This week’s Pipeliners Podcast episode features first-time guest Lalit Chilana of Burns & McDonnell discussing the fundamental elements of pipeline horizontal directional drilling (HDD).
In this episode, you will learn about the history of HDD, why HDD has been utilized more often in recent years, and the risks associated with HDD. You will also learn about the three-step process involved in horizontal directional drilling.
Pipeline HDD: Show Notes, Links, and Insider Terms
- Lalit Chilana is a Senior Pipeline Engineer at Burns & McDonnell. Connect with Lalit on LinkedIn.
- Burns & McDonnell is a family of companies bringing together an unmatched team of 7,600 engineers, construction professionals, architects, planners, technologists and scientists to help those who work in critical infrastructure sectors deliver on their imperative responsibilities.
- Horizontal Directional Drilling (HDD) is a minimal impact trenchless method of installing underground pipelines in a shallow arc or radius along a prescribed underground path using a surface-launched drilling rig.
- Trenchless Technology is a fast-growing form of subsurface construction work that requires few trenches or no continuous trenches.
- Martin Cherrington conceived the use of Horizontal Directional Drilling as a practical alternative to conventional trenching methods beginning in the 1960s.
- HDD 3-Step Process:
- Stage 1: Drilling the Pilot Hole
- Stage 2: Reaming
- Stage 3: Product Pipe Pullback
- HDD 3-Step Process:
- Boreholes are deep, narrow holes made in the ground, either vertically or horizontally, which helps locate the presence of hydrocarbons or water.
- Open cut installation is a method of pipeline installation that requires opening up the surface of the ground to the required depth for installing a pipeline.
- ILI (Inline Inspection) is a method to assess the integrity and condition of a pipe by determining the existence of cracks, deformities, or other structural issues that could cause a leak.
- Soil boring is a method of surveying the contents of soil by taking samples from the sediment.
- Stress Analysis (thermal flexibility analysis) predicts stresses in piping and loads on equipment resulting from thermal gradients, thermal transients, weights, pressure, and bolt-up strain.
- ASCE Pipeline Manual 108 is a set of standards, Pipeline Design for Installation by Horizontal Directional Drilling (MOP 108). The manual is available for purchase.
- PR-277-144507-Z01 is the Installation of Pipelines by Horizontal Directional Drilling Engineering Design Guide by the PRCI.
- PRCI (Pipeline Research Council International) is a community of the world’s leading pipeline companies, vendors, service providers, equipment manufacturers, and other organizations supporting the oil and gas industry.
- Listen to Pipeliners Podcast episode 54 with PRCI president Cliff Johnson on how the PRCI has developed a data hub to store information from across the pipeline industry.
Pipeline HDD: Full Episode Transcript
Russel Treat: Welcome to the Pipeliners Podcast, episode 144, sponsored by Burns & McDonnell, delivering pipeline projects with an integrated construction and design mindset, connecting all the project elements, design, procurement, sequencing at the site. Burns & McDonnell uses its vast knowledge and the latest technology with an ownership commitment to safely deliver innovative, quality projects. Learn how Burns & McDonnell is on-site through it all at burnsmcd.com.
Announcer: The Pipeliners Podcast, where professionals, Bubba geeks, and industry insiders share their knowledge and experience about technology, projects, and pipeline operations.
Now, your host, Russel Treat.
Russel: Thanks for listening to the Pipeliners Podcast. I appreciate you taking the time. To show that appreciation, we give away a customized YETI tumbler to one listener every episode. This week, our winner is Sarah Gol with Con Edison. Congratulations, Sarah, your YETI is on its way. To learn how you can win this signature prize pack, stick around ‘til the end of the episode.
This week, Lalit Chilana of Burns & McDonnell is joining us to talk about horizontal directional drilling. I’ve just got to say before we jump into this and get Lalit on the mic that I was running very steep on the learning curve. This is a very complex subject.
Lalit, welcome to the Pipeliners Podcast.
Lalit Chilana: Thank you, Russel. Good to be here.
Russel: I asked you to come on to talk to us about horizontal directional drilling. Again, this is another one of those subjects that I don’t know very much about. I’m really glad to have you here because I’m looking forward to learning myself.
Maybe before we get started, just tell us a little bit about your background, experience, and how you got into pipelining and more specifically how you got into horizontal directional drilling.
Lalit: Sure. My name is Lalit Chilana. I’m a senior pipeline engineer at Burns & McDonnell. I got into pipeline industry back in 2011. My first job was with one of the largest HDD contractors in North America. I spent about three years with that company and learned about the directional drilling through HDD projects. I spent some time on-site and some time in-office doing the calculations.
Then I moved on to another oil and gas pipeline design and engineering consultancy company where mostly I was focused on learning about the other aspects of the pipeline, but my specialization or my focus was still on HDDs. Then, back in 2018, I joined Burns & McDonnell. I’m here for two years now. I’m the HDD subject matter expert here.
Russel: What attracted you to horizontal directional drilling?
Lalit: Back in 2010, I was doing my master’s. One of my professors, he’s also the director of our program at UT Arlington. He introduced us to a course called Trenchless Technology. In that, he gave us the introduction to various methods which include HDD microtunneling, pipejacking, and all the other trenchless methods.
Then we had a site visit where a construction company was doing a project across Lake Arlington. When we went to the site, that was very fascinating to me. Typically, when you’re talking about installing a pipeline, you’re imagining that you have to dig up a trench, weld a pipe, put it back in the trench, backfill it, and clean up and go.
What if you come across these obstacles or features that you cannot simply open cut? That was the live example that I got to see. That attracted me to this industry.
Russel: Have you actually been someone who ran the machines?
Lalit: No. I have been in the machines, in the drill cab at the site. I have seen it live, but no, I have never had the pleasure of doing it myself.
Russel: A sidebar conversation, Lalit. When I was in the Air Force, I was a construction engineer and did all kinds of civil projects. I made sure that I knew how to drive every piece of heavy equipment, meaning I could get on it, I could start it, and I could move it, but I didn’t know how to operate any of it. There’s a big difference between driving it and operating it.
Russel: That’s why I was asking that question. I love big gear. I love playing with big gear. I love understanding how it works, all that kind of stuff. If you’d have said yes, I’d have been jealous and trying to figure out how I could get an opportunity to do that myself.
Lalit: I wanted to. Trust me, I wanted that badly. It was one of those things that it becomes a liability if something goes wrong.
Russel: Exactly. You want to, but it’s not the right thing to do.
Russel: I get it. What’s the history of HDD? How long has it been around? Where does it come from?
Lalit: Before I jump into that, I would like to maybe define it, on broader terms. For people who are not aware about this, the HDD stands for horizontal directional drilling. I define it from backwards.
First thing is drilling. That’s the last word in the acronym that you are seeing, or the definition. Drilling is simply just cutting through the formation using a drill bit. Then the middle word is directional, meaning you have the ability to steer the drill bit and provide directional control.
The first word is the horizontal, which means typically when we think about drilling or we hear the word drilling, mostly what comes to mind is you’re going to drill something vertical, vertical borehole.
In this case, you have horizontal, which means you can do the drilling in the horizontal plane. That’s how the definition is the horizontal directional drilling. It’s basically you have the ability to drill through a formation using a steering capability, and you can do it in horizontal plane.
The history of it is, there was a guy named Martin Cherrington. He was into construction. He was helping his father with a construction business. He learned the trade through working with him. He was pretty good in civil, mechanical, had all sorts of trade training and experience.
He saw another contractor working out on a pipeline and using the air drilling. That basically sparked an idea. He tried to use that technique and tried to make his own drilling rig. He was successful in doing so. He formed a company named Titan Contractors. This is late ’60s.
Then he did his first crossing back in 1971. That was for Pacific Gas & Electric. I believe it was in California. It was a four-inch pipeline installed across a river. It was about 600 feet long crossing. He attempted that crossing. That was the first HDD project ever to take place in the United States or anywhere else. He was successful.
After that success, he was being asked to do other crossings. Started in 1971 and within 10 years, from one drill rig, it went up to 100 drill rigs. The market was just exploding. People were catching this. They were following this. This was becoming a hot market for everyone.
In the 20 years, from ’70s to ’90s, it became very popular because it was a convenient method. You could install a pipeline beneath the river or any other obstacle. It was quick. It was convenient. It was minimal impact to those features. That’s how it came into the picture.
From ’90s onwards, the technology just improved a lot. They started working on electronics. The tracking, the machines, everything was being upgraded. Now, in 2000s and this decade, everything is just more advanced and advancing.
Russel: My first experience with this kind of technology was actually at the wellbore well drilling, where back in the late ’80s, one of the big technologies was measurement while drilling.
They were beginning to be able to locate the drill bit in three dimensions and steer it as well as instrument it and take other information about the formation they’re going through and the cuttings they’re getting back and all that kind of stuff. It’s been around for a while.
It seems to me though that recently within the last 5, 10 years, it’s kind of in a second Renaissance. Is that just my imagination or am I reading more advertising?
Lalit: No. You’re right, actually. It is becoming more prevalent these days. You hear a lot more about HDDs now.
Russel: Why is that? Why are we hearing more about it?
Lalit: There are a couple of reasons. First one being that now you have more environmental restrictions or regulations. It’s not getting easier for the pipeline companies to install the crossings across, whether it’s a wetland or you’re crossing any environmental sensitive areas.
You will get a lot of pushback from the regulating agencies. They are not going to let you simply do open cut across those features. That’s why HDD is one of the most popular methods that’s available to the contractor.
A lot of contractors have the ability. They understand the technique. They understand the market. They have the capabilities to do the installation, that’s this method! That’s why it’s becoming more and more popular, and it’s easily available now. You don’t have to rely on a specialized contractor to do this.
Based on the geography or the local region where you are, you may be able to find 5 or 10 contractors that can bid on a single project.
Russel: I guess one of the things that’s changing is pretty much every pipeline contractor has a HDD capability at this point.
Lalit: I wouldn’t say every pipeline company, but I would say most of them have or are trying to get into that market.
Russel: That makes sense. Certainly, the ability to get around these environmental and other kinds of features is it’s becoming a bigger issue in our business in general.
Lalit: That is true. The other reason is the type of features that you’re trying to cross. For example, I’m in Houston, I have seen crossings across I-10. Let’s say, I make a decision. No, I don’t want to cross I-10 using any of the trenchless methods. What option do I have?
I don’t have any other choice because I-10 is approximately 1,500 miles long, so you’re not going to go around that highway to get to the other side. You will have to cross it somewhere. To cross it, you’re not going to tear it apart using open cut installation. The only option you have is using one of these trenchless methods. This is where HDD comes into the picture.
Russel: I think that’s an interesting point because you’re not shutting down I-10. You have to be the Department of Transportation doing a construction job and widen it before you can shut it down.
Russel: Even those guys don’t shut it down. They just narrow it till they can make it wider.
Lalit: Absolutely. It’s going to cause a major headache for people. It’s going to be very inconvenient for the public. Then, of course, you’re going to lose so much money if you try to shut down a major highway that is basically going through the heart of the city and provides useful transportation.
Russel: The other thing, the latest I’m thinking about this is that if you’re going to do an open cut, you’d have to shut it all the way down in both directions to open the cut, to do your work.
Russel: How feasible is that?
Lalit: That’s not going to happen.
Russel: Exactly. You can’t say that strongly enough, right?
Lalit: Yeah! You will have a hard time even doing the open cut across county roads, let alone interstate. You’re not going to get a green light from the county or the city or any agency to do this.
Russel: No doubt. Let’s talk a little bit about planning and doing feasibility analysis. The first question I want to ask is, what’s the largest diameter pipe that you can use HDD?
Lalit: You can go up to 48, 54 inches. Personally, I have worked on a project which was basically 44 inches across a river, but I haven’t worked any other project which had even larger diameter than that. I know the limitation of 48 to 54 inches and that will be the maximum limit, I would say.
Russel: Then how far out can you run this? What’s the limit in terms of how far you can go before you can take the pipe back to the trench?
Lalit: That depends on a couple of parameters. First, you need to consider first your pipe, how strong your pipe is. What you’re doing is when you are installing the pipe using HDD, you are pulling the pipe. The pipe is being subjected to tensile forces.
If you want to go longer length, the amount of force that you’re applying on the pipe during installation is going to be directly proportional to your length. The longer you go, the more forces you are applying to the pipe. That means the more stronger pipe you need.
To do that, you need to increase the wall thickness of the pipe and have higher grade of the pipe. That’s going to increase the cost of the pipe. Economics come into play at that point.
The other limitation would be the drilling rig that is going to be pulling the pipe.
Drilling rig comes in various sizes with limited pull force capacity. The largest drilling rig that I know of that is available in market is a million-pound-capacity rig. That means it can exert up to one million pounds of force on the pipe.
I know there are HDD contractors who can customize the rig. They can modify the existing rig to create a 1.5 million pound or 2 million pound capacity, but that happens on a very special crossing. Of course, customization is going to cost you a lot more money.
Russel: Yeah. Bigger, longer, more specialized, more money.
Lalit: Exactly. The diameter of the pipe, the length of the pipe will come into play when you are calculating the length because your diameter is going to dictate your bending radius of the drill, and that’s going to dictate your geometry.
All these parameters will come into play to determine how long you can go before you say this is the point where I need to get out. It could be either the pipe limitation or it could be the drilling rig limitation itself.
Russel: To what degree does this method of placing pipe cause integrity management concerns after it’s been placed? You’re talking about putting some pretty significant loads on this pipe and they’re going in an orientation that is not typical of what they’re going to experience once they’re placed in service.
Lalit: I am glad you brought this point because this is often one of the aspects that is overlooked by some designers. Coming from the construction side when I was working with a contractor, I saw some designs which made us scratch our heads and we’re like, “How are we going to install this?”
You’re talking about installing a 36 inch pipe and you are basically drawing a U-pin. That’s not going to happen.
The pipe is not a piece of straw that you can bend and create a U-pin. It’ s pretty strong. The bigger the size, the more stronger pipe you need. It’s not going to be that flexible. This was one of the limitations on the engineers’ part that I noticed.
Maybe engineers who do not have a lot of experience designing the drills, they try to design it in such a way that the pipe will be subjected to extreme stresses.
What that means is you can install the pipe safely. During the installation, you’re exerting a lot of force on the pipe, it can take it, but it’s going to stay there for the rest of its life. It may be 40 years, 50 years, 60 years. It’s going to stay in the ground in that position. If you overstressed the pie, it’s going to cause concerns when it goes in operations.
Russel: I would think not only that, but if you did something that then ended up requiring a dig to mitigate any features, then by definition, because I had to put the pipe in using horizontal drilling, then any dig is going to be a high-risk, high-cost dig.
Lalit: Typically, you don’t dig any of the pipe which is installed via HDD, unless it is very shallow. Most of the time, you will install the HDDs and those are going to be pretty deep. It may be 40, 50 feet deep. You’re not doing any maintenance on that section, if you have integrity issues.
Let’s say you have corrosion issues and your wall thickness is reduced, and you need to replace a section, you’re basically abandoning that pipe in place and you have to install a new line or new replacement for that portion.
Lalit: Absolutely. That’s what I try to determine at the beginning. When I’m doing the design, I’m not looking just at the installation stresses, but I’m thinking about the operations down the road — 20 years — of what’s going to happen to this pipe.
To start or to mitigate those issues, I start all the designs making sure that the pipe is strong enough. It’s going to take all those stresses. Not just installation, but the operational stresses also. It’s going to meet all the requirements that we have.
Typically, we apply safety on top of what is the minimum requirement, so that we have some buffer for the future capabilities.
Russel: Lalit, have you ever had the opportunity to go back and look at ILI tool run data on something that you did the original design and construction of using HDD and see how your calculations and plans related to what you find five years later when you run a tool?
Lalit: So far, I have not been able to get a tool run on one of my projects. What happens is when the installation is complete, and typically we require the HDD contractor to run a sizing plate, to make sure there’s no issues with the wall thickness or there is no buckling in the pipe at any location.
Lalit: I agree. That doesn’t help me, but it at least helps me in terms of design, that the way I was designing is how it was installed, and how much variation I can find. At least that I can confirm and go back, and do my stress analysis again based on the install parameters to make sure that’s okay.
Let’s say I design the 36-inch pipe with a 3,600 radius, but at the end of the installation, the actual radius comes out to be 3,000 feet. I want to make sure that 3,000 feet is good enough, that it’s not going to cause any issues 10 years or 20 years down the road.
Russel: It’s interesting, because before we got on this podcast and started going down this line of questioning, I’ve not thought about those issues before, but it makes a lot of sense. It does raise, for me, another question and that is to what degree does the actual soil that I’m drilling through factor into all of this?
Lalit: That’s a whole can of worm.
Lalit: That is one of the most important factors I would say in the success of any HDD. There was this image and I don’t know who came up with that image, but it was a brilliant way of conveying the message, how important the geotechnical or the soil data is for the drilling.
What that image conveyed was basically you have the ground, you have the drilling rig setup on one side and, within the ground itself, they had a dragon sleeping.
Lalit: I think there’s no better way to convey that message. You get into territories, which are unknown. People say, “But you’re going to do some soil borings.” It’s like “Yes.” Let’s say you’re installing a 3,000 feet long crossing and you do five or six soil borings along the path at 500 feet interval or so, you’re getting a lot of information, basically.
Soil bore is just doing a vertical bore. It can go up to 100 feet or 200 feet, depending upon the depth of your drill. You’re collecting a lot of concentrated information over a very small area.
The soil boring, it’s going to be four to six inches in diameter. That’s it. You are collecting a lot of good information over a very small area, and then you’re trying to generalize it over the length of the crossing.
Russel: Man, you’re a preach into the converted on this particular subject. I have direct experience with this when I was doing construction. We’re building a runway in Germany. We had all the engineering. We started putting dozers to dirt and we found all kinds of things that we’re not in the soil survey.
Russel: All kinds of stuff. Including abandoned concrete bunkers and such that weren’t picked up. It was nuts.
Lalit: Depending upon where you are in the world, you will find interesting stuff that could be very detrimental to your drill, but it’s going to be interesting to see what comes out of the ground.
Russel: Do you have the ability when you’re doing one of these projects to back the pipe out if you come up against something that was unanticipated?
Lalit: Typically, HDD is a three-step process. First one is the pilot hole, which is six to eight inches in diameter. When you’re doing the pilot hole itself, let’s say you come across an obstacle, let’s say you hit a boulder or maybe a tree log. You will notice the driller will get a feel for that “We hit something.”
He will immediately know “Something is happening,” so he will try to pull it back up, go back again and see if we can get through it. If not, then he definitely knows that there is an obstacle. At that point, the decision is made in the field, whether we want to change the drill path or we want to keep trying.
If you try for one or two more times, and if you’re successful, you can drill through it, but if you’re not successful, then you may have to change the path, which may mean that you pull it out a little bit back, you try to go deeper with a deeper angle or you try to go shallower using a shallower angle.
Russel: The first step is pilot hole, what’s the second step?
Lalit: Second step is reaming. Let’s say you’re installing a 36-inch pipe. First thing what we will do is do the pilot hole which is going to be about eight inches in diameter. You have the drill bit, you have the drill pipe, you’re just drilling. You get to the other side. Then, second step is the reaming step which means you are enlarging the pilot hole.
You attach a reamer behind the drill pipe, and then you try to pull that reamer. Maybe from eight inches you try to go to a 20 inch. First step will be in the reaming itself, you may have multiple steps that you have to do. You don’t want to go from…or you can go, but it’s not recommended to jump from 8 inches to 36 inches right away.
Russel: You don’t do that step, sure.
Lalit: 20 inch maybe and then 32 inch. The rule of thumb is that when you’re installing a 36-inch pipe, you want to ream it up to 12 inches larger than the product pipe itself that you’re trying to pull. You will ream it up to 48 inches to pull the 36-inch pipe, so you have some space for the pipe to get adjusted.
Russel: You’re pulling the pipe? For some reason, I thought with HDD, you pushed the pipe.
Lalit: No. It’s always a pull. Once you have completed the pilot hole, you do the reaming. You enlarge the hole. You get it on the other side, then you push ream. You get it on the final side, and then where you have the pipe string ready, you attach reamer rack again. You have a swivel in between the pipe and the reamer. Then you attach the pipe itself to the pull head and then pull it.
Russel: It makes so much sense. Again, it’s one of those things, Lalit, that if I hadn’t got on this podcast with you, I would have made some false assumptions, but the minute you start explaining what you’re doing, I’m like, “That makes sense.”
I can integrate that in my head, given what I know about construction and pipe, and such. It makes more sense to pull it. Interesting.
I want to ask some other questions around the site issues around doing this. Once you get this hole opened up, I would expect that you have or could have issues around getting water into that borehole?
Lalit: Your borehole is full of drilling fluid. That’s basically bentonite mixed with water because that’s how you support the borehole. Otherwise, the hole is going to collapse itself. Unless you are in the rock, then it can sustain, but otherwise, if you’re drilling through clay, sand, or any type of formation, it’s going to collapse.
Russel: Sure. Again, that’s going to another question I was going to ask because you’re usually not drilling through rock. You’re usually going through some kind of soil — sand or clay, or something like that — which is not going to hold its shape.
Lalit: Yes. If you have the option to go through the rock. If you know that rock is more competent compared to the soil. What happens is wherever you will have the bedrock, typically there is a transition layer, so you’re not going to directly go from soil to the rock. There will not be a clean interface.
It’s always going to be a transitional layer, where you will have a lot of gravel or mix of soil and weathered bedrock. Then you will get into nice competent bedrock.
In some cases, let’s say you are drilling somewhere, for example, northeast in the United States, 10 feet, 20 feet, you may be in bedrock. If you’re trying to cross a river, there is no option, but to drill through the bedrock.
Sometimes it’s easier for the contractor to drill through the bedrock because you can maintain a nice hole. You don’t have the borehole collapsing on you or those signs or concerns.
Russel: I feel like we’re coming to the end of our time. I feel like we’re just starting to scratch the surface on this whole topic.
Lalit: [laughs] That is true. I would say that is true.
Russel: You’re mostly illustrating how little I know. Well done. Well played.
Lalit: Thank you. I appreciate that. I’m also learning. This is a never-ending process.
Russel: It’s fascinating. I would suspect there’s a lot of listeners that would love to get their hands on a document or something that explains how this works. Do you guys have anything like that that you could make available through the show notes?
Lalit: Absolutely. There are some industry references. Those are available to anyone like ASCE Pipeline Manual 108. That tells you about the process, explains the three steps that I was explaining earlier, and talks about geotechnical importance and all those things.
Then there are other guidelines. PRCI has a document that basically tells you, if you’re into the technical side and you want to do the stress analysis, then there is a document that explains how to calculate the stresses during the installation and the operation. Then there is a horizontal directional drilling guidelines.
There are multiple books available on the market on Amazon. Those are good resources and that’s how I started reading about the process.
Russel: This is not something that you learn. This is so true about so many specialized areas in engineering. You don’t learn it in school, you learn it at an industry. You learn in school the fundamentals that allow you to learn the specialization once you get into the industry.
Lalit: Yes, that is true. If you’re lucky like me, you might be exposed to these methods in the school, during the summer program. Sometimes that is just enough to push you over to the other side and you want to learn more.
Russel: Exactly. Lalit, this has been awesome, man. I appreciate you coming on the podcast. I have learned a ton and I’m eager to learn more about this subject matter. Thank you very much.
Lalit: Thank you, Russel. It’s been a pleasure.
Russel: Take care.
Lalit: You, too.
Russel: I hope you enjoyed this week’s episode of the Pipeliners Podcast and our conversation with Lalit Chilana. Just a reminder before you go, you should register to win our customized Pipeliners Podcast YETI tumbler. Simply visit pipelinerspodcast.com/win to enter yourself in the drawing.
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Transcription by CastingWords