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2003 - 2005
All rights reserved.

Royall Pump
& Well Company
Robert W. Royall, Owner

2958 Anderson Highway
Powhatan, VA  23139


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Dual Rotary Drilling Method

Our dual rotary rig can handle difficult formations without the use of casing hammers, under-reamers or drilling mud. Because the drives are independent, the bit drill can drill inside, flush with, or ahead of the casing depending on the type of overburden encountered.

In situations where heaving is a factor or sample accuracy is important,
the casing is advanced ahead of the drill bit for hole stability and minimal cross-contamination of cuttings.

Dual Rotary System
"Heavy Formation"
Casing advances
ahead of drill bit.

In situations where boulders are encountered, the drill operator can stop the casing rotation, and continue
through the boulder with a drill string. Once a pilot hole is established in the boulder, the operator begins rotating the casing again, and it follows the drill string through the boulder.
This "pilot hole" technique combines with the rotation of the casing to deliver an uncommonly straight borehole. Once the desired casing depth is achieved, the dual rotary drill continues drilling like a conventional top-drive air drill.

Dual Rotary System
with "boulder encountered"
Drill bit leads casing straight through cobbles and boulders.

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