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From Fossil To Fuel™
From Fossil To Fuel™

Episode 21 · 2 years ago

Episode 20 - Artificial Lift

ABOUT THIS EPISODE

What is artificial lift? What are the different kinds and when do we use them?

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 to 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.

When you let a can of coke sit for a few days, it goes flat. What's happened is that all of the carbon dioxide that was dissolved in it has come out. The carbon dioxide is pumped under pressure into the cope when it's made to begin with, which is why the cans and bottles have to be sealed. It's to keep the pressure in and by keeping the pressure and you're keeping the COETWO, which gives it that bubbly taste. But it's also why they spray everywhere when you shake them up, because effectively you're adding more pressure to the system. This is more or less how producing oil...

...and gas works. Think of it like that shaken up bottle of coke, example, that we talked about last episode. The coke is under pressure, so as you unscrew the lid it's going to want to come out. So what do you do? You unscrew it a little bit at a time to let a little pressure out. Eventually there's no more pressure left and the COP won't spray all over the place. Well, when we first drill and complete and oil, well, it's kind of like the bottle of coke that was shaken up. It'll come out on its own as soon as you open the TAP. By over time, as you continue to produce it, the pressure inside the raw walk. Remember we call this the reservoir pressure. This pressure decreases. Eventually it will get to a point where it won't be able to flow on its own. So what do you do when you're well, is no longer able to lift oil on its own? Well, you need something...

...called artificial lift. Artificial lift is an all encompassing term for equipment that AIDS and bringing oil and gas from the reservoir, Aka the formation, Aka the rock that helps bring it to surface. We call it artificial because we are now helping the reservoir lift fluid because it can't do it by itself anymore. When I say oil and gas, the first picture that will come to most people's minds is a pump Jack. So this is a form of artificial lift, and really I want to spend this episode to cover the main types of artificial lift and how they work. Pop Jacks. Pump Jacks are also known as beam pumps or sucker rod pumps, and are probably the oldest and most...

...widely used form of artificial lift, which is probably why so many people will recognize them. If you ever were to google a picture of a pump Jack. The Pump Jack is attached to a metal rod. We call this the Sucker Rod, and the Sucker Rod runs all the way from surface down to the bottom of the well where there's a pump. So these are at least the wells that have pump jacks. Are Typically Limited to shallower wells because you're going to have to have a sucker rod from surface all the way to the bottom of the well, and so the cost of running a sucker rod increases as you get deeper. But a lot of people like them because it's a simple design. As long as you're well isn't crooked, because if it is, the sucker Rod, which is going to be a straight piece of metal,...

...is going to be rubbing up against the side of the well or the inside of the well if there are any bents. So you got to make sure you're well as straight. As the pump jack moves up and down, it strokes the Rod, the Sucker Rod, up and down, which then activates the pump at the bottom of the hole or the bottom of the well. So each time the rods and pumps are stroke, it activates the pump and a volume of fluid is lifted up electrical submersible pump. That is a mouthful and so most people just call them esps. Esps, like pump Jacks, have a pump and a motor, but everything is located down at the bottom of the well. There are no rods. It means you have a lot more room at surface for other equipment if need be, but it also...

...means that when something breaks down whole and needs to be fixed or replaced, it can get pretty expensive. They are fairly flexible in which situations they can work in and they're fairly simple to operate, which is why they are a popular choice when you have to move larger volumes of liquid gas left. Remember the cold bottle example. Well gas lift is kind of like reinjecting cootwo back into the coke. Gas Lift is basically just reinjecting gas down whole to help lighten the fluids to get them to surface. You know the feeling when you're deep underwater in a swimming pool. If you go too deep and you can feel a lot of pressure on your body, what you're feeling is the weight of all the water above you pushing down on you due to gravity. Remember,...

...water is much heavier than air, so when you're under water it exerts a lot of pressure. The same can be said of most fluids, not just water. So when your well bore is full of fluid, the reservoir, which is at the bottom of your well, is kind of feeling like you when you're under a lot of water. It's feeling a lot of pressure from all of the fluid above it and it just can't have enough pressure to push any oil and gas out because it can't overcome the weight of that column of fluid that's weighing down on it. so by injecting gas and having the gas mixed with the fluid in the well boar, we're effectively making the fluid in the well bore lighter by mixing the gas with it, so that the reservoir has a little bit of help and doesn't have to push as hard because the weight of the column of fluid that's now been injected with gas isn't pushing down as hard because it's not as heavy. It's kind of like giving the...

...oil and gas a life jacket to help it get to surface. Gas Lift can be really effective for bigger wells, as long as the fluid you're trying to get out isn't too heavy or too viscous, and you obviously have to have some gas available for this to work as well. Hydraulic pump hydraulic pumping has probably been around for a century and is one of the most flexible systems around. It can operate effectively in many different scenarios, and it's so flexible because it has such a wide range of operating parameters. Will also allowing you to mix in water and or chemicals needed to treat the reservoir. Hydraulic pumps rely on a hydraulic fluid system to transmit power from the surface to the well boar. It works a lot like the car lift at your local mechanic.

For them, power is transmitted similarly through the hydraulic fluid to a Piston that lifts your car up off the ground so the mechanic can get underneath and work on it. Hydraulic pumping for oil and gas, artificial lift does the same thing by lifting, or basically pushing, fluid up and out of the well bore. The biggest issue with hydraulic pumps is their inefficiency. The power is transferred by momentum, but this momentum is over hundreds, if not thousands, of meters, which means most pumps only probably get about ten to thirty percent of their power down whole, because most of it is lost along the way. Think of it like a wave crashing on beach. The initial amount of power and energy when it first crashes is huge, but the further it has to go, the more energy and momentum is it loses. It's the same...

...thing with hydraulic pumps to some extent. PLUNGER lift. plunger lift systems are also widely used and are very economical because they don't require a lot of equipment. It's typically used to remove liquids in gas wells or with low volume oil wells. The plunger in the plunger lift system is just a solid piece of metal that's allowed to fall to the bottom of the well. Once it's at the bottom of the well, the well is shut in, and remember we call this we closing the taps. We shut in the well so there's no production coming out. And basically what happens when you shut your well in is it gives the reservoir chance to build up some pressure against the plunger and eventually they'll be enough pressure built up behind it that when the taps are opened again, the plunger as the pressures pushing it will help lift the fluids above it.

Because of the pressure underneath it. The plunger, which is fueled by the resource pressure which has been built up over that period of time, will push all of the liquid in the well above it to surface until the plunger reaches surface. And once the plunger is at surface, now the gas that was behind it can flow by it. You can program the system to time how often the plunger is allowed to go up and down to maximize the efficiency of the system. The biggest advantage of the plunger lift system is that it's so cheap relative to other options, but it's only really viable for certain scenarios and definitely takes a little extra engineering to fine tune the settings for timing the plunger cycles. Progressive Cavity pumps, or PCP's progressive cavity pumps, were actually invented in the industrial and manufacturing industry and we're only later adapted to oil and...

...gas. The easiest way to think of what happens is if you think of a power drill when drilling through a piece of wood. The bits for your power drill are shaped and the they actually have grooves spiraling grooves, kind of like on a candy cane, how they spile around and their shape such that as you keep drilling further into the wood, the SAWDUST is carried out through these grooves or by these grooves. As the bit spins and drills further, the grooves create a cavity between the hole in the wood and the metal body of the bit. As the bit spins, this progressive cavity space, and that's where we get the term progressive cavity pump, this progressive cavity space is...

...able to carry the sawdust out of the hole. This is exactly how a PC pump works, but as it spins downhole, it moves liquid up, not sawdust. PC pumps are limited in what they can produce, but are very efficient in terms of energy use. They're sort of the option that doesn't have a ton of obvious strengths, but not a lot of weaknesses either. If they're configured properly for the right application, pc pumps can be an excellent choice. At the end of the day, there are a wide range of different types of artificial lift that we can use, but really they're there to accomplish the same objective, which is to get after that secondary production or to help the well produce when it can't produce anymore because it just has lost the ability to do so because we've produced so much oil and or gas from it...

...that the reservoir pressure has come down to a point where it just can't do it. So, whether you're using pump jacks or whether you're using progressive cavity pumps, the way you get about it is going to be different, but the end goal is going to be the same enhanced oil and gas production. 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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