Around the world, well drillers routinely cut miles-deep holes through various rock formations. Many of those well bores are steered through complex hole geometries, often while the drill bit is tens of thousands of feet deep. The technology that aids this process uses a combination of Measurement While Drilling (MWD) and Rotary Steerable Systems (RSS) mounted immediately behind the drill bit to take real-time measurements of borehole position and control the trajectory. This measurement data is transmitted up the hole, enabling well operators to make intelligent decisions on where to steer the wellbore.
Aside from the obvious difficulties faced when cutting rock with a flexible tool longer than the Indianapolis Motor Speedway, the pressurized fluid used to cool the drill head and flush away cuttings is abrasive, and zooms past faster than a commuter late for work. This can wreak havoc on the down-hole systems, as well as on many other types of drilling equipment, destroying even super tough Inconel and 17-4 stainless steel.
“You’ve got this sandy, silty liquid going by at sixty feet per second. It erodes parts pretty quickly,” said Paul Seaton, vice president of marketing at APS Technology, Inc., a global designer and contract manufacturer of drilling optimization products headquartered in Wallingford, Connecticut, U.S.A. “It’s amazing to see how fast these expensive, precision-machined steel components are eroded by the flow of the drilling fluid.”
This is just one of the many challenges faced by energy producers today. APS aims to help well operators with a variety of intelligent tools, including steerable drill motors, vibration dampers, modeling and analysis tools, and logging sensors, in addition to its MWD systems. Seaton has been with the company since 2005 and says he and the rest of the APS team are focused on ways to continuously improve products. “Better flow paths, reducing pressure drops, eliminating erosion and turbulence—these are all a big deal for us.”
Previously, many of the continuous improvement efforts at APS were accomplished using a variety of additive-manufacturing (AM) methods such as selective laser sintering (SLS) and fused deposition modeling (FDM). These processes produce accurate models of most any design imaginable, and do so in Nylon, ABS, and other engineering grade polymers. There’s only one problem: these materials don’t survive very long in the harsh environment in which APS products are used.
“We’ve had lots of plastic parts made for us,” said Seaton. “And while it’s nice to get your hands on them, and see how they fit together, they’re of little value for testing our equipment. They just don’t last.
“However, now we’ve developed the ability to make those components in stainless steel, Inconel, and other metals, which is a huge advantage to us, because we can 3D print actual parts and use them under real-world conditions.”
Seaton is talking about APS’s integration of Direct Metal Laser Sintering (DMLS) technology from EOS. Senior mechanical engineer Chris Funke was APS’s new team member when the EOSINT M 280 system arrived, and was part of the team tasked with putting the AM technology to work.
One of the early tests done with the additive machine is a five-stage turbine used to power a steerable drilling head and its onboard MWD system. Each turbine contains several parts printed or “grown” using DMLS. The EOSINT M 280 uses a 200 to 400-watt Yb-fibre laser and precision scanning optics to trace tissue-thin slices of a CAD model onto a bed of fine metal powder. As the laser passes, each individual metal particle melts and becomes fused to its neighbors, “growing” the part. Once each slice has been scanned and melted, a fresh layer of metal powder is spread over the workpiece and the process is repeated, layer-by-layer, until complete.
Each turbine contains “some complicated end housings” and five sets of stators and rotors, all of which are built on the additive machine. Funke said these components are definitely seeing real world drilling action, including service in the company’s own test well, currently 3,000 feet deep.
“With many of our tools, we have significant space constraints. Everything has to fit inside a drill collar, which by the time you get several thousand feet deep becomes quite small, oftentimes leaving us with a space just a couple inches across to run seals, hydraulic lines, wiring and all the electronics needed to operate the MWD system,” he said.
The “impossible” made possible
Because DMLS enables designers to make complex geometries that were previously un-manufacturable, design challenges become far more manageable. Honeycomb lattice structures, for example, and thin but strong webbing can be created, producing parts that are far more space efficient than traditionally machined counterparts, maximizing available real estate.
Another advantage of DMLS is the ability to create “organic” shapes, such as gently sloped surfaces and curved holes. “We used to drill these long, angled holes, maybe 3/16 inch diameter by 10 inches or so deep, and get them to intersect similar holes drilled from the other end,” Funke said. “Deburring features like that is difficult, and you run the risk of sharp internal edges that might chafe wires or cause inefficient hydraulic fluid flow. Now, with the EOSINT M 280, we just print a smooth, curved hole, in whatever profile is needed for the application. It solves a lot of problems for us.”
DMLS also allows APS to “compress” the total length of its drill assembly, bringing the MWD components closer to the drilling head. This improves well drilling accuracy and reduces product cost. “Because we have greater design freedom, we can potentially shorten the entire drill stream, minimizing the delay between what’s just been drilled and the actual measurement,” said Funke. “That’s the end goal of any MWD system.”
Steering towards the future
Paul Seaton agreed. “If you look at some of our devices, they’re very angular because that’s been the easiest—and often the only—way to machine them. DMLS opens the possibility of building parts with streamlined, natural shapes. This provides an optimal flow path for the drilling fluids and helps minimize the erosion caused by sharp turns. That’s not something we’ve done yet, but it’s certainly a potential for some of our high erosion areas. The possibilities are really quite fascinating.”
So Funke and his fellow engineers are busy working on additional component redesigns, including one that “looks like a piece of Swiss cheese” and has reduced the part count in a drilling assembly from four separate components to just one. DMLS is also providing cost savings in the company’s extensive machine shop, where jigs and fixtures that once took days or even weeks to machine can now be printed, unattended, overnight.
Aside from the advantages APS has seen in part-count reduction and novel component shapes, designers are finding that product development cycles are substantially shorter. “Many of our components have historically been made of cast materials with very long lead times,” Funke said. “It sometimes took months to get the prototype parts needed for a complete system evaluation. Now we can design several variations of whatever is needed, print a batch of parts, and complete a test cycle in just a few weeks.”
Furthermore, there’s no need for APS to invest in molds and other tooling that might only be used once. All that’s needed is a CAD model and the metal powder to build them.
The use of DMLS may be opening other doors for APS. Because the AM process can produce parts that are far closer to their intended geometry than previously possible, downstream machining operations are often reduced, and in some cases eliminated. “We might give the shop a DMLS part that once took 18 hours to traditionally produce from bar stock,” Funke pointed out. “That part would have taken 22-26 hours to print, but it could have features that could not have been traditionally manufactured, such as organic holes.
“Now to finish that part would only take 3 to 4 hours to machine sealing surfaces and tight tolerance features. So by using DMLS we’ve freed up the machine shop by 14 to 15 hours to run other product. DMLS is changing our entire manufacturing flow, potentially giving us greater capacity to work on other projects, or even bid on outside work.”
The opportunities are endless, Seaton pointed out. “Traditional manufacturing methods have gotten us this far, but the improved efficiencies of parts created with DMLS are game changers,” he said. “It creates a domino effect, where longer product lifespans lead to less disruption for equipment maintenance, greater drilling time, and lower costs. Ultimately, this makes for a happier customer and additional sales orders.