Cost of Getting into Rock Drilling

Thinking of taking on a job that requires drilling rock? Or, do you need a solution for a job that's unexpectedly hit rock? If so, you'll specifically need hard rock directional drilling solutions &#; but finding the right HDD rock bit for your job is about more than just buying the right bit. Rock drilling requires big-picture thinking about the full scope of needs that will enable you to tear through these challenging ground conditions; that includes having a realistic idea of what you'll need to spend on equipment. Here's what you need to know to assess true rock drilling cost.

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A basic HDD set-up just won&#;t cut it

Trying to use a standard duckbill on the end of your drill string while upping the power of your rig will only result in frustration &#; and possibly broken HDD equipment. The only way to get through rock successfully is to invest in buying or renting hard rock directional drilling equipment.

Mud Motor (+ Drill Fluid)

A mud motor tackles rock drilling by chipping away at the rocks' surface while a two-degree bend in its shaft enables steering. A mud motor is specialty equipment &#; and its price reflects that. This type of high-impact grinding requires significantly more drill fluid to power the mud motor and slurry out cuttings. For comparison, conventional drilling (using a duckbill blade) may consume about 5-15 gallons per minute &#; but even the smallest mud motor will require at least 40 gallons per minute. Together, the cost can add up:

• Mud Motor (Rent): $1,000-$3,000 per week

• Mud Motor (Buy): $14,000-$65,000

• Drill Fluid: (See end of article)

Rock Drilling Accessories Matter

When using a mud motor, you'll also need a few critical pieces of additional hard rock directional drilling equipment before you even displace the first foot of earth.

High-flow housing

Because of all the drill fluid required to move through your mud motor, you'll need a specialized high-flow transmitter housing. A high-flow housing provides better protection for your transmitter and other electronics in your drill string but, more importantly, it allows a larger volume of liquid to flow through without restriction.

• Cost to Buy: $3,000-$,

Drill fluid reclaimer

Since your rock drilling operation will require so much drill fluid, it doesn't make economic sense to use the fluid just once. A drill fluid reclaimer siphons off the cuttings, leaving you with clean drill fluid to reuse.

• Cost to Buy: $40,000-$300,000+

Tri-cone or PDC bit

Tricone bits or PDC bits are specialty HDD tooling solutions that are built to stand up to ultra-hard surfaces. Without a bit like this, you'll spend hours drilling rock (or ineffectively grinding away at it) with little progress to show for it. The good news is that Tricone and PDC bits will get the job done efficiently. The bad news is that they're a bigger investment than a standard duckbill.

• Cost to Buy (Used): $1,500-$4,000

• Cost to Buy (New): $4,000-$7,000

Hole-opener

So far, we've only covered the rock drilling equipment necessary for your pilot shot. Anything bigger than a 4"-6" hole will require a hole opener designed to back ream through solid rock. The cost of a hole opener relates to its size &#; a good ballpark is about $1,000 per inch. So, drilling an 8" final hole using a hole opener would set you back about $8,000.

• Cost to Buy: ~$1,000 per inch

More bentonite & additives

Drill fluid volume aside, you'll need more additives when you're drilling rock. Drill fluid must have a higher viscosity to hold the weight of the cuttings and move them out of the hole. If not, rock chips build up at the bottom of the hole and can cause you to get stuck and lose your mud motor down hole. Upping your additives protects your equipment. See the chart below for a comparison of necessary drill fluid vs. a standard HDD job.

Slower production and other hidden costs

In addition to the investment in hard rock directional drilling equipment and accessories, rock drilling is, by nature, slower going than dirt drilling: it's a double whammy. Plus, you'll incur added personnel costs since the jobs take longer. Here's a quick run-down of the areas where you can expect greater investment than you might be used to:

• Additional 1-2 people to mix fluid and keep the reclaimer clean

• More time spent sucking and dumping cuttings into pits

• Renting or buying a bigger vacuum to manage the extra flow

• More operating hours on your equipment

• Additional equipment maintenance

• Increased labor costs (due to a longer job)

• Consultant fees to help inexperienced crew plan the bore path and use equipment properly

Comparison: Dirt vs. Rock Drilling Jobs

Curious about how rock drilling stacks up against a standard job? Here's a side-by-side comparison of rate of production, tooling required and fluid costs while drilling a pilot shot in dirt vs. rock. Check out the specs for this sample pilot bore:

• 100k drill rig (JT10, D100x140, etc.)

• 6-7" bit

• 600' shot

• Standard walk-over locator

• Reclaimer cost not factored

We've made some assumptions (as noted), but this will give you a good comparison of rock drilling cost compared to the cost of drilling in dirt.

*Fluid required is in gallons

*Bentonite required is in pounds

Go into rock drilling jobs with your eyes open. Though job budgets are bigger, so is overall associated rock drilling cost. Slower production and greater investment in HDD tooling and accessories might make the job less profitable than you originally anticipated. Even on non-rock jobs, it's always a good idea to insert a clause into your bid or contract that enables you to rescope the project if you run into rock.

For more rock drilling toolinformation, please contact us. We will provide professional answers.

Head Into Your Next Rock Drilling Job Prepared with Melfred Borzall

As with any HDD job, unknowns will arise. But, if you're geared up right and know what you're getting into, you'll be able to successfully complete that rock drilling project on time and within budget.

Want to know more about the right tooling for drilling rock &#; or any ground? Our HDD experts are ready to help.

There comes a time in every driller&#;s life when a new rig has to be bought. It&#;s time to start looking when the cost to keep the old rig running negatively affects revenue, you don&#;t have enough rigs or the right kind to meet customer demand, your business is expanding into new drilling markets, or you&#;re building a brand new business altogether. Finding the right rig to drill with is easier said than done, so

reached out to industry experts for advice on rig buying in our most popular markets. They touched on when to buy new, used or lease, and what qualities to look for in a drilling rig.

National Driller

Article Index:

Water Wells

When you&#;re drilling wells for water, location is everything. Generally speaking, &#;East and west of the Mississippi the demands on a rig change drastically,&#; says Brock Yordy, product manager and drill trainer for GEFCO, an Astec Industries Company.

In Michigan, for example, he says the average water well is quite shallow, around 120 feet down, whereas a lot of the western United States consists of rock and it isn&#;t uncommon to have to drill to depths of more than 6,000 feet to reach water. Taking that into consideration, looking into a used water well rig for work in the Midwest is totally sensible. Head west and the stress on a rig increases, meaning buying new could be a worthwhile investment.

Although going brand new can cost more than $1 million easily, the perks can be especially useful for rigs that deal with tough geologies and experience high rates of wear and tear. &#;You have a warranty on it and so your cost of ownership other than the monthly payment is pretty much capped. And even once the warranty expires, your cost of maintenance for the first five years on a new machine is relatively low,&#; says Tom Moffitt, business development manager of Atlas Copco Drilling Solutions, Deep Hole in the U.S.

As for leasing, Moffitt says a lot of people in the water well market confuse it with renting. He hears from drillers wanting to &#;lease&#; a drilling rig for just six months, making it hard to find a financial institution to help finance. Another point he makes is that truck mounted drills have to be licensed and titled, and short term deals complicate that process.

Geology matters in terms of features to focus on as well. Yordy says safety has been a major theme for the past couple of years, so rigs without catheads are in. The deeper you have to drill, the more pieces of drill rod necessary and the more important this innovative quality becomes in shrinking jobsite liability.

Once the local geology has been determined, Moffitt says relevant attributes to look for are pretty straightforward. If drilling 500 to 1,000 feet down in rocky places, he suggests looking for a rig with an air compressor. In coastal areas, where soils are sandy and holes are shallow, a mud rig or hollow stem machine is ideal. As for combination areas or overburden and rock, combination machines are a smart option. Drilling rigs like these come with an air compressor and mud on board, or they have the capabilities off board to add them.

Geothermal

Generally, water well and geothermal drilling tend to intersect quite a bit, but differences do exist, and reliability is especially important in this market. &#;You need a high producing machine that&#;s not going to be breaking down and having down time because if you&#;re doing a big commercial geothermal job or you&#;re doing wells or boreholes for a school or hospital or something like that, you have kind of a timeline that you&#;re working on for the project,&#; Moffitt says.

For this reason, Yordy says brand new rigs are ideal and leasing is a great option for drillers who suddenly win a contract for a large scale project with an established timeline. Leasing contracts can be formed to offer all of the benefits that buying new does, including warranties, services and maintenance. If you don&#;t already have a set of brand new geothermal drilling rigs to drill a bunch of boreholes and you aren&#;t sure if or when the next large scale opportunity will come around, leasing offers peace of mind and means you don&#;t have to store and pay off the impractical equipment once the project&#;s over.

As for everyday residential jobs, Yordy says geothermal is a good market for buying used. After all, the borehole depth, around 500 to 600 feet, is pretty straightforward and consistent. &#;A rig that used to be 100 percent efficient, if it&#;s 65 percent efficient and it&#;s a cable drive and it still can drill 300 feet pretty easily or 400 feet pretty easily, they&#;ll use it,&#; he says.

In thinking about rig features, something geothermal makes a lot more of than water wells is mud. Yordy says a lot of drillers in this market go with a rig that weighs less than 50,000 pounds and has an all-wheel drive function so they can maneuver jobsites without getting stuck. Other qualities to avoid getting stuck in the mud include six-by-six trucks &#; larger than typical six-by-four water well trucks &#; and trucks with short wheel bases.

Foundations

Similar to commercial geothermal drilling, the foundations market faces high pressure to be unwaveringly efficient. The choice between buying used, new or leasing is really specific to each end user&#;s needs, according to Ed Radford, director of commercial operations at Watson Drill Rigs. He says the risk in buying used is that determining how much life is left in the machine can be more challenging.

Risking reliability might not be the best route, as speed is everything to the drillers and clients in this market. &#;In the foundations industry, you&#;re in the critical path from the start of the project,&#; Radford says. &#;So if you are falling behind on production you affect the entire project and there&#;s potentially, in some cases, liquidated damages associated with that.&#;

With schedule and time being of the utmost importance, Radford recommends purchasing very productive machines, several machines or several very productive machines. The speed of the rig, the reliability of the rig, and the availability of parts and service for the rig are important features to consider.

Another aspect to keep in mind when tracking down rig qualities is space. Yordy, who&#;s worked with a company drilling foundation holes in the locker room of a college football stadium, says finding a drill that can fit into and function in the space in need of services is crucial. Carefully considering if it needs to be truck or track mounted to travel through a given site, and sizing the rods based on overhead clearance are key.

Geotechnical

The geotechnical drilling market is just as focused on speed as foundations. Yordy says he&#;s never seen a leased geotechnical rig and he doesn&#;t suggest buying used. &#;They&#;re usually owned by construction companies that are always buying capital equipment anyway, and so they want to go with what&#;s easy to maintain and what&#;s going to work and when something&#;s depreciated out they get the next piece of equipment.&#;

Maneuverability matters for geotechnical drillers. If you&#;re planning a lot of work along the highway, checking for salt intrusion for example, truck mounted rigs are the most sensible. For work around, say, a gas station, Yordy recommends a remote track mounted system. As for drilling methods, auger and sonic are two of the most effective ways to go if sampling.

Mining

Within the mining sector contractors traditionally buy new or lease to own rigs if they are intended for large projects, according to Todd Courtney, business line manager for blasthole drills at Atlas Copco USA. For relatively small jobs, like a road cut, or if they don&#;t own the right equipment, he says it&#;s common and practical to rent the drill and return it after completion.

A new rig is particularly ideal for mining because jobsites are often rife with hazards and avoiding them is very important. Older rigs don&#;t promise to meet the latest safety inspection standards, so keeping equipment updated is ideal or you risk not being able to even get the drill onsite.

Keeping with safety, key qualities to look for in a drill include cages around the rods that spin in the top head and hands free rod loading functions.

The scope of work you plan to do largely determines what machine is right for you. Unlike water wells and geothermal, which can more or less be tapped into anywhere, Yordy points out that Mother Nature has placed precious metals in very interesting places. If you&#;re going to be drilling 6,000 feet, he suggests automated rod handling with every bell and whistle that&#;s possible. If you&#;re planning to drill into the mine from the side of a mountain then it has to be very portable since getting it there could require flying it in with a helicopter. In this case, he says to just look for the basics that would make the rod spin and provide good rotational torque for getting to the required depth.

For blasthole mining, Courtney suggests finding a drill that will allow you to drill projects with single path. &#;If you can avoid changing steel in production drilling, there&#;s a lot of benefit,&#; he says. Because there is such a wide variety of mines, he says it&#;s important to determine what size holes you plan to drill and what kind of material you&#;ll be drilling into when drill hunting. The harder the rock, the more air pressure necessary.

Exploration

Gregory Guillot, global product manager for capital equipment at Boart Longyear, says the purchasing method for a drilling rig in the exploration market all depends on the contractor. Buying brand new is smart for a financially strong drilling company with visibility over the long run. For drillers with less of a sense of where they&#;ll be, say, a year down the road, Guillot suggests buying used to avoid the risk associated with the bigger investment of brand new. It&#;s most economical to rent, he says, if a specific job comes up at a specific location that&#;s well defined in time.

Exploration drilling, according to Yordy, seems to have more stringent expectations regarding minimal invasiveness than production sites. &#;It seems like mineral exploration is not as favorably viewed upon as when we say &#;Hey, we&#;re going to drill for water and when we leave you&#;re going to have a new source of life,&#; or when we drill for geothermal we leave and we go, &#;We&#;ve made it so you don&#;t have to use as much fossil fuel and you&#;re going to save money.&#;&#;&#;

That said, surface exploration very much revolves around keeping everyone around the jobsite happy. That means the drilling rig needs to be as clean and pristine as possible. Drilling can, of course, be quite loud, so noise mitigation is important. A quieter rig, even if it needs to be customized, is a great idea.

Another quality to look for in an exploration rig is a sliding angle mast if you&#;re going to be drilling angle holes, Moffitt says. He says he knows of contractors that get away with using drilling rigs purposed for water wells for exploration, but without a sliding angle mast, they&#;re limited to vertical holes.

Primary Percentage Rule

No matter the market, finding the right drilling rig and selecting the best purchase option are key steps in building a strong business. It all comes down to what&#;s most practical for the driller&#;s wallet, the kind of drilling being done and the geology of jobsites.

A lot of drillers, understandably, have an unrealistic image in their heads of a multipurpose drilling rig that can transcend all drilling markets, soils and depths, Yordy says. &#;What these guys need to think about is, do I invest $750,000 that&#;s going to do most of my work, or do I try to buy a $1 million plus piece of equipment in hopes of a couple extra jobs?&#;

Knowing the scope of one&#;s work and finding a rig that meets it is the safest, smartest way to go. Yordy advises drillers to go by a simple rule to stay practical and prosperous.

&#;What they need to do is they need to think about 75 or 80 percent of what their primary business is and look for a rig that&#;s going to do that.&#;

Valerie King is associate editor of National Driller.

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