Hydrostatic and Hydro-Testing in the Oil and Gas Field

By Khosrow M. Hadipour

This book is an introductory reference guide to hydro-testing and hydrostatic pressure testing in the oil and gas field. The book examines the common techniques of pressure testing the oil and gas tubing and casing string to ensure its quality and mechanical integrity. The author introduces the reader to the tools, equipment, and application methods of hydro-testing and hydrostatic pressure testing. It also talks about the safety precautions one must take during the process. This work may appeal to readers who are interested in oil and gas field techniques.

• Language: English
• Publisher: Xlibris US
• Release date: Dec 27, 2018
• ISBN: 9781984561510

Khosrow M. Hadipour

Graduate of Texas A&M University, Khosrow M. Hadipour has over forty-two years of offshore and onshore downhole experience in drilling, completion, production, fracturing, downhole fishing, sidetrack drilling, cementing, coiled tubing operation, oil and gas remedial workover repairs, artificial fluid lift, gravel packing, and plug and abandonment as well as consulting experience. He has worked for companies such as Gulf Oil Company, Chevron USA, Pennzoil Company, Devon Energy, and AmeriCo Energy in Texas, Mississippi, Louisiana, New Mexico, the Gulf of Mexico, and Venezuela.

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Copyright © 2019 by Khosrow M. Hadipour. 783120

Library of Congress Control Number:   2018912650

ISBN:   Softcover     978-1-9845-6152-7

             Hardcover   978-1-9845-6153-4

             EBook         978-1-9845-6151-0

All rights reserved. No part of this book may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopying, recording, or by any information storage and retrieval system, without permission in writing from the copyright owner.

Rev. date: 12/26/2018

Xlibris

1-888-795-4274

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The subject

material is based on forty-one years of offshore and onshore downhole experience in drilling, completion, production, fracturing, downhole fishing, sidetrack drilling, cementing, coiled tubing operation, oil and gas workover, artificial fluid lift, gravel packing, and plug/abandonment while working for Gulf Oil Company, Chevron USA, Pennzoil Company, Devon Energy, and AmeriCo Energy Resources in Texas, Mississippi, Louisiana, New Mexico, and Venezuela.

It is not the purpose of this book to be used as final procedure and/or definite guidelines. This book is prepared to act as basic reference based on my experience only.

The Hydro-testing Techniques in Oil and Gas Wells

Hydro-testing is a vast applied method of using nonflammable and nontoxic fluid medium such as fresh water or nitrogen (N2) to conduct mechanical integrity test (MIT) on casing string, production tubing, pipelines, and production vessels in the oil and gas industry.

All the production vessels such as the horizontal separator, the spherical fluid separator, and the flow lines must be hydro-tested. Liquid fuel tanks, nitrogen transport vessels, acid-carrying tanks, and all toxic transporting vessels must be hydro-tested for safety and durability before they are put to service.

The hydrostatic testing is a common technique of pressure testing the oil, gas tubing, and casing strings for the purpose of quality and mechanical integrity.

Fresh water will be used to conduct hydro-testing on the tubing or the production equipment. Trapped air or gas will be purged or displaced by water, and required pressure will be applied to achieve testing results.

Application of dye water is a preferred method of hydrostatic testing on surface equipment such as flow line or production vessels.

Hydrostatic pressure (HP) is often referred to as hydrostatic head.

Hydrostatic pressure is defined as a force exerted by the height of a column of fluid at rest.

Hydrostatic pressure is expressed in pounds per square inch (PSI).

Pressure = force per unit area.

HP = 0.052 × height × fluid density (HP is not based on the size of container).

One gallon of pure fresh water = one pound = 231 cubic inches.

Tubing and Casing Hydro-testing Techniques in the Oil Field

The purpose of hydro-testing tubulars in oil and gas wells is to detect corrosion holes, pipe splits, tool joint leaks, and tight spots in the tubing and/or casing string.

The tubing and casing string must be free of holes, leaks, and shifted tight spots in order to successfully operate and lift oil, water, and gas products out of a wellbore.

Hydro-testing is one of the high-demand operations in the oil and gas fields.

Demands for hydro-testing the oil field tubulars will make the hydro-testing service one of the important segments in the oil field.

Hydro-testing and drifting the tubing string while going in a well is the most preferred method of testing the tubing string.

The following are the causes of tubular failures and holes in casing and tubing:

A. Corrosion failure

B. Human error and negligence

C. Erosion and wear

A. Oil and Gas Well Corrosion

There are numerous types of corrosion attack in oil and gas fields. Differentiating the type of corrosion is based on the appearance or signature of corrosion on the damaged tools and equipment.

Corrosion will create deformation and loss of identity on production equipment such as sucker rods, fluid pumps, production tubing and casing string.

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Our atmospheric gases become corrosive when they react with other natural elements. Corrosion is responsible for millions of dollars in damages to oil field tools and equipment across the world.

The air we are breathing consists of nitrogen, oxygen, water vapor, hydrogen, helium, argon, and corrosive carbon dioxide.

There are several types of known corrosion in oil and gas wells:

I will explain some of the major corrosion sources in the oil field briefly.

• Sour Corrosion

Sour corrosion in oil and gas wells is referred to as hydrogen sulfide (H2S) corrosion. Most of equipment failures in oil and gas wells are due to untreated corrosive hydrogen sulfide fluid.

Hydrogen sulfide (H2S) is a very toxic element in nature and is dangerous to human health.

H2S is heavier than air with an offensive smell like rotten eggs.

Hydrogen sulfide is referred to as a silent killer.

Sour crude oil is the source of hydrogen sulfide gas in solution.

Untreated H2S will have serious damaging effects on oil field production equipment.

H2S causes localized pits, and the CO2 attack appears like worm groove patterns or blister effects on the surface of rods and tubing.

FeO + H2S + moisture = FeS + H2O

The effect of CO2 and H2S on tools and equipment will be presented later.

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• Sweet Corrosion

Sweet corrosion is due to the presence of carbon dioxide (CO2) gas. Carbon dioxide is colorless, odorless (at low concentration), and very corrosive.

Carbon dioxide is toxic with an acidic smell at higher concentration.

CO2 is practically present in most oil and gas well fluids across the world.

CO2 is an unwanted by-product of oil and gas production. The source of carbon dioxide is carbonate rock formations and decay of organic material. Some wells may produce 30% of CO2 gas.

Tons of H2S, CO2, and other toxic gases are released into the atmosphere daily by human activities in form of emission and blowdown.

• Oxygen Corrosion

Oxygen corrosion is the result of introducing