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From Fossil To Fuel™
From Fossil To Fuel™

Episode 2 · 2 years ago

Episode 1 - Formation of Fossil Fuels

ABOUT THIS EPISODE

This is an overview of how fossils turn into hydrocarbons and become trapped in reservoirs.

My name is Brendan McDougall and I'm a professional engineer. Or the last decade I've worked in many different facets of the oil and gas industry. While I have a pretty solid technical background in oil and gas, I don't really know a whole lot about the other non technical departments that help run an oiling gas company. Recently I took a course to help develop my business acumen and better understand how the financial side of the business works. What a novel concept to educate the technical people on the business and financial side. I thought it would be a really cool idea to return the favor and educate the non technical people on the technical side. This is how the concept from fossil to fuel was born. Through these twenty four episodes, we will take a journey from how oil and gas was formed millions of years ago to how it is refined into the fuel that runs our cars and heats our homes. Come join me on this adventure as we learn how the oil and gas industry operates. From fossil to what is a fossil fuel? Most people, when they hear fossil fuels,...

...think of oil and gas that has been created by the dinosaurs. Or that's a common story that I've been told. While this is partly true, it should be clarified that fossil fuels were formed from the organic matter of both animals and plants that lived hundreds of millions of years ago. This does include dinosaurs, but considering the amount of plant life on earth relative to dinosaurs in that time, fair to say that the organic matter from dinosaurs only makes up a very small fraction of what we now call fossil fuels. We're talking about...

...a time when land masses were still forming, the climate was a lot warmer and the planet was covered by a diverse range of strange plants, animals and organisms. As they died, they decomposed and became buried. Much like the ancient ruins that archeologists dig up from moment empires and times before that, the same is true with dead organic material. As time passes by, everything gets buried beneath dusts and and soil. As the material gets deeper and deeper over time, the pressure rises and so does the temperature, and so really what's happening is, as this organic material gets deeper and deeper into the ground, it's kind of like if you were to lie on the ground and I re lay on top of you, you would feel the pressure of my weight on top of you, and if more and more people were to start piling up on top of you, you would feel more and more pressure because there's more and more weight on top of you. And so the same thing is happening...

...with this organic material. As it gets deeper and deeper into the ground, there's more and more rock on top of it and so there's more and more pressure, and as the pressure increases, so does the temperature. And so really what's happening is this organic material, as it's getting deeper and deeper, starting to cook. The high pressure and temperature breaks down the decomposed organic material into hydrocarbons, also known as oil and gas. And so it's probably worth stopping here and just talking. When we say organic material or organic matter, really what we're talking about is something that was alive at some point, and so, technically speaking, when we say organic it means that it is composed of carbon, the atom carbon. So that would be things like plants, animals, humans, we are all considered as as if we were composed of organic material, where something like rocks, which are not composed of carbon,...

...would be considered inorganic hydrocarbons, on the other hand, are long molecular chains composed primarily of, guess what, hydrogen and carbon. As this stuff starts to cook, the Hydrocarbon Molecules get broken up into smaller and smaller pieces, and the smallest pieces are what we call natural gas. And really the smallest piece is called methane. It's one carbon atom and methane really is the vast majority of what makes up what we call natural gas. So generally speaking, natural gas is made up of the smaller hydrocarbon molecules and oil is made up of the bigger ones. So that's how some wells produce oil and some produce gas. It really just depends on how long it's been cooking for and and what has been cooking. So the deeper you get, the harder you get right, and so therefore the higher the pressure is. So by that logic,...

...the deeper wells, which have more pressure, which have more temperature, which have been cooking for longer, tend to produce hydrocarbon molecules that are the smaller pieces. So the deeper wells tend to have more gas. To put it in perspective, as a general rule of thumb, you can probably say something like oil reservoirs are about two to four plometers below the surface of the earth, where temperatures are kind of in that sixty to a hundred and twenty degree Celsius range, but as you get deeper, say three to six kilometers, the temperature goes up into that hundred to two hundred plus degree Celsius range and gas starts to form. Obviously we're oversimplifying here and there are other factors at play too, but because these processes take a long time, you'll often see wells that produce both oil and gas rather than one or the other. Also probably worth noting to is that when we talk about organic matter coming from...

...plants, depending on what type of plants you are or what type of plants originate, you tend to produce different products. So woody plants like trees tend to form oil and gas products like coal, whereas mushy plants like algae will tend to form things like oil. So the oil and gas molecules are lighter than water molecules because they have a smaller density. So it's kind of like if you've got salad dressing in the oil sits on top of the vinegar, it's because it has a lighter density than the vinegar and it has a tendency to rise up because of that lighter density. So much like that example with salad dressing, because oil and gas has a smaller density than the water that's in the Rock, it has a tendency to rise up. Sometimes the oiling...

...gas is rising up from deep in the earth and it'll run into a barrier and get trapped. These barriers are rocks that are dense enough to prevent most of the oil and gas from passing through them. So let's take a break here and talk about this for a second. Oil and gas can pass through rocks. The word that we use to describe this ability for a fluid to move through something is permeability. It's important word to know when we're talking about oil and gas, and I'll give you an analogy that I think applies well to this, and it's sound. So let's say you have a neighbor on the other side of your apartment and he's really loud. If you can hear him, that means your walls are very permeable to sound. Or maybe you're lucky and you've got concrete walls or you decide to put up a sound barrier in your apartment. The walls are no longer permeable to sound, which means...

...it can't get through. So high permeability means it can get through something easier. Low permeability means it is more difficult to get through. So the same is true with oil and gas. As it's continuing to rise up, it reaches an impermeable barrier and it just gets trapped and starts to accumulate. This accumulation is what we call an oil reservoir. It's a giant pool of oil and gas trapped underground that can be the size of a city or bigger. These reservoirs are where we get most of our conventional oil and gas from, and so it's probably worth known in here as well that when people talk about oil reservoirs you hear the term pool, a pool of oil, pool of gas. It's not like you've got this big void underground that's just full of liquid oil and it's like dropping a straw into a glass of water and sucking it out. The oil is still trapped in the little spaces in between the...

...rocks. So it's does not when I say pool. There's not a giant pool of oil under there that we're tapping into. That's just the terminology that we use to describe it. So the oil is still in the rocks, it's just accumulating into one area. And so this kind of takes us to the next point. You hear about oil as a non renewable energy source or an unsustainable energy source, it's because we're dealing with something that took hundreds of millions of years to form and we're using it up over a matter of a few hundred years. It's just not going to last forever. That's why you see such a big push in the media for renewable energy sources. Well, that in them environmental impact that you get from things like greenhouse gases, and so I have no intention of talking about climate change or greenhouse gases too much in this episode or even in this podcast, but I think it is important...

...to give some context. So I mentioned before that oil and gas is made up of hydrocarbons. When we burn oil and gas in our cars and our homes, in our facilities, the chemical reaction that takes place has two main products, water and carbon dioxide. The carbon dioxide, which is one carbon atom and two oxygen atoms, is what gets us into trouble with greenhouse gases and climate change. Because it's lighter than air, it rises up into the atmosphere and acts sort of like a blanket that keeps the earth's warm. It's kind of like putting on a blanket when it's cold outside. The blanket helped keeps your body heat in so you don't get cold. That's what's happening with climate change. Now. Carbon Dioxide is only one of the gases that's contributing to climate change, but now you know how it all ties back to oil and gas. Oh and, by the way, if you haven't figured it out, they're called greenhouse gases because they cause an effect similar to what you...

...see in a greenhouse that keeps the inside nice and warm for your plants to grow. Anyways, let's talk about some of the rocks involved. There are some basic terms that you need to know. First, we talked about the oil and gas rising up through the earth until it gets trapped by a barrier. The oil and gas has to come from somewhere, and we call this, quote unquote, somewhere, the source rock. The source rock is where the organic material was originally deposited millions of years ago. That kept getting buried and buriding buried. So basically, some plats and animals died millions of years ago. As there remains mix in with the soil, they start to be decomposed by bacteria. Over time, the mixture of soil and decomposed material turns into rock. As it gets more and more compacted, the deeper it gets. Eventually it gets deep enough that bacteria can no longer survive, but by this time they've already converted the Plat and animal remains into organic matter. When...

...this combination of rock in organic matter gets deep enough to start cooking, it becomes a source rock, meaning it is now a source for creating oil and gas from the decomposed organic matter. The oil and gas of actually gets released by the source rock and starts to migrate upwards through the Earth's crust until it hits a beer barrier. Sometimes there is no barrier in the oil and gas will come all the way to surface. There are some examples of this where there are natural pools of oil or lakes that bubble with natural gas. However, if the oil and gas does run into an imperial barrier called a Cap Rock. It becomes trapped in the layer below, which is what we call a reservoir, and this, like I mentioned before, is where we get most of our conventional oil and gas from today. Hey, guys, if...

...you like today's episode, make sure you subscribe to the podcast. Unlike most podcasts that release an episode every week or two, I did all twenty four at once, Netflix style, so you can listen to them all right now if you just hit subscribe. If you like today's episode, make sure you leave me a comment or thumbs up, or you can email me at from fossil to fuel at GMAILCOM, or look me up on Linkedin. I'm Brendan McDougall.

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