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From Fossil To Fuel™
From Fossil To Fuel™

Episode 5 · 2 years ago

Episode 4 - Drilling Overview

ABOUT THIS EPISODE

The history of drilling and a high level visualization of the whole process.

My name is Brennan 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 how it is refined into the fuel that runs our cars and keeps our homes. Come join me on this adventure as we learn how the oiling gas industry operates from fossil to fee. There are many components that make up what we call the oil and Gas Industry today, but the most visible one, aside from fracking in the last decade is drilling. Drilling is a cutting or boring process whose purpose is to provide access to oil and gas reservoirs deep below the surface of the earth. Oil and gas are essentially trapped in a reservoir below the earth's surface, and the drilling process allows us to create a pathway for it to get to surface so we can process and use it. The first known oil wells were drilled, as far as we know, as early as three hundred and fifty a D...

...in China. They were drilled using bits attached to bamboo poles and were only up to two hundred and fifty meters deep. The oil was burnt to evaporate brine and produce salt. Go figure. Over the centuries, the drilling process was refined and the different uses for oil were discovered, such as heating homes, lighting homes, think like kerosene lamps, and eventually, of course, military weapon applications. It wasn't until the late nineteenth century that oil really became a commercial product and the modern petroleum industry as we know today was born. Initially, the first oil wells were drilled percussively, which basically means that they use something to smash repeatedly against the rock to break it up and go deeper. It wasn't until the twenty century that we started using rotary drilling, where wells could be drilled much deeper and faster. So when I say percussively, think kind of like hitting a nail with a hammer repeatedly into a piece of wood, whereas rotary drilling is more like using a screw, so you can do it much more efficiently. Drilling Technology improve steadily over the twenty century, with the most recent major step being directional drilling. Directional drilling equipment and techniques gave us control over the well path, as opposed to always drilling the wells vertically and having no control over natural deviations. So what I mean by this is, and it maybe it's not the best analogy, but it'll kind of give you an idea of what I'm talking about, is that when you're drilling a well with no directional drilling equipment, the trajectory or the path of the well boar kind of follows whatever the rock formation dictates, whatever's going on down there. It's not as simple as we think. So it's kind of like if you're out swimming in the ocean and you're trying to go a certain direction...

...will, depending on which way the currents going, you might not be able to go that direction at all and you'll be swimming completely opposite to where you want to go, but you don't have any control because the ocean sweeping you that way. Well, directional drilling is kind of like give being yourself a boat or a motor in the ocean, and so, while there's still those currents and forces that exist, you can now have much more control in terms of steering which way you want to go. So it's the same thing with drilling. Well, the forces down there still exist, but now we have the ability to steer which way we want to go. So this ability resulted in a variety of improvements, such as accessing previously inaccessible zones, whether it's under a mountain or a lake, for example, accessing multiple zones from the same service location and vastly increasing exposure to the reservoir. Let's take a look at an example. So let's say you have a reservoir and it's completely horizontal and it's a hundred meter stick. So before, if we were drilling vertically through it, and that's what we did, used to do. They were all vertical wells. Then your exposure to the reservoirs a hundred meters because it's a hundred meter stick. But now, if you can drill horizontally through it, your exposure could be several kilometers. This means a lot more production from the well. It also means that you have to drill fewer wells to get the same production, which is not only much cheaper, but is also better for the environment and requires a smaller ground disturbance on the surface. So to put that in perspective, let's say we're trying to get two thousand barrels of production and, to keep it simple, we're using that hundred meter thick reservoir that we're just talking about. Let's say I get for every hundred meters of rock that I drill, I get a hundred barrels of production. So that would mean that if I drill a vertical well that's a hundred meters or exposure...

...of a hundred meters to the reservoir, I'm going to get a hundred barrels from that well. So to get my two thousand barrels, I need to drill twenty wells to get there, or I can drill one two thou meter long horizontal well. Obviously I'm over simplifying there, but it gives you the idea of why horizontal wells are so much more efficient than vertical wells. Okay, so let's take a step back and talk of both the basics of drilling and how it works today. The most basic way to describe drilling is they drill a hole, they put metal pipe in the hole and then they fill the space between the pipe and the rock with cement to fix it in place and isolate any formation fluids from coming in. Technically speaking, the metal pipe that I was just talking about is called casing and the space between the casing and the rock is called the annulis. We use metal pipe for strength. After all, we drill through a whole bunch of different formations or rock. Some are harder than granite and others are weaker fractured. So at some point the week zones will create too much trouble for us and we solve that by putting a metal pipe in there and cementing it in place. Once the problematic zone is behind steel and cement, we can use a small bit that fits inside the pipe and carry on drilling deeper until we run into more trouble, and this needs to be done again when we do run into trouble and we put casing and cement in. That's called setting the casing or setting a casing string, knowing that there's going to be typically multiple casing strings in a well. So we usually start drilling with a fairly large hole and as we set more and more casing strings, each section gets smaller as it has to fit...

...through the one above it. So I'm just going to run through this again quickly because it's an important concept to understand. So I drill a big hole and then I put metal pipe in it and I cement the metal pipe in place. In order to keep going further or deeper, I now need to go through that metal pipe to get to the bottom. So in order to go through the metal pipe now I need a smaller bit to keep drilling because it has to go through that size of metal pipe. And so when I get to the bottom of the next casing string or casing section and I want to run pipe again, that piece of pipe has to run inside the pipe that's already in the ground, and so it has to be smaller than that pipe and if you keep doing it, the pipe or the casing that you're running get smaller and smaller because it has to keep fitting through the casing string above it. And so that's why it's really important, when we talk about casing, to pick where and how big those casing strings are going to be, because they are costly and it does take time. Remember, the casing provides structural integrity to the well, to the well bore, which is a terminal that is very common in oil and gas. Is a term that we use for the actual hole that is being drilled. The cement helps close up the annulus so that the fluids can't sneak by on the outside. Remember, the casing in the cement help you keep the well under control. There's a ton of pressure down there and the oil and gas wants to come to surface, so you have to have protective measures in place to control it until you're ready with surface facilities and pipelines in place. Why is there so much pressure? Well, we talked about it in some of the previous episodes, but remember that you've got this oiling gas down there, these molecules that are basically...

...trapped and they've got typically hundreds or thousands of meters of rock on top of them pushing down, and it's kind of like when you blow up a balloon. You've got pressure that's trapped in there and it wants out, but it can't get out that because it's trapped. And like a balloon, if you've blown it up and you're pinching it with your fingers, as soon as you give it a chance to get out, it's going to rush out. And so if you lose control the well an oil and gas comes to surface before you're ready, you'll have what's called a blowout. This is pretty much the worst thing that can happen. Remember the BP incident on the Macondo well that was offshore in the US, the one they made a movie about with Mark Wahlberg called deepwater horizon. Well, that was a blowout of absolutely enormous proportions. When oil and gass comes to surface, because it's hydracarbons, it can ignite and explode, causing major damage, environmental disaster and, of course, human injury or fatality. It is of the utmost importance that drilling engineers and rig crews do everything in their power to keep the well under control at all times. This is something, when you talk to a drilling engineer or rig crew, that they take very, very seriously. Of course, there are times when they're drilling and they don't yet have casing or cement in place to help protect them. So what do they do then? Well, the two main protection systems that they use are drilling mud and blow out preventers, which are usually called Bope's. So drilling mud is usually made from water or oil and serves multiple purposes, but the main ones are to keep the well under control, to cool and lubricate the drilling equipment that's down in the hole and to clean up the bits of rock, which we call cuttings, that are being drilled and carry the cuttings out of the well. The biggest concern,...

...though, as I made apparent, is well controlled. Think of it this way. So the fluids trapped in the rock or the reservoir under a certain pressure, like we just talked about. When we drill into that rock, we expose the well boar to those pressurized fluids and unless we have enough force to hold those fluids back, they will rush all the way to the surface through our well boar. So remember Newton's law. You have to have an equal and opposite force. So, like the balloon example that I just talked about, when you create an opening for that air to rush out of the balloon, you have to have an equal and opposite force against it to keep it in place, otherwise it's going to come out. So you've got this pressureized balloon down in the ground and when you drill into it it's going to want to come out, and so what we do is we use drilling mud, which is like a weighted fluid, to help push back on it so that it keeps it in place. So when this happens and when we produce oil and gas later, we want to keep those fluids where they are. So to keep those fluids where they are, like I said, we use the drilling mud to provide and that when I talk about weight, what it's actually called is hydrostatic pressure to overcome the formation pressure and to keep the two and balance. We do this by adjusting the mud density, and the density is what makes the mud heavier. However, if the mud density is race too high, it can actually overcome the formation pressure, break into the Rock and escape into it. This can become highly problematic because you're losing the mud into the formation, probably not getting it back, and mud is expensive. On top of that, if you get mud into your formation or too much mud into your formation, it can cause damage which further complicates drilling and potentially...

...could ruin your well. So engineers need to plan the mud densities carefully to keep it within a certain range. We call this the density window, where it's high enough to keep the highly pressurized for formations or pressurized oil and gas from flowing into the well, but low enough not to break the weaker formations. When too many formations are exposed or you start having problems and the density required to control one formation would break into another, we need to stop drilling and run casing. That way we can isolate the zones before we resume drilling again. So this is one of the areas, and one of the key areas really, that helps us determine where we're going to set the first casing string because we need to isolate some zones. Maintaining the right density and running casing at the right times is critical to the drilling operation success and safety. The second protection system is the biopas, or the blow up preventers. They are special devices on surface designed to seal off the well boar when needed and stop any fluids from reaching surface. They always include redundancies because they are such a critical component of the drilling operation. They are essentially the last line of defense. The two main types of bopas are called annulers and rams. annular blow up preventers have a bunch of almost look like rubber fingers that, when pressurized, can close around pretty much any type of equipment in the well in the event of a blow up. So remember, most of the time when we're drilling it's just a round piece of pipe that is going to be going through the BOP, but if there's any sort of weirdly shaped piece of equipment that we need to close and isolate against, the annulers have these kind of flexible rubber fingers that can close against a bunch of different shapes and sizes.

So they're maybe not the highest pressure rating because of that flexibility, but it is nice to have because you can close off the well with pretty much anything that could be in the well at the time. So because of this feature and versatility, you'll find them on every drilling rig. So, conversely, though, there are three different types of Rams. There's pipe ramps, blind rams and sheer rams. All three types of rams use opposing Steel Pistons to function. So the Pistons are basically what provide pressure to close the rams either around whatever pipe is in your wellboard. Or if there's nothing, then they'll still close. But the idea is that you need to shut the well off because you're in a situation where there could be oil and gas coming up the well and you basically need to turn the taps off before it gets to surface. So let's talk about pipe ramps. So pipe ram ramps are kind of like sea shaped rubber elements, and so really what they're used for is that if you have pipe in the well, these sea shaped rubber elements will close against the pipe and form a seal around it, so that the sea shape. If you think about it, when you Bring Two seas together, it makes a circle, and so that way, when they come together, they completely close off the annulus around the pipe. The blind rams, however, are flat pieces of rubber, and so they're meant to be used when there's no pipe in the well and so then that way, when they're operated, the two rubber elements will come together and form a seal against each other when the well has nothing in it. The sheer ramps are kind of like blind rams in the sense that they come together against each other, but they have...

...blades on each end of the opposing ramps, so when they're operated, the two steel blades come together to actually cut the pipe in half. This is a last stitch effort to control a well that's blowing out and is only used as an absolute resort, and that's part of part of the reason why it's an absolute last resort is because, if you think about it, if I cut the pipe and seal it off, okay, great, now I've sealed my well, but the pipe on the bottom side that I just cut is now going to haul down into the well because there's nothing holding it up, which means that once we solve the problem with whatever is going on with the blowout, we're going to go into the well afterwards and have to retrieve the piece of casing that fell off down the hole, and trust me, that is not easy to do. So if you're ever on a drilling rig and you see a big red button that says do not push, it is probably the button to operate the sheer rams. Bop's are used everywhere in the world and come in every shape and size. They are of the utmost importance because we have to at all times maintain well control when we're drilling. 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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