Downhole drilling fluid separation device and method

Abstract

The invention belongs to the technical field of drilling fluid separation, and particularly relates to an underground drilling fluid separation device and method. The device is organically composed of a shell, a filtering turbine mechanism, an outer filter screen, an inner filter screen, a discharging mechanism and a communicating pipe. Solid-phase particles are left in the solid-phase filter cavity, and only a liquid phase passes through the filter screen, so that the liquid phase can be well separated under the action of multiple times of the turbine, the liquid phase in the outer filtrate cavity and the liquid phase in the inner filtrate cavity are converged through the communicating pipe and finally conveyed to a drill bit, and the liquid phase almost contains no solid phase, so that the solid phase is well prevented from entering the drill bit, and the drill bit is prevented from being damaged. Therefore, the drill bit is protected, and the service life of the drill bit is prolonged. The solid phase content in the drilling fluid entering the drill bit can be guaranteed, and the problem that in the prior art, the solid phase amount in the separated liquid phase is uncontrollable, and consequently the service life of the drill bit is shortened is solved.

Description

Technical Field

[0001] This invention belongs to the field of drilling fluid separation technology, specifically relating to a downhole drilling fluid separation device and method. Background Technology

[0002] Drilling fluid is an essential drilling fluid in conventional oil and gas drilling, playing multiple vital roles such as cleaning the bottom of the well, carrying cuttings, cooling the drill bit, and balancing formation pressure; it is often referred to as the "blood" of drilling. Solid content is a crucial indicator of drilling fluid performance; it refers to the percentage of the total volume of solid phase in the drilling fluid. The level of solid content, as well as the type, size, and properties of these solid particles, directly impact downhole safety and drilling speed. Excessively high solid content in drilling fluid, when sprayed from the drill bit nozzle to the bottom of the well, can easily cause severe pressure holding effects, leading to accelerated drill bit wear and consequently affecting drilling speed. This impact is particularly severe during plugging operations while drilling, where the addition of solid particles such as ultrafine calcium carbonate and ultrafine silica to the drilling fluid is necessary. Studies have shown that drilling speed decreases with increasing solids content in drilling fluid. When the solids content reaches 7%, the mechanical drilling speed decreases by 50% compared to clean water drilling fluid. Furthermore, for every 1% decrease in solids content, the drilling speed can increase by at least 10%. Downhole cyclone separator technology connects a cyclone separator between the drill bit and the drill string. Before the drilling fluid flows into the drill bit, it separates some of the solids in the drilling fluid and discharges them into the wellbore annulus, effectively reducing the solids content of the drilling fluid ejected from the drill bit nozzles. The low-density, low-solids drilling fluid flowing into the wellbore helps alleviate the pressure effect of the drilling fluid on the cuttings at the bottom of the well, slows down drill bit wear, and extends the working life of the drill bit while increasing drilling speed.

[0003] Patent CN112282676B discloses a downhole vortex solid-liquid separation drilling acceleration tool. This patent utilizes a guide vane structure to generate a vortex flow field and employs the principle of hydraulic vortex separation to achieve solid-liquid separation of the drilling fluid within the tool. This patent reduces the solid content of the drilling fluid injected to the bottom of the well through downhole vortex separation, mitigating its pressure effect on cuttings and improving the drilling fluid's cuttings removal efficiency. However, this patent uses centrifugal force to transfer the solid phase to the outer side of the casing. This can easily lead to the mixing of a large amount of liquid phase, and more importantly, the separated liquid phase also contains solids. The amount of this solid phase is uncontrollable, thus still resulting in a high solid content in the drilling fluid ejected from the drill bit nozzle, thereby affecting the drill bit's service life. Summary of the Invention

[0004] This invention provides a downhole drilling fluid separation device and method, the purpose of which is to solve the problem of uncontrollable solid phase content in the separated liquid phase in the prior art, which leads to a reduction in the working life of the drill bit.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A downhole drilling fluid separation device includes a shell, a filter turbine mechanism, an outer filter screen, an inner filter screen, a discharge mechanism, and a connecting pipe. The shell is a hollow cylindrical structure with open top and bottom, with a drilling fluid inlet at the upper end and a drilling fluid outlet at the lower end. The filter turbine mechanism is connected inside the shell and coaxial with it, and has an inner filtrate chamber. The outer filter screen is fitted onto the outside of the filter turbine mechanism. The inner filter screen is connected to the inner wall of the filter turbine mechanism. A solid phase filter chamber is formed between the filter turbine mechanism and the outer filter screen, and an outer filtrate chamber is formed between the outer filter screen and the inner wall of the shell. The upper end of the solid phase filter chamber is connected to the inlet of the shell. A discharge mechanism is provided at the lower part of the shell, which connects the solid phase filter chamber to the outside of the shell. The connecting pipe connects the outer filtrate chamber and the inner filtrate chamber.

[0006] It also includes a motor, a coupling, and a bracket; the motor is connected to the upper inner wall of the housing via the bracket, which has holes for drilling fluid to pass through, and the output shaft of the motor is connected to the upper end of the filter turbine mechanism via the coupling.

[0007] The filter turbine mechanism includes a filter turbine shaft, several turbines, and a connecting mechanism. The filter turbine shaft has an internal filtrate chamber, and an internal filter screen is provided on the inner sidewall of the filter turbine shaft. The pore size of the internal filter screen is smaller than the diameter of the solid particles. The turbines are connected to the outer sidewall of the filter turbine shaft. The filter turbine shaft is coaxial with the housing. The upper and lower ends of the filter turbine shaft are rotatably connected to the upper inner sidewall and the lower inner sidewall of the housing, respectively, through the connecting mechanism.

[0008] The turbine has an internal hollow structure, and the interior of the turbine is connected to the internal filtrate chamber; filter holes are provided on the side wall of the turbine, and the diameter of the filter holes is smaller than the diameter of the solid particles.

[0009] A scraper is connected to the outer edge of the turbine, and the outer edge of the scraper abuts against the inner wall of the outer filter screen.

[0010] The connecting mechanism includes a fixed cylinder, a mounting ring, and a bearing; the mounting ring is connected to the inner wall of the housing, the fixed cylinder is coaxially disposed within the mounting ring, and a bearing is disposed between the fixed cylinder and the mounting ring.

[0011] Several through holes are opened on the side wall of the filter turbine shaft.

[0012] The discharge mechanism is a discharge ring, and a filter ring is provided at the outlet of the discharge ring. The filter pore diameter of the filter ring is larger than the diameter of the solid particles.

[0013] The solid-phase filter cavity includes an upper filter cavity and a lower filter cavity; the upper part of the filter cavity is a first cylindrical cavity, and the lower part of the upper filter cavity is a first conical cavity. The first conical cavity has a conical structure, and the lower end of the first cylindrical cavity is connected to the large-diameter end of the first conical cavity; the upper part of the lower filter cavity is a second cylindrical cavity, and the lower part of the upper filter cavity is a second conical cavity. The second conical cavity has a conical structure, and the lower end of the second cylindrical cavity is connected to the large-diameter end of the second conical cavity; the upper end of the second cylindrical cavity is connected to the small-diameter end of the first conical cavity.

[0014] A downhole drilling fluid separation method, employing a downhole drilling fluid separation device, includes the following steps: Connect the upper end of the downhole drilling fluid separator to the drill collar and the lower end of the downhole drilling fluid separator to the drill bit, and then lower it into the well. The drilling fluid output from the drill collar enters the solid phase filter chamber through the inlet at the upper end of the casing. As the drilling fluid flows downward, it drives the filter turbine shaft in the filter turbine mechanism to rotate. During the downward movement of the drilling fluid, the following process repeats: the drilling fluid moves towards the outer filter under the action of centrifugal force, the liquid phase of the drilling fluid passes through the outer filter and enters the outer filtrate chamber, the solid phase is blocked by the outer filter and moves downward in the solid phase filtrate chamber, and part of the liquid phase passes through the inner filter and enters the inner filtrate chamber. The solid phase and a portion of the liquid phase are discharged from the bottom of the solid phase filter chamber to the space between the shell and the wellbore through the discharge mechanism; The liquid phase in the outer filtrate chamber merges with the liquid phase in the inner filtrate chamber through the connecting pipe, and then is transported to the drill bit water hole through the outlet of the shell and enters the wellbore. Subsequently, the drilling fluid from the two locations merges and returns upward.

[0015] The beneficial effects of this invention are as follows: 1. This invention can retain solid particles in the solid filter chamber in real time, and the filter screen only allows the liquid phase to pass through. Therefore, the liquid phase can be well separated by the action of the turbine multiple times. The liquid phase in the outer filter chamber merges with the liquid phase in the inner filter chamber through the connecting pipe and is finally transported to the drill bit. This part of the liquid phase contains almost no solid phase, thus effectively preventing solid phase from entering the drill bit, thereby protecting the drill bit and extending the working life of the drill bit.

[0016] 2. The turbine in this invention can drive the drilling fluid downwards and move it towards the external filter screen, thereby achieving the separation of the solid phase. During this process, the surface of the turbine contacts and applies force to the drilling fluid. Therefore, setting filter holes on the side wall of the turbine can transport the liquid phase into the interior of the turbine and into the internal filtration chamber during the application of force by the turbine, achieving the purpose of further separating the solid phase and thus improving the separation efficiency.

[0017] 3. The present invention is designed with a scraper. When the filter turbine shaft rotates once, the scraper scrapes the inner wall of the outer filter screen once, thereby achieving the purpose of removing the solid particles attached to the outer filter screen.

[0018] 4. The motor design in this invention can increase the rotational speed of the filter turbine shaft, avoiding the problem of poor separation effect caused by excessive drilling fluid resistance. The coupling can mitigate the vibration caused by the filter turbine shaft, playing a vibration-absorbing role, thereby protecting the motor.

[0019] 5. The filter ring design in this invention effectively prevents dirt and grime from entering the well shaft, thus playing a role in isolation.

[0020] 6. In this invention, when the inner diameter of the first cylindrical cavity is larger than the inner diameter of the second cylindrical cavity, more liquid phase can be transported to the inner filtrate cavity and the outer filtrate cavity, and the flow rate of the liquid phase containing the solid phase can also be increased, thereby improving the separation effect.

[0021] 7. In this invention, the outer and inner filter screens are provided with conical portions, thereby forming a first conical cavity and a second conical cavity. The turbine can drive the drilling fluid downward. When the drilling fluid moves downward, it impacts the portions of the outer and inner filter screens in the first and second conical cavities. During the impact, the liquid phase enters the inner and outer filtrate cavities, achieving the purpose of further separating the solid phase, thereby improving the separation efficiency.

[0022] The above description is merely an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention and to implement it in accordance with the contents of the specification, the preferred embodiments of the present invention are described in detail below with reference to the accompanying drawings. Attached Figure Description

[0023] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0024] Figure 1 A schematic diagram of the structure of the downhole drilling fluid separation device provided in an embodiment of the present invention. Figure 1 .

[0025] Figure 2 A schematic diagram of the structure of the downhole drilling fluid separation device provided in an embodiment of the present invention. Figure 2 .

[0026] Reference numerals: 1-Housing; 2-Filter turbine shaft; 3-Turbine; 4-Outer filter screen; 5-Outer filtrate chamber; 6-Solid phase filter chamber; 7-Inner filtrate chamber; 8-Inner filter screen; 9-Discharge mechanism; 10-Connecting pipe; 11-Upper connecting section; 12-Lower connecting section; 13-First cylindrical cavity; 14-First conical cavity; 15-Second cylindrical cavity; 16-Second conical cavity; 17-Conical section; 18-Filter ring; 19-Flexible section; 20-Pulling block; 21-Fixing rod; 22-Scraper; 23-Motor; 24-Coupling. Detailed Implementation

[0027] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0028] Example 1: According to Figure 1 and Figure 2 A downhole drilling fluid separation device is shown, comprising a housing 1, a filter turbine mechanism, an outer filter screen 4, an inner filter screen 8, a discharge mechanism 9, and a connecting pipe 10. The housing 1 is a hollow cylindrical structure with open top and bottom, with a drilling fluid inlet at the upper end and a drilling fluid outlet at the lower end. The filter turbine mechanism is connected inside the housing 1 and is coaxial with the housing 1, and has an inner filtrate chamber 7 inside. The outer filter screen 4 is fitted onto the outside of the filter turbine mechanism. The inner filter screen 8 is connected to the inner wall of the filter turbine mechanism. A solid phase filter chamber 6 is formed between the filter turbine mechanism and the outer filter screen 4, and an outer filtrate chamber 5 is formed between the outer filter screen 4 and the inner wall of the housing 1. The upper end of the solid phase filter chamber 6 is connected to the inlet of the housing 1. The discharge mechanism 9 is provided at the lower part of the housing 1, and the discharge mechanism 9 connects the solid phase filter chamber 6 to the outside of the housing 1. The connecting pipe 10 connects the outer filtrate chamber 5 and the inner filtrate chamber 7.

[0029] In this embodiment, the solid phase filter chamber 6 is used to isolate the solid phase and the downstream liquid phase, the discharge mechanism 9 is used to discharge the solid phase and the downstream liquid phase, and the connecting pipe 10 combines the liquid phases of the outer filtrate chamber 5 and the inner filtrate chamber 7 and then transports them to the drill bit.

[0030] In practical use, the upper end of the downhole drilling fluid separator is connected to the drill collar, and the lower end is connected to the drill bit, and then it is lowered into the well. The drilling fluid output from the drill collar enters the solid phase filter chamber 6 through the inlet at the upper end of the casing 1. When the drilling fluid flows downward, it drives the filter turbine shaft 2 in the filter turbine mechanism to rotate. During the downward movement of the drilling fluid, the following process repeats: the drilling fluid moves towards the outer filter screen 4 under the action of centrifugal force, and the liquid phase of the drilling fluid passes through... The solid phase enters the external filtrate chamber 5 through the external filter screen 4 and moves downward in the solid phase filter chamber 6. Part of the liquid phase passes through the internal filter screen 8 and enters the internal filtrate chamber 7. The solid phase and part of the liquid phase are output from the bottom of the solid phase filter chamber 6 to the space between the shell 1 and the wellbore through the discharge mechanism 9. The liquid phase in the external filtrate chamber 5 merges with the liquid phase in the internal filtrate chamber 7 through the connecting pipe 10, and then is transported to the drill bit water hole through the outlet of the shell 1 and enters the wellbore. Subsequently, the drilling fluid from the two places merges and returns upward.

[0031] In practical applications, the upper end and lower end of the housing 1 are respectively provided with an upper connecting section 11 and a lower connecting section 12. The internal thread on the inner wall of the upper connecting section 11 is used to connect the drill collar, and the internal thread on the inner wall of the lower connecting section 12 is used to connect the drill bit. The upper connecting section 11 and the lower connecting section 12 can also adopt other structures, which are existing technologies and will not be described further in this embodiment.

[0032] This invention can retain solid particles in the solid filter chamber in real time, while the filter screen only allows the liquid phase to pass through. Therefore, the liquid phase can be well separated by the action of the turbine multiple times. The liquid phase in the outer filter chamber merges with the liquid phase in the inner filter chamber through the connecting pipe and is finally transported to the drill bit. This part of the liquid phase contains almost no solid phase, thus effectively preventing solid phase from entering the drill bit, thereby protecting the drill bit and extending its working life.

[0033] The turbine in this invention drives the drilling fluid downwards and towards the external filter screen, thereby achieving solid phase separation. During this process, the turbine surface contacts and applies force to the drilling fluid. Therefore, by providing filter holes on the turbine sidewall, the liquid phase can be transported to the interior of the turbine and enter the internal filtration chamber during the turbine's force application, achieving further solid phase separation and thus improving separation efficiency.

[0034] In some embodiments, the system further includes a motor 23, a coupling 24, and a bracket. The motor 23 is connected to the upper inner wall of the housing 1 via the bracket, which has holes for drilling fluid to pass through. The output shaft of the motor 23 is connected to the upper end of the filter turbine mechanism via the coupling 24. The motor 23 can increase the rotational speed of the filter turbine shaft 2, avoiding the problem of poor separation effect caused by excessive drilling fluid resistance. The coupling 24 can mitigate the vibration caused by the filter turbine shaft 2, playing a vibration-absorbing role, thereby protecting the motor 23.

[0035] In some embodiments, the filter turbine mechanism includes a filter turbine shaft 2, a plurality of turbines 3, and a connecting mechanism; the filter turbine shaft 2 has an internal filtrate chamber 7, and an internal filter screen 8 is provided on the inner sidewall of the filter turbine shaft 2, the pore size of the internal filter screen 8 being smaller than the diameter of the solid particles; the turbines 3 are connected to the outer sidewall of the filter turbine shaft 2; the filter turbine shaft 2 is coaxial with the housing 1; the upper end and lower end of the filter turbine shaft 2 are rotatably connected to the upper inner sidewall and lower inner sidewall of the housing 1 respectively through the connecting mechanism.

[0036] Furthermore, the turbine 3 has an internal hollow structure, and the interior of the turbine 3 is connected to the internal filtrate chamber 7; filter holes are provided on the side wall of the turbine 3, and the diameter of the filter holes is smaller than the diameter of the solid particles.

[0037] In practical applications, turbine 3 drives the drilling fluid downwards and towards the outer filter screen 4, thereby achieving the separation of the solid phase. During this process, the surface of turbine 3 contacts and applies force to the drilling fluid. Therefore, setting filter holes on the side wall of turbine 3 can transport the liquid phase into the interior of turbine 3 and into the inner filtration chamber 7 during the application of force by turbine 3, achieving the purpose of further separating the solid phase and thus improving the separation efficiency.

[0038] In some embodiments, the upper and lower ends of the filter turbine shaft 2 are connected to the housing 1 via a flexible section 19.

[0039] Both the upper and lower flexible sections 19 are provided with levers 20 on their outer walls. The inner wall of the housing 1 is provided with a fixing rod 21 at the corresponding position of the levers 20. The end of the fixing rod 21 is used to cooperate with the end of the levers 20.

[0040] It should be noted that when the filter turbine shaft 2 rotates one revolution, the fixed rod 21 and the toggle block 20 collide once, which can cause the filter turbine shaft 2 to vibrate slightly through the flexible section 19, thereby achieving the purpose of removing solid particles attached to the filter screen.

[0041] In some embodiments, a scraper 22 is connected to the outer edge of the turbine 3, and the outer edge of the scraper 22 abuts against the inner sidewall of the outer filter screen 4.

[0042] When the filter turbine shaft 2 rotates once, the scraper 22 scrapes the side wall of the outer filter screen 4 once, thereby removing the solid particles attached to the outer filter screen 4. In some embodiments, the connecting mechanism includes a fixed cylinder, a mounting ring, and a bearing; the mounting ring is connected to the inner wall of the housing 1, the fixed cylinder is coaxially disposed within the mounting ring, and a bearing is disposed between the fixed cylinder and the mounting ring. Both ends of the filter turbine shaft 2 are connected to the fixed cylinder.

[0043] In some embodiments, the sidewall of the filter turbine shaft 2 has several through holes to facilitate the filtration of the liquid phase from the solid phase filter chamber 6 into the inner filtrate chamber 7.

[0044] In one embodiment, the discharge mechanism 9 is a discharge ring, and a filter ring 18 is provided at the outlet of the discharge ring. The pore size of the filter ring 18 is larger than the diameter of the solid particles. The filter ring 18 is used to prevent impurities from entering the well shaft, thereby playing a role in isolation.

[0045] In some embodiments, the solid-phase filter cavity 6 includes an upper filter cavity and a lower filter cavity; the upper part of the upper filter cavity is a first cylindrical cavity 13, and the lower part of the upper filter cavity is a first conical cavity 14, the first conical cavity 14 having a conical structure, and the lower end of the first cylindrical cavity 13 is connected to the large-diameter end of the first conical cavity 14; the upper part of the filter cavity is a second cylindrical cavity 15, and the lower part of the upper filter cavity is a second conical cavity 16, the second conical cavity 16 having a conical structure, and the lower end of the second cylindrical cavity 15 and the large-diameter end of the second conical cavity 16 being connected; the upper end of the second cylindrical cavity 15 is connected to the small-diameter end of the first conical cavity 14.

[0046] It should be noted that the outer filter screen 4 and the inner filter screen 8 are provided with conical sections, thereby forming a first conical cavity 14 and a second conical cavity 16. The turbine 3 can drive the drilling fluid to move downward. When the drilling fluid moves downward, it impacts the portions of the outer filter screen 4 and the inner filter screen 8 in the first conical cavity 14 and the second conical cavity 16. During the impact, the liquid phase enters the inner filtrate cavity 7 and the outer filtrate cavity 5, achieving the purpose of further separating the solid phase, thereby improving the separation efficiency.

[0047] The inner diameters of the first cylindrical cavity 13 and the second cylindrical cavity 15 can be equal, or the inner diameter of the first cylindrical cavity 13 can be larger than the inner diameter of the second cylindrical cavity 15. When the inner diameter of the first cylindrical cavity 13 is larger than the inner diameter of the second cylindrical cavity 15, more liquid phase can be transported to the inner filtrate cavity 7 and the outer filtrate cavity 5, and the flow rate of the liquid phase containing the solid phase can also be increased, thereby improving the separation effect.

[0048] In this embodiment, the upper end of the second cylindrical cavity 15 is connected to the small-diameter end of the first conical cavity 14 via a conical segment 17, where the conical segment 17 has a conical structure. The upper end of the second cylindrical cavity 15 is connected to the large-diameter end of the conical segment 17, and the small-diameter end of the conical segment 17 is connected to the small-diameter end of the first conical cavity 14.

[0049] It should be noted that the tapered section 17 serves as a transition and slightly enlarges the inner diameter of the second cylindrical cavity 15.

[0050] Example 2: A downhole drilling fluid separation method, employing a downhole drilling fluid separation device, includes the following steps: Connect the upper end of the downhole drilling fluid separator to the drill collar and the lower end of the downhole drilling fluid separator to the drill bit, and then lower it into the well. The drilling fluid output from the drill collar enters the solid phase filter chamber 6 through the inlet at the upper end of the casing 1. When the drilling fluid flows downward, it drives the filter turbine shaft 2 in the filter turbine mechanism to rotate. During the downward movement of the drilling fluid, the following process is repeated: the drilling fluid moves towards the outer filter screen 4 under the action of centrifugal force, the liquid phase of the drilling fluid passes through the outer filter screen 4 and enters the outer filtrate chamber 5, the solid phase is blocked by the outer filter screen 4 and moves downward in the solid phase filter chamber 6, and part of the liquid phase passes through the inner filter screen 8 and enters the inner filtrate chamber 7. The solid phase and a portion of the liquid phase are discharged from the bottom of the solid phase filter chamber 6 through the discharge mechanism 9 to the space between the shell 1 and the well barrel; The liquid phase in the outer filtration chamber 5 merges with the liquid phase in the inner filtration chamber 7 through the connecting pipe 10, and then is transported to the drill bit water hole through the outlet of the shell 1 and enters the wellbore. Subsequently, the drilling fluid from the two places merges and returns upward.

[0051] This invention can retain solid particles in the solid filter chamber in real time, while the filter screen only allows the liquid phase to pass through. Therefore, the liquid phase can be well separated by the action of the turbine multiple times. The liquid phase in the outer filter chamber merges with the liquid phase in the inner filter chamber through the connecting pipe and is finally transported to the drill bit. This part of the liquid phase contains almost no solid phase, thus effectively preventing solid phase from entering the drill bit, thereby protecting the drill bit and extending its working life.

[0052] The turbine in this invention drives the drilling fluid downwards and towards the external filter screen, thereby achieving solid phase separation. During this process, the turbine surface contacts and applies force to the drilling fluid. Therefore, by providing filter holes on the turbine sidewall, the liquid phase can be transported to the interior of the turbine and enter the internal filtration chamber during the turbine's force application, achieving further solid phase separation and thus improving separation efficiency.

[0053] Where there is no conflict, those skilled in the art can combine the relevant technical features in the above examples according to the actual situation to achieve the corresponding technical effects. Specific details of the various combinations will not be elaborated here.

[0054] It should be noted that all directional indications (such as up, down, left, right, front, back, etc.) in the embodiments of the present invention are only used to explain the relative positional relationship and movement of each component in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indication will also change accordingly.

[0055] Furthermore, the use of terms such as "first" and "second" in this invention is for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of those features.

[0056] The above description is merely a preferred embodiment of the present invention. The present invention is not limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein. Any simple modifications, equivalent variations, and alterations made to the above embodiments based on the technical essence of the present invention shall still fall within the scope of the present invention.

Claims

1. A downhole drilling fluid separation device, characterized in that: The system includes a housing (1), a filter turbine mechanism, an outer filter screen (4), an inner filter screen (8), a discharge mechanism (9), and a connecting pipe (10). The housing (1) is a hollow cylindrical structure with open top and bottom, with an inlet for drilling fluid at the upper end and an outlet for drilling fluid at the lower end. The filter turbine mechanism is connected inside the housing (1) and is coaxial with the housing (1). The filter turbine mechanism has an inner filtrate chamber (7). The outer filter screen (4) is fitted onto the outside of the filter turbine mechanism. The inner filter screen... (8) Connected to the inner wall of the filter turbine mechanism; a solid phase filter chamber (6) is formed between the filter turbine mechanism and the outer filter screen (4), and an outer filtrate chamber (5) is formed between the outer filter screen (4) and the inner wall of the shell (1); the upper end of the solid phase filter chamber (6) is connected to the inlet of the shell (1); a discharge mechanism (9) is provided at the lower part of the shell (1), and the discharge mechanism (9) connects the solid phase filter chamber (6) to the outside of the shell (1); the connecting pipe (10) connects the outer filtrate chamber (5) and the inner filtrate chamber (7).

2. The downhole drilling fluid separation device as described in claim 1, characterized in that: It also includes a motor (23), a coupling (24) and a bracket; the motor (23) is connected to the upper inner wall of the housing (1) through the bracket, the bracket has a hole for drilling fluid to pass through, and the output shaft of the motor (23) is connected to the upper end of the filter turbine mechanism through the coupling (24).

3. A downhole drilling fluid separation device as described in claim 1 or 2, characterized in that: The filter turbine mechanism includes a filter turbine shaft (2), several turbines (3) and a connecting mechanism; the filter turbine shaft (2) is provided with an inner filtrate chamber (7), and an inner filter screen (8) is provided on the inner side wall of the filter turbine shaft (2), the pore size of the inner filter screen (8) is smaller than the diameter of the solid particles; the turbines (3) are connected to the outer side wall of the filter turbine shaft (2); the filter turbine shaft (2) is coaxial with the housing (1); the upper end and the lower end of the filter turbine shaft (2) are rotatably connected to the upper inner side wall and the lower inner side wall of the housing (1) respectively through the connecting mechanism.

4. The downhole drilling fluid separation device as described in claim 3, characterized in that: The turbine (3) has an internal hollow structure, and the interior of the turbine (3) is connected to the internal filtrate chamber (7); the side wall of the turbine (3) is provided with filter holes, and the diameter of the filter holes is smaller than the diameter of the solid particles.

5. A downhole drilling fluid separation device as described in claim 3 or 4, characterized in that: A scraper (22) is connected to the outer edge of the turbine (3), and the outer edge of the scraper (22) abuts against the inner wall of the outer filter screen (4).

6. The downhole drilling fluid separation device as described in claim 3, characterized in that: The connecting mechanism includes a fixed cylinder, an mounting ring, and a bearing; the mounting ring is connected to the inner wall of the housing (1), the fixed cylinder is coaxially disposed in the mounting ring, and a bearing is disposed between the fixed cylinder and the mounting ring.

7. The downhole drilling fluid separation device as described in claim 3, characterized in that: The filter turbine shaft (2) has several through holes on its side wall.

8. The downhole drilling fluid separation device as described in claim 1, characterized in that: The discharge mechanism (9) is a discharge ring, and a filter ring (18) is provided at the outlet of the discharge ring. The filter hole diameter of the filter ring (18) is larger than the diameter of the solid particles.

9. The downhole drilling fluid separation device as described in claim 1, characterized in that: The solid-phase filter cavity (6) includes an upper filter cavity and a lower filter cavity; the upper part of the filter cavity is a first cylindrical cavity (13), the lower part of the upper filter cavity is a first conical cavity (14), the first conical cavity (14) is a conical structure, and the lower end of the first cylindrical cavity (13) is connected to the large-diameter end of the first conical cavity (14); the upper part of the lower filter cavity is a second cylindrical cavity (15), the lower part of the upper filter cavity is a second conical cavity (16), the second conical cavity (16) is a conical structure, and the lower end of the second cylindrical cavity (15) is connected to the large-diameter end of the second conical cavity (16); the upper end of the second cylindrical cavity (15) is connected to the small-diameter end of the first conical cavity (14).

10. A method for separating downhole drilling fluid, characterized in that: The downhole drilling fluid separation device as described in any one of claims 1-9 includes the following steps: Connect the upper end of the downhole drilling fluid separator to the drill collar and the lower end of the downhole drilling fluid separator to the drill bit, and then lower it into the well. The drilling fluid output from the drill collar enters the solid phase filter chamber (6) through the inlet at the upper end of the casing (1). When the drilling fluid flows downward, it drives the filter turbine shaft (2) in the filter turbine mechanism to rotate. During the downward movement of the drilling fluid, the following process is repeated: the drilling fluid moves towards the outer filter (4) under the action of centrifugal force, the liquid phase of the drilling fluid passes through the outer filter (4) and enters the outer filtrate chamber (5), the solid phase is blocked by the outer filter (4) and moves downward in the solid phase filter chamber (6), and part of the liquid phase passes through the inner filter (8) and enters the inner filtrate chamber (7); The solid phase and part of the liquid phase are discharged from the bottom of the solid phase filter chamber (6) through the discharge mechanism (9) to the space between the shell (1) and the well shaft; The liquid phase in the outer filtrate chamber (5) merges with the liquid phase in the inner filtrate chamber (7) through the connecting pipe (10), and then is transported to the drill bit water hole through the outlet of the shell (1) and enters the wellbore. Subsequently, the drilling fluids from the two locations merge and return upwards.

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