Direct Circulation Drilling

This system allows you to drill into any terrain and reach the maximum depth currently allowed by drilling technologies. This technique, which is generally used in the construction of small and medium diameter wells, allows drilling without the use of temporary casing pipes.
The direct circulation method takes place by pumping the circulation fluid (bentonite and/or polymer-based mud) into the rods. It is then returned to the ring between the rods and the material from which the tip is drilled and the hole.
The pressure and flow of the drilling fluid at the drill bit and just behind it effectively removes the drilled material from the drill and also prevents the hole from collapsing.
In addition, the hydrostatic head of the drilling fluid ensures stability of the hole and its viscosity (calculated from the fluid flow from the drill rig and the diameter of the hole) must be such as to allow it to be transported into the well, the surface of the perforated material.
The outlet velocity of the liquid should not be less than 0.2 m/sec to ensure that the material is removed effectively without exceeding the viscosity.
The excavation system may use the impact force of a tool operating primarily by impact/compression, or the combined shearing action resulting from the combination of rotation of the tool and the torque applied to it.
The minimum retraction of the rig must be at least 50% greater than the weight of the drill string. Optimum depth: 0 to 1000 m. Optimum diameter: 152 to 444 mm (6” to 17”1/2)
This technique can be used effectively on both alluvial sedimentary rocks and any type of crystalline soil. It may be necessary to use cementing or coating pipes in severely fractured formations.

Reverse Circulation Drilling

This system is generally used for large bore wells and consists of returning the drilled material and flushing medium to the surface inside the drill pipes.
The pressure and flow of the drilling fluid at the drill bit and just behind it effectively removes the drilled material from the drill and also prevents the hole from collapsing.
In addition, the hydrostatic head of the drilling fluid ensures the stability of the hole and its viscosity (calculated from the fluid flow from the drill rig and the diameter of the hole) must be such as to allow it to be transported into the well. . the surface of the perforated material.
The fluid consists of water or natural light mud, although bentonite polymer-based mud can also be used if required.
The outlet velocity of the liquid should not be less than 2.5 to 3 m/sec to allow the removal of coarser material.
The excavation system can use the impact force of a percussion tool or the combined action of the tool's rotational motion and the torque applied to it.
Optimum depth: 3 to 400/500 m. Optimum diameter: 600 to 1,000 mm.
It is best to use this technique when drilling loose alluvial soils, including boulders and large stones (especially percussion ones).
This technique can also be applied (but less effective) to congruent formations such as sandstones, conglomerates, marls.

Compressed Air Drilling

This technology can be used when there is no need to support the well walls. It is generally used for drilling cohesive soils, but can also be used in loose soils.
In this case, the casing pipes perform the supporting function of the walls of the borehole. To be able to lift the drilling material produced by the tool, the compressed air, since it is a compressible liquid and slightly viscous, must have a very high velocity (at least 15 m/s along the material exit path, optimal value 20 m/s):
To define the rate of ascent, the variation of air volume associated with overpressures must be taken into account, which occurs at various points in the output path of the drilling material.
The pressure and flow of the drilling fluid just behind the drill bit effectively removes the drilled material from the bit, and also prevents the drilling hole from collapsing, further back than that, the hydrostatic head of the drilling fluid ensures the stability of the drill bit.
The hole and its viscosity (calculated from the fluid flow from the drill rig and the diameter of the hole) must be such as to allow transport to the surface of the material to be drilled. It also serves to control and direct the air and material flow. Optimum depth: 0 to 600 m. Optimum diameter: 152 mm (6") to 375 mm [14"3/4")
It is very productive in sticky soils. Downhole hammer use is particularly strong in soils with high compressive strength. On loose soils it may be necessary to use guards to accompany the advancement of the tool.
The usage limit of each casing pipe is determined by the total lateral frictions affecting the pipes.

Percussion Drilling

This system is used for medium-large diameter and low-medium depth drilling.
The action is performed by three main types of cable percussion instruments:
-Buckets, used in the absence of water;
-Bores or scoops, used in loose or moderately compact soils and in the presence of water;
-Chisels, used on compact soils.
The tool must be attached to the free fall crane with a steel rope and repeatedly lifted and dropped to the bottom of the well.
After proper drilling progress and at regular intervals, the tool is pulled out of the well and the drilled material is removed.
If the ground is inconsistent, the hole should be stabilized by placing temporary or permanent coverings.
The enclosure may be advanced by rotary, direct thrust or percussion methods.
Increasing arrays of smaller diameter enclosures are referred to as "telescopic enclosures" when build-up between enclosure and ground restricts advancement and risks rebound later on.
Casing pipes can be socketed, threaded or welded.
Optimum depth: 0 to 100 m. Optimum diameter: 400 to 1,200 mm
Cable strike technology can be used for all loose alluvial soils, including rocks and cobblestones. It can also be used for consistent formations. But in this case, the feed rate is significantly reduced.

Wireline Coring

The cable core system is used for mining operations in all kinds of soils. Discover how this works:
Used primarily for mining operations, the cable core allows rapid insertion and retraction of the core barrel into the drill rods, so there is no need to remove the rods to retrieve each core sample.
The overload recovery device, which is connected to the crane by a steel cable, is lowered down the middle of the bars. When the core reaches the back of the barrel, it locks and separates it from the drill rods, then the winch pulls the entire barrel and core sample to the surface.
The only time drill rods are removed is when the borehole needs to be completed or the core bit replaced.
Optimum depth: 0 to 1000 m. Optimal diameter: AQ, BQ, NQ, HQ, PQ, SQ.
This technique can be used effectively on any type of soil.