Mine Dewatering Rescue Well Drilling Rig: CMD100 Cuts a Φ710 mm Well in 18 Days
Executive Summary
A legacy mine in Henan Province had accumulated serious underground water over years of production: the water table kept rising and directly threatened safety. A large-diameter emergency dewatering well had to be drilled fast. The ground was severely fractured with very high water inflow and poor stability — conditions that defeat ordinary rigs, which have weak wall support and low pumping throughput. The CORTECH® CMD100 truck-mounted rig, fitted with large-diameter DTH rotary-percussion bits and dual-wall drill pipe, and using an air reverse circulation process, completed a Φ710 mm, 280 m-deep dewatering well in 18 days. The well delivered more than 5,000 m³ of drainage per day, quickly removed the water hazard and created the conditions for the mine to restart. The project has become a benchmark for mine dewatering rescue work in China.
Project Background & Challenge
The emergency was time-critical and geologically hostile:
- Rising water threat: long production had left the mine with worsening underground water accumulation; the rising water level was an immediate safety threat.
- Fractured, water-bearing ground: the target area was badly fractured with extremely high water inflow and poor stability.
- Conventional rigs unsuited: standard rigs offered weak borehole wall support and low dewatering throughput — inadequate for an emergency of this scale.
Our Solution
Given the urgency and complexity, we combined the CMD100 with tools and fluid methods built for water-bearing, fractured ground:
- Large-diameter DTH rotary-percussion bits for fast penetration in broken rock.
- Dual-wall drill pipe to support reliable cuttings and water handling in the annulus.
- Air reverse circulation to lift cuttings and water efficiently, strongly improving wall protection and dewatering capacity compared with conventional direct circulation.
- Rig enablers: the CMD100's 100 t (1,000 kN) pullback handled the large dual-string tooling, its 20.6 MPa integrated air/mud manifold supports high-volume reverse circulation, and its 2.08 m BOP-ready worktable plus six outriggers kept the operation stable in fractured, water-affected ground.
Key Results
| Metric | Value |
|---|---|
| Finished well diameter | Φ710 mm |
| Well depth | 280 m |
| Project duration | 18 days |
| Daily drainage | >5,000 m³/day |
| Formation | Severely fractured, high water inflow |
| Drilling process | Air reverse circulation, dual-wall pipe, large DTH bits |
| Outcome | Water hazard removed; mine restart enabled |
For the full technical specifications of the CORTECH® CMD100, see the CMD100 product page.
Customer Value & ROI
- Fast hazard removal: an 18-day build meant the rising-water threat was relieved quickly, with >5,000 m³/day of drainage taking the pressure off the underground workings.
- Mine restart enabled: by controlling the water level, the well created the conditions for resuming production — turning an emergency stoppage back into operation.
- Stable hole in hostile ground: air reverse circulation and dual-wall pipe protected the borehole wall despite severe fracturing and high inflow, avoiding the collapse that would have delayed the rescue.
- Benchmark method: the project is now a reference for large-diameter dewatering rescue wells nationwide.
FAQ
What is a mine dewatering rescue well?
It is a large-diameter borehole drilled to drain accumulated underground water when a mine is flooded or threatened by rising water. This Φ710 mm, 280 m well delivered more than 5,000 m³ of drainage per day.
How fast can a rescue dewatering well be drilled?
This 710 mm, 280 m dewatering well in water-bearing fractured ground was completed in 18 days using the CMD100 with air reverse circulation.
What is air reverse circulation drilling?
Air reverse circulation lifts cuttings and water up the inner string (or annulus arranged for reverse flow), rather than pushing mud down the pipe. In fractured, water-bearing ground it improves hole cleaning, wall protection and dewatering throughput — exactly why it was chosen here.
Which rig handles water-bearing fractured ground?
A 100 t-pullback, high-air-flow large-diameter rig such as the CMD100 — with dual-wall pipe, large DTH bits and a 20.6 MPa reverse-circulation manifold — provides the pull, air volume and stability needed to keep such a borehole open and productive.
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