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Program Development for

Predicting Corrosion Rate in

Two-Phase Pipeline

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1.Introduction

Fluid produced from well is usually a

mixture of oil, gas, water

Surface production facilities aredesigned to turn this mixture into

separate streams of oil and gas and

water.

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1.Introduction

Production of oil and associated gas

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1.Introduction

The liquid coming off the separator is

assumed to be in single-phase flow eventhough it will contain some gas after it has

taken a pressure drop.

The products have to be transported long

distances as a multiphase mixture to centralproduction platform or onshore separating

facilities

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1.Introduction

platform & pipeline schematic

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1.Introduction

One of the main problems encountered in

transportation of gas/oil/water multi-phaseproducts is internal corrosion in the pipelines.

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2.Motivation

Little research has been performed in the

past on coupling CO2 corrosion model.

There are no studies on more mechanistic

corrosion model with a comprehensive two-phase fluid model.

This proposal describes a newly developedCO2 corrosion multiphase flow model

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3.Review-Basic of two-phase flow

Two-phase flow patterns in horizontal flow.

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3.Review-Basic of two-phase flow

SUPERFICIAL GAS VELOCITY, VSG , FT/SEC

0.1 1.0 10.0 100.0 500.0

SUP

ERFICIALLIQUID

VELOCITY,VSL

,FT

/SEC

20.0

10.0

1.0

0.1

0.01

SLUG

FLOW

WAVE

FLOW

ANNUL AR,

ANNULAR MIST

FLOW

BUBBLE,

ELONGATEDBUBBLE FLOW

STRATIFIED FLOW

Mand hane et al. Hor izontal Flow Pattern Map

Flow regime for horizontal pipes.

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3.Review-Fundamentals of Corrosion

Mechanisms The material in this section is presented

under three general headings: Wet Corrosion

Dry Corrosion

Biological Corrosion

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3.Review-Fundamentals of Corrosion

Mechanisms Wet Corrosion

There are eight forms of wet corrosion1. Uniform Corrosion

2. Galvanic Corrosion

3. Crevice Corrosion4. Pitting

5. Intergranular Corrosion

6. Selective Dealloying7. Erosion corrosion

8. Stress Corrosion Cracking (SCC)

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3.Review-Basics of Upstream

Corrosion Predicting CO2 Corrosion Rates

The standard equation used industry-wide topredict CO2 corrosion rates for carbon steel is

a correlation derived by deWaard & Milliams3

and is expressed as:

log10 (CR) = 5.8 - 1710/T + 0.67log10(pCO2)

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4.Objectives

The objective of this thesis is to improve new

corrosion model by combined a CO2corrosion model and a two-phase flow model

in oil and gas pipeline system.

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5.Scope of the Thesis

The scope of this thesis is to establish new

correlation corrosion model which consistsof two main models:

1. the CO2 corrosion model and

2. the multiphase flow model

This combined model will be compared withmeasurement data from the field.

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Theory

The corrosion rate can be calculated by theapplication of well established mass transfer

correlations of dimensionless groups. In general

Sh = a Reb Scc

Wherea, b and c = the constants determined by

experiments

Sh = the Sherwood numberkd/D

Re = Reynolds numberUd/

Sc = Schmidt number

/D.

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Theory

The Berger-Hau correlation, one of the most

widely accepted mass transfer correlationsfor fully developed turbulent flow in smoothpipes, a corrosion rate (CR in mm/y), is given

by

CR = 4923 Cb (D02 /d)Re0.86 Sc0.33

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Theory

RELATIVE ROLES OF EROSION ANDCORROSION

Erosion + Corrosion ybU

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7.Research Procedure

Collect pipeline corrosion data from corrosion

inspection survey.

Set up mathematical model for pipeline

corrosion.

Develop corrosion rate model using webprogramming such as JAVA, PHP.

Perform model verification.

Summary and discussion of the corrosion model.

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8.Benefit of the Thesis

develop corrosion model that provides highly

accuracy for internal corrosion in the pipelinetransportation of gas/oil/water three phase

products.