Core drilling - hard rocks 119-138 mm

Pakast Technical Services uses a set of technical means for сore drilling air hammer, which allows drilling exploration wells on mineral deposits.

At present, impact-rotational drilling of the pneumatic hammer is be-coming increasingly widespread during geological exploration work on hard and strong rocks.

The tools for pneumatic impact drilling includes drilling bit, a core pipe, an adapter. Together they form a pneumatic shock column projectile. Then, through a special adapter, the air hammer is connected to the projectile. The drill pipes included in the projectile set ensure the rotation of the entire column.

Drill Bit it is a ribbed body reinforced at the end with spherical inserts of a hard alloy. The crown is made of low-alloy steel of the 40X grade with subsequent heat treatment. The connection to the core pipe is carried out by a special conical thread. In the crowns, the core is held using a flexible core breaker, which is a V-shaped staples with a diameter of 5 mm.

The difference from the core pipe is that the pipe has a special thread that allows you to perceive shock dynamic loads. As a material, a seamless pipe with a 10 mm wall made of grade 45 steel is used. The curvature of the pipes for 1 m of length does not exceed 1 mm.
An adapter is used to transmit dynamic impulses to the projectile from the airstrike.

Core diameter: 88 or 107 mm
The length of the core receiving tube is 1000 or 1500 mm
Hammer CIR-110 or CIR-130

Core hammer - soft rocks

The technology is suitable for searching for alluvial mineral deposits
The complex is designed for drilling wells with a diameter of 168 mm in rocks of the IX-XII category of drill ability.

When drilling flooded sections, the highest technical and economic indicators are achieved by installing a casing string with a diameter of 219 mm, which ensures the overlap of the water horizons and the trouble-free operation of the pneumatic hammer in the wellbore.

Rocks of the V-IX category of the complex allows you to pass in a rotating way. To do this, it is necessary to exclude the air hammer from the column and replace the air hammer crown with the appropriate one for rotary drilling.
Because it is necessary to ensure the selection of a “representative” sample with a diameter of 168 mm, it is required to use a high-performance pneumatic hammer that provides an operating pressure of 1.0-1.2 MPa, an air flow of 10-15 m3/min. The rotation speed varies in the range of 15-30 r/pm. A highperformance compressor works together with a pneumatic hammer, at a pressure of 1.2 MPa and a capacity of 12 m3/min.

Drill bit it is a ribbed body reinforced at the end with spherical inserts of a solid joint of the VK8 – B brand. The bit is made of 40X steel with subsequent heat treatment. The connection to the single core pipe is carried out by a special conical thread. The crowns are designed for rotary drilling with a projectile in cases when working with a pneumatic hammer is ineffective.

Because the drilling technology when extracting the core from the core pipe does not imply the removal of the crown, the presence of flexible core breakers or core break rings as part of the drilling projectile is not provided. When drilling monolithic, fractured, dry rocks, core retention in the core pipe is carried out due to its own friction forces between the rock particles. If the section is represented by watered soils, then petal-type devices are used to hold the core

For effective operation of the projectile and obtaining a representative sample, the adapter provides air circulation in such a way that it does not disrupt the structure of the selected samples during pneumatic impact drilling. On the one hand, the adapter has a special nipple thread for the column pipe, on the other hand, the internal thread of the coupling-locking connection. The adapter is made of 40X grade steel with subsequent thermal hardening.

Casing While Drilling 219 mm

In the case when the section is represented by watered rocks, or it is necessary to isolate one horizon from another, during drilling, an operation is introduced to install a leading casing string. I.e., first a casing pipe with a diameter of 219 mm is drilled by pneumatic or rotary method to a depth of 1-2 m, then samples of the undisturbed structure are taken inside the column by rotational or pneumatic method. As the selection is carried out, the casing is again increased with the subsequent deepening of the well.
In some cases, the pneumatic column projectile goes with a slight advance from the casing by the amount of selection.

The casing string with a diameter of 219 mm is designed for installation on rocks of category V-XII by rotational or pneumatic impact method, depending on the type of crown installed.

Auger While Drilling 240mm

When drilling engineering-geological, hydrogeological and geological development wells in unstable and watered rocks, a complex of equal – bore hollow augers is used. Its application makes it possible to increase the productivity of the drilling process by drilling wells with continuous casing in rocks of the I-IV category of drill ability.
The complex provides sampling of core tools, and also makes it possible for pneumatic impact shells to work on stronger rocks below the underlying horizons, while eliminating the collapse of the well walls in water-saturated soils, thereby blocking the aquifer.

The complex is a column of auger, the connection of which is made in the form of a smooth cone with a key. The nipple and coupling are fixed with special bolts for an internal hex key. Sealing of this connection is achieved by using rubber rings in the connection of the nipple and the coupling.

Complicated geological conditions

The design of the chisel is a complete cylinder with welded blades. They are reinforced with VK-8 hard alloy cutters, and VK-15 is used for hard rocks. The bit diameter is 240 or 233 mm.

Equal-pass augers with an equal internal diameter of 135 mm pipes are a seamless pipe with welded connecting tips (nipple, coupling). A rib with a thickness of 8 mm is wound and welded on both sides of the pipe. The winding pitch of the reboard is 150 mm. The torque from the screw to the screw is transmitted by a keyway connection. The axial fixation of the screws is made by a bolt connection.

Adapter need for connection of through-pass augers with a drilling rod or with the spindle of the rotator of the drilling rig.
The inner diameter of the auger is 135 mm, the outer diameter is 200 mm

Core extraction device​

The core extraction device is designed for mechanized extraction of soil samples from a core pipe. It is used for core drilling in a rotational way.

This device provides the fastest possible transition from obtaining the core to its extraction, which reduces the time of operations compared to existing extraction methods.
The principle of operation of the device is as follows: Instead of a milling adapter, core extraction devices are installed in the drilling shell column. The presence of a hexagon connection and a stop pin allows you to transfer the torque to the rock – breaking tool and perform descent and lifting operations during drilling.

To extract the core, it is necessary to lift the column, knock out the finger. Continue lifting the column to the height of the column pipe so that it is possible to install a thrust ring in the trunk of the mast. Lower the column to the stop of the carbide column into the ring. Slowly lowering the rotator, squeeze out the core.

Drilling of seismic exploration wells

Due to the high productivity, auger drilling of shallow wells has found wide application in drilling seismic exploration wells for solid and liquid minerals.

The technology of drilling with conventional augers turned out to be powerless in persistent and watered rocks. In such sections, it is impossible to lower the explosive layer below the ground water level, since after removing the screw column, the well swam or collapsed.

For such conditions, a auger column has been developed, consisting of hollow auger with a pass – through diameter for an explosive charge, a drilling cutting opening bit that provides drilling and feeding an explosive charge through it to the bottom of the well when reaching a given depth, a half – lock for connecting the column to the drilling rig spindle.

The chisel is designed for drilling soft and medium-hard rocks of the II-IV category in terms of drillability. The design consists of a housing with a through axial hole, a lid pivotally connected to the housing, end cutters, peripheral cutters located on the chisel body, sealing the lid with the housing in the form of an elastic ring placed in the annular groove, fixing the lid in the closed position when drilling the well and the reliability of its opening when an explosive is charged.

Auger drilling

The technology of rotary drilling with augers consists in the fact that the rock destroyed by the chisel rises to the surface simultaneously with the deepening of the hole with the help of rotating drilling augers.

Blade bits or chisels of the cutting-chipping type are designed for drilling in grades from I to V of the drillability category. In recent years, two-and three-bladed chisels with improved geometry with a stepped cutting edge have been most widely used. Reinforcing bits with carbide weapons allows you to destroy rocks of medium hardness in the cutting and abrasion mode. The destruction of the rock occurs with the blades tilted in the direction of rotation of the bit.


Bit diameter, mm: 75, 95, 112, 151, 198, 250, 320, 370, 420, 450, 530, 990
Auger diameter, mm: 64, 80, 108, 135, 180, 230, 300, 350, 400, 450, 500, 960

Auger it is seamless pipe on which a steel strip is helically wound with a thickness of 3 to 8 mm, depending on the size of the size. The tips (nipple and coupling) are welded together. Structural steel is used for the manufacture of augers. No heat treatment is required. The column of augers forms a screw conveyor, which provides high speeds of well penetration by quickly destroying and lifting large rocks chipped with a chisel, without additional crushing.
The drill rod is designed to transfer the axial load and the torque of rotation to the rock-forming tool from the rotator of the drilling rig. Ensures the execution of the descent and lifting operations of the drilling projectile. The rod is a pipe with welded hexagon – type connecting tips (nipple, coupling). To increase the rigidity of the rod and transmit high torque, the pipe wall thickness was increased to 6 mm, and the auxiliary hole for holding the column during descent and lifting operations was transferred from the pipe body to the cylinder of the nipple tip.

Drilling on mud

216 or 320 mm


In the practice of drilling wells on sands and clays the rotational drilling method with direct flushing is most suitable.

Air rotary drilling

110 or 250 mm

For drilling water borehole in hard rocks, the method of drilling with a solid face is used.

The composition of the projectile includes a bit, a pneumatic hammer, an adapter, drill pipes.


In search of optimizing the drilling process, PAKAST™ has developed a combintion of BITS PAKAST and drilling equipment with almost endless technological capabili ties.

Unique approach to design process makes BITS PAKAST™ turn these opportunities to benefits.

Drilling fluids engineering

Development of op mal formula ons of drilling fluids for the construc on of wells, including drilling in di cult compa ble geological condi ons.

Drilling fluids engineering support

  • Qualifica on
  • Technologies
  • Result

For hard rock drilling, the company plans to use the technology of drilling boreholes with compressed air blowing, using Hammer and bit.