A borehole wall protection device for collapsed and fractured rock formations in geological drilling
By using a combination of a jetting nozzle and a rubber plug to inject cement slurry into the borehole, the technical problem of rock blocks in collapsed and fractured rock strata was solved, an effective wall protection effect was achieved, the problem of deep wall protection was solved, the cost of wall protection was reduced, and the borehole formation rate was improved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- POWERCHINA BEIJING ENG CORP
- Filing Date
- 2025-08-25
- Publication Date
- 2026-06-30
AI Technical Summary
In collapsed and fractured rock formations, existing wall protection methods are ineffective in preventing rock fragments from falling off, leading to stuck drill bits. Furthermore, existing technologies cannot effectively improve the hole formation rate, especially in deep boreholes where wall protection costs are high.
A combination device of a jetting cylinder and a rubber plug is used. Cement slurry is sprayed onto the inner wall of the borehole through the jetting cylinder. The cement slurry binds the rocks and forms a solid protective wall. After the jetting cylinder is connected to the drill rod, it goes deeper into the borehole. The rubber plug expands and fits against the inner wall of the borehole, separating the borehole space and preventing groundwater from affecting the protective wall effect.
It effectively prevents rock fragments from falling off, increases the hole formation rate, reduces wall protection costs, and is suitable for deep boreholes, ensuring smooth extraction of drill bits and subsequent drilling operations.
Smart Images
Figure CN224432501U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the technical field of geological drilling, and in particular to a borehole wall protection device for collapsed and broken rock strata in geological drilling. Background Technology
[0002] Conducting geological drilling in collapsed and fractured rock formations is a significant challenge in the field. For example, rock fragments breaking off from these formations can cause the drill bit to become stuck, severely impacting drilling operations and even preventing the extraction of the drill string from the strata. This results in the abandonment of the borehole and drilling tools, leading to substantial economic losses. Statistics show that borehole wall protection costs account for 20% of the total cost and 30% of the cost per borehole in the drilling industry. With advancements in drilling technology, drilling depths are continuously increasing, and drilling areas are expanding from land to sea. This has led to a corresponding rise in wall protection costs as drilling difficulty increases.
[0003] Currently, the main method for borehole wall protection involves adding various drilling muds and flushing fluids to the borehole. These methods are divided into two types: physical and chemical. Physical methods primarily utilize casing to achieve the required wall protection, while chemical methods use various slurries and flushing fluids to ensure lubrication and viscosity within the borehole. Currently, chemical methods are still under development, while among physical methods, only casing is commonly used.
[0004] The casing method is generally suitable for shallow, fractured rock formations; it is ineffective in deeper, collapsed, fractured rock formations. Chemical methods are also unreliable and cannot completely prevent rock fragmentation within the borehole. Utility Model Content
[0005] In order to reduce the probability of problems such as drill jamming caused by rock fragments falling off and to improve the hole formation rate, this utility model provides a drilling wall protection device for collapsed and broken rock strata in geological drilling.
[0006] This utility model provides a borehole wall protection device for collapsed and fractured rock formations in geological drilling, which adopts the following technical solution:
[0007] A hole-keeping device for collapsed and fractured rock formations in geological drilling includes a jetting cylinder and a rubber plug. The rubber plug is fixed at one end of the jetting cylinder in the axial direction, and a reverse drill bit is provided at the other end of the jetting cylinder. Multiple grouting holes are opened on the jetting cylinder. After the hole-keeping device for collapsed and fractured rock formations in geological drilling is connected to the drill rod, the rubber plug is in a compressed and expanded state.
[0008] In one specific implementation, the diameter of the spraying cylinder is equal to the borehole diameter minus 4 mm, the wall thickness of the spraying cylinder is 10-20 mm, and the diameter of the spraying hole is 10 mm.
[0009] In one specific implementation, the spray cylinder has an input pipe at one end with the rubber stopper, and the input pipe is connected to the spray cylinder.
[0010] In one specific implementation, the end of the rubber plug away from the injection cylinder is provided with an abutment ring.
[0011] In one specific implementation scheme, the borehole wall protection device for collapsed and fractured rock strata in the geological drilling is connected to the drill rod to form the first section of the drill rod.
[0012] In summary, this utility model has the following beneficial effects:
[0013] 1. By spraying cement slurry into the inner wall of the borehole, the cement slurry binds stones and other materials together, thus reinforcing the inner wall of the borehole and achieving a protective effect.
[0014] 2. The shotcrete device can be connected to the drill rod and follow the drill rod into the borehole, enabling it to protect the borehole wall in deep boreholes. Attached Figure Description
[0015] Figure 1 This is an overall structural diagram of the wall protection device.
[0016] Figure 2 This is a cross-sectional view of the wall protection device.
[0017] Explanation of reference numerals in the attached diagram: 1. Injection tube; 2. Rubber plug; 3. Inlet pipe; 4. Abutment ring; 5. Reverse drill bit; 6. Injection hole. Detailed Implementation
[0018] The following combination Figures 1-2 The present invention will be described in further detail below.
[0019] Reference Figure 1 and Figure 2 In geological drilling, a borehole wall protection device for collapsed and fractured rock formations includes a jetting cylinder 1 and a rubber plug 2. The rubber plug 2 is fixed at one end along the axis of the jetting cylinder 1, and a reverse drill bit 5 is fixed at the other end of the jetting cylinder 1. One end of the rubber plug 2 is fixed to the jetting cylinder 1, while the other end can slide along the axis of the jetting cylinder 1, allowing the rubber plug 2 to expand and contract in the direction of the diameter of the jetting cylinder 1. An abutment ring 4 is fixed to the free end of the rubber plug 2.
[0020] Reference Figure 1 and Figure 2The spraying cylinder 1 has multiple spray holes 6 on its circumferential surface. One end of the spraying cylinder 1, equipped with a rubber plug 2, is connected to an input pipe 3 for supplying cement slurry into the spraying cylinder 1. A contact ring 4 is fitted onto the input pipe 3. The outer diameter of the spraying cylinder 1 is equal to the borehole diameter minus 4mm. The wall thickness of the spraying cylinder 1 is 10-20mm, and it is generally made of seamless steel pipe. The diameter of the spray holes 6 on the spraying cylinder 1 is 10mm, and the distance between adjacent spray holes 6 is 20mm. The height of the rubber plug 2 is 150mm.
[0021] After the injection nozzle 1 is inserted into the borehole, cement slurry is introduced into the input pipe 3, allowing cement slurry to be sprayed onto the inner wall of the borehole to achieve wall protection. Specifically:
[0022] The drill bit is slowly pulled out of the borehole from the fractured rock strata.
[0023] The input pipe 3 is threadedly connected to the drill rod of the drilling rig, forming the first section of the drill rod with the injection cylinder 1. As the threads are screwed in, the drill rod gradually applies pressure to the abutment ring 4, causing the rubber plug 2 to expand outwards under pressure. The connection between the input pipe 3 and the drill rod is complete, and the rubber plug 2 expands to the required diameter. The expanded rubber plug 2 then conforms to the inner wall of the borehole.
[0024] Water is pumped out of the borehole using pumping equipment such as water pumps, leaving the borehole dry or with little water.
[0025] The drill rod is lowered back into the borehole, and the jetting nozzle 1 is moved to the fractured rock section of the borehole. A high-pressure pump delivers cement slurry mixed with an accelerator or quick-setting agent into the jetting nozzle 1 through the input pipe 3. The jetting nozzle 1 sprays the cement slurry onto the inner wall of the borehole while the drill rod descends. The cement slurry adheres to the inner wall of the borehole and binds any rocks or other debris there. After the cement slurry solidifies, the rocks and other debris are fixed to the borehole wall by the adhesive effect of the cement slurry, achieving a wall protection effect.
[0026] The expanded rubber plug 2 divides the borehole into upper and lower sections. Subsequent wall protection work below the rubber plug 2 will not significantly affect the area above it. Furthermore, during wall protection, if the groundwater content is sufficient and water seeps into the borehole from the inner wall, the rubber plug 2's barrier function can prevent groundwater from flowing into the wall protection area, thus avoiding any impact on the cement slurry.
[0027] After the cement slurry on the borehole wall has solidified for a certain period of time, restart the drilling rig and rotate the drill rod at a low speed to gradually pull the drill rod out of the borehole from bottom to top. During the process of pulling the drill rod out of the borehole, the reverse drill bit 5 rotates to repair the hole from bottom to top, eliminating uneven protrusions formed on the borehole wall during the wall protection process, ensuring that the entire drill bit is smoothly pulled out of the borehole and that subsequent drill bits can smoothly enter the borehole.
[0028] The above are all preferred embodiments of this utility model, and are not intended to limit the scope of protection of this utility model. Therefore, all equivalent changes made to the structure, shape and principle of this utility model should be covered within the scope of protection of this utility model.
Claims
1. A borehole wall protection device for collapsed and fractured rock formations in geological drilling, characterized in that: It includes a jetting cylinder (1) and a rubber plug (2). The rubber plug (2) is fixed at one end of the jetting cylinder (1) in the axial direction. The other end of the jetting cylinder (1) is provided with a reverse drill bit (5). Multiple grouting holes (6) are opened on the jetting cylinder (1). After the hole wall protection device for collapsed and broken rock layers in the geological drilling is connected to the drill rod, the rubber plug (2) is in a compressed and expanded state.
2. The borehole wall protection device for collapsed and fractured rock strata in geological drilling according to claim 1, characterized in that: The diameter of the spraying cylinder (1) is equal to the borehole diameter minus 4mm, the wall thickness of the spraying cylinder (1) is 10-20mm, and the diameter of the spraying hole (6) is 10mm.
3. The borehole wall protection device for collapsed and fractured rock strata in geological drilling according to claim 1, characterized in that: The spray cylinder (1) has an input pipe (3) at one end with the rubber stopper (2), and the input pipe (3) is connected to the spray cylinder (1).
4. The borehole wall protection device for collapsed and fractured rock strata in geological drilling according to claim 1, characterized in that: The rubber plug (2) has an abutment ring (4) at the end away from the spray cylinder (1).
5. The borehole wall protection device for collapsed and fractured rock strata in geological drilling according to claim 1, characterized in that: In geological drilling, the hole wall protection device for collapsed and fractured rock strata is connected to the drill rod to form the first section of the drill rod.