A side slag discharge device for large-diameter reverse circulation drilling

Abstract

A side slag discharging device for large-diameter reverse circulation drilling, comprising a slag discharging body and a central body. The slag discharging body is in the shape of a short cylinder, and the central body passes through the slag discharging body, with the two being rotationally matched. The central body is of a hollow structure, and the slag discharging body is of a cavity structure. An annular cavity is formed between the central body and the slag discharging body. The slag discharging body is provided with a slag discharging port, which is located tangentially on the side of the slag discharging body, and the slag discharging port communicates with the annular cavity of the slag discharging body. An internal plug is provided inside the central body, and the internal plug closes the upper part of the central body. An air passage of the central body is provided on the side wall of the central body, and an air passage of the internal plug communicating with the air passage of the central body is provided above the internal plug. A side window is provided in the middle of the central body, and the side window communicates with the annular cavity. When the device of the present invention is installed on a common power head drill and a rotary table drill, it can be used for large-diameter reverse circulation drilling construction, which can greatly improve the construction efficiency and reduce the production cost. The present invention is not only suitable for power head drills with a small through diameter, but also can be used for rotary table drills in oil drilling and engineering drilling.

Description

Technical Field

[0001] The present invention relates to a slag discharging device for a drilling rig, in particular to a side slag discharging device for large-diameter reverse circulation drilling. Background Art

[0002] Reverse circulation drilling is a drilling method in which the flushing medium flows from the annular space between the drill pipe and the hole wall to the bottom of the hole, carries the cuttings and then returns to the surface through the inner hole of the drill pipe. The small-diameter air-lift reverse circulation drilling technology uses drilling equipment (such as a power head drilling rig, a rotary table drilling rig) to carry out small-diameter deep well and exploration well drilling using the reverse circulation drilling technology, which is a relatively advanced drilling technology at present. Its slag discharging method is to send compressed air through an air supply pipe, an air box, and the annular space of a double-wall drill pipe to the mixing chamber in the drill tool by an air compressor, and then enter the inner pipe of the double-wall drill pipe, so that it is mixed with the flushing fluid and cuttings and rock powder in the inner pipe to form a mixture with a specific gravity less than that of the flushing fluid, reducing the liquid column pressure in the drill pipe, forming a pressure difference inside and outside the drill pipe. Under the action of the flushing fluid pressure on the outside of the drill pipe string, the mixture in the drill pipe rises, passes through the through hole of the power head (swivel), and then is discharged out of the hole through the slag discharging pipe and sent to a vibrating screen. The vibrating screen separates the cuttings and rock powder, and the flushing fluid flows back into the hole to form a cycle. At present, the through hole diameters of the power head and the upper elbow of most power head drilling rigs and the swivel through hole of the rotary table drilling rig are designed to be relatively small. This is because in small-diameter reverse circulation construction, the flow rate of the upward-returning mud-gas mixture carrying the cuttings is relatively small and the amount of rock slag is small. If directly used for large-diameter reverse circulation drilling construction, the power head (swivel) is much smaller than the through hole of the lower drill pipe, and the flow rate of the upward-returning mud-gas mixture carrying the cuttings at the power head (swivel) will increase several times, increasing the wear on the power head (swivel) components and easily causing blockage. If the diameter of the through hole is increased, it is necessary to make a large modification to the power head (swivel) of the drilling rig, which is very difficult and costly; in addition, when drilling deep wells in oil fields, if the reverse circulation drilling process is adopted, due to the too fast flow rate of the upward-returning gas-liquid mixture in the reverse circulation, the wear on the mud pipe and manifold system will surely increase. Therefore, reverse circulation mud is prohibited from entering the mud pipe and manifold system in oil fields. Summary of the Invention

[0003] The object of the present invention is to overcome the drawbacks of the prior art and provide a side slag discharging device for large-diameter reverse circulation drilling. By using the slag discharging device, the drilling efficiency can be greatly improved without changing the structure of the power head or swivel of the existing small-diameter drilling rig.

[0004] The problems of the present invention are solved by the following technical solutions:

[0005] A side slag discharging device for large-diameter reverse circulation drilling, comprising a slag discharging body and a central body. The slag discharging body is in the shape of a short cylinder, and the central body passes through the slag discharging body with rotational fit therebetween. The central body is of a hollow structure, and the slag discharging body is of a cavity structure. An annular cavity is formed between the central body and the slag discharging body. The slag discharging body is provided with a slag discharging port, which is located tangentially on the side of the slag discharging body and communicates with the annular cavity of the slag discharging body. An internal plug is provided inside the central body, which closes the upper part of the central body. An air duct of the central body is provided on the side wall of the central body, and an air duct of the internal plug communicating with the air duct of the central body is provided above the internal plug. A side window is provided in the middle of the central body, and the side window communicates with the annular cavity.

[0006] For the above-mentioned side slag discharging device for large-diameter reverse circulation drilling, conical threaded holes are respectively provided at the upper and lower openings of the central body. The upper opening of the central body is connected to the swivel of the rotary drilling rig or the power head of the down-the-hole drilling rig through an external taper joint, and the lower opening of the central body is connected to a double-wall drill pipe. The air duct of the central body communicates with the annular gap between the double-wall drill pipes.

[0007] For the above-mentioned side slag discharging device for large-diameter reverse circulation drilling, a groove is provided at the top of the internal plug. Four air ducts of the internal plug are evenly distributed on the internal plug, and the inlets of the air ducts of the internal plug are arranged on the groove wall. The air ducts of the internal plug are inclined relative to the axis. The internal plug is provided with a buffer chamber, which is butted against the inner hole of the central body, and a sealing ring is provided between the lower part of the internal plug and the central body.

[0008] For the above-mentioned side slag discharging device for large-diameter reverse circulation drilling, the diameter of the buffer chamber matches the diameter of the inner hole of the central body, and the height H of the buffer chamber is 80 - 120 mm.

[0009] For the above-mentioned side slag discharging device for large-diameter reverse circulation drilling, two side windows are provided on the central body.

[0010] For the above-mentioned side slag discharging device for large-diameter reverse circulation drilling, bearings are provided between the upper and lower parts of the slag discharging body and the central body. End caps are provided at the outer ends of the bearings, and sealing rings are provided between the end caps and the central body.

[0011] The device of the present invention discharges the mixed liquid from the side slag discharging port of the slag discharging device, without passing through the power head (swivel) any more. The power head (swivel) only serves as an air intake channel, realizing gas-liquid separation. By using the said device, the slag discharging amount can be greatly increased and the slag discharging speed can be improved. Without changing the existing drilling equipment, the problems such as wear and blockage of the power head (swivel) components caused by the upwelling mixed liquid in large-diameter drilling construction are solved, and the drilling efficiency is improved. Currently, a large number of ordinary down-the-hole drilling rigs and rotary drilling rigs can be used for large-diameter reverse circulation drilling construction after adopting the device of the present invention, which can greatly improve the construction efficiency and reduce the production cost. The present invention is not only suitable for down-the-hole drilling rigs with small through diameters, but also can be used for rotary drilling rigs in oil drilling and engineering drilling. Brief Description of the Drawings

[0012] The present invention will be further described below with reference to the drawings.

[0013] Figure 1 is a schematic structural view of the present invention ( Figure 2 A-A cross-sectional view of);

[0014] Figure 2 is Figure 1 top view of;

[0015] Figure 3 is a schematic cross-sectional view of the inner plug;

[0016] Figure 4 is Figure 3 top view of;

[0017] Figure 5 is a schematic view of the present invention for a power head drill;

[0018] Figure 6 is a schematic view of the present invention for a rotary table drill.

[0019] The reference numerals in the figure are: 1, central body; 1-1, central body air duct, 1-2, side window, 2, inner plug, 2-1, inner plug air duct, 3, end cover, 4, bearing, 5, slag discharging body, 5-1, annular cavity, 6, slag discharging port, 7, double-wall drill pipe, 7-1, annular gap, 8, outer taper joint, 9, power head drill, 10, rotary table drill. Detailed implementation manners

[0020] Refer to Figures 1 - 4, the present invention includes a slag discharging body 5 and a central body 1. The slag discharging body is in the shape of a short cylinder, and the central body is a cylinder with a hollow structure. The central body passes through the slag discharging body, and the two are rotationally matched. The upper and lower openings of the central body are respectively provided with conical threaded holes. The upper opening of the central body can be connected to a drill rig through an external tapered joint 8, and the lower opening of the central body is connected to a double-wall drill pipe 7. The slag discharging body is a cavity structure, and an annular cavity 5-1 is formed between the central body and the slag discharging body. The slag discharging body is provided with a slag discharge port 6, and the slag discharge port is located on the side of the slag discharging body along the tangent direction, and the slag discharge port communicates with the annular cavity of the slag discharging body. An internal plug 2 is provided inside the central body. The internal plug closes the upper part of the inner hole of the central body, and the channel for the upward flow of the mud-gas mixture is closed by the internal plug. Two side windows 1-2 are provided in the middle of the central body. The side windows communicate with the annular cavity. The upward-returning mud-gas mixture carrying cuttings from the inner hole of the double-wall drill pipe is discharged from the slag discharging body and the slag discharge port. An air duct 1-1 for transmitting gas is provided on the side wall of the central body. The internal plug is provided with an internal plug air duct 2-1. The top of the internal plug is provided with a groove. The four internal plug air ducts are evenly distributed on the internal plug. The inlet of the internal plug air duct is arranged on the groove wall, and the internal plug air duct is inclined relative to the axis. Each internal plug air duct corresponds to an air duct of the central body, and the air duct of the central body communicates with the annular gap 7-1 between the double-wall drill pipes. The above structure conveys gas from the upper opening of the central body to the annular gap of the double-wall drill pipe. The internal plug is provided with a recessed buffer chamber 2-2. The buffer chamber is docked with the inner hole of the central body. The diameter of the buffer chamber matches the diameter of the inner hole of the central body, and the height dimension of the buffer chamber is 80-120 mm. The buffer chamber is provided to form a buffer for the upward-returning fluid here. The lower part of the internal plug is closely matched with the central body and provided with a sealing ring for sealing. Bearings are provided between the upper and lower parts of the slag discharging body and the central body to reduce rotational friction. End caps 3 are provided at the outer ends of the bearings, and sealing rings are provided between the end caps and the central body.

[0021] See Figure 5 , Figure 6 , when the present invention is in use, it is installed between the power head of the power head drill rig 9 and the double-wall drill pipe, or installed between the swivel of the rotary table drill rig 10 and the double-wall drill pipe. The air inlet hole of the power head or swivel of the drill rig serves as the air inlet channel for reverse circulation drilling, and the side slag discharging device serves as the discharge channel for the upward-returning drilling fluid to achieve slag-gas separation. In this way, it can avoid the problem that the through hole of the power head or swivel is too small and easy to block, and can also discharge slag smoothly and efficiently.

[0022] The working principle of the present invention is as follows: High-pressure air enters the slag discharging device through the central hole of the power head (swivel), enters the annular gaps inside and outside the double-wall drill pipe through the air duct of the central body and the air duct of the internal plug; the solid-gas-liquid mixture returning upward inside the drill tool enters the annular cavity of the slag discharging body through the side window of the central body; due to the centrifugal force generated by the rotation of the central body, the fluid in the vertical direction is transformed into a rotating fluid in the horizontal direction, and the discharge speed of the fluid is accelerated by rotation, so that the solid-gas-liquid mixture is accelerated into the slag discharge port and discharged from the slag discharge port.

[0023] After the present invention is applied to a traditional power head drill or rotary table drill, the mixed liquid no longer discharges through the power head (swivel), and the power head (swivel) only serves as an air intake passage, achieving gas-liquid separation, greatly increasing the slag discharge volume, improving the slag discharge speed, solving the problems such as wear and blockage of the power head (swivel) components by the upward-returning liquid in large-diameter construction without changing the existing drilling equipment, and improving the drilling efficiency.

Claims

1. A side slag discharging device for large-diameter reverse circulation drilling, characterized in that: It includes a slag discharging body (5) and a central body (1). The slag discharging body is in the shape of a short cylinder. The central body passes through the slag discharging body, and the two are rotationally matched. The central body is a hollow structure, and the slag discharging body is a cavity structure. An annular cavity (5-1) is formed between the central body and the slag discharging body. The slag discharging body is provided with a slag discharging port (6). The slag discharging port is located on the side of the slag discharging body along the tangent direction, and the slag discharging port communicates with the annular cavity of the slag discharging body. An internal plug (2) is arranged inside the central body. The internal plug seals the upper part of the central body. The side wall of the central body is provided with a central body air duct (1-1). The upper part of the internal plug is provided with an internal plug air duct (2-1) communicating with the central body air duct. A side window (1-2) is arranged in the middle of the central body, and the side window communicates with the annular cavity. The top of the internal plug is provided with a groove. Four internal plug air ducts are evenly distributed on the internal plug. The inlet of the internal plug air duct is arranged on the groove wall. The internal plug air duct is inclined relative to the axis. The internal plug is provided with a buffer chamber (2-2). The buffer chamber is butted with the inner hole of the central body. A sealing ring is arranged between the lower part of the internal plug and the central body. The diameter of the buffer chamber matches the diameter of the inner hole of the central body, and the height H of the buffer chamber is 80-120 mm.

2. The side slag discharging device for large-diameter reverse circulation drilling according to claim 1, characterized in that: The upper and lower mouths of the central body are respectively provided with tapered threaded holes. The upper mouth of the central body is connected to the swivel of the rotary drilling rig or the power head of the down-the-hole drilling rig through an external tapered joint. The lower mouth of the central body is connected to a double-wall drill pipe (7), and the central body air duct communicates with the annular gap (7-1) between the double-wall drill pipes.

3. The side slag discharging device for large-diameter reverse circulation drilling according to claim 2, characterized in that: Two side windows are arranged on the central body.

4. The side slag discharging device for large-diameter reverse circulation drilling according to claim 3, characterized in that: Bearings are arranged between the upper and lower parts of the slag discharging body and the central body. End caps (3) are arranged at the outer ends of the bearings, and sealing rings are arranged between the end caps and the central body.

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