Deep hole drilling technology and management of endogenetic metal ore

(Henan Nonferrous Metals Bureau of Geology and Mineral Resources)

Finding large and good mines for the country is the basic duty of geological prospecting units and the foundation of survival; Developing mining industry and taking the road of integration of exploration and mining is the direction to strengthen the strength of geological prospecting units under the new situation; Prospecting engineering is not only an indispensable means of geological prospecting, but also an important means to obtain economic benefits and improve comprehensive competitiveness. In the development goal of "highlighting the main business, broadening the industry, developing auxiliary businesses and getting rich" formulated by our bureau, prospecting technologies such as drilling and pit exploration are listed as auxiliary businesses. This paper briefly discusses the position and function of drilling in geological prospecting units, as well as the construction technology and management of deep hole drilling, and discusses it with you.

First, the position of drilling engineering in geological exploration

As a geological exploration unit, geological work is the core, and geophysics, geochemistry, remote sensing, surveying, trench exploration and well surface engineering are indispensable methods and means in the preliminary geological work. When the local, physical, chemical and remote work is carried out to a certain extent, drilling verification will be started, the scale, shape and thickness of the ore body will be controlled, and the core will be taken out and submitted to the laboratory to determine the ore grade. Geophysical logging will obtain a lot of geological information. At present, when geophysical exploration and other methods and means can not accurately control the spatial position and ore grade of ore bodies, drilling engineering is an indispensable and important means for deep prospecting.

As we all know, drilling is an important prospecting method, and the discovery of 100 large and extra-large foreign deposits introduced in the book Information Prospecting Strategy and Exploration is closely related to drilling. 1957 The Australian Olympic Dam Cu-Au-U deposit, which started geological work, made a major breakthrough only after the drilling engineering system was controlled in 1975, becoming the largest uranium deposit and the sixth largest copper deposit in the world. In the exploration of mineral resources in Australia, South Africa, Canada, the United States and other countries, the application of pit exploration in the early exploration is less, and the deep verification is mainly based on drilling. The famous Bayan Obo mining area in China, molybdenum ore fields, coal fields and numerous bauxite mining areas in Henan Province have all proved their advanced reserves through a large number of drilling projects. In the past, drilling played an important role in geological exploration. At present, in the exploration of "drilling deep to find the blind and exploring the edge to find the bottom", drilling is a means that geological exploration must rely on. Therefore, it is particularly important to improve the level of drilling technology and equipment and the quality of employees.

Second, drilling engineering is an important means to expand economic scale and obtain economic benefits.

In recent years, our bureau has undertaken a number of government and social geological exploration projects every year, and the annual designed drilling workload of geological projects is about 70,000 ~ 80,000 m. According to the statistical data of our bureau 1979, 28 drilling rigs were started that year, and the drilling workload in 16 mining area was 69,997 m, and the drilling technicians and service personnel were about 1000. Drilling not only serves geological prospecting, but also places a large number of employees, maintaining the stability of the team and the continuation and development of drilling technology. During the Ninth Five-Year Plan period, the depression of geological work drastically reduced the drilling workload. Five-year planned drilling workload 10722m, a large number of equipment is idle or used for other purposes, personnel are laid off, and technical equipment is seriously weakened. In the past four years, our province has injected a lot of funds into the equipment renewal of geological prospecting units by using the project funds of "two rights and prices", and the drilling equipment of our bureau has been strengthened accordingly. At present, there are more than 30 sets of core drilling equipment. After reasonable organization, the drilling workload can be about 65,438+10,000 m per year according to the existing equipment scale. In 2008, the designed drilling workload in the planned and social geological projects of our bureau was 6.5438+0.3 million m. If all of them are constructed by our drilling team, the output value will be about 50 million yuan, which will play a greater role in arranging personnel, training teams, improving drilling technology and obtaining economic benefits.

Five units of Henan Coalfield Geology Bureau have the drilling construction strength, and there are about 150 rigs with drilling depth exceeding 1000m, forming a strong production capacity. Large-diameter and ultra-deep coal mines have ventilation, drainage and ice conveying holes, and the horizontal drilling technology of coalbed methane has reached the national advanced level. In recent years, he has been engaged in the drilling of coalfield geology, coalbed methane, shallow oil, oil shale and coal mine ventilation and drainage holes in 8 provinces (regions) such as Henan, Xinjiang, Shaanxi, Shanxi, Inner Mongolia, Jilin, Guizhou and Yunnan. The annual drilling workload is about 700-654.38+00,000 m, with an annual output value of 300-400 million yuan, which not only arranges a large number of employees, but also improves the drilling technology level. The second team of coalfield geology used drilling income to transform the old base, making the residential area of workers become a national civilized community. The No.4 Team of Coalfield Geology used the drilling income and invested150,000 yuan to complete the waterway reconstruction of Pingdingshan workers' residential area, installed gas and heating, and improved the quality of life of workers. The successful experience of many domestic drilling companies and geological teams in drilling construction deserves our serious study and reference. Their practice has proved that drilling equipment and drilling technicians in geological prospecting units are not a burden. Drilling construction industry not only provides guarantee for geological exploration, but also can arrange employees and keep the team stable. More importantly, it can enhance the comprehensive competitiveness of the unit, improve its popularity, and obtain huge economic benefits from drilling construction.

Three, deep hole drilling technology and equipment and construction technology

The geological exploration team of nonferrous metals has its own characteristics and has accumulated rich exploration experience of endogenetic metal deposits. Because of the complex genesis of endogenetic metal deposits, the mineralization is seriously restricted by geological structures, and the integrity and mechanical properties of rocks are quite different, technical problems such as coring in fractured zone and altered zone, hard rock drilling, borehole bending, borehole collapse and leakage are easily encountered in drilling construction. Especially in the work of "drilling blind, exploring the edge and finding the bottom", the drilling depth is relatively deep, and the technical problems encountered in drilling will multiply. If exploration is carried out in the periphery and bottom of the old mining area, the problems encountered in drilling construction will be beyond imagination due to the influence of early mining, dense mined-out areas and loose rocks.

Academician Teng Jiwen proposed that the exploration depth of metal mineral resources in the second depth space of lithosphere is 500 ~ 2000m. If the designed drilling depth is 2000 m, the drilling cost per meter will increase by 30% for every 300m increase in hole depth, and the average price per meter for the 0 ~ 500m hole section is 170 1856.47 yuan. If the drilling cost per 300m interval is increased by 40%, the single hole cost is 2.548 million yuan.

Table 1 Calculation Table of Drilling Cost for Single Hole Section

The calculation of single hole cost is only based on the market price, and the single hole cost will be increased according to the budget standard of land and resources investigation. An investment of more than 2 million yuan in a drilling hole is a huge expense for the decision-making and investment departments of geological prospecting, and also has high expectations for drilling construction.

(1) Deep hole drilling equipment and tools

1. Selection of drilling rig

Drilling with exploration depth 1500 ~ 2000 m is affected by factors such as formation integrity, rock mechanical properties, drilling diameter and drilling design vertex angle, which puts forward higher requirements for drilling rig performance. It is more suitable to choose a hydraulic feed rig with low center of gravity, wide speed range and large vertical shaft stroke. The existing XY-5 and XY-6B vertical drilling rigs and CS 1000P6 and CS300 1 full hydraulic drilling rigs in our bureau can meet the drilling requirements of 1000 ~ 2000 m deep holes. In practical work, the drilling rig is selected according to the designed drilling depth (Table 2). It should be noted that CS300 1 full hydraulic drilling rig is self-assembled, with poor dismountability, climbing ability of 25, rig body width of 2.7m and self-weight of 22t when crawling, which is suitable for plain and hilly operations. If construction is carried out in mountainous areas, construction access roads must be built.

Table 2 Selection Table of Drilling Equipment

Note: The final aperture is based on φ 75 mm ..

2. Other supporting equipment

In order to improve the construction speed and quality, rope coring drilling technology is often used. In view of the deep drilling depth, small drilling annulus and large pressure loss of flushing fluid or mud, BW320 mud pump can basically meet the pressure requirements of 2000-meter deep hole drilling after taking measures to increase the outer diameter of bit. Power machine should match the needs of drilling rig and mud pump. As for the drilling tower, in addition to strict requirements on strength and bearing capacity, its height can be appropriately relaxed.

3. Specification and model of drill pipe

There are many uncertain factors in deep hole drilling construction, and the drill pipe has complex force and large torque. Materials used for drill pipes and joints should have sufficient tensile, compressive, torsional, bending and shear strength. The threaded connection must be firm and reliable, easy to unscrew and have good sealing performance. In order to improve the strength of drill pipe, the wall thickness of drill pipe can be increased, but it is bound to increase the weight of drill pipe, increase the rotary resistance and correspondingly reduce the drilling depth of the same type of drilling rig. Aluminum alloy drill pipe is widely used in deep hole core drilling abroad, and its weight is about 1/2 of steel drill pipe. Due to the increase of wall thickness, it has strong wear resistance, long service life, strong impact resistance and corrosion resistance. It is suggested that when adding technical equipment, we should purchase aluminum alloy drill pipes to make a bold attempt.

At present, diamond wire rope coring drilling technology is often used for deep hole drilling of endogenetic metal. Φ φ75mm is the conventional drilling diameter, NQ series (Φ φ69.9mm) is used in foreign drill pipes, and Φ 71× 5 mm is used in domestic drill pipes.

In order to ensure that the deep hole construction reaches the design depth, φ60mm diameter is used as the backup diameter, and each geological prospecting unit should be equipped with a set of φ56×4.75mm rope drill pipe and coring drilling tool that meet the requirements of hole depth; In order to meet the needs of wall protection and plugging in complex strata, a set of φ54×6mm ordinary drill pipe and corresponding drilling tools should be equipped.

4. Requirements of coring tools

The existing wireline coring drilling tools can ensure the core recovery rate of general strata, but reliable coring drilling tools should be developed or introduced for core recovery in altered zone and broken zone. The quality of drilling tools for oil core drilling is reliable, but the outer diameter is large. According to the structure of oil coring drilling tools, how to develop φ75mm high-quality drilling tools will be explored and studied in practice.

5. Bit structure and service life requirements

Wireline coring drilling technology is used in deep hole drilling. Because the annular gap between the outer diameter of drill pipe and the hole wall is small, the pressure loss of flushing fluid is large when circulating at the bottom of the hole. With the deepening of drilling, the pump pressure will rise sharply, which will affect the normal operation. According to the hole depth, the degree of soft and broken rocks, whether mud is used, etc. The outer diameter of the drill bit should be appropriately increased and controlled between 2 and 5 mm. At the same time, the technical rules such as bit queuing should be followed.

The drill bit used for deep hole drilling should have high service life and drilling speed, prolong the working time of the drill bit at the bottom of the hole and reduce the tripping times. At present, most of the bits used in mechanical diamond coring drilling in China are impregnated with domestic synthetic diamonds, which have low diamond grade and short service life. When the drilling depth exceeds 1000m, the rotary resistance increases, and the high rotation speed required by the impregnated diamond bit cannot be started. Therefore, we can consider using natural diamond surface impregnated drill bit or developing long-life artificial diamond impregnated drill bit. In order to improve the drilling efficiency of hard rock, more diamond bits with different cutting surfaces have been prepared.

(2) Design and technology of deep hole drilling.

1. Deep hole drilling construction technology design

Deep hole drilling requires large investment and high geological requirements. In order to ensure that each drilling hole achieves the design purpose, there must be a complete construction technical scheme, that is, the single-hole construction organization design is compiled according to the drilling situation. The design includes the formation conditions of the mining area and the physical and mechanical properties of rocks, the selection of equipment and power, the selection of drilling tools and methods, the design of drilling structure and technical casing, flushing fluid and drilling parameters, quality and safety measures, efficiency and construction schedule design, construction organization and management, etc.

2. Drilling structure and drilling diameter

According to the requirements of geological design, the final hole diameter of drilling is determined first, and then the hole structure of drilling is determined according to the complexity of stratum, the type of flushing fluid used, the method and technology of hole protection, and the principle of economy and practicality.

The rocks of endogenetic metal deposits are hard, and there may be a lot of fracture zones. A borehole can see several or dozens of layers of ore. For shallow drilling at 2000m, the final hole diameter is determined as φ 75mm. If it is more than 2000m, the final well diameter is determined as φ 60mm. ..

The rock is relatively complete and the drilling structure is simple. The aperture is φ 1 10mm, and φ75mm rope coring is used to drill to the final hole, with φ60mm diameter as backup.

Bored rocks are relatively broken, joints and fissures are developed, and broken zones and faults appear frequently, so mud must be used to effectively protect the wall. The diameter of this borehole can be designed as φ 150mm or φ 130mm, and φ 127mm, φ 108mm and φ89mm technical casings are prepared. The conventional caliber is still φ75mm, and the standby caliber is φ60mm. Under special circumstances, φ75mm rope coring drill pipe can also be used as technical casing.

When geological design requires borehole logging or borehole geophysical method testing, the final borehole diameter should be determined according to the external diameter of downhole instruments, and the upper borehole structure should be determined in turn. The construction cost of deep hole is high, and the one-time investment is large, but the geological information obtained is also large. When the geological department has special requirements for drilling diameter, the design of the geological department shall prevail.

3. Formula and performance index of deep hole drilling flushing fluid

The complexity of deep hole drilling is several times higher than that of shallow hole, and the construction is difficult, so the performance of flushing fluid should meet the requirements of deep hole drilling. When entering a new area and lacking the data of deep strata, mud is used as flushing fluid from the opening, which simplifies the drilling structure and reduces the amount of technical casing running into the well while ensuring the stability of the hole wall. According to different formation conditions, the recommended mud formula and performance indicators are as follows:

(1) Non-dispersive low solid mud is used to stabilize the formation. Prepare 1m3 mud, add 30 ~ 40kg clay powder, 0 ~ 2kg Na2CO3 1~2kg hydrolyzed polyacrylamide (PHP) and 0.2kg calcium polyacrylate (CPA). Mud performance: relative density 1.02, viscosity 18 ~ 20s, and water loss less than 20mL/30min.

(2) Mud in water-sensitive stratum and collapsed stratum (potassium humate mud). Prepare 1m3 potassium humate slurry, and add 50-80kg of clay powder, 33-4kg of Na2CO3, 3-5kg of potassium humate and 0.5-0.8kg of Na-CMC. Mud properties: relative density 1. 15 ~ 1.20, viscosity 20 ~ 30s, water loss 4 ~ 10 ml/30min, and pH 9 ~ 10.

(3) Mud in fractured formation and water gushing formation (sodium carboxymethyl cellulose mud). Prepare 1m3 mud, and add 150 ~ 200kg clay powder, 5 ~ 150~200kg soda ash and 6kg Na-CMC. Mud performance: relative density 1.3, viscosity 30 ~ 40s, and water loss less than 8mL/30min.

When there are deep data, clean water with lubricant or solid-free flushing fluid can be selected for the whole layer to realize rapid drilling.

In deep hole drilling, mud should be reasonably mixed according to the complexity of the formation and good wall protection performance should be maintained, which will help improve drilling efficiency and drilling quality. Deep hole drilling must be equipped with mud performance indicator tester, good mud circulation system and effective sand removal equipment. With the gradual deepening of drilling and the change of lithology, the mud performance index should be adjusted appropriately.

4. Drilling technical parameters

WOB and rotational speed of deep hole drilling are different from those of ordinary shallow holes. Conventional drilling parameters can be used in the interval before 800 meters. When the hole depth is more than 800 m, as long as the drilling rig has the ability, it should keep the high speed as much as possible. Adjust the pressure in time according to the rock mechanical properties, drillability, bit lip shape and deviation prevention needs, and appropriately adjust the pump quantity according to the annular gap and drilling efficiency.

5. Measures to prevent well deviation

The stratum inclines, resulting in serious bending of the borehole. In Dahe copper mine area, Tongbai County, Henan Province, when the designed drilling top angle is 8 and the hole depth is 400m, the drilling trajectory deviates from the exploration line by 60 m.. A domestic drilling company is operating in Africa, and the hole depth is 1300m, which is 300m away from the exploration line. The serious bending of the borehole failed to drill through the expected concealed ore body, and the huge investment failed to achieve the geological purpose. The following measures should be taken to prevent deviation in deep hole drilling: controlling the gap between drill pipe and hole wall; Using different types of drills to control WOB；; When using the enlarged bit, use the centralizer; When changing the diameter, use steering drilling tools.

6. Deep well drilling and logging technology

In addition to core and geological logging, geophysical logging technology should be used in deep hole drilling to improve the utilization rate of drilling and obtain more geological information for geological prospecting.

7. Carry out research activities on deep hole drilling technology.

Deep hole drilling is characterized by large investment, long cycle and high risk. Drilling construction units should set up drilling technology research teams according to specific conditions, and focus on developing and solving the following technologies: drilling wall protection in mined-out areas around old mines, structural design of deep-hole drilling, technical casing drilling and pulling, inclinometer while drilling and deviation correction, deep-hole directional drilling and branch hole construction technology, and drilling coring technology in complex strata.

Four, the organization and management of deep hole drilling

1. Deep hole drilling construction management

Deep hole drilling includes construction organization and drilling technology. The selection and matching of drilling technology and equipment has been described before, and the organization and management of production are also very necessary. Our bureau has little experience in ultra-deep drilling construction. This year, the Third Team completed a drilling with a depth of 1076.50m in the anomaly verification drilling of iron ore in Yicheng County, Shanxi Province, which was the first deep-hole drilling for endogenetic metal in our bureau and accumulated some deep-hole construction experience. However, this tunnel has many accidents, too long construction time and low economic benefit.

On the premise of matching equipment and instruments, deep-hole drilling construction needs high-level technical management personnel to guide drilling operations, and more skilled technical workers to operate. In the future, more ultra-deep drilling holes will be designed in deep exploration, and how to ensure the completion of the task in drilling construction will be a problem we face. At present, the two-level management departments of the bureau and team should have drilling technicians responsible for the management and technical research of drilling production, and need to train a group of skilled workers. In terms of equipment purchase, technical research and personnel training, the focus is on deep-hole drilling construction.

2. Training and use of drilling technicians

In order to give full play to the role of existing hydraulic feed rigs and full hydraulic rigs, actively serve geological exploration and realize economic benefits, it is necessary to optimize organizational management methods. Technical and management personnel shall be responsible for the use and maintenance of the drilling rig. It is suggested that each drilling rig should be equipped with 7 skilled workers (1 team leader, squad leader 3 and driller 3), and the remaining 8 ~ 10 workers can be solved by hiring temporary workers. Drilling technicians should be trained and used regularly. The working mode is mainly three shifts and eight hours, which not only ensures the normal production, but also maintains the good physical strength of workers and maximizes the potential of equipment and human resources. 1500 ~ 2000 m deep hole construction, with 4 shifts and 6 hours working system, equipped with skilled workers and 2 ~ 3 technicians.

At present, there are 30 sets of core drilling rigs in the world. According to the configuration of 7 skilled workers, each rig needs 2 10 people. However, at present, there are few skilled workers with drilling qualifications, and they are older, so it is necessary to recruit a group of contract workers to operate the drilling rig. The experience of Henan Coalfield Geology Bureau in recruiting contract workers is worth learning. First of all, these workers passed the technical training of drilling specialty in technical school; Secondly, sign long-term employment contracts with workers through social security departments; Thirdly, contract workers implement enterprise employment management, and the unit pays basic old-age insurance, medical insurance, unemployment insurance, work injury insurance and maternity insurance for employees, and the payment base, payment ratio and treatment are treated equally with employees of social enterprises; Finally, contract workers enjoy equal treatment during their work. The status of the workers recruited is a contract system, which belongs to the local labor and social security department. In addition to contract skilled workers, ordinary workers are also needed on drilling rigs. Considering the particularity of the geological prospecting industry, these people can sign temporary employment contracts with workers by means of on-demand employment to ensure that the drilling rig is full and give full play to the role of technical equipment.

3. Matching of drilling equipment

In recent years, the drilling equipment of our bureau has been updated by injecting the purchase fee of two rights equipment, but there is a problem that the drill pipe is not matched in application. For example, XY-5 drilling rig is equipped with φ7 1mm rope drill pipe at the time of purchase, which can guarantee the construction under normal circumstances. When the rock stratum is complex, the drilling hole collapses and leaks, and it is necessary to frequently lift the drill or inject mud to protect the wall, the rope drill pipe loses its advantage. It is suggested that each geological team should be equipped with a set of ordinary drill pipes to meet the needs of drilling production.

4. Preferential policies and requirements

In order to ensure the existing drilling equipment to play its due role as a whole, the geological prospecting units of our bureau give priority to their own internal drilling rigs when outsourcing the drilling workload, so as to create a more relaxed internal environment for them. At present, the use of drilling equipment in this bureau is based on teams. If we concentrate on contracting projects to the society, we should take the geotechnical company and the fourth team as the leaders and give full play to their first-class qualifications and management advantages. All kinds of equipment in the bureau should establish ledgers, improve the effective utilization rate of the equipment, extract the depreciation expenses of the equipment on time, and not lease the equipment to individuals.