Oil and Gas Engineering for Non-Engineers

Quinta Nwanosike Warren

• Publisher: CRC Press
• Year: 2022
• Print ISBN: 9780367607722
• eBook ISBN: 9781000614855
• Edition: 1
• Topic: Technology & Engineering
• Subtopic: Sustainability in Business
• Index: Technology & Engineering

Oil and Gas Engineering for Non-Engineers explains in non-technical terms how oil and gas exploration and production are carried out in the upstream oil and gas industry. The aim is to help readers with no prior knowledge of the oil and gas industry obtain a working understanding of the field.

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• Focuses on just the basics of what the layperson needs to know to understand the industry

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• Uses non-technical terms, simple explanations, and illustrations to describe the inner workings of the field

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• Explains how oil is detected underground, how well locations are determined, how drilling is done, and how wells are monitored during production

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• Describes how and why oil and gas are separated from impurities before being sent to customers

Aimed at non-engineers working within the oil and gas sector, this book helps readers get comfortable with the workings of this advanced field without the need for an advanced degree in the subject.

1 Introduction

DOI: 10.1201/9781003100461-1

1.1 What Is Crude Oil?

Oil is an integral part of our world today. It is in the clothes we wear, our cellphones, cosmetics, medication, and more. Let us not forget how important it is for transportation whether by land, air, or sea. It is the primary source of energy in the world, and as such, it is the most important commodity in the world.

Gas is usually produced alongside crude oil as a by-product. The composition of this associated gas can vary but often includes methane, also called natural gas, and propane. In some cases, associated gas is sold to help with the production of the crude oil. In other cases, it is an undesirable product so it is vented into the air, flared or burned in a controllable way, or re-injected into the reservoir. Flaring is increasingly being viewed as unsustainable and, of course, bad for the environment due to the global warming properties of methane. In some countries such as Nigeria, gas flaring is no longer allowed, leading to development of gas utilization projects. Natural gas can also be produced on its own from natural gas reservoirs. In this case, the gas is called non-associated gas.

Oil and gas are used to produce materials, fuels, electricity/heat, and petrochemicals. Materials include plastics and synthetic fabrics such as polyester, nylon, and rayon. Petrochemicals include fertilizers, medication, paint, and cosmetics. Fuels such as gasoline, diesel, and jet fuel are primarily used for transportation for cars, planes, and ships. In electricity generation, fuels such as natural gas, and heavy fuel oil, are combusted to generate steam. Uses of oil and gas are illustrated in Figure 1.1.

Figure 1.1 Products from oil and gas.

Crude oil is refined into different products by heating. At different temperatures, different fuels boiloff from the crude oil mixture. The typical products of refining are fuels, naphtha, and residue. The fuels include propane, butane, gasoline, jet fuel, kerosene, diesel, and fuel oil. Naphtha is used as a precursor for other chemicals in the petrochemical industry. The residual materials are asphalt, and lube stock which is used for lubricants, waxes, and polishes. Products of crude oil refining are illustrated in Figure 1.2.

Figure 1.2 Products of crude oil refining.

1.2 How Oil Is Formed

Petroleum, or crude oil, is a liquid mixture of hydrocarbons formed underground from the remains of plants and marine life such as algae and plankton. It is a mixture of compounds called hydrocarbons which are made up of mostly carbon and hydrogen. The color of crude oil can vary from yellow to black depending on its composition: heavier hydrocarbons will lead to a darker colored crude.

The plankton remains are buried and subjected to high pressures and temperatures due to the depth of burial. The deeper the remains are buried, the higher the temperature and pressure. The longer the remains are subjected to these conditions, the more likely they will be converted to natural gas rather than crude oil. The hydrocarbons are formed in source rock and then migrate into shallower rock called reservoir rock. It is from reservoir rock that most crude oil is produced. The exception is shale oil and gas which are produced from source rock.

Wells are drilled into the reservoir as shown in Figure 1.3 to create a conduit through which oil and gas can be produced. In the reservoir, gas is usually found at the top because it is light, followed by oil in the middle and water at the bottom because it is heaviest. Reservoir depths may vary from as shallow as 3,500 ft to as deep as 12,000 ft.

Figure 1.3 Oil and gas production from hydrocarbon reservoirs underground.

1.3 Classification of Crude Oil

Crude oil may be classified in a number of ways either based on the physical characteristics of the crude or based on the reservoir it is extracted from. One classification method is on the density of the oil. API gravity is a measure of how dense a hydrocarbon is compared to water, and it is measured in degrees. The smaller the API of a petroleum liquid, the denser it is, with extra heavy crude oil being the densest.

Crude oil with an API of 10° has a density the same as that of water. Crude oil with an API less than 10° will sink in water while crude oil with an API greater than 10° will float on water. The viscosity of crude oil increases as temperature increases.

API and density are connected through the following equation.

$\mathrm{API}=\frac{141.5}{\mathrm{Specific}\mathrm{Gravity}}-131.5$1.1

where

$\mathrm{Specific}\mathrm{Gravity}=\frac{{\rho }_{\mathrm{liquid}}}{{\rho }_{\mathrm{water}}}$1.2

and ρ_liquid is the density of the crude oil liquid in kg/m³, ρ_water is the density of water, which is 999 kg/m³, and API is in degrees (°).

The API and density ranges for each type of crude vary for different countries and different sources. One set of ranges is given in Table 1.1.

Table 1.1 Oil types and their associated APIs and densities at reservoir conditions

Oil type	API (°)	Density (kg/m^3)
Extra heavy crude oil	<10	>999
Heavy oil	10–20	933–1000
Conventional oil	20–40	824–933
Light crude oil	>40	<824

Examples of extra heavy crude oil include bitumen and tar sands or oil sands. Light crude such as shale oil is easy to refine and is therefore more desirable and more expensive.

Another way of classifying oil is by sulfur content. The oil that contains less than 1% sulfur is called sweet crude. Sour crude is crude that contains greater than 1% sulfur. Sweet crude is more valuable because sulfur is undesirable and must be removed from sour crude. West Texas Intermediate (WTI) is a light sweet crude sourced from inland Texas’ Permian Basin. It is used as a benchmark or reference for crude oil pricing in North America. Brent crude is a light sweet crude from the North Sea between the United Kingdom and Norway which is used for benchmarking two-thirds of crude oil traded worldwide. It is less light and less sweet than WTI but is more widely ...

Table of contents

• Cover
• Half Title
• Title Page
• Copyright Page
• Contents
• List of Figures
• List of Tables
• Preface
• Author
• Abbreviations
• 1 Introduction
• 2 Exploration and Geology
• 3 Reservoir Engineering
• 4 Drilling Engineering
• 5 Completions Engineering
• 6 Production Engineering
• 7 Facilities Engineering
• 8 Oil Refining
• Glossary
• Index