Water Well Journal Q&A

Published On: July 17, 2023By Categories: Drilling, Features

The product manager of casing advancement and DTH at Mitsubishi Materials USA helps design new systems to meet the customers’ needs.

By Mike Price

Mitsubishi Materials USA MD DTH hammer that either of the casing advancement devices (ring bit or underreamer) attach to. Photo courtesy Justin Lewis, Mitsubishi Materials USA.

With water well contractors looking for better methods to drill through overburden dating back 30-plus years, down-the-hole (DTH) casing advancement systems emerged as a viable option.

The systems continue to improve, and as the name suggests, a DTH casing advancement system uses a hammer to drill through overburden while advancing casing into the hole at the same time.

“There is much more to a casing advancement system than just the bit, and everything has to be designed to work together,” says Justin Lewis, product manager of casing advancement and DTH at Mitsubishi Materials USA in Mooresville, North Carolina.

Lewis, who joined Mitsubishi Materials USA in September 2021 after working at Bill Johnson Equipment Co. in Phoenix, Arizona, for nearly 20 years, designs new systems to meet the customers’ needs and handles requests from drillers and distributors. His territory spans multiple time zones, which means he generally works until 8 p.m. to ensure everyone is taken care of. He also frequently travels to see customers.

“When I’m on the road, I never know what my day is going to look like,” says the 40-year-old. “I could be on a rig, in someone’s office, or just driving to the next state on the list.

“The water well industry is what I really enjoy focusing on, but we also sell into the foundation and environmental markets. With the growth we have seen across the country, Mitsubishi’s casing advancement market is doing well in all areas.”

Lewis worked with and learned from many different people throughout the industry while at Bill Johnson Equipment. Most notably, Lewis’ boss and mentor, Louis Sanders, taught him early on about the intricacies involved in building a casing advancement system.

“My favorite part of this industry is helping people and building relationships,” Lewis shares. “My only goal throughout my entire career has been to be the first phone call people make if they need something or even if they just want to vent about their day.

Justin Lewis

“When I do training or presentations on casing advancement systems, my favorite part is interacting with the audience and answering questions.”

Lewis was gracious enough to answer Water Well Journal’s questions about casing advancement systems and share his thoughts on the future of them. In fact, Lewis is helping develop new pilot bit and ring bit designs with a driller that will be featured in September’s issue of WWJ.

Water Well Journal: Let’s start with the different types of casing advancement systems on the market and which perform the best in certain geological formations?
Justin Lewis: Oh boy, there are so many different types from many different manufacturers and the answer to this question could be an article on its own covering much more than just the water well industry. For this conversation, I will highlight the two most common in our water well industry.

Ring bit systems have two main pieces: a pilot bit that is attached to the hammer and a ring bit assembly that is welded to the bottom of the casing. The pilot bit gets locked into the ring bit assembly to drill the hole and advance casing. Ring bit systems are generally used to drill in ground containing boulders and harder rock formations.

Underreamers. There are so many different types of underreamers on the market these days and it seems that everyone makes one that is different from the others. Unlike ring bit systems where the drilling gauge is on the ring bit assembly, underreamers will typically have some type of retractable bit wing or bit head that will extend to start the drilling process. Underreamers are generally used in softer formations containing sands and gravels. They can also be used in harder formations, but the leading edge of the wings/heads will wear out faster and can cause increased rotational torque.

Both the ring bit and underreamers are engaged when you turn to the right. To retract the underreamer wings or unlock from the ring bit, you would turn a half rotation to the left.

WWJ: How long have casing advancement systems been used in the water well industry and how have they grown in use over the years?
Lewis: In the mid-20th century, advancements in drilling technologies led to the development of the first DTH [downthe- hole] casing advancement systems. In the past 10 years, use of casing systems have increased significantly and almost every DTH tooling manufacturer has introduced some type of casing system for use in almost any type of ground formation.

(Left) The face of a Mitsubishi Materials USA SMB-G underreamer. The wings are extended here. (Right) The SMB-G underreamer in use.

WWJ: What are the top advantages of using casing advancement systems?
Lewis: Increased safety. By advancing the casing while drilling, you reduce the risk of washouts that can lead to cave-ins and rigs falling over.

Less equipment on site. The use of a casing system can reduce the need to mud up in certain cases. With no mud being used, there is no need for big pits, tanks, mixers, etc.

Improved efficiency. Using a DTH casing system can be faster drilling through hard formations than tricone.

Versatility. Casing systems can be used in a variety of ground conditions.

WWJ: How do you advise customers on using good technique methods for attaching shoe-based systems to casing for increasing depth prior to shoe failure?
Lewis: For underreamer drive shoes:

  1. Bevel the end of the casing to an angle of about 30 degrees. Be sure that all surfaces to be welded are clean and free from any dirt or contamination, including moisture. Pre-heat the end of the drive shoe and casing to 210°F.
  2. Insert the drive shoe inside the casing. Be sure the drive shoe is centered.
  3. Tack-weld the casing to centralize. Tack welds should be done across from one another like tightening lug nuts on a truck.
  4. Welding on the circumference. Normally three passes are recommended. Mitsubishi recommends welding rod [JIS E4316 or E4916] [AWS E7016 or E7018] for our drive shoes.
  5. After welding, use a grinder to smooth the weld. This will help the casing not to drag dirt from the formation into the borehole on the outside of the casing, causing drag during installation.
  6. I also recommend torching plug weld holes in the casing to strengthen the weld to the drive shoe.

Mitsubishi Materials USA UMB ring bit system. The gray ring bit is attached to the gold pilot bit. Photos courtesy Lewis.

The procedure for ring bit assemblies is the same except you need to make sure the ring bit is pushed against the casing before welding. This will allow the ring bit to freely rotate after welding is done. Mitsubishi Big Bore ring bit assemblies also have the advantage of having plug weld holes already machined into them.

WWJ: What are the air volume and pressure requirements and overall best suggested practices for using casing advancement systems?
Lewis: Most casing systems need to run at a lower pressure than standard DTH bits, around 150 to 200 pounds per square inch [PSI] depending on formation and an uphole velocity of 3000 to 7000 FPM [feet per minute] in order to flush cuttings. With higher pressures you run the risk of breaking the welds at the drive shoe or ring bit assembly as well as damaging the device itself. When using a casing system, it is also recommended to flush the hole regularly in order to keep the inside of the casing from building up cuttings.

Rotation speeds vary from 10 RPM to 80 RPM depending on device size and formation.

Weight on bit also varies depending on device size and formation, but I do recommend running a heavy stabilizer on top of the hammer anytime a hammer is used, not just when using a casing system.

WWJ: What are the casing requirements (wall thickness, etc.) for using casing advancement systems?
Lewis: The most common sizes sold in the water well market are going to be for 6⅝ inches, 8⅝ inches, and 10¾ inches OD [outside diameter] casing having a wall thickness of 0.250 inches. With that said, Mitsubishi manufactures and stocks casing systems for casing as small as 3½ inches OD all the way up to 60-inch OD and for any wall thickness that is available on the market. If we don’t have it in stock, we will design a system to work with whatever casing you have.

WWJ: Regarding safely handling casing systems at the surface, how do you advise customers on handling these systems and casings above their head to get them into the tower?
Lewis: The drill rod needs to be loaded into the casing before being lifted into the mast, and since each operation has different equipment available to them, I recommend doing that in the safest way possible. When the casing and rod are ready to be raised, a special sling should be used that has a hook allowing the drill rod to stick out of the top of the casing enough to make the connection at the tophead and to hold the casing while raising. There then needs to be a sling towards the top of the assembly that will choke on the OD of the casing to lift it off of the hook and to lower the casing down in order to weld.

WWJ: What are the maintenance requirements for casing advancement systems?
Lewis: Underreamer systems have moving parts like wings, heads, or lugs. These parts are held in by various means depending on their manufacturer and should be inspected after every hole for damage and wear.

The foot valve should be inspected after every hole and the buttons should be checked and sharpened when they start to wear. Drive shoulders on shoed systems should be checked to ensure adequate surface area to prevent from binding in the drive shoe. The drive shoulder surfaces can be built up and machined to be like new, greatly prolonging the life of the tool. Whichever type of retaining pin system is used on the device should also be inspected for damage and wear.

Since ring bit systems only have two parts, the pilot bit and ring bit assembly, they do not require as much maintenance. On the pilot bit, the foot valve should be inspected after every hole and the buttons should be checked and sharpened when they start to wear. The drive shoulder surfaces and locking tabs should also be monitored and repaired when worn. Ring bit assemblies mostly stay in the hole with the casing, so the important part with them is that welding procedures are correctly followed.

WWJ: What are the limitations of casing advancement systems in water well drilling?
Lewis: I learned a long time ago not to tell a driller what they can and cannot do with tools. The limitations on the tools are determined by the driller and how they operate the tool.

WWJ: You will present on casing advancement systems at Groundwater Week 2023. What do you hope to convey to attendees?
Lewis: I hope my presentation lays out the basics of casing advancement systems. There is a lot going on with these systems and it can be a bit overwhelming trying to figure it all out.

WWJ: Lastly, what does the future of casing advancement systems look like in the water well industry?
Lewis: The future looks good. Even with more and more drillers converting to DR [dual rotary] and some even going the route of sonic drilling, there will always be a need for casing advancement systems to drill into the formations that the other rigs can’t.

Also, with the advances in equipment technology and the need to drill deeper for water, everything is getting bigger. Mitsubishi has also been designing new and stronger underreamers and ring bit systems to keep up with the changing market. Our newly designed NMB-G wing bit system incorporates larger bit wing shanks, increasing their strength by as much as 50 percent. We are also developing a drill-through design for our UMB ring bit systems.

Checklist of General Questions to Consider When Deciding Which System to Run
Below are some of the general questions Lewis asks drillers when deciding which type of system to run. Based on the answers to these questions, either Lewis or the driller may have more questions until everyone agrees as to which type would be best.

  1. Have you used a casing system before?
    a. If so, which type and what did you like or dislike about it?
  2. Which types of formations are you encountering when you need a casing system: sands and gravels, boulder fields, rock shelves, etc.?
  3. How deep are you planning to drill with the system?
  4. Will the casing be removed after the system is used?
  5. Do you need to drill through the bottom of the casing?
    a. What size hole do you need to drill through the bottom?
  6. Which type of wells are you using the system on: water well, environmental, geotech, construction, etc.?
  7. Which type of rig do you have?
  8. What air package do you have?
  9. What is the casing OD and wall thickness you will use the system on?
  10. Which hammer shank are you running?
Groundwater Week 2023 Workshop on Casing Advancement
Lewis will present the workshop “Casing Advancement 101” at Groundwater Week 2023, December 5-7 in Las Vegas, Nevada. Click here to learn more.

Mike Price is the senior editor of Water Well Journal. In addition to his WWJ responsibilities, Price contributes to the Association’s scientific publications. He can be reached at mprice@ngwa.org, or at (800) 551-7379, ext. 1541.

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