(1) SCG three-tube coring drilling tool
SCG three-tube coring drilling tool developed by Prospecting Engineering Technology Research Institute of 3 13 Geological Team of Anhui Bureau of Geology and Mineral Resources can take undisturbed core samples from Quaternary and Tertiary strata. When drilling, the core directly enters the third layer of organic transparent plastic pipe. When coring, the plastic pipe is directly pulled out together with the core, and both ends of the plastic pipe are sealed to ensure that the core sample is free from pollution, water loss and secondary weathering and remains intact for a long time. The drilling tool has obtained the national patent (patent number: ZL20082004 1782.3).
1. Drilling tool structure
SCG three-tube single-acting undisturbed coring drilling tool is mainly composed of outer tube assembly, inner tube single-acting assembly and core holder (Figure 4-2). Wherein, the outer tube assembly comprises an upper joint, an outer tube, an outer tube nipple and an outer drill bit; Inner tube single-acting assembly consists of upper limit steel ball, bearing, bearing bush, lower bearing seat, sealing ring, shaft, upper adjusting locking nut, inner pipe joint, lower adjusting locking nut, shaft valve spring, ball valve, valve seat, inner tube seat or inner tube leading drill bit. The core-containing device consists of the valve cover of the pipe, the piston sealing ring, the piston, the ball valve, the core-containing pipe and other parts.
Figure 4-2 Structure Diagram of SCG Three-pipe Undisturbed Coring Drilling Tool
1-multipurpose connector; 2- outer tube; 3- steel ball; 4— Upper bearing; 5— Bearing bush; 6— Lower bearing; 7— Bearing seat; 8— sealing ring; 9 axis; 10-Lock the mother; 1 1- inner pipe joint; 12-Lock the mother; 13-spring; 14- ball valve; 15- valve seat; 16- bonnet; 17- sealing ring; 18-piston; 19- ball valve; 20— Inner tube; 21-heart tube (plexiglass tube); 22— Outer pipe nipple and clamping device; 23— Heart tube seat; 24— Drill bit; ? High-level bit; ? a little
2. Working principle of drilling tools
In the process of drilling, the outer tube assembly of drilling tool is used to transmit the rotating torque of reaming drilling, and the inner tube assembly does not rotate to reduce core disturbance. At the same time, the core-containing tube (plexiglass tube) placed in the inner tube makes the core enter without pollution and keeps its original sample. During drilling, mud passes through the water diversion hole of the upper joint and is sent to the bottom of the drill bit through the gap between the inner and outer pipes, which cools and lubricates the drill bit and returns to the ground with chips. No mud is directly washed in the inner tube and the core containing tube. In the process of tripping in, a small amount of mud in the containing tube will be discharged into the gap between the inner tube and the outer tube through the one-way valve of the containing tube and the one-way valve with the core entering, and return to the ground. After the last drilling, after the drilling tool is lifted off the surface, pull out the inner and outer pipes, remove the inner pipe joint, connect the special joint, pump out the piston of the enclosure pipe by pumping mud, and push out the whole enclosure pipe, so that the core taken out can be kept in a good original state. Then seal both ends of the containment tube and mark the direction, length and hole depth of the rock sample.
If the soft mud layer is drilled, it can be replaced by an advanced inner tube press-in bit or a flap-type outer bit. By adjusting the spindle lock of the inner tube, the matching length of the inner tube and the outer tube can be fine-tuned.
3. Special bit and core catcher
In order to meet the requirements of taking undisturbed samples from different formations, a special bit and sticking device are designed. Its drill bit structure and coring device design have the following characteristics.
(1) Selection of Abrasive for Bit
1) cemented carbide bit is selected for quaternary loose layer. Generally, octagonal columns and square columns are used, and spherical and octagonal alloys are used when encountering coarse gravel layers.
2) Cemented carbide and diamond compact bits are selected for Tertiary and 4 ~ 6 layers.
3) Diamond (mainly hot-pressed impregnated) or needle-like alloy bit is selected for gravel formation.
(2) Lip design
The bit lip of the Quaternary loose layer bit is designed to be stepped and ribbed, so as to prevent the drilling hole from shrinking and blocking the drilling tool, and reduce the suction effect when running the drilling tool (Figure 4-3). It is best to design the bottom lip of the drill bit in gravel stratum as a flat bottom to reduce the vibration during drilling and improve the service life of the drill bit.
(3) Waterway design
Soft stratum is easy to be washed away by water during drilling, and the design of bit channel should avoid mud directly washing and polluting the core. Therefore, bottom injection and side injection bit structures are usually used to ensure that mud will not wash the core during drilling, but also to cool the bit and remove cuttings (Figure 4-3).
Figure 4-3 Special coring bit and coring device
(a) An alloy drill bit is injected at the bottom side; (b) an alloy drill bit sprayed on the bottom of the outer rib; (c) advanced coring device for ring cutter; (d) a flap coring device; (e) Pricked coring device
(4) Design of core catcher
In addition to the conventional bit clamp spring, the triple pipe drilling tool has also designed advanced press-in coring device, flap coring device and spring tongue coring device on the bit body or sub according to different complicated conditions, as shown in Figure 4-3.
4. Application effect
SCG three-tube undisturbed sample coring drilling tool has been popularized and applied in 2 1 geological exploration drilling holes and scientific drilling holes (including 4 environmental science drilling holes, 8 seismic fault section sampling holes, 7 urban three-dimensional geological survey holes and 2 geological exploration holes). The cumulative drilling workload is 6488.5 1m, and the deepest drilling hole is 862.66m m. See Figure 4-4 for the undisturbed sample. See table 4- 1 for the scientific drilling and coring quality index of construction, and table 4-2 for the coring yield of different formations.
Figure 4-4 Triple Tube Without Interference with Core Samples
Table 4- 1 List of quality indicators of drilling and coring in construction science
Table 4-2 List of Core Recovery in Different Strata
(2) Semi-closed coring drilling tool
Semi-combined pipe drilling tool is a coring tool which is improved on the basis of ordinary single-acting double pipe and does not disturb the core (sample). At present, the commonly used semi-assembled drill pipes in China include KZ series (designed by Institute of Exploration Technology, Chinese Academy of Geological Sciences), SDB series (designed by Chengdu Gong Li Drilling Equipment Co., Ltd.) and WX series (designed by Wuxi Drilling Tool Factory Co., Ltd.). The drilling tool shows a good performance advantage of undisturbed sampling when drilling complex broken loose strata.
1. Drilling tool structure
The semi-closed tube coring drilling tool consists of an outer tube, a single-acting assembly, a water diversion joint, a semi-closed inner tube assembly, a core clamping system and a drilling isolation head. KZ and SDB series semi-connected coring drilling tools are shown in Figure 4-5 and Figure 4-6.
Figure 4-5 KZ single-acting double-pipe drilling tool
1-upper connector; 2— Bearing cavity; 3- spring; 4- mandrel; 5- reamer; 6— Nut; 7— Inner pipe joint; 8- outer tube; 9— Inner tube; 10- righting ring; 11-circlip seat; 12-circlip; 13;
B 1- bearing; B2 bearing; B3-waterproof steel ball; B4- elastic washer
2. Working principle of drilling tools
According to the invention, the inner tube of a common single-acting double-tube is designed as a semi-combined tube. When drilling, the inner tube and the outer tube rotate, and the semi-combined tube is in a non-rotating state. The core enters the semi-composite pipe, and the mud reaches the waterproof drill bit through the annular gap between the inner pipe and the outer pipe, and then returns to the orifice from the gap between the outer pipe and the hole wall, so that the core in the semi-composite pipe is not polluted and stirred by mud erosion. When coring, the original core can be taken out of the half tube by pulling the half tube out of the outer tube and removing the clamp of the half tube. Thus, the interference, confusion and structural deformation caused by the traditional method of knocking on the outer tube or core pulling are avoided. The waterproof and anticorrosive drill bit matched with this drilling tool is shown in Figure 4-7.
3. Application effect
The semi-tubular coring tools of KZ, SDB and WX have been used in five drilling projects of Wenchuan earthquake fault zone scientific drilling project. Under rare and complicated formation conditions, the original state of the core is guaranteed (Figure 4-8), and the average core recovery rate is over 90%, which fully meets the requirements of scientific drilling and provides high-quality physical samples for geoscience research. For example, the 3 13 geological team of Anhui Bureau of Geology and Mineral Resources scientifically drilled the WFSD 3 hole in the Wenchuan earthquake fault zone, and the final hole depth was 1502.30m, and the whole hole was cored with a semi-closed tube, with an average core recovery rate of 92.5%. See Table 4-3 for statistical data of semi-closed tube coring drilling with different diameters.
Figure 4-6 SDB semi-closed tube coring drilling tool
1-outer tube; 2- semi-closed tube; 3- Zhong Ding; 4- grit chamber; 5— One-way valve mechanism; 6— Upper single-acting mechanism; 7 axis; 8— Single-acting mechanism
Figure 4-7 Typical Waterproof and Corrosion-resistant Drill Bit
Figure 4-8 Pictures of Undisturbed Core Samples
Table 4-3 List of Drilling Data 4-3 WFSD 3-hole Core
(3) Hydraulic piston coring drilling tool
The hydraulic piston coring drilling tool developed by Beijing Institute of Survey and Engineering is mainly used to take undisturbed cores (samples) in soft or semi-consolidated strata. The drilling tool has obtained the national patent (patent number: ZL 201120295071).
1. Drilling tool structure
The hydraulic piston coring drilling tool consists of an inner pipe assembly, a fishing joint, a shear pin, an inner pipe sealing ring, an outer pipe sealing ring, a quick release device, a drill pipe, a drill collar, a lower support bearing, a buffer, a piston head and sealing ring, a cutting shoe and an outer drill bit, as shown in Figure 4-9.
Figure 4-9 Structure and principle of hydraulic piston coring drilling tool
2. Working principle of drilling tools
The drilling tool inner tube assembly is positioned and sealed in the rope coring outer tube. The high-pressure mud from the surface pump pressurizes the inner pipe assembly through the drill pipe, and the pressure gradually increases until the safety pin is cut, and the inner pipe is instantly pressed into the stratum. Its screw-down speed can reach 6 ~12m/s. Because of the high screw-down speed, the drilling tool does not rotate, the core disturbance is minimal, and the upper and lower parts are not confused, and the core recovery rate reaches 100%. Because the piston separates mud, the core is pollution-free, and the core taken out is fine, in-situ and fidelity.
3. Method and effect of use
When sampling in soft (loose) formation, the outer tube and the outer bit mainly play the role of reaming after coring, and the inner tube and the cutting shoe are used for static pressure to quickly cut into the formation for coring. After the core enters the inner tube, the inner tube assembly is salvaged with a rope coring fisherman, and the undisturbed core sample is taken out. Then the bottom of the last sampling hole is reamed with the outer pipe drilling tool, and then another set of sampling drilling tools is put into the drill pipe, and so on.
The coring drilling tool has been sampled in deep water in the South China Sea for three times, and the success rate and undisturbed recovery rate of core reach 100%, which has achieved good application effect.