressure diagram [24]. Oil formation volume factor versus pressure [24]. Major flow patterns in horizontal flow [12]. Major flow patterns in vertical flow [13].
Control volume and relevant variable describe a system for flow through a pipe section [9]. Workflow of flow regime prediction. Physical model for bubble flow [11]. Equilibrium stratified flow.
Physical model for slug flow [11]. Physical model for annular flow [11]. A cylinder with conduction surface condition [18]. Composite hollow cylinder with convection both surface: a) Temperature distribution and b) Equivalent thermal circuit [18].
An illustration of computational workflow presented in Figure 3-2 in which the pressure and temperature is calculated in each incremental length of pipe. 43 Figure 3-2 The flow chart for the pressure and temperature prediction. Flow chart for inner diameter selection when pressure and temperature is predicted. Pipeline profile from OLGA_sample_case.
Temperature distribution predicted by OLGA and computational program along 400-m pipeline. Pressure distribution predicted by OLGA and computational program along 400-m pipeline. Pipeline Profile between X2-WHP to X1-CPP, X field. A PT phase diagram of hydrocarbon components generated by Multiflash software.
Temperature distribution comparison between TMT’s data and calculation. Pressure distribution comparison between TMT’s data and calculation. Summary of general wax deposition and control methodologies. The flow chart for wax thickness prediction in seabed pipeline.
An illustration of Figure 4-2 about application of wax deposition model to calculate the wax thickness in seabed pipeline over a period of time ∆𝑡. Schematic flow line diagram in the OLGA software. Pressure profiles in pipeline after 50 days in X field’s pipeline. Temperature profiles in X field’s pipeline after 50 days.
Thickness of wax deposition in X field’s pipeline after 50 days. Deposited wax thickness after 50 days in PIPE-50 and PIPE-51 section, X field’s pipeline. Temperature at the pipe wall of seabed pipeline in X field. 65 vi TABLE OF TABLES Table 2-1.
Important Dimensionless Group in convection heat transfer. Constants for the Hilpert Correlation for Circular (Pr≥0.7) and Noncircular (Gases only) Cylinders. Bathymetry data for the production pipeline from OLGA_sample_case. Input parameter for OLGA_sample_case.
Pipeline details for OLGA_sample_case. Material properties for OLGA_sample_case. Material/Coating thickness for OLGA_sample_case. Statistical analysis of results compared between OLGA_sample_case and computational program.
Major programming verification activities. Bathymetry Data for the Production Pipeline from the X2-WHP to the X1-CPP, X field. Hydrocarbon components of oil and gas gathering in seabed pipeline, X field. Critical parameters which require for gathering oil and gas in pipeline, X field.
Pipeline details to gathering oil and gas in X field. Material properties of X field’s pipeline. Material/Coating thickness of X field’s pipeline. Seawater temperature - Surface.
Seawater temperature - Seabed. Results of temperature distribution prediction calculated by Thap Minh Thu and computational program in pipeline from X2-WHP to X1-CPP. Results of pressure distribution prediction calculated by Thap Minh Thu and computational program in pipeline from X2-WHP to X1-CPP. 𝑁𝑆𝑅 expressed for each flow pattern proposed in Matzain model.
BACKGROUND Over recent decades, large amounts of oil and gas are found in extreme conditions as they are buried at thousand meters deep with special reservoir characteristics. This situation raises new challenges within the field of petroleum exploration, production, and transportation.