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In The News
Source: Horizontal Technology, Inc.
Author: John English
Three Unique Projects Highlight Durability, Versatility & Value.>
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Source: Horizontal Technology, Inc.
Author: John English
"The hardest thing to explain is the glaringly evident which everybody has decided not to see."
Ayn Rand, The Fountainhead
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Source: Underground Construction
Author: John English
In just a few short decades the use of Horizontal Directional Drilling...
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Horizontal Technology News

New Viper RockReamer Resets HDD Standards

by John English
Horizontal Technologies Inc.

Horizontal Technology Inc.'s new Viper RockReamer is designed in part to alleviate the epidemic of split-bit reamers catastrophically losing cutters down-hole. The Viper provides added strength and the best possible down-hole cutter security in addition to longer hours, smoother rotation and better penetration rates. This amazing HDD tool is the compilation of decades of down-hole tool experience, engineering and HDD customer input. From 8 ¾-inch to 72-inch, the Viper is now on the shelf and ready to go, offering a variety of features to benefit drilling contractors.

Right after it was introduced, three, unique, out-of-the-box, projects highlighted the new Viper's durability, flexibility and direct economic value. There couldn't have been more challenging tests. The Viper offered solutions in these real life circumstances, providing bottom line economic benefits to the HDD contractors.

Project #1 - Durability:

Drilling 1,500 LF of parallel 32-inch and 36-inch lines in 30,000 PSI granite with high quartz content was the equivalent of taking final exams on the first day. Final hole sizes of 48 inches and 54 inches had to be completed in some of the world's toughest rock.

The 32-inch line was first and the 8 ¾-inch pilot hole times confirmed the hard formation reports with some joints taking up to 5 hours. Because the Viper is designed to allow greater weights with less torque, the decision was made to do passes of 24-inch, 36-inch and 48-inch passes - big bites out of a hard formation like this! The Viper is designed with the largest bearing capacity of any HDD tool ever used. This reduces torque, allowing the operator to increase weight which improves the penetration rate with less stress on the rig. The V8 with 24-inch TCI cutters were pulled towards the rig and the performance exceeded expectations. The reaming times matched the pilot hole even though almost five times the amount of formation was being removed. After about 57 reaming hours the Viper and the 24-inch cutters still looked great so the reaming continued.

The next pass used a five cutter, JV-20 Jumbo Viper dressed with 36-inch TCI cutters. Getting the large bite to shoulder up in such hard formation would take a few joints. Basically the tool was bouncing on the harder rock, just inching its way down while being pulled towards the rig. After the tool shouldered up many of the gage inserts were damaged. To avoid reaming an under gage hole the 36-inch was opened with a new set of TCI cutters. Although removing about 40% more formation than the 24-inch, the Viper's 36-inch penetration rates remained about the same. The performance through hard rock was impressive.

The next pass used the original 36-inch in tandem, just ahead of the JV-32 Jumbo Viper dressed with 48-inch TCI cutters. The idea was to stiffen the reaming assembly and centralize the 48-inch helping it transition into the rock until fully shouldered up. This worked much better as the tool was allowed to cut its way down, eventually shouldering up across the full 360 degrees. At that point the 36-inch Viper was removed and the 48- inch pass proceeded.

Although the amount of formation being removed was again substantially greater, the penetration rates weren't much slower. This was attributed to the Jumbo Viper five cutter design, the increased bearing capacity and the skills of the driller. The tool was being rotated at the right RPM to ensure maximum penetration rates with the matching pull weight. A good mud program kept as clean a hole as possible and the combination allowed the Viper to perform as designed.

With the experience from the first drill, the second finished even quicker. Was it possible to "one up" the first accomplishment by going to 54-inch in three passes? The 28-inch, 42-inch and 54-inch plan was ready before the second pilot hole was completed. The great thing about Viper RockReamers is the versatility – sizes can be changed simply by adjusting the body size and cutter size. This saves contractors money and avoids down time.

The Viper's first test couldn't have been better, an incredible success. The Viper cutters lasted longer than any cutter anyone had ever seen. Some runs were in the 150 hour range with the cutters appearing to have many hours left. The entire project was completed ahead of schedule and the contractor used less than a third of the hole openers expected.

Project #2 - Versatility:

The second project, consisting of 6 bores totaling almost 14,000 LF, demonstrated another aspect of the Viper's advantage to HDD contractors. The plan was to drill 12 ¼-inch pilot holes and then open to 26- inch, 36-inch, 46-inch, 58-inch and possibly 64-inch. The contractor estimated that reaming would take about 6,000 hours and more than 61 hole openers would be needed to bore through what was expected to be an extremely hard formation. Even the smallest split-bits were in the $50,000 range and the largest approached $150,000 for each tool. Millions would be spent just on hole openers alone.

Rigs and equipment were mobilized and the pilot holes began, encountering only hard clay and shale, none of the very hard formation projected. Wow – this was an extreme change from the conditions expected! What now? Every hole opener on the job site was TCI but the proper cutter style for these conditions was MT. Before the first pilot hole was even finished the TCI cutters were replaced with MT, at no cost to the contractor or downtime waiting for the appropriate tooling.

The Viper's ability to adjust cutter styles to match the formation meant that the 26-inch, 36-inch 46-inch and 58-inch tools already on site could be converted quickly and easily. And this wasn't the final change. The actual drilling factors dictated multiple changes in the planned hole opening sizes: from pilot hole to 26-inch, 40-inch and then a reduced final hole size of 54-inch. To further complicate the situation, some segments did require a combination of interchangeable MT and aggressive TCI cutters.

All these adjustments were made at no cost to the contractor. A high percentage of the project costs were related to hole openers. With the Viper, the contractor saved by not having to buy 64-inch hole openers (up to 17 had been projected) and didn't have to buy the 58-inch either. The cost of each size would have ranged around $150,000 per tool.

The Viper allowed the contractor to use the same cutters on a variety of bodies creating different size openers with already purchased cutters. Numerous sets of cutters were used in the 100 hour range and not a single set of arms were damaged. In addition to its outstanding down-hole performance, the Viper enabled the contractor to adjust to changing conditions without delays or down time.

Project #3 – Value:

A 60-inch sewer line required a 72-inch final hole opening pass in limestone, two drills totaling about 4,000 LF. Milled tooth HDD hole openers of 30-inch, 42-inch, 54-inch, 66-inch and 72-inch were necessary. Based on the projected hours, at least two tools of each of the five sizes would be required, built in advance to prevent expensive down time.

Instead of having to buy ten expensive split bit hole openers, the Viper gave the ability to use the same cutters on multiple size passes. The cutters from the 42-inch were reused on the 66-inch. The cutters from the 54-inch were used again on the 72-inch. After this, the same cutters were taken off the larger tools and placed back on the 42-inch and 54-inch for the second drill. One cutter set had over 160 hours and another set finished with just under 200 hours. Both were still in relatively good condition and could have gone further and longer.

Three unique projects, three tough tests demonstrating the new Viper RockReamer durability and flexibility - all resulting in tremendous savings for the HDD contractors, and dramatically raising the HDD hole opening standard. The Viper RockReamer is the latest and greatest in the evolution of HDD hole openers.

According to John English, President of Horizontal Technology Inc., "The best engineers & the best HDD rock drillers have had a major impact on the design of this tool. The Viper RockReamer has improved the hole opening capabilities of the entire HDD industry".

About the Author

John English, President of HTI has worked with, and on, roller cone reaming tools since 1977, starting with Grant Oil Tools. He first became involved in horizontal hole openings for river crossings in 1988 and found the drilling conditions were far different than vertical hole opening. The harsh conditions dictated design changes. With Kent Rives he built the first custom HDD hole opener using the "Q" cutters in 1990. This evolution continued with the variable sized Lo-Torque in 1994 and then the more versatile, stronger, RockReamer in 1998. These improvements continue today, as HTI celebrates 20 years serving the HDD industry.



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