Underground coal mine air-tight seal blowout preventer

Abstract

The invention belongs to the technical field of drilling tools, and relates to a coal mine underground air-tight seal blowout preventer, which is used for realizing air-tight seal of a drill rod and preventing leakage of gas and rock debris in drilling construction, and comprises a pressure balancing device, a gas-slag separation device and an air cushion sealing device which are sequentially arranged on a special-shaped drill rod in a sleeving manner in the direction far away from a drill hole, and the pressure balancing device, the gas-slag separating device and the air cushion sealing device are communicated with the drill hole. The annular gap is dynamically adjusted through the pressure balancing device, efficient air sealing of the special-shaped drill rod is achieved in combination with an air film formed by the air cushion sealing device, and the failure problem caused by abrasion of traditional contact type sealing is avoided. Meanwhile, the gas-slag separation device effectively separates and treats gas and rock debris, and safe and reliable technical guarantee is provided for coal mine underground drilling construction.

Description

Technical Field

[0001] The invention belongs to the technical field of drilling tools and relates to an air-sealed blowout prevention device in an underground coal mine. Background Art

[0002] Gas extraction drilling and other types of drilling are common and critical processes in underground coal mines. However, gas blowouts are a common occurrence during these operations, and have become a major hazard to mine safety. When a gas blowout occurs, the pressure within the hole rises dramatically in a very short period of time. Subsequently, a large amount of gas, accompanied by high-speed flying debris, violently gushes out of the hole. This phenomenon has multiple negative impacts. First, the worksite environment deteriorates rapidly. The pervasive gas and flying debris cause significant inconvenience to workers, severely impacting their work efficiency and operational accuracy. More seriously, it significantly increases safety risks. Gas is a flammable and explosive gas. Under certain conditions, a gas blowout can become a trigger for catastrophic accidents such as gas explosions, posing a significant threat to overall mine safety and the lives of personnel.

[0003] Given the serious hazards posed by gas blowouts, orifice blowout preventers (BOPs) have become a necessary safety measure during underground coal mine drilling. Currently, existing BOPs primarily utilize rubber pads or fillers in the annular gap between the drill pipe and the BOP to achieve sealing. This traditional sealing method can be effective under certain conditions, preventing gas and rock debris leakage to a certain extent for standard drill pipe shapes. However, with the continuous advancement of coal mining technology, drill pipe shapes are becoming increasingly diverse. When it comes to drill pipes with unusual shapes, such as triangular or grooved, traditional sealing methods become increasingly limited. Due to the complex surface structures of these drill pipes, traditional rubber pads or fillers struggle to form a tight seal with the drill pipe surface, failing to achieve an effective seal. Consequently, gas and rock debris can still leak through the gaps, failing to achieve the desired BOP prevention goal. Furthermore, traditional contact sealing methods present a significant challenge: direct contact friction between the sealing components and the drill pipe. Over extended drilling operations, this friction can cause wear on the sealing components, reducing sealing performance and ultimately leading to seal failure. Once the seal fails, the leakage of gas and rock chips will become more serious, further exacerbating the safety risks at the work site.

[0004] In view of the technical difficulties existing in the above-mentioned existing technologies, it is urgently necessary to propose a new sealing solution for blowout preventers to provide reliable technical support for the safety of underground drilling construction in coal mines. Summary of the Invention

[0005] In view of this, the purpose of the present invention is to provide an air-tight blowout preventer device for underground coal mines to solve the sealing problem between special-shaped drill rods and blowout preventers. By forming a pressure gas film at the contact point between the two through pressurized gas, efficient sealing is achieved to prevent the leakage of harmful gases such as gas and rock cuttings, thereby ensuring the safety of underground drilling construction in coal mines.

[0006] In order to achieve the above object, the present invention provides the following technical solutions:

[0007] An underground coal mine air-sealing blowout prevention device is used to achieve an airtight seal on a drill pipe and prevent gas and rock debris leakage during drilling construction. The device comprises a pressure balancing device, a gas-slag separation device, and an air cushion sealing device, which are sequentially sleeved on the special-shaped drill pipe in a direction away from the drill hole. The pressure balancing device, the gas-slag separation device, and the air cushion sealing device are connected to the drill hole.

[0008] The pressure balancing device is provided with a deformable rubber sleeve that can move axially along the drill pipe, and the inner cavity of the pressure balancing device is divided into a feedback pressure chamber and an air cushion pressure chamber by the deformable rubber sleeve. The feedback pressure chamber is connected to the drill hole, and the air cushion pressure chamber is provided with an air connection hole connected to the external air intake system. The deformable rubber sleeve moves axially under the pressure difference between the feedback pressure chamber and the air cushion pressure chamber.

[0009] The pressure balancing device is provided with a guiding inclined surface in the direction of the force of the feedback pressure chamber, so that when the deformable rubber sleeve is subjected to the pressure of the feedback pressure chamber, the guiding inclined surface squeezes the deformable rubber sleeve to reduce its diameter, thereby reducing the annular space gap between the drill pipe and the deformable rubber sleeve;

[0010] The air cushion sealing device includes an air cushion ring and an outer shell arranged from the inside to the outside, the inner cavity of the air cushion ring is connected to the drilled hole, and an annular air channel is provided between the air cushion ring and the outer shell, a plurality of jet holes connected to the annular air channel are provided on the air cushion ring, an air connection hole connected to the external air intake system is provided on the outer shell, and the air cushion pressure chamber and the annular air channel are connected through the air connection hole on the outer shell and the air connection hole of the air cushion pressure chamber.

[0011] Furthermore, the guide slope adopts a tapered structural design, with a larger size at the opening and gradually narrowing along the inner direction;

[0012] The deformable rubber sleeve is provided with a corresponding inclined surface structure that matches the guiding inclined surface.

[0013] Furthermore, an annular groove is provided on the outer side of the air cushion ring to form a closed annular air passage with the outer shell.

[0014] Furthermore, the jet hole sprays the pressurized gas in the annular air passage toward the surface of the special-shaped drill pipe, and the jetting direction is directed toward the gas-slag separation device to form an air film to prevent gas leakage.

[0015] Furthermore, the pressure balancing device, the gas-slag separation device and the air cushion sealing device are sealed and connected via a connector to prevent gas and rock debris from leaking from the connection between the pressure balancing device, the gas-slag separation device and the air cushion sealing device.

[0016] Furthermore, the feedback pressure chamber is arranged at an end of the pressure balancing device close to the drill hole, and is used to push the deformable rubber sleeve to move toward an end away from the drill hole;

[0017] The guide slope is arranged at an end of the pressure balancing device away from the drill hole to squeeze the deformable rubber sleeve.

[0018] Furthermore, the inner cavity of the gas-slag separation device is connected to the drill hole, and is provided with an air intake port and a slag discharge port connected to its inner cavity. The slag discharge port is used to discharge rock cuttings and drilling fluid during normal drilling, and the air intake port is used to suck away gas when performing blowout prevention holes to reduce the pressure of gas when entering the air cushion sealing device.

[0019] Furthermore, during normal drilling, the pressure in the air cushion pressure chamber is greater than the pressure in the feedback pressure chamber, and the pressurized gas pushes the deformable rubber sleeve to a position away from the guide slope, so that the annular space between the drill pipe and the deformable rubber sleeve is fully opened, and the drilling fluid and rock cuttings are recovered through the gas-slag separation device;

[0020] When the blowout prevention hole is opened, the pressure in the feedback pressure chamber rises, so that the pressure in the air cushion pressure chamber is lower than the pressure in the feedback pressure chamber. The pressurized gas pushes the deformed rubber sleeve to move toward the side close to the guide bevel. The guide bevel squeezes the deformed rubber sleeve to reduce its diameter, thereby reducing the annular space gap between the drill pipe and the deformed rubber sleeve, so that the pressure of the gas entering the gas-slag separation device and the air cushion sealing device is lower than or equal to the pressure in the air cushion pressure chamber, and the gas leakage is prevented by the air film formed by the air cushion sealing device.

[0021] The beneficial effects of the present invention are:

[0022] 1. This invention provides an airtight blowout prevention device for underground coal mines, used for preventing blowouts and sealing drill pipes. Designed specifically to address the sealing challenges faced by irregularly shaped drill pipes, the device comprises a pressure balancing device, a gas-slag separation device, and an air cushion seal. This device uses pressurized gas to create an airtight seal in the annular space, effectively sealing irregularly shaped drill pipes while also avoiding the failure of traditional contact seals due to long-term wear. Its simple structure and convenient operation provide safe and reliable technical support for drilling operations.

[0023] 2. The pressure-balancing device adjusts the annular gap via a movable, deformable rubber sleeve, dynamically adapting to the construction conditions. During normal drilling, the air cushion pressure chamber pushes the rubber sleeve to open the gap, facilitating the discharge of drilling fluid and cuttings. During jetting, the pressure in the feedback pressure chamber rises, squeezing the rubber sleeve to reduce the gap and restrict gas flow. The air cushion seal utilizes high-pressure gas ejected from the jet orifice to form an air film on the drill pipe surface, effectively preventing gas and cuttings from escaping. This non-contact air film seal, combined with a dynamic adjustment mechanism, significantly improves sealing efficiency and durability, ensuring construction safety.

[0024] 3. The gas-slag separation device processes gas and rock debris separately through the air intake and slag discharge ports, avoiding the safety hazards associated with mixed emissions. The air intake extracts gas, while the slag discharge port removes solid debris, ensuring a clean and stable construction environment. This feature not only improves the accuracy of gas management but also reduces the risk of rock debris clogging the device, providing additional safety for underground coal mine drilling operations and significantly improving overall construction efficiency.

[0025] Other advantages, objects, and features of the present invention will be described in part in the following description and, in part, will be apparent to those skilled in the art upon examination of the following description or may be learned from practice of the present invention. The objects and other advantages of the present invention may be realized and obtained through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention will be described in detail below with reference to the accompanying drawings, in which:

[0027] Figure 1 Schematic diagram of the structure of a gas-sealed blowout prevention device for an underground coal mine in an embodiment;

[0028] Figure 2 for Figure 1 Schematic diagram of the local structure in.

[0029] Figure markings: 1-drill bit; 2-special-shaped drill rod; 3-pressure balancing device; 4-air cushion sealing device; 5-gas-slag separation device; 301-guide slope; 302-air cushion pressure chamber; 303-deformable rubber sleeve; 304-feedback pressure chamber; 401-housing; 402-jet hole; 403-air cushion ring; A-air connection hole; B-air suction port; C-slag discharge port. DETAILED DESCRIPTION

[0030] The following describes the embodiments of the present invention by means of specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the illustrations provided in the following embodiments are only schematic illustrations of the basic concept of the present invention, and the following embodiments and features in the embodiments can be combined with each other without conflict.

[0031] Among them, the accompanying drawings are only for illustrative purposes and represent only schematic diagrams rather than actual pictures, and should not be understood as limiting the present invention. In order to better illustrate the embodiments of the present invention, some parts of the accompanying drawings may be omitted, enlarged or reduced, and do not represent the dimensions of actual products. For those skilled in the art, it is understandable that some well-known structures and their descriptions may be omitted in the accompanying drawings.

[0032] The same or similar numbers in the drawings of the embodiments of the present invention correspond to the same or similar parts; in the description of the present invention, it should be understood that if there are terms such as "upper", "lower", "left", "right", "front", "back", etc. indicating directions or positional relationships, they are based on the directions or positional relationships shown in the drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operate in a specific direction. Therefore, the terms describing the positional relationship in the drawings are only used for illustrative purposes and cannot be understood as limiting the present invention. For ordinary technicians in this field, the specific meanings of the above terms can be understood according to specific circumstances.

[0033] Example 1: Air-sealed blowout preventer under normal drilling conditions

[0034] like Figure 1 and Figure 2 As shown, this embodiment provides an airtight blowout prevention device for underground coal mines, used to airtightly seal a special-shaped drill pipe during drilling operations and prevent gas and rock debris leakage. The device includes a pressure balancing device 3, a gas-slag separation device 5, and an air cushion sealing device 4. These are sequentially sleeved onto the special-shaped drill pipe in a direction away from the borehole and communicate with the borehole through an internal passage.

[0035] The specific device structure is as follows:

[0036] 1. Pressure balancing device

[0037] The pressure-balancing device 5 houses a deformable rubber sleeve 303 that can move axially along the shaped drill pipe 2. The deformable rubber sleeve divides the internal cavity of the pressure-balancing device into two independent areas: a feedback pressure chamber 304 on the side closest to the borehole and an air cushion pressure chamber 302 on the side away from the borehole. The feedback pressure chamber 304 is directly connected to the borehole via a passageway, while the air cushion pressure chamber 302 is equipped with an air inlet A for connection to the external air intake system. The deformable rubber sleeve can move axially along the drill pipe under the influence of the pressure difference between the two pressure chambers. In the direction of the force acting on the feedback pressure chamber (i.e., the end away from the borehole), a guide ramp 301 is provided within the pressure-balancing device. The guide ramp 301 features a tapered design, with a large opening that gradually narrows inward. The deformable rubber sleeve 303 also has a matching bevel structure. The deformable rubber sleeve can deform radially under external force and return to its original shape without external force. When the guide ramp compresses the deformable rubber sleeve, its diameter decreases, thereby reducing the annular gap between the shaped drill pipe 2 and the deformable rubber sleeve 303.

[0038] 2. Air cushion sealing device

[0039] The air cushion sealing device 4 consists of an inner air cushion ring 403 and an outer shell 401. The inner cavity of the air cushion ring is connected to the drill hole, and an annular groove is machined on its outer surface, forming a closed annular airway with the outer shell. Multiple jet holes 402 are distributed on the air cushion ring. These jet holes connect to the annular airway and spray gas onto the surface of the special-shaped drill pipe, with the direction of the gas-slag separation device 5. The outer shell is provided with an air connection hole A, which is connected to the external air intake system. A pipe connecting the two air connection holes A connects the air cushion pressure chamber 302 with the annular airway and the inner cavity of the air cushion ring 403.

[0040] Specifically, the number of the jet holes 402 is set according to actual conditions, and can be set to 3 or 4 evenly spaced holes.

[0041] 3. Gas-slag separation device

[0042] The inner cavity of the gas-slag separation device 5 is connected to the borehole and is equipped with an air intake port B and a slag discharge port C. The air intake port B is used to absorb gas, while the slag discharge port C is used to discharge drilling fluid and rock cuttings. Connectors tightly seal the pressure balancing device 3, the air cushion seal 4, and the gas-slag separation device 5, preventing gas and rock cuttings from leaking through the joints. These connectors can be flanges, sleeves, or other components.

[0043] The working process is as follows:

[0044] During normal drilling, the end of the special-shaped drill pipe 2 is connected to the drill bit 1 for drilling, and the external air intake system inputs high-pressure gas to the air cushion pressure chamber 302 and the annular air channel through the two air inlet holes A. At this time, the pressure in the air cushion pressure chamber 302 is greater than the pressure in the feedback pressure chamber 304. Under the action of the pressure difference, the deformable rubber sleeve 303 moves to the side away from the guide bevel 301 (i.e., the end close to the borehole), so that the annular gap between the special-shaped drill pipe 2 and the deformable rubber sleeve 303 is completely opened. The drilling fluid and rock cuttings generated during the drilling process smoothly pass through the annular gap into the gas-slag separation device 5 and are discharged from the slag discharge port C. At the same time, the air cushion sealing device sprays high-pressure gas onto the surface of the special-shaped drill pipe through the jet hole, forming a layer of air film. This layer of air film acts as an invisible barrier, preventing a small amount of drilling fluid and rock cuttings from leaking out, ensuring the cleanliness and safety of the construction environment.

[0045] Example 2: Air-sealed blowout preventer under blowout preventer hole working conditions

[0046] Based on Example 1, this example further describes the working scenario of the device when a spray hole occurs.

[0047] The overall structure of the device is the same as that of Example 1, including a pressure balancing device 3, an air-slag separation device 5 and an air cushion sealing device 4, and the connection relationship and function of each component remain consistent.

[0048] The working process is as follows:

[0049] When a blowout occurs during drilling, high-pressure gas in the borehole rapidly flows into the feedback pressure chamber 304, causing the pressure in that chamber to rise sharply. When the pressure in the feedback pressure chamber 304 exceeds that in the air cushion pressure chamber 302, the deformable rubber sleeve 303 moves toward the guide bevel 301 due to the pressure differential. During this movement, the guide bevel gradually squeezes the deformable rubber sleeve 303, reducing its diameter and significantly reducing the annular gap between the special-shaped drill pipe and the deformable rubber sleeve. This change restricts the flow of gas, reducing the speed and amount of gas outflow, and consequently lowering the gas pressure. The pressure balancing device 3 ensures that the gas pressure entering the gas-slag separation device 5 is always less than or equal to the pressure within the air cushion pressure chamber 302. Because the air cushion ring 403 maintains communication with the air cushion pressure chamber 302, the pressure within the air cushion ring 403 is consistent with that within the air cushion pressure chamber 302. If the high-pressure gas continues to increase, the annular gap between the drill pipe and the deformable rubber sleeve will continue to decrease until it is completely closed.

[0050] At the same time, the gas-slag separation device 5 continuously draws away some of the gas through the air intake port B, further reducing the gas pressure entering the air cushion sealing device 4. The jet holes 402 of the air cushion sealing device 4 continue to eject high-pressure gas, forming an air film on the surface of the special-shaped drill pipe 2. Because the pressure of the air film is greater than that of the gas, the gas is effectively trapped inside the air cushion sealing device 4, preventing it from leaking out. Furthermore, the gas sealed within the gas-slag separation device 5 is continuously depressurized through the air intake port B.

[0051] As the blowout eases and the gas pressure in the borehole gradually decreases, the pressure in the feedback pressure chamber 304 also decreases. Once the pressure in the air cushion pressure chamber 302 exceeds that in the feedback pressure chamber 304 again, the deformable rubber sleeve 303 moves away from the guide slope, and the annular gap between the shaped drill rod and the deformable rubber sleeve gradually returns to its fully open state, returning the device to normal drilling mode.

[0052] This invention achieves a highly efficient airtight seal for irregularly shaped drill pipes by dynamically adjusting the annular gap through a pressure balancing device, combined with the air film formed by the air cushion sealing device. This avoids the wear-induced failure of traditional contact seals. Furthermore, the gas-slag separation device effectively separates and processes gas and rock debris, providing a safe and reliable technical guarantee for underground coal mine drilling operations.

[0053] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not limiting. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention can be modified or replaced by equivalents without departing from the purpose and scope of the technical solutions, which should all be included in the scope of the claims of the present invention.

Claims

1. An airtight blowout prevention device for underground coal mines, used to achieve airtight sealing of the drill pipe and prevent gas and rock debris leakage during drilling construction, characterized by: It includes a pressure balancing device, a gas-slag separation device and an air cushion sealing device which are sequentially sleeved on the drill pipe in a direction away from the drill hole, and the pressure balancing device, the gas-slag separation device and the air cushion sealing device are connected to the drill hole; The pressure balancing device is provided with a deformable rubber sleeve that can move axially along the drill pipe, and the inner cavity of the pressure balancing device is divided into a feedback pressure chamber and an air cushion pressure chamber by the deformable rubber sleeve. The feedback pressure chamber is connected to the drill hole, and the air cushion pressure chamber is provided with an air connection hole connected to the external air intake system. The deformable rubber sleeve moves axially under the pressure difference between the feedback pressure chamber and the air cushion pressure chamber. The pressure balancing device is provided with a guiding inclined surface in the direction of the force of the feedback pressure chamber, so that when the deformable rubber sleeve is subjected to the pressure of the feedback pressure chamber, the guiding inclined surface squeezes the deformable rubber sleeve to reduce its diameter, thereby reducing the annular space gap between the drill pipe and the deformable rubber sleeve; The air cushion sealing device includes an air cushion ring and an outer shell arranged from the inside to the outside, the inner cavity of the air cushion ring is connected to the drilled hole, and an annular air channel is provided between the air cushion ring and the outer shell, a plurality of jet holes connected to the annular air channel are provided on the air cushion ring, an air connection hole connected to the external air intake system is provided on the outer shell, and the air cushion pressure chamber and the annular air channel are connected through the air connection hole on the outer shell and the air connection hole of the air cushion pressure chamber.

2. The coal mine underground airtight seal blowout prevention device according to claim 1, characterized in that: The guide slope adopts a tapered structural design, with a larger size at the opening and gradually narrowing along the inner direction; The deformable rubber sleeve is provided with a corresponding inclined surface structure that matches the guiding inclined surface.

3. The coal mine underground airtight seal blowout prevention device according to claim 1, characterized in that: An annular groove is provided on the outer side of the air cushion ring to form a closed annular air passage with the outer shell.

4. The coal mine underground airtight seal blowout prevention device according to claim 1, characterized in that: The jet hole sprays the pressurized gas in the annular gas channel toward the surface of the drill pipe, and the jetting direction points to the gas-slag separation device to form a gas film to prevent gas leakage.

5. The coal mine underground airtight seal blowout prevention device according to claim 1, characterized in that: The pressure balancing device, the gas-slag separation device and the air cushion sealing device are sealed and connected via a connecting piece to prevent gas and rock debris from leaking from the connection between the pressure balancing device, the gas-slag separation device and the air cushion sealing device.

6. The coal mine underground airtight seal blowout prevention device according to claim 1, characterized in that: The feedback pressure chamber is arranged at an end of the pressure balancing device close to the drill hole, and is used to push the deformable rubber sleeve to move toward an end away from the drill hole; The guide slope is arranged at an end of the pressure balancing device away from the drill hole to squeeze the deformable rubber sleeve.

7. The coal mine underground airtight seal blowout prevention device according to claim 1, characterized in that: The inner cavity of the gas-slag separation device is connected to the drill hole, and is provided with an air intake port and a slag discharge port connected to its inner cavity. The slag discharge port is used to discharge rock cuttings and drilling fluid during normal drilling, and the air intake port is used to suck away gas when performing blowout prevention holes to reduce the pressure of gas when entering the air cushion sealing device.

8. The coal mine underground airtight seal blowout prevention device according to any one of claims 1 to 7, characterized in that: During normal drilling, the pressure in the air cushion pressure chamber is greater than the pressure in the feedback pressure chamber, and the pressurized gas pushes the deformable rubber sleeve to a position away from the guide slope, so that the annular space between the drill pipe and the deformable rubber sleeve is fully opened, and the drilling fluid and rock cuttings are recovered through the gas-slag separation device; When the blowout prevention hole is opened, the pressure in the feedback pressure chamber rises, so that the pressure in the air cushion pressure chamber is lower than the pressure in the feedback pressure chamber. The pressurized gas pushes the deformed rubber sleeve to move toward the side close to the guide bevel. The guide bevel squeezes the deformed rubber sleeve to reduce its diameter, thereby reducing the annular space gap between the drill pipe and the deformed rubber sleeve, so that the pressure of the gas entering the gas-slag separation device and the air cushion sealing device is lower than or equal to the pressure in the air cushion pressure chamber, and the gas leakage is prevented by the air film formed by the air cushion sealing device.

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