Podcast: What is a Natural Gas Compressor Station? | Ep. #10

In this episode of Stuff You Should Know About Oil and Gas Production, Chase Hendley talks about his experience with the Natural Gas Compressor Station.

Topics in Natural Gas Compressor Station

  • What does a natural gas compressor station do?
  • What are the key components?
  • Why is a natural gas compressor station important in oil/gas operations?
  • Where do you typically find gas compressors? 
Resources mentioned in this episode: 

gas compressor stationgas compressor, podcastnatural gas compressor, podcast

Transcript

Curtis: Well, hello, Chase. It’s good to see you today. This is your first podcast, right?

Chase: It is. Yeah.

Curtis: Thanks for getting on with us. Let us get to know you a little bit. Where’d you grow up?

Chase: I grew up in Edmond, Oklahoma, originally from Lubbock, Texas, but moved to Edmond what I was 5.

Curtis: Where’d you go to school?

Chase: Graduated from Oklahoma Christian, up in Edmond. Went to Oklahoma State for three years, but transferred.

Curtis: The reason we’re having having you on today is because of your experience—you’ve worked in gas compression quite a bit. Can you tell us a little bit about that?

Chase: Compressors are pretty much my entire background. So started out as a field compressor mechanic and did that for awhile, then transferred on to become an applications engineer for compression. So basically telling the customer what size and how many compressors to put at a particular location, then moved into the supply chain side, where I actually purchased the compressors and help do the applications for the customer to, again, tell them how many compressors they needed. Then most recently before Kimray, I was a branch manager of a bulk oil distributor that. We distributed oil antifreeze, things like that to compressor facilities. Gotcha. 

Curtis: And where all were you in those jobs?

Chase: Yukon, Oklahoma, spent a lot of time out in East Texas, the Kilgore area. A lot of time out in Pampa. Saw a lot of time, months at a time. Then got transferred to Conway, Arkansas, for about 11 months. Then to Fort Worth for or three years. And then back here to Oklahoma City.

Curtis: Ok, let’s just define our terms first of all, Chase. So a natural gas compressor station. What is it and what’s happening there?

Chase: Basically it can be anywhere from one to 15, 20 compressors. There are lots of factors that could play into that, but the station is in a nutshell, it’s compressing the gas to either inject it back into the well to bring oil and other products out or it’s compressing the gas so that it’s pressurized enough to move down the pipeline to another facility. Be it a storage location, an end user. Um, you name it.

Curtis: So up to 20 compressors at one site. So the factors of why you have to pressurize your gas?

Chase: Say if you’re sending it to a booster station or a storage location, a booster station is just to re-pressurize the gas. The further distance that travels, the more pressure it loses and needs to be boosted back up to pressure. A booster station is larger compressors, but you may only have one or two or a few there. So it just depends on where it’s traveling, it’s going to go to a distant location and volume of gas, diameter of pipeline to gas, terrain.

Curtis: Is it a very wet gas coming out of the ground or can it be dry?

Chase: Yeah. It differs. If it’s wet, you’re going to have to send it through some scrubbers and some things like that in order to get the liquid out. You can compress gas and make it smaller and pressurize it. But you can’t compress liquid. That only goes so far.

Curtis: We said, what was the distance between compressors?

Chase: 40 to 100 miles.

Curtis: Is there a difference between a natural gas compressor station and a booster station or is it synonymous essentially?

Chase: They’re basically the same thing. It’s just, booster station, again, it’s just boosting that pressure up to continue sending that gas down the line, whereas a compressor station that may be boosting it up to send it into a storage tank or send it somewhere else other than pushing it further down the line.

Curtis: And the country is basically, there’s a spiderweb of these gas lines going across the country.

Chase: Right. They’re everywhere. There are a million different pipelines out there.

Curtis: Talk some about the uses for the gas. We’re pulling this resource out of the ground. We’re separating it from the oil and then compressing it and then what?

Chase: Yeah, there’s so many different places it could go. So first, I mean, you have like gas injection or gas lift, where they pressurizing it enough to pump it back down hole in your well. So if your gas injection, you’re pumping it into the oil zone of your well, and if you’re a gas lift, you’re going to be pumping it into the casing. But both of those are designed in order to push oil and more gas, push it out. You’re pumping it down to the bottom and pushing what’s sitting on top out.

Curtis: Alright. I have a question though about storage, because I’ve seen some things about, uh, like underground storage for gas. 

Chase: Yeah. Yeah. Um, you see a lot in the Gulf, they’ve got these salt dome storage places. They are salt domes that they’ve mined and taken it out. And it is basically an empty cavern and underground where you’ll see them. They use them primarily for oil, but you’ll see them used for natural gas as well.

Curtis: So, so it was just waiting there to be, to be used.

Chase: Yeah. If we have a surplus, like we do have with oil right now, they’re going to be used.

Curtis: Utility companies—do they do some of the processing as well?

Chase: Yeah, typically like ONG. They’ve got processing facilities.

Curtis: Oklahoma Natural Gas.

Chase: Yes, they’re they’re partnered with other companies like ONEOK who is on the midstream side. 

Curtis: So really Oklahoma Natural Gas is a downstream customer of ONEOK’s. Gotcha. So what are the key components at a natural gas compressor station? Compressor station or compressor package?

Chase: Uh, let’s go station first station. You’re going to have your compressor. You’re going to have your inlet separator, you may have a dehydrator, which is taking the liquid out of the gas. You’ll have, uh, gas processing units there. There’s a wide variety. You’ll have, uh, burners on there. Just a wide variety of equipment. It all kind of depends on what that facility is, what its intended use is.

Curtis: Okay. So that would be what you’re talking about. Is that like a gathering station typically?

Chase: Yeah. They’re taking them from multiple wells. They’re taking that gas and yeah, multiple wells will come into this one gathering location, go through separation—one, two, or three phase, however many stages of separation they need to dry it. They need go through a dehydrator, back through any other equipment that they’ve got, then you’ll go through the compressor then maybe a more separation, gas processing units, things like that. And then it’ll discharge or leave the facility down the pipeline.

Curtis: How about the compressor itself?

Chase: The components would be engine, compressor, cooler, scrubbers and pulsation bottles. Those are going to be your five main parts. The big one to note there is the engine and compressor are two separate piece. In the past—and there may be still some manufacturers out there that do this—manufacturers would combine those into one piece of equipment. But I would say 99% of the time, these days you’ll see them as two separate pieces of equipment. The engine, which powers the compressor, it’s using the gas that it’s pulling out of the ground to run itself, powering that compressor, to compress the gas and push it down the line or storage or, or back into the, well, wherever it is.

Curtis: And earlier you said there were some other power sources that could use as well?

Chase:  Yeah. So there’s electric driven motors. You’ll see those quite a bit as well. It’s basically like an electric motor that you would run like a generator is producing the power to drive that compressor. And those can get significantly larger in horsepower terms and just in sheer size.

Curtis: Okay. We talked a little bit about that. How big?

Chase: You can range anywhere from like a 55, sometimes even smaller, all the way up to 4,400 or so. Um, I think they’ve come out with some new engines since I’ve kind of stepped out of that side of the business that are even larger than that, that I’m just not up to terms on there, but, uh, when you’re looking at electric driven, you can get upwards of 5,000 to 10,000 horsepower motors out there that get pretty, pretty large and they move a substantial amount of gas.

Curtis: Yeah.

Chase: So, and then the, the, the other way that’s not near as common anymore, I’ve actually never run into it in the field, is a diesel-driven engine.

Curtis: So, as you compress your gas, it heats up and as you continue compressing the gas, it will continue to heat up. So you need a cooler. 

Chase:  Yes. Every piece of equipment is manufactured for heat tolerances, and the compressor is the piping on the compressor package. The scrubbers, pulsation bottles, everything is. And so you need to cool that gas down because once you exceed certain temperatures, you’re gonna cause failures and fires and, and it’s just not safe. So after you compress the gas, you’ve got to divert it through the cooler to cool that gas down. It acts like a radiator on your car, or, even your AC unit at the house, it’s got little fins on it. You see the fins that get bent over on the AC unit at your house, same thing. That allows air to flow through it, and the gases traveling through tubing or piping inside that radiator and cooling it down.

Curtis: And it is, is that the loud piece of equipment on it?

Chase: No, the loud is going to be your engine.

Curtis: Okay. And yeah, the engine, the, obviously the larger the engine, the louder it’s probably going to be. We were out of a few months ago. Do some video work on a dehy station, and they were out there doing some work on the compressors and then they kicked one on and it was just like all audio was gone.

Chase: Couldn’t hear anything else, right? Yeah, that’s that’s the engine. Now the cooler can be somewhat loud depending on how the wind’s blowing. And inside that cooler, I mentioned the, basically like a radiator and everything, but you also have a big fan in there with blades on it that they’ve gotta be pitched to a certain degree, depending on your atmospheric temperature and the temperatures of your gas and everything. But that fan, depending on how the wind’s blowing and how fast that fan travels that can create some noise as well, but not anything in comparison to the actual engine.

Curtis: Okay, the scrubbers?

Chase: So as you compress the gas, I said it’s heating up. So you heat it up, then you’ve got to cool it down so you don’t cause a failure. So you send it through a cooler. Well, just like with anything, a food or a beverage that you’re drinking as it heats up and cools down and heats up and cools down, you’re creating condensation. So this is, this is different than just condensate that you would get out of the ground with your oil or gas. It’s condensation, it’s water. Cause it’s just liquid.

And so you have to remove that liquid before sending that gas back through another stage of compression. Because gas, you can continue smashing it and compressing it to get smaller and smaller. Those particles are getting smaller and smaller. But you can only compress liquid so far. So if you don’t get that liquid out before sending it through your compressor, you’re gonna blow the ends of your cylinders out. And you’ve got a piston that’s traveling pretty quickly. And you can’t compress that liquid. And so it’s only got one place to go and that’s going to blow equipment out.

Curtis: Wow. Okay, so you gotta get the moisture out of there. And then these pulsation bottles. This is new to me.

Chase: Yeah, so pulsation bottles are a bottle that is on the top and the bottom of your cylinder. So as you compress the gas, you’re pushing it to the left and right. Well, then it’s got to change directions to go through the piping on your compressor package. So as it’s traveling out of the cylinder into this piping, well, that can create vibration and turbulence, just like you would see in a Kimray valve, a turbulence because the flow is changing directions. These pulsation bottles, they act a whole lot like our Kimray pot, they’re gonna just kind of redirect and reroute that gas. And they do a little bit of scrubbing as well, removing the liquid, but their primary focus and purpose is to change or redirect that flow.

Curtis: So it travels smoothly through your pipes.

Chase: Right, so the compressors are not shaking and all over the place, because as you start shaking and vibrating, other things break that have absolutely nothing to do with the pulsation of the gas.

Curtis: Right. So you see this in all three segments of oil, gas, production: upstream, upstream, midstream, downstream?

Chase: Upstream, you’ll see it more than likely a gathering station. Midstream you’ll see it on a pipeline, which is going to be more of your like booster station. Cause it’s just boosting the gas on that pipeline to continue traveling that pipeline. Uh, you’ll see it on like a storage line in the midstream, which is going to be your gas injection or with withdrawal of gas to a storage location and then downstream, you’ll see it more on like the process side.

Curtis: So where do you pull off different gases? Like your propane, because your natural gas is, it’s not just not one.

Chase: It’s not a hundred percent natural gas. You’ve got propanes, you’ve got residue gas, you’ve got methane, ethane, hexane.

Curtis: All the “anes.”

Chase: All the anes. Yeah. And so they’ll send it on the process side through different other types of equipment outside of compression that remove these gases, heat up the gas in order for certain molecules of that gas to fall out. And then they’ll cool it for others to fall out. And so you’ll see them see compressors at those locations, just to pressure it up, to go into these other pieces of equipment.

Curtis: Gotcha. Another thing when I first got into the industry I didn’t realize was that we’re not just, I mean, we do pull out the gas as a resource to sell, but it’s useful in so many other areas, like for heaters, for instrument gas.

Chase: Yeah. And they’ll pull off other gases, like H2S, that are harmful and they’ll send them either to a flare or a vapor recovery unit, things like that. 

Curtis: You’ve been in this a long time—any tips for somebody just trying to learn, trying to figure out what a compressor is? We’ve shared a lot, but if they’re onsite trying to figure out what’s what?

Chase: Definitely. One thing would be don’t go just poking around—ask somebody. People are usually willing to help and assist and they can always come to me or anybody else, and we can assist with that. 

Curtis: We were on site a few months ago and the guy was saying that sometimes the fellow working on the compressor will not be familiar with the guy working on the dehy.

Chase: Yeah.

Curtis: So they don’t know what their gauges look like and so on, just because there’s, there’s a lack of communication. Communication seems key, even if you don’t ever touch the dehy and you’re strictly a compressor guy or vice versa.

Chase: Yeah. Communication is key because at some point though, the dehy process is going to affect the compressor and the compressor process is going to affect the dehy, same with the separator. And if you have a different guy running all of those pieces of equipment, then he needs to communicate, especially if you’re going to shut the compressor down. One thing can, one small change on one piece of equipment can be a catastrophic failure or change on another piece of equipment.

Curtis: So it doesn’t have to be catastrophic, but do you have one or two stories you want to share from your experience? 

Chase: Let’s see. Yeah, we went out once and there was a guy working on a dehy. This was back when I was mechanic, so this would have been back 2010, 2011 timeframe. And we weren’t notified of it. And we were out there to work on the compressor, and we were pulling up to the compressor station and we found the end of the cylinder was actually blown out. Those pistons that are compressing the gas in the cylinder move so fast and with so much force I mentioned earlier that they’ll blow the end of that cylinder out. We actually found that cylinder 300 yards across location.

Curtis: Cause it shot it that far, this cylinder.

Chase: The end of it. Yeah. There’s a thing on the end of the cylinder called the volume pocket which, you either you screw in or screw it out to allow more gas in the end of that cylinder to help with temperatures, to help with—we’re getting deep in here—things like rod load and volumetric efficiencies and engineering talk for just how that compressor operates. And so you’ll, you’ll add those on the end and that’s the first weak point there.

Curtis: 300 yards?!

Chase: Yeah, it was, it was out there. 

Curtis: And you just happened to find it or was there a trail? 

Chase: You could kind of see the trajectory because there was moisture there.

Curtis: Wow. So. Alright. Any others, any good stories? When everything goes, right there’s no big story, right? 

Chase: I’ve got plenty of stories. Probably not all suited for the podcast. So maybe another time.

Curtis: How about Kimray equipment? Let’s touch on that with some Kimray parts you might see on a natural gas compressor station.

Chase: You might see our regulators, our A-line, high pressure control valves. You’ll see those as the suction control for the inlet of the compressor. So they’re going to hold, they’re going to be a pressure reducing regulator. Let me say it that way. Before it gets to the compressor you’ve got to cut that pressure down in order for it to be the right pressure going into the compressor so that it can compress it and remove liquids and everything else.

Curtis: Okay.

Chase: And so you’ll see that pressure reducing regulator cut it down to the right pressure. If you’re on a dehy at a compressor station, you’ll see things like a T-12, which is our thermostat or our temperature controller, and you’ll also see dump valves on separation. Kimray also has a ball valve line and butterfly valves. You’ll see those at a number of spots out there. And of course actuators to run either the valves, things like that. The big one I didn’t talk about on the dehy you’ll see is our Kimray Glycol Pump.

Curtis: Oh yeah. Very good. Well, thanks for sharing, Chase. Appreciate your time today. You’ll find links to the products and resources we mentioned in this show in the show notes, and we’ll catch you next time on Stuff You Should Know about Oil and Gas Production.


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