Driller’s Invention Satisfying Thirst in Developing Countries
The drilling industry is ripe with innovators. Earlier this year, we got to talk with Russell C. “RC” Crawford, who fits that mold quite well. Crawford, a veteran driller, earned recognition in late 2018 from the U.S. Patent and Trademark Office’s Patents for Humanity program. The program “showcases the power of innovation to help the less fortunate around the globe,” according to a release from the patent office.
Crawford’s patent is for a new method of drilling reverse flow. He explains it himself here, but the drill he designed helps charity drillers install deeper wells, increasing the likelihood they’ll last longer without fouling, while keeping equipment portable and easy for two people to use.
Along with Sam Crawford, he founded One Million Wells with the goal making this method available free to any group or person who wants to access water.
Our interview is edited for space and clarity.
Q. Let’s start off with your background, your experience, how this all started.
A. I was pretty much born in the well drilling business. My dad had a drilling business in Tennessee in a little town. Then they went to a water district, and it kind of put him out of making his primary income from drilling water wells. He continued to drill water wells, kept his license and all of that, and went into the general drilling business where he drilled bell piers and did all kinds of stuff. He expanded and did dewatering all over the United States. He was, you know, a nice-sized little drilling company.
I worked for him about 25 or 30 years, something like that. While I was with him, I was a driller. I drilled all types of holes for just about anything you can imagine. I did, like, 800 under a dam on the Tennessee-Tombigbee Waterway, to anchor the dam down. They were wet. We bored them in wet with the top drive, and we did some unusual things back in that period of time. We had things … like our drill stem was all one piece. I think it was 70-feet long and top drive. So, we were pretty progressive as drillers and drilled a lot of dewatering wells. I drilled from Fort Lauderdale to Miami, every few feet, for a dewatering project we had down there. I drilled all types of wells for farmers, irrigation and stuff like that. I did a lot of drilling.
I ended up getting a patent on a reverse-flow drilling rig that we used on the banks of the Mississippi to dewater a steel mill, and it was that patent that led me to invent a new method of drilling reverse flow. It’s the basis for my Patents for Humanity Award from the U.S. patent office. What that original one was, it was also a really long drill stem. We had it both top drive and we ran through a rotary table. I think the one we used on the river, we went through a rotary table. We had an 80- to 100-foot-long Kelly bar, all handled with a crane. We drilled 3-foot diameter wells and dewatered the site.
After I got that patent and decided that I could do more with it, it was time for me to be retired. I’m 70 now. I guess I started this when I was like 67, something like that. With what I invented, I was trying to try to come up with a way to help people in developing countries drill wells, because there’s a water shortage and a lot of people dying because they don’t have water.
I noticed that there were a lot of NGOs (non-governmental organizations) doing hand drilling. They were trying to use the jetting process where, you know, it’s like direct circulation — is what a driller would call it. They were using direct circulation, but there are problems with direct circulation. If you get very deep using really cheap equipment like they have to use in Africa and in India … where they’re just drilling with 2-inch and maybe a 6-horsepower centrifugal pump, then what happens is that, as they get deeper, the amount of water the pump will blow through the bit and push up the borehole decreases. It reaches a point where it won’t bring gravel, sand, clay or anything up from the bottom of the excavation. That was a problem, because they needed to go deeper.
Another problem they had was they were using steel to drill with, and the steel was heavy. At some point, it became too heavy for people to lift and use as a percussion drill. I wanted to alleviate that problem. I began working on a model in my mind of how that could occur, and the obvious solution for a driller was an airlift reverse-flow drill, because the deeper you go with an airlift, the better it is for the circulation. If you’re using an airlift reverse-flow, as you get deeper the velocity actually increases of the material coming up the center of the drill stem. That’s what my design parameters were. I wanted to use an airlift reverse-flow drill rig made out of plastic. That’s what I ended up getting my first patent on, this tooling.
Q. Can you give a brief explanation of airlift reverse-flow, in layman’s terms?
A. To make it simple, the way an airlift reverse-flow works is you have a borehole and in that borehole, generally, there’s a starter hole. The way most of the drill rigs work now with airlift reverse-flow, they dig a 30- or 40-foot starter hole, then they insert the drill stem in with a bit and they inject air inside of the drill stem. It’s all submerged within the starter hole. The air mixes with the water inside the drill stem, and that makes the air and water mixture inside the drill stem weigh less than the water on the outside of the drill stem. The tendency is for the water on the outside of the drill stem within the annulus of the borehole, the tendency is for that material to move into the interior of the drill stem where it also mixes with air. Once it mixes with air, it sets up a circulation. In the normal airlift reverse-flow drill rig, the material then comes up the drill stem and goes through a swivel into a discharge hose and then into the mud pit. That’s the way it normally works.
They generally use up to 300-cubic-feet a minute of air, which I was trying to get away from. I didn’t want to have that requirement for air. What I did is I calculated the amount of air that would be required to go up. My first calculations were with 2-inch drill stem. The amount of air it would require to go up a 2-inch drill stem, to get a flow rate up the middle, was at least 150 feet per minute, which is sufficient slip velocity to bring gravel up from the bottom of the hole. I wanted to be able to drill small gravel with that tool. I worked on the calculations for that, and discovered that what I needed to do was to move the discharge ports as the drill got deeper in the borehole. What I did was to calculate the slip velocity, say, for a 3-foot-deep hole and a 75-percent submersion ratio. I could get a slip velocity of 150 feet per minute. If I take it down to that depth, I go to 4 feet and I use my formula again, and multiply it again. Then I get the location of the second, third, fourth and fifth if it progresses upward. It turns out that it’s not ideal with the mathematical progression, but if you use a mathematical progression and you locate your discharge ports, then you always have a slip velocity above 150, and that’s what the goal is. So I got the patent for that.
So, anyway, what I ended up getting a patent on, is a method of reverse-flow drilling where the ports are located by the formula that I use. With a normal reverse-flow airlift rig, you have a top swivel. What the patent allowed me to do is, I was able to eliminate the swivel and then to avoid a swivel for the air hose. I attached the air hose to the side of the drill and I just turned. I located the teeth on the bit at 90-degree angles, and then I designed the bit to turn 180 degrees and then return, so it’s just turning back and forth. That eliminated the need for a swivel on the air hose. What I ended up with was a drill that could be used by poor people that was really inexpensive — and it would bring up gravel from the bottom of the borehole and keep the slip velocity high. It turned out to be a pretty good invention.
After I did that, I realized that I could use the same method to drill with a hydraulic top drive drill. What I’ve done now is built a hydraulic top drive drill. In that hydraulic top drive drill, I’ve eliminated the top swivel, the discharge hose and the air swivel. The way I did that is I took a top drive rig with a mast — a single I-beam mast — and I enclosed the top drive on all sides. I put four walls around it, and the walls open. They’re like a door — three doors on a rigid frame. Those doors enclose the discharge that comes out of the ports. I took the same process that I used with the hand drill and I transferred it into something that I think will be valuable for the drilling industry as a whole. I think what we are going to see in the future, is a drill rig. I have a manufacturer, I think. I don’t want to go into that yet because I don’t have a contract with him. But I think I have a manufacturer to build those for me. What it will do is, it will allow a drilling contractor, a well driller, to have a drill rig that doesn’t require the discharge hose and swivel, and the air swivel.
The important thing is that, with a reverse-flow airlift, you eliminate the pump that would normally be on a drill rig, that would pump direct circulation down the center of the drill stem. … The fluid that causes the circulation, that frequently contains sand, gravel or whatever doesn’t fall out in the mud pit or doesn’t get filtered out, deteriorates the pump. But there’s no water pump. The water in the borehole is circulated by air, so it’s never contaminated. And it doesn’t take a whole lot of air on the smaller rig. For example, on the 2-inch test drill that I built, I only had 4-cubic-feet per minute of air. With a 4-inch drill stem, I’m using somewhere between 13- and 18-cubic-feet per minute of air, depending on the density of the material I’m drilling through. So it takes considerably less air than the standard airlift reverse-flow that usually carries a 300-cubic-foot per minute air compressor.
I’m able to do that because I keep my submersion ratio really high. You may have a 50 percent or less submersion ratio in a regular drill. With mine, I keep the submersion ratio between 75 and 100 percent. Sometimes my discharge is actually below the level of the water in the mud pit. It’s a different way of drilling. It’s considerably less expensive. The drill rig is going to be cheaper. It won’t require mud pumps. It’s just, you know, a different way of doing things.
Q. Well those all sound like positive advances for the industry.
A. I think it will be. I think it’ll take it a while. People have to chew on something for a while before they’ll swallow it. … It’s been about four five months since I’ve had the commercial model, the one I’m going to sell. So it hasn’t been completely tested. I’ve drilled with it on about three occasions. One of them, I was in rock in El Paso and I drilled with an 8-inch diameter PVC drill stem through gravel down about 60 feet into the gravel, and I brought up a stone up the middle of the drill stem that was 9.5-inches-by-4.5 inches. If you can imagine bringing that up through a drill stem and depositing it in a mud pit, you can imagine how excited I was about that successful test. I drilled that with a 7-horsepower motor, so it is just unbelievable. My eyes bugged out, as did the person I was drilling with.
It’s a pretty good system and, you know, it doesn’t have to drill with PVC. I can drill with steel. There’s no reason to just be limited to PVC. If you drill with PVC, I’ve never broken it, even though I had hydraulic pump drives turning the drill stem. I didn’t break it. The only problem I can see with PVC is that it’s going to wear out faster than steel, but it’s a whole lot cheaper.
Q. Is there anything else that you think our readers should know?
A. There are a lot of well drillers who do charity work, and you can just tell them that I license that for free. If they wanted to use it in, Africa, South America, Mexico or even in the United States, and they’re drilling charity wells it’s absolutely free to use the patent. All they have to do is just let me know, and I’ll write them a license. It’s no big deal. It was originally designed for charity work. That’s the whole idea.