Petroleum Past and Present

Published by The MAPG

Petroleum Geology

Petroleum Geology plays an important role in today's society. Petroleum Geologists are the men and women who know how to read the story told by the very earth beneath our feet in order to find oil and natural gas, which are vital resources in our lives. Politics and prices often overshadow the story of what happens before the oil and gas ever reaches the headlines.

This website is built and maintained by actual geologists, who want to share with you their passion for the Earth and what they do. They want to answer your questions about where oil actually comes from and share their role in exploring the wonders of our planet. Their goal is to help you better understand the history of oil and gas exploration and the role oil and gas plays in today's world. Who better to talk about these topics than the very people who search for and discover oil and gas? At, you can learn about the source, from the source!

Petroleum Past and Present

The history of petroleum is almost as long as the history of civilization itself. There are accounts of natural oil springs being utilized as early as ancient Babylon and in China.

However, the story of the Petroleum Industry as we know it begins in the nineteenth century. This section provides information about the world's history with petroleum, as well as the growth and evolution of the petroleum industry

What Is Petroleum?

A thick, flammable, yellow-to-black mixture of gaseous, liquid, and solid hydrocarbons that occurs naturally beneath the earth's surface, can be separated into fractions including natural gas, gasoline, naphtha, kerosene, fuel and lubricating oils, paraffin wax, and asphalt and is used as raw material for a wide variety of derivative products. (American Heritage Dictionary)

The word petroleum comes from the Latin petra, meaning “rock,” and oleum, meaning “oil.”

The oil industry classifies "crude" by the location of its origin and by its relative weight or viscosity ("light", "intermediate" or "heavy"). The relative content of sulfur in natural oil deposits also results in referring to oil as "sweet," which means it contains relatively little sulfur, or as "sour," which means it contains substantial amounts of sulfur.

Petroleum Exploration History

From the time humans realized naturally occurring petroleum had myriad uses, they organized means and methods to try and collect it and utilize it to its fullest potential. The history of petroleum exploration around the world is colorful and fascinating. Each country, and even regions within countries, has its own distinct path of discovery that influences it to this day.

Museums and Historical Sites

The history of petroleum geoscience goes hand-in-hand with the history of the world. The technology and culture of petroleum geology reflect those of the time, past and present. There are many museums, memorials, and other historical establishments commemorating the contributions of the petroleum industry to the world's cultural landscape.

All About the Oil and Gas Industry

The oil and gas industry is a diverse and vital part of the global economy. A wide range of expertise goes into the discovery, production, and distribution of petroleum products, and Petroleum Geology plays a central role in the exploration and production process.

Oil and Gas Prices

While standing next to the fuel pump, many of us have all asked the same question: "Why am I paying so much for gas?" Where does all the money go?

The answer is not as straightforward as we might wish, but there are many great primers out there for reference. For a good introduction to the oil market, check out some of the following resources

This section explains the business side of Petroleum Geology: what Petroleum Geologists do in the industry, the economics of how the industry works, and -- yes -- why oil and gas prices are the way they are.

Careers in the Oil and Gas Industry

The petroleum industry is a growing, global industry with many opportunities for those interested in the geosciences. The types of jobs are diverse and suit any interests and personality types. There are careers to be had in virtually every part of the world--the petroleum industry is a great gateway to foreign countries and exotic locations.

If you're wondering if a career in petroleum geoscience is for you, or if you'd just like more information on what these men and women do in their jobs, check out the links below.

Exploration Today

The petroleum industry involves people of all levels and areas of expertise, in civilian and government sectors, non-profit and for-profit, all over the world. The industry touches our everyday lives in many obvious ways, and petroleum geologists are well aware of the impact their work has on their own lives, as well as the lives of others all around the world. It truly does connect us all.

There are many associations and organizations for petroleum geologists and others involved or interested in the industry. People are brought together by common specialty, geographic location, and other factors.

When Geology Meets Petroleum

There are many ways the field of Geology contributes to the Petroleum Industry. The varied disciplines of Geology explore the history of the Earth itself in hopes of understanding in greater detail where oil comes from and where more oil might be found, as well as the best ways to retrieve oil and utilize it once it has been retrieved.

Sedimentology and Stratigraphy

Sedimentology studies sand, mud (or silt) and clay, and the various ways they are deposited. Using these studies, sedimentologists apply their understanding of modern processes to ancient rock, to try to understand how it formed.

Most of the rocks on earth are sedimentary rocks, and it is in these kinds of rocks you find fossils and many of the other historical markers. Sedimentary rocks are also where petroleum deposits are found.

Sedimentology is tied to stratigraphy, which studies the relationships between rock layers and how they can shift and move. This also affects where petroleum deposits can be found, as well as how the extraction of petroleum affects the sediment around the deposit.

Structural Geology

Structural geology is the study of the three dimensional distribution of large bodies of rock, their surfaces, and the composition of their inside in order to try and learn about their tectonic history, past geological environments and events that could have changed or deformed them. These can be dated to determine when the structural features formed.

If the nature of these rocks can be determined, petroleum geologists can discover if petroleum, natural gas, or other natural resources are trapped within the rocks.

Paleontology and Biostratigraphy

Paleontology, or palaeontology, is the study of prehistoric life forms on Earth through the examination of plant and animal fossils. This includes the study of body fossils, tracks (ichnites), burrows, cast-off parts, fossilised faeces (coprolites), palynomorphs and chemical residues.

Biostratigraphy uses those fossils, tracks, and other finds in an effort to figure out how old a certain layer of rock and sediment is.

Once a petroleum geologists knows how old a particular area is, they know the potential for finding natural resources such as oil or natural gas.


The field of geochemistry involves study of the chemical composition of the Earth and other planets, the composition of rocks and soils, the cycles that involve the earth's chemical components, and the interaction of those cycles with land and water.

Some questions geochemistry tries to answer include what elements and chemicals are present in various soils and rocks in different locations? What can we learn from those differences? How are these soils and rocks changing, and how have they changed through the centuries? How do once-living things like plants and animals decompose after their deaths and what sorts of new things do they form as they interact with the environment (such as fossils or hydrocarbons, a.k.a, oil)? How do these various processes affect the environment, and how does the environment, weather, and other influences affect them?

Seismology and Geophysics

Geophysics is the study of the Earth using physics to determine Earth properties. Some of the physical properties studied are the earth's size and gravity, the weather and atmosphere, volcanoes and hot springs, the oceans, water in the ground, and the movements through the earth (otherwise known as seismology).

Plate Tectonics

According to the theory of Plate Tectonics, the surface of the Earth is comprised of several plates, some very large, and several smaller. The plates slowly move through time, changing size and shape. When the plates move against each other, they create geologic events such as earthquakes, volcanoes, mountains. The type of event depends on how the plates move relative to each other.

This movement of the Earth's surface impacts where oil and natural gas deposits can be found, which is why the study of Plate Tectonics is important to Petroleum Geologists.

Seismology studies seismic waves that move through and around the earth, including earthquakes. Geophysicists can study how these waves move and affect the earth to learn the nature of the earth deep below the surface, where it can't be directly seen. The seismic waves can be from a naturally occurring event, like an earthquake, or they can be artificially produced.


Paleogeography focuses on the way the earth looked in ancient times. This is done by studying layers of rock, soil, artifacts, and fossils. Paleogeographers want to learn more about the configuration and movement of the oeans and continents and what kinds of plants and animals existed through history. They study how species of plants and animals evolved, and how certain species became extinct.

These ancient plants, animals, lands and seas have left traces today that give us clues toward finding natural resources, such as oil and gas.

Geologic Maps

Explorers have been making maps for more than four thousand years! As explorers for oil and gas, no introduction to petroleum geology is complete without first discussing the geologic map.

A geology map is used just like your handy highway map that you or your parents might keep in their car. Important data is stored on that road map – locations of cities, roads, mountains, and rivers – just to name a few. The geologic map is used in much the same way, only instead of capturing surface features such as cities and roads, the goal is to describe the subsurface. One of the most common uses for geologic maps is by construction firms, as they need to look for potential hazards such as faults before building buildings or roads.

Once We've Found It, What Do We Do With It?

Exploration is only a part of the field of Petroleum Geology. There are many technologies available to extract petroleum from the ground and then process it into one of the hundreds of everyday items made from petroleum-based products. This section talks about the structure of a found petroleum accumulation and the techology used to model it for scientists to determine how to best utilize its resources, as well as the refining process, and the end results of that process.

Petroleum Products

You might be surprised at the everyday items that are made with petroleum products. For example:



Synthetic fibers



CDs / DVDs

Candles (wax)


Here are some links to show that petroleum is for more than fueling our cars!

Tools of the Trade

Petroleum Geologists use a wide range of technologies to study the earth and its properties. From simple hand tools to multi-million-dollar computers and machinery, the variety of tools used in the study of petroleum geology is as vast as the discipline itself.

Refining and Chemicals

It is a long path from finding oil in the ground to using it in detergent to wash dishes after dinner. Before we put gasoline into our fuel tanks or pick up some Tupperware at the grocery story, the petroleum in these products passes through a refinery, and probably to a chemical plant.

In the oil industry, "Upstream" refers to petroleum exploration and development. "Downstream" refers to pipeline, refining, and chemicals.

As captured in the illustation below from the US Department of Energy, of all the petroleum produced, only about 20% of it goes to put gas in our cars. The rest goes to fueling our economy - literally! Take a moment to look at your credit card - it's plastic! (part of those"other products").

MAPG | BuildBarrel.gif

Petroleum Chemistry

Petroleum comes from many different substances, such as oil and natural gas, from which various products are derived, such as: gasoline, kerosene propane, fuel oil, lubricating oil, wax, and asphalt. These substances are mainly compounds of only two elements: carbon (C) and hydrogen (H). They are called, therefore: hydrocarbons.

MAPG - Hydrocarbon

The specific study of petroleum is referred to as petroleum geochemistry. Understanding petroleum geochemistry is critical in the exploration and development of petroleum.

Anatomy of an Oil Accumulation

A hydrocarbon accumulation forms when six fundamental elements to develop in the correct sequence: the source for the hydrocarbon (any carbon bearing element such as plants or marine plankton), maturation (enough heat and pressure), migration (movement of the hydrocarbon from deep in the subsurface to shallow), reservoir (a porous sedimentary rock in which the liquid or gas hydrocarbon can be held), trap, and seal (something preventing the hydrocarbon from leaking out).