LoneStar Drilling & Elevator Caissons LTD.
Dual Rotary Drilling
Power, Precision, and Performance in
Unstable Ground
At LoneStar Drilling, we use Foremost DR24 rigs to deliver precise, stable boreholes through some of the most difficult ground conditions. Our dual rotary drilling method, typically performed with 6-inch to 24-inch casing, offers a distinct advantage when drilling through unconsolidated formations like sand, gravel, glacial till, and boulders. This technique ensures superior alignment, casing integrity, and borehole stability which is especially critical in foundation, infrastructure, and alignment-hole applications.
What sets dual rotary drilling apart is its use of two independently operated rotary drives. The lower rotary head is responsible for advancing the steel casing, gripping it with high-strength steel jaws fitted with carbide inserts. As the casing is rotated and pushed downward through loose or unstable material, the upper rotary head simultaneously powers the drill string. This drill string can be equipped with a variety of tooling—such as a down-the-hole hammer, roller cone bit, or drag bit—depending on the geological conditions.
By advancing the casing and drill string at the same time, the dual rotary system minimizes borehole collapse and prevents deviation, ensuring that the hole remains true to the planned path. It also allows for continuous drilling without the need to remove tools when switching from cased to open-hole operations. Once the casing reaches its target depth, the rig seamlessly transitions to conventional drilling to continue advancing the borehole.
This method is not only faster and cleaner than many traditional techniques, but it also provides enhanced control over cuttings. Most often, material is evacuated using compressed air, but our Foremost DR24 rigs can also be adapted for mud circulation or flooded reverse circulation, depending on project requirements.
Dual rotary drilling is ideal for projects that demand accuracy and borehole integrity in complex ground conditions, such as water well installation, foundation piling, and alignment drilling for infrastructure and tunneling projects. The ability to independently control both rotary drives gives our operators flexibility to adjust in real-time, ensuring precision no matter the challenge underground.