Against All Odds

Sometimes jobs defy what the numbers say.

By LaTisha Shipman

I would like now to preface this column with this statement: We all knew what we were up against.

I met Freeman Schrock, owner and operator of Schrock Well Service LLC in Thomas, Oklahoma, standing at the back of a Versa-Drill V-155 in December 2023. I was showing him the rig, and while we were discussing how this investment could expand his drilling business, he mentioned to me some of the hurdles he had to overcome in drilling a particular formation in western Oklahoma.

The first 100 feet of drilling was pretty easy. But then they had to drill through 40 feet of sand that almost was a quicksand as it was difficult to keep the hole open and the rig upright while mud drilling. From 140 feet to 160 feet, they hit a harder gypsum referred to as gyprock by the locals. Then from 160 feet to 420 feet, they encountered a sandstone and shale formation.

He told me no one in their region had the proper equipment to drill in this difficult area. People had to call in companies from Texas, and naturally, Freeman wanted this work.

I introduced and explained the method of the casing advancement system (CAS) to him. I told him how the CAS would be able to keep that layer of sand open while simultaneously advancing the casing. Freeman was new to air drilling, but by acquiring this rig, DTH drilling was now a possibility for him.

Freeman bought the rig, and as we started to tool it out over the following months, I assumed he was drilling 6-inch to 8-inch holes. I didn’t ask, which I could call a rookie mistake, but I’m not necessarily a rookie! So, lesson learned. I soon found out that he needed to drill an 18-inch OD hole with the casing advancement system. I started to panic a little bit.

Here’s the job specs: 18-inch OD hole to set 16-inch OD casing that Freeman wanted to retrieve if at all possible. We would run a 12-inch hammer and the Spiral Flush casing advancement system, and drill through with a 14¼-inch bit to set 12-inch PVC casing. We would set surface casing to 140 feet, and then drill through to a total depth of 420 feet. The rig was set up for 4½-inch drill pipe.

I think that is sufficient information to explain why I was in panic mode.

Taking a Risk

I started frantically making phone calls with many questions running through my mind. Was the rig even capable of handling this tooling? We had 70k pullback, so technically yes, but the rig manufacturer let us know that this rig wasn’t necessarily built for this. To their knowledge this type of job had never been done with a Versa-Drill.

I spoke with a couple of hammer and casing advancement manufacturers, but the customer ultimately chose the Mincon Spiral Flush. We knew immediately we didn’t have enough air as the rig had a 900/350 air compressor. By my calculations for uphole velocity (183.4 × CFM/bit diameter squared minus rod diameter squared), I was still coming in at less than 1000 feet/minute, and all of the industry specifications call for a minimum of 3000 feet/minute.

There was just too much annular space to fill up between the ID of the casing at 15.75 inches and the drill pipe OD of 4.5 inches. We would lose velocity in that area and the cuttings would fall back down on top of the hammer.

I called Freeman with the bad news. The job was impossible, we didn’t have sufficient air to clear cuttings, and we could bury the hammer, I said. I have never seen such determination in any individual. Freeman doesn’t hear, “I don’t think this will work.” Regardless of the odds, he wanted to try it.

I believe the backbone of our industry is made up of individuals like Freeman. Namely, men who are willing to take the risk of trying something new, different, and something that has never been done before. Without men like this in our industry, we would never come up with new and innovative products. Having worked in manufacturing, I will say it is often the idea of a driller and handwritten drawings on the back of a napkin from lunch that helps a manufacturer improve their products.

Freeman had what he called a practice job coming up in a dry riverbed. We only needed to drill 90 feet with the Spiral Flush and get the casing set to keep the hole open below the sand-bearing formation, and then he would go back in with a tricone to total depth at 240 feet.

It was a good opportunity to put the hammer on and try it out, and for Freeman and his crew to familiarize themselves with hammer drilling. He had gotten another compressor to tie into the deck compressor to increase uphole velocity as much as possible, but we knew we were still short.

On an unseasonably hot June morning, we loaded up to head to the jobsite. Our group consisted of Freeman, his crew of three, my Drilling Equipment Resources rig mechanic Steve, Matt with Mincon, and me.

Hot red sand was blowing at what felt like about 50 miles per hour. I certainly didn’t need to use any exfoliant later that night! We were armed with plenty of drill foam to help evacuate cuttings, and we knew we needed all the help we could get.

It took a while to set up and to sling the hammer into the casing, but it was nothing out of the ordinary for someone’s first time setting up. I was impressed with the way Freeman made use of his oilfield experience and how that transferred to the way he operates as a water well driller.

It was music to my ears when that hammer fired up; there’s nothing quite like that sound. I began to see the cuttings coming out of the hose attached to the diverter shortly after that. I was excited to see the cuttings because my biggest fear throughout the process was not having sufficient air to evacuate any cuttings, thereby eventually burying his drill string.

The first 20 feet went great; we were getting good cuttings returned, although they were sandy, and in hammer drilling that can cause a concern of blowing out the formation and creating a void that tips the rig over.

What I like about the Spiral flush is that it’s designed to sweep the surface, which I think in part prevents blowing out that sand. The biggest problem we faced later that day and the next was that the deeper we went, the harder it became to evacuate cuttings. The returns were more or less surging for lack of a better word.

At one point the pressure buildup caused the diverter to pop off the top of the casing a bit, and we all got a good sand bath. There was not a place to weld the diverter to any part of the tophead or rig, so Freeman had a three-point chain strapped to the casing, which was a good call. That kept the string together.

Freeman successfully finished the well, and even went back later to retrieve the casing—a little bit unconventionally! Freeman discovered there was no water below the 55 feet where they hit the red bed. They drilled the 16-inch casing into the bed 15 feet, so they didn’t have to cut it, and then backfilled the hole to 80 feet, set 10-inch casing, and gravel packed 30 feet to start pulling the casing.

Water well drillers are some of the most innovative individuals I have ever met. I was truly shocked when he sent me photos of them pulling the casing out. In my more than 20 years of working with hammers and bits, I have to say I have never seen casing retrieved this way. Please take a look at the photos with this column.

Mincon had wisely advised to quote the job as if Freeman couldn’t retrieve the casing. He did, but we were all pleased that he was able to complete the job just as he had hoped. That well is now producing 120 gallons per minute! I think everyone was pleasantly surprised with the outcome.

The author recently watched a job where casing was retrieved unconventionally. Among steps, the contractor backfilled the hole to 80 feet, set 10-inch casing, and gravel packed 30 feet to start pulling the casing.

Still Crunching Numbers

My takeaway from this project is this: I can sit in my office and crunch numbers all day long. There were a lot of things to consider for this job, and I was particularly hung up on the uphole velocity calculations. Based on the numbers, this job should have never worked. We probably shouldn’t even have been able to get cuttings returned at 90 feet. But we did.

Numbers are just that—numbers. In the field, this job worked against all odds. It defied logic and everything that I’ve been taught. I believe this is in part to excellent workmanship from Mincon and Versa-Drill, where the equipment outperformed expectations. It is also in part to Freeman’s determination to make this work.

On the next job, I’ll still crunch the numbers, and just like I did with Freeman, I will still give advice based on the numbers. I always want to be realistic with my customers and let them know that “This might not work, and here’s the reason why.” Freeman was well-informed and we all knew what might go wrong. He was fully prepared to dig his hammer out if it got stuck, but I’m glad that wasn’t how this job ended.

I’m thankful for the field experience. I’ve never been on a job like this one, and I learned a lot from this gracious, tenacious driller who I now call my friend.

While Freeman’s practice job was successful, he has a game plan in place to move on to the next job which will be deeper, thus requiring more air and possibly a modification to the diverter. He is considering shrouding the drill pipe to increase the uphole velocity. This is still a work in progress.

LaTisha Shipman is the Texas branch manager for Drilling Equipment Resources. She has more than 20 years of experience in the drilling industry, with most of that time spent working in manufacturing with DTH hammers and bits. She can be reached at latisha@drillingequipmentresources.com.