Concept and Classification of Drilling Knowledge


1. Basic Concepts of Drilling

1. Drilling: Use a drilling rig to drill into the ground according to a certain design angle and direction, and by taking out the core and cuttings in the hole or inserting a test instrument in the hole, to find out the underground mineral reserves, understand the stratigraphic structure, rock properties and To meet other engineering construction requirements, this kind of engineering is called drilling.

2. Core drilling: when drilling, keep the core at the bottom of the hole, and mainly use the proposed core to study and understand the drilling method of underground geology and mineral conditions.

3. Drilling: Use the drill bit to work at the bottom of the hole, break the rock and continue to deepen the drilling operation. It includes two aspects of breaking the rock at the bottom of the hole and extending the hole as required.

4. Drilling method: the general term for the methods and technical measures for breaking the rock at the bottom of the hole when drilling into the ground.

5. Drilling process: how to use certain equipment and tools to break the rock (soil layer), create a smooth and regular hole with a certain diameter and depth in the formation, and take certain technical measures to ensure the smooth progress of the drilling work all work.

6. Drilling hole: a cylindrical hole drilled by drilling machinery or other methods to drive the drill bit for the purpose of ore deposit exploration or other engineering purposes. It has the characteristics of large depth, small diameter and arbitrary direction.

7. Three elements of drilling space ① Hole depth (L): the length of the drilling axis from the orifice to the measuring point; ② Vertex angle (θ): The clamping point between the drilling axis (or its tangent) and the plumb line at the measuring point ③Azimuth (α): the angle between the projection of the borehole axis at the measuring point on the horizontal plane and the direction of magnetic north.

8. Drilling structure: refers to the change in the diameter of the hole from the opening to the final hole. It includes the borehole diameter, the number of diameter changes, the number of casing layers, the pipe diameter, the length, the depth of the diameter change, and the water-stop sealing method at the bottom of the casing.

9. Circulation: The mud pump sends the flushing fluid to the bottom of the hole through the inner hole of the drill string (or the gap between the drill string and the hole wall). (or drill string bore) the process of returning to the surface and carrying rock dust out of the bore.

10. The purpose of geological core drilling is to take out the core from the ground. Through the analysis, research, observation, identification and testing of the rock core, one can intuitively understand the thickness, burial depth, occurrence, distribution, mineral composition, ore grade, chemical composition, physical and mechanical properties and structure of the ore and rock. construction, etc. The quantity and quality of rock cores directly affect the accuracy and reliability of judging geological structures, evaluating mineral resources, submitting mineral reserves and mining design. Geological core drilling is the most efficient method for obtaining subsurface physical samples. During the drilling process, not only high drilling efficiency is required, but also the cores taken are required to have sufficient volume in quantity, and to maintain the primary structure and ore-bearing grade as much as possible in terms of quality. These requirements are expressed in core drilling quality management by the core extraction rate.


2. Classification of drilling

1. According to the purpose of construction, see the table below

2. Cemented carbide drilling, steel grain drilling, diamond drilling, roller cone drilling, etc.

3. According to the nature and method of applying external force: percussion drilling, rotary drilling, percussion rotary drilling, etc.

4. According to the type of flushing fluid: clear water drilling, mud drilling, emulsion drilling, saturated salt solution drilling, foam drilling, air drilling, etc.

5. Classification by flushing fluid circulation mode: positive circulation drilling, reverse circulation drilling, etc.

6. According to whether coring is classified: coring drilling, full drilling, etc.

7. According to the way the cores are transported from the hole to the surface

8. Special drilling methods Wireline coring, orientation, DTH hammer, following pipe, center sampling, bottom hole power drilling, etc.


3. Core drilling production process

1. Drilling construction process: It is the whole process from the flat foundation to the dismantling of the equipment after drilling the final hole. It includes positioning the hole → leveling and building the foundation → installing drilling equipment and ancillary equipment → installation and acceptance → preparation work before opening → opening and lower orifice pipe → changing diameter → drilling → sorting, cataloging and storage of rock cores →Other work (running casing, correcting hole depth, simple hydrological observation, borehole bending measurement, logging) →pulling casing at the end hole →hole sealing →hole sealing quality inspection.

2. Prepare before drilling. It is all the preparatory work before drilling into the opening, such as leveling the foundation, installing equipment (drilling tower, drilling rig, water pump, power machine, etc.), installing ancillary facilities (yard room, safety facilities, circulation system, water pipes, lighting, etc.), Installation acceptance and test drilling.

3. Drilling process. Refers to the construction process of drilling from the opening to the final hole.

4. End hole. It refers to all the work carried out from the stop of drilling to the disassembly of the equipment, including the measurement of the bending of the borehole, the measurement of the water level, the pumping test, the sealing of the hole, the pulling of the casing, and the disassembly of the equipment.

5. Core drilling process: the power machine drives the drilling rig to rotate, and the drill string is composed of the drill pipe, core pipe and drill bit, and the drilling rig supplies the drill string with a certain axial pressure and torque, so that the drill bit with the cutting tool will produce engraving. The role of rock in order to achieve the purpose of continuous drilling to the depths. The rock powder that should be taken off during drilling, along with the flushing fluid sent to the bottom of the hole by the mud pump through the drill string, rushes to the surface through the annular gap of the hole wall. The core is drilled into the core tube, and the core is snapped off by lifting the drilling tool or other coring methods, and lifted from the bottom of the hole to the surface. From drilling down to core extraction, one drilling pass is counted as one round. The lifting and lowering of the drilling tool is accomplished by the hoist of the drilling tower and the drilling rig.


Fourth, the main content of core drilling

Drilling equipment, drilling method (drilling process), drilling quality and measurement, drilling flushing and wall leakage plugging, accident prevention and treatment, airport production management, safety technology, related knowledge (mechanical basic knowledge, mechanical processing and repair knowledge, electrical knowledge , basic knowledge of geology, knowledge of mineral deposits), etc.


5. Rock drillability

1. The concept of rock drillability: a comprehensive index reflecting the difficulty of drilling into rock under certain technical conditions. Generally, the ROP (m/h, m/s) is used as the drillability index.

2. Classification of rock drillability The rock drillability classification table frequently distributed by the former Ministry of Geology in 1958 and the diamond core drilling drillability classification table issued by the Ministry of Geology and Mining in 1984 both classified rock drillability into 12 grades.

3. There are four grades and twelve grades: soft - fairly drillable grades 1-3; medium hard - fairly drillable grades 4-6; hard - fairly drillable grades 7-9; hard - Fairly drillable level 10-12.


6. Knowledge of drilling caliber


Note: The DCDMA standard is the standard of the American Diamond Rig Manufacturers Association.


7. Characteristics of drilling production

1. "Small, real and complete". Small - the organizational structure is small, it is the most basic administrative unit of the geological prospecting unit; real - the work is the most specific and practical; full - refers to the drilling production management is very comprehensive.

2. The drilling construction mainly serves the national infrastructure construction.

3. The work object is rock. Due to the ever-changing rock and stratigraphic structure, its construction technology and technical specifications are difficult to achieve standardized production, and the drilling efficiency is greatly affected by the drillability of the drilling rock.

4. Drilling and production are carried out in the field, the work flow is scattered, and the production and living conditions are difficult.

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