A supercritical carbon dioxide sand mixing device for underground wells

Abstract

The present invention specifically relates to an underground supercritical carbon dioxide sand mixing device, including a jet pipe, on which a supercritical carbon dioxide inlet channel and a sand inlet channel are arranged, the supercritical carbon dioxide inlet channel and the sand inlet channel are connected, and an opening and closing control mechanism is arranged at the connection point between the supercritical carbon dioxide inlet channel and the sand inlet channel; the pressure of the supercritical carbon dioxide entering the supercritical carbon dioxide inlet channel controls the opening and closing of the opening and closing control mechanism. The purpose is to make the sand output match the pressure of the supercritical carbon dioxide, realize the synchronous change of the supercritical carbon dioxide flow rate and the sand flow rate, avoid the occurrence of time difference, and realize the timely control and change of the sand concentration.

Description

Technical Field

[0001] The invention belongs to the technical field of petroleum production equipment, and in particular relates to an underground supercritical carbon dioxide sand mixing device. Background Art

[0002] Supercritical carbon dioxide fracturing process is a promising fracturing technology. The supercritical state is a fluid form different from the gaseous and liquid states. Supercritical carbon dioxide has a high density close to that of a liquid and a low viscosity close to that of a gas, and has a strong solubility and a high diffusion coefficient. Supercritical carbon dioxide fracturing fluid is one of the best working fluid systems for connecting microcracks in reservoirs and forming a fracture network. The mixing of liquid carbon dioxide and proppants such as quartz sand requires a ground sand mixing device, and must be carried out under high pressure and low temperature conditions. Therefore, extremely high requirements are placed on the ground sand mixing device. The existing method for controlling the concentration of ground fracturing sand is to use a ground sand mixing device to press a well-proportioned fracturing fluid with a certain sand concentration into the formation through a fracturing pump truck and a pipe column; when the concentration needs to be adjusted, the fracturing fluid concentration needs to be readjusted, and it can only be sent underground after a long transportation, which will cause a time difference, and the sand concentration cannot be changed in time according to the concentration of the fracturing fluid, resulting in the inability to control the sand concentration of the fracturing fluid reaching the formation in real time. Summary of the invention

[0003] In order to solve the problem that the sand delivery concentration cannot be changed in time according to the concentration of supercritical carbon dioxide, the present invention provides an underground supercritical carbon dioxide sand mixing device, which can adjust the amount of sand produced according to the pressure of supercritical carbon dioxide, so that the amount of sand produced is adapted to the pressure of supercritical carbon dioxide, realizes the synchronous change of the supercritical carbon dioxide flow rate and the sand flow rate, avoids the occurrence of time difference, and realizes the timely control and change of sand concentration.

[0004] To achieve the above-mentioned purpose of the invention, the technical solution adopted by the present invention is: an underground supercritical carbon dioxide sand mixing device, including a jet tube, on which a supercritical carbon dioxide inlet channel and a sand inlet channel are provided, the supercritical carbon dioxide inlet channel and the sand inlet channel are connected, and an opening and closing control mechanism is provided at the connection point between the supercritical carbon dioxide inlet channel and the sand inlet channel; the pressure of the supercritical carbon dioxide entering the supercritical carbon dioxide inlet channel controls the opening and closing of the opening and closing control mechanism.

[0005] Preferably, the opening and closing control mechanism includes a pressure sensor and an opener and closeer, and the pressure sensor and the opener and closeer are connected. The pressure sensor is used to sense the pressure of the supercritical carbon dioxide entering the supercritical carbon dioxide inlet channel, and the opener and closeer is used to open / close the connection between the supercritical carbon dioxide inlet channel and the sand inlet channel.

[0006] Preferably, the pressure sensor includes a first piston, which is arranged in a first accommodating cylinder, and a first connecting rod is connected to the first piston, and the first connecting rod is connected to the opener and closeer; an air duct and an air outlet are provided on the first accommodating cylinder, and the first accommodating cylinder is connected to the air duct and the air outlet respectively, and the other end of the air duct and the air outlet are connected to the supercritical carbon dioxide inlet channel, and the air duct and the air outlet are located on the first accommodating cylinder near the inlet end of the supercritical carbon dioxide inlet channel; the other end of the air duct is located upstream of the air outlet in the flow direction of the supercritical carbon dioxide.

[0007] Preferably, the pressure sensor includes an articulated rod, one end of which is hinged to a first connecting rod, and the first connecting rod is connected to the opener and closeer; the other end of the articulated rod extends into the supercritical carbon dioxide inlet channel, and the middle part of the articulated rod is hinged to the jet tube to form a seesaw structure.

[0008] Preferably, the end of the hinged rod extending into the supercritical carbon dioxide inlet channel is fan-shaped, and the fan surface faces the direction of supercritical carbon dioxide inlet.

[0009] Preferably, a counterweight block is fixedly provided on the first connecting rod, and the counterweight block can move up and down relative to the jet tube following the first connecting rod.

[0010] Preferably, the opener and shutter comprises a valve, the valve is connected to a first connecting rod, the valve is arranged at the sand outlet, the first connecting rod drives the valve to move relative to the sand outlet, and the area of ​​the valve is not less than the area of ​​the sand outlet.

[0011] Preferably, a nozzle is further provided in the jet tube, the size of the inlet of the nozzle is larger than the size of the outlet, and the nozzle is connected to a lifting mechanism, and the lifting mechanism drives the nozzle to move up and down relative to the jet tube.

[0012] Preferably, the lifting mechanism includes a second piston, the second piston is connected to the support through a second connecting rod, the support is connected to the nozzle, the second piston is arranged in a second accommodating cylinder, the second accommodating cylinder is provided with a first air inlet and a second air inlet, the first air inlet and the second air inlet are respectively located on both sides of the second piston, the first air inlet and the second air inlet are respectively connected to the supercritical carbon dioxide inlet channel through a control valve; one-way valves are respectively provided at the first air inlet and the second air inlet.

[0013] Preferably, a throat and a diffuser are further provided in the jet tube, and the throat and the diffuser are connected; the diameter of the throat is larger than the diameter at the nozzle outlet, the throat is located on the side close to the upper outlet of the nozzle, the throat is located on the downstream side after the supercritical carbon dioxide and sand are mixed, the inlet surface of the throat is set as an inclined plane, and the inclination direction of the inclined plane is downwardly inclined toward the central axis of the throat; the diffuser is a reducer, and the end with a smaller diameter of the diffuser is connected to the throat, and the smaller diameter of the diffuser is equivalent to the diameter of the throat.

[0014] The present invention has the following beneficial effects:

[0015] 1. The present invention is provided with a lifting control mechanism, which can adjust the lifting height according to the pressure of supercritical carbon dioxide, so as to realize the opening and closing degree of the valve in the opening and closing control mechanism through the pressure control of supercritical carbon dioxide, so that the flow rate of sand matches the pressure value of supercritical carbon dioxide, realizes the synchronous change of the flow rate of supercritical carbon dioxide and the flow rate of sand, avoids the occurrence of time difference, and realizes the timely control and change of sand concentration;

[0016] 2. The nozzle of the supercritical carbon dioxide in the present invention can be adjusted in height. By adjusting the height of the nozzle of the supercritical carbon dioxide, the volume of the jet device can be changed, so that the volume of the sand mixing at different speeds can be changed according to the actual situation to improve the sand mixing efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a structural schematic diagram of the present invention;

[0018] Figure 2 It is a structural schematic diagram of the lifting mechanism;

[0019] Figure 3 It is a structural schematic diagram of the shutter;

[0020] Figure 4 is another embodiment of the present invention;

[0021] Figure 5 It is a structural diagram of the hinged rod.

[0022] Among them: 1-sand inlet channel; 2-jet pipe; 3-throat; 4-diffuser; 5-nozzle; 6-valve; 7-first air inlet; 9-first connecting rod; 10-counterweight; 11-first accommodating cylinder; 12-first piston; 13-airway; 14-air outlet; 15-support; 16-second connecting rod; 17-second accommodating cylinder; 18-second piston; 19-second air inlet; 20-cavity; 21-hinged rod; 22-sand outlet. DETAILED DESCRIPTION

[0023] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Unless otherwise specified, the technical means used in the embodiments are conventional means well known to those skilled in the art.

[0024] In the description of the present invention, it should be understood that the terms "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside" and "outside" etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0025] like Figure 1-5 As shown, a downhole supercritical carbon dioxide sand mixing device includes a jet tube 2, which is usually arranged at the place where the jet sand mixing device is connected to the continuous tubing slip. The jet tube 2 is provided with a supercritical carbon dioxide inlet channel and a sand inlet channel 1, which are independently arranged, and the supercritical carbon dioxide inlet channel and the sand inlet channel are connected. An opening and closing control mechanism is arranged at the connection point between the supercritical carbon dioxide inlet channel and the sand inlet channel; the pressure of the supercritical carbon dioxide entering the supercritical carbon dioxide inlet channel controls the opening and closing of the opening and closing control mechanism. The opening degree of the opening and closing control mechanism is controlled by the flow rate of carbon dioxide, so as to eliminate the time difference of mixing carbon dioxide and sand, and the sand concentration is controlled by the flow rate of carbon dioxide, so that the flow rate of carbon dioxide is adapted to the sand concentration.

[0026] The opening and closing control mechanism includes a pressure sensor and an opener and a shutter. The pressure sensor is connected to the opener and the shutter is used to sense the pressure of the supercritical carbon dioxide entering the supercritical carbon dioxide inlet channel. The opener and the shutter are used to open / close the connection between the supercritical carbon dioxide inlet channel and the sand inlet channel. The pressure sensor controls the opening of the shutter by the flow rate of carbon dioxide. When the pressure is high, the opening of the shutter is large, and when the pressure is low, the opening of the shutter is small, so that the flow rate of carbon dioxide is adapted to the concentration of sand.

[0027] Embodiment 1

[0028] In the present invention, an implementation manner of the pressure sensor is that the pressure sensor includes a first piston 12, the first piston 12 is arranged in a first accommodating cylinder 11, the first piston 12 is connected to a first connecting rod 9, and the first connecting rod 9 is connected to an opener and closeer; an air duct 13 and an air outlet 14 are provided on the first accommodating cylinder 11, the first accommodating cylinder 11 is respectively connected with the air duct 13 and the air outlet 14, the other end of the air duct 13 and the air outlet 14 are connected with a supercritical carbon dioxide inlet channel, the air duct 13 and the air outlet 14 are located on the first accommodating cylinder 11 near the inlet end of the supercritical carbon dioxide inlet channel; the other end of the air duct 13 is located upstream of the air outlet 14 in the flow direction of the supercritical carbon dioxide. The air inlet end and the air outlet 14 of the air channel 13 are both located on the inner wall of the jet tube 2. When the supercritical carbon dioxide enters the jet tube 2, the air channel 13 is opened for ventilation, and a small portion of the supercritical carbon dioxide enters the first accommodating cylinder 11 along the air channel 13, and then goes out from the air outlet 14, thereby forming a negative pressure in the first accommodating cylinder 11, causing the first piston 12 to move upward ( Figure 1 When the supercritical carbon dioxide enters the first accommodating cylinder 11 at a faster speed, the negative pressure formed in the first accommodating cylinder 11 is larger, the first connecting rod 9 rises a longer distance, and the amount of sand flowing out is larger; when the supercritical carbon dioxide enters the first accommodating cylinder 11 at a slower speed, the negative pressure formed in the first accommodating cylinder 11 is smaller, the first connecting rod 9 rises a shorter distance, and the amount of sand flowing out is smaller.

[0029] A counterweight 10 is fixedly arranged on the first connecting rod 9, and the counterweight 10 can move up and down relative to the jet tube 2 following the first connecting rod 9. The arrangement of the counterweight 10 can ensure that when no carbon dioxide enters, the shutter can be at the sand outlet 22 by its own gravity and the gravity of the counterweight 10, and remain in a closed state, so that the sand entering the sand inlet channel 1 will not flow out.

[0030] The shutter includes a valve 6, which is connected to a first connecting rod 9, and is disposed at a sand outlet 22. The first connecting rod 9 drives the valve 6 to move relative to the sand outlet 22, and the area of ​​the valve 6 is not less than the area of ​​the sand outlet 22. When the first connecting rod 9 moves upward, the valve 6 is driven to move upward at the same time, so that the sand outlet 22 is exposed, and when the first connecting rod 9 moves downward, the valve 6 is driven to move downward, so that the sand outlet 22 is closed.

[0031] The jet pipe 2 is also provided with a nozzle 5, the size of the inlet of the nozzle 5 is larger than the size of the outlet, and the nozzle 5 is connected to a lifting mechanism, and the lifting mechanism drives the nozzle 5 to move up and down relative to the jet pipe 2. The movement of the nozzle 5 can change the volume of the jet device, that is, when the nozzle moves, the distance from the nozzle to the throat changes, and the volume of the jet sand mixing device is also changed.

[0032] The lifting mechanism includes a second piston 18, which is connected to the support 15 through a second connecting rod 16, and the support 15 is connected to the nozzle 5. The second piston 18 is arranged in a second accommodating cylinder 17, and the second accommodating cylinder 17 is provided with a first air inlet 7 and a second air inlet 19, which are respectively located on both sides of the second piston 18, and the first air inlet 7 and the second air inlet 19 are respectively connected to the supercritical carbon dioxide inlet channel through a control valve; the first air inlet and the second air inlet 19 are respectively provided with a one-way valve. When the volume of the jet device needs to be changed, the first air inlet 7 is opened and the second air inlet 19 is closed. At this time, a small amount of supercritical carbon dioxide fluid enters from the first air inlet 7, thereby pushing the second piston 18 to move downward, and pressing the gas in the second accommodating cylinder 17 out from the one-way valve, and the second piston 18 drives the second connecting rod 16 to move downward, the second connecting rod 16 drives the support 15 to move downward, and the support 15 drives the nozzle 5 to move downward, thereby reducing the volume of the jet device; when the second air inlet 19 is opened and the first air inlet 7 is closed, a small amount of supercritical carbon dioxide fluid enters from the second air inlet 19, thereby pushing the second piston 18 to move upward, the second piston 18 drives the second connecting rod 16 to move upward, the second connecting rod 16 drives the support 15 to move upward, and the support 15 drives the nozzle 5 to move upward, thereby increasing the volume of the jet device.

[0033] A throat pipe 3 and a diffuser pipe 4 are also provided in the jet pipe 2, and the throat pipe 3 and the diffuser pipe 4 are connected; the diameter of the throat pipe 3 is larger than the diameter at the outlet of the nozzle 5, the throat pipe 3 is located on the side close to the upper outlet of the nozzle 5, and the throat pipe 3 is located on the downstream side after the supercritical carbon dioxide and sand are mixed, and the inlet surface of the throat pipe 3 is set as an inclined plane, and the inclination direction of the inclined plane is downwardly inclined toward the central axis of the throat pipe 3, so that the mixed sand can quickly enter the throat pipe 3 and flow toward the diffuser pipe 4.

[0034] The diffusion tube 4 is a reducing tube, and the end with a smaller diameter of the diffusion tube 4 is connected to the throat tube 3, and the smaller diameter of the diffusion tube 4 is equivalent to the diameter of the throat tube 3. The function of the throat tube 3 is to fully mix the proppant (the proppant is quartz sand or the like) with the supercritical carbon dioxide, and the diffusion tube 4 reduces the speed of the mixed liquid and increases its pressure energy (through diffusion, the kinetic energy of the solid-liquid mixture at the throat outlet is converted into pressure energy).

[0035] Embodiment 2

[0036] The difference from the first embodiment is that, in this embodiment, the pressure sensor includes an articulated rod 21, one end of the articulated rod 21 is hinged to the first connecting rod 9, and the first connecting rod 9 is connected to the opener and closeer; the other end of the articulated rod 21 extends into the supercritical carbon dioxide inlet channel, and the middle part of the articulated rod 21 is hinged on the jet tube 2 to form a seesaw structure.

[0037] One end of the hinge rod 21 extending into the supercritical carbon dioxide inlet channel is fan-shaped, and the fan surface faces the direction in which the supercritical carbon dioxide enters.

[0038] The hinged rod 21 is hinged to the upper end of the first connecting rod 9 in the cavity 20, and the middle part of the hinged rod 21 is hinged to the side wall of the jet tube 2. When the supercritical carbon dioxide fluid enters the jet tube 2, the fan surface of the hinged rod 21 is pushed downward by the supercritical carbon dioxide fluid, so that the hinged rod 21 is tilted upward at one end of the cavity 20, thereby driving the first connecting rod 9 to rise, thereby realizing the opening and closing of the shutter controlled by the flow rate of the supercritical carbon dioxide, and the opening and closing of the shutter depends on the flow rate of the supercritical carbon dioxide flowing into the jet tube 2, so that the concentration of the supercritical carbon dioxide is adapted to the concentration of the sand.

[0039] The device of the present invention controls the opening and closing of the shutter by the flow rate of supercritical carbon dioxide, thereby realizing synchronous change of the flow rate of supercritical carbon dioxide and the flow rate of sand, avoiding the occurrence of time difference; a lifting mechanism is provided to control the lifting and lowering of the nozzle 5, thereby changing the volume of the jet device, so as to change the volume according to actual conditions for sand mixing at different speeds, so as to improve the sand mixing efficiency.

[0040] The embodiments described above are only descriptions of the preferred modes of the present invention and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various deformations, modifications, and substitutions made to the technical solutions of the present invention by ordinary technicians in this field should all fall within the protection scope determined by the claims of the present invention.

Claims

1. An underground supercritical carbon dioxide sand mixing device, comprising a jet pipe (2), wherein the jet pipe (2) is provided with a supercritical carbon dioxide inlet channel and a sand inlet channel, characterized in that: The supercritical carbon dioxide inlet channel is connected to the sand inlet channel, and an opening and closing control mechanism is provided at the connection point between the supercritical carbon dioxide inlet channel and the sand inlet channel; the pressure of the supercritical carbon dioxide entering the supercritical carbon dioxide inlet channel controls the opening and closing of the opening and closing control mechanism; The opening and closing control mechanism includes a pressure sensor and an opener and closeer, the pressure sensor is connected to the opener and closeer, the pressure sensor is used to sense the pressure of the supercritical carbon dioxide entering the supercritical carbon dioxide inlet channel, and the opener and closeer is used to open / close the connection between the supercritical carbon dioxide inlet channel and the sand inlet channel; The pressure sensor comprises a first piston (12), the first piston (12) being arranged in a first accommodating cylinder (11), the first piston (12) being connected to a first connecting rod (9), and the first connecting rod (9) being connected to an opener and closeer; an air passage (13) and an air outlet (14) being arranged on the first accommodating cylinder (11), the first accommodating cylinder (11) being connected to the air passage (13) and the air outlet (14) respectively, the other end of the air passage (13) and the air outlet (14) being connected to a supercritical carbon dioxide inlet passage, the air passage (13) and the air outlet (14) being located on the first accommodating cylinder (11) close to an inlet end of the supercritical carbon dioxide inlet passage; the other end of the air passage (13) being located upstream of the air outlet (14) in the flow direction of the supercritical carbon dioxide; A nozzle (5) is further provided in the jet tube (2); the size of the inlet of the nozzle (5) is larger than the size of the outlet; the nozzle (5) is connected to a lifting mechanism; the lifting mechanism drives the nozzle (5) to move up and down relative to the jet tube (2); The lifting mechanism comprises a second piston (18), the second piston (18) being connected to a support (15) via a second connecting rod (16), the support (15) being connected to a nozzle (5), the second piston (18) being arranged in a second accommodating cylinder (17), the second accommodating cylinder (17) being provided with a first air inlet (7) and a second air inlet (19), the first air inlet (7) and the second air inlet (19) being respectively located on two sides of the second piston (18), the first air inlet (7) and the second air inlet (19) being respectively connected to a supercritical carbon dioxide inlet channel via a control valve; and one-way valves are respectively provided at the first air inlet (7) and the second air inlet (19).

2. The underground supercritical carbon dioxide sand mixing device according to claim 1, characterized in that: The pressure sensor comprises an articulated rod (21), one end of the articulated rod (21) being articulated to a first connecting rod (9), the first connecting rod (9) being connected to an opener and closeer; the other end of the articulated rod (21) extends into the supercritical carbon dioxide inlet channel, and the middle portion of the articulated rod (21) is articulated to the jet tube (2) to form a seesaw structure.

3. The underground supercritical carbon dioxide sand mixing device according to claim 2, characterized in that: One end of the hinged rod (21) extending into the supercritical carbon dioxide inlet channel is fan-shaped, with the fan surface facing the direction in which the supercritical carbon dioxide enters.

4. The underground supercritical carbon dioxide sand mixing device according to any one of claims 2 and 3, characterized in that: A counterweight block (10) is fixedly arranged on the first connecting rod (9), and the counterweight block (10) can move up and down relative to the jet tube (2) following the first connecting rod (9).

5. The underground supercritical carbon dioxide sand mixing device according to claim 4, characterized in that: The shutter comprises a valve (6), the valve (6) being connected to a first connecting rod (9), the valve (6) being arranged at a sand outlet (22), the first connecting rod (9) driving the valve (6) to move relative to the sand outlet (22), and the area of ​​the valve (6) being not less than the area of ​​the sand outlet (22).

6. The underground supercritical carbon dioxide sand mixing device according to claim 1, characterized in that: A throat pipe (3) and a diffuser pipe (4) are also provided in the jet pipe (2), and the throat pipe (3) and the diffuser pipe (4) are connected; the diameter of the throat pipe (3) is larger than the diameter at the outlet of the nozzle (5); the throat pipe (3) is located on a side close to the upper outlet of the nozzle (5); the throat pipe (3) is located on the downstream side after the supercritical carbon dioxide and sand are mixed; the inlet surface of the throat pipe (3) is arranged as an inclined surface, and the inclined surface is inclined downwardly toward the central axis of the throat pipe (3); the diffuser pipe (4) is a variable diameter pipe, and the end of the diffuser pipe (4) with a smaller diameter is connected to the throat pipe (3), and the smaller diameter of the diffuser pipe (4) is equivalent to the diameter of the throat pipe (3).

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