A four-stage sand sealing and filtering screen pipe

Abstract

The present invention relates to a four-stage sand-sealing and sand-filtering screen pipe. The invention mainly solves the problem that the sand returned after the existing oil well fracturing causes sand jamming, burying the sand-proof screen pipe and the oil pump, thereby causing the oil pump lifting failure. The invention is characterized in that: the bottom of the upper end screen pipe (1) is connected to the middle section screen pipe (2), the bottom of the middle section screen pipe (2) is connected to the packer (3), and the bottom of the packer (3) is connected to the lower end screen pipe (4); a plurality of ceramic filter core assemblies (104) are arranged inside the upper end screen pipe (1); the packer (3) comprises a packer core pipe (302), the outer sides of the two ends of the core pipe (302) are respectively connected to an upper guide shoe (303) and a rubber tube lower pressure cap (305), and a rubber tube (304) is arranged between the upper guide shoe (303) and the rubber tube lower pressure cap (305). The four-stage sand-sealing and sand-filtering screen pipe can filter out the fracturing sand and fine sand generated after fracturing, prevent the returned sand from burying the sand-proof screen pipe and the oil pump, and ensure the normal operation of the oil pump.

Description

Technical Field

[0001] The invention relates to the field of oil fields, in particular to a four-section sand sealing and filtering screen pipe. Background Art

[0002] Oil well fracturing is one of the important measures to increase oil field production. After oil well fracturing is put into production or after production is resumed after fracturing, there is generally a phenomenon of sand return. Fracturing sand flows into the wellbore from the formation along with the oil. In order to prevent fracturing sand from entering the oil well pump and causing sand jam, affecting the lifting effect of the oil well pump, it is currently usually adopted to connect a sand-proof screen pipe under the oil well pump to filter out the fracturing sand, so as to ensure that the oil well pump is not affected by the fracturing sand and can operate normally and smoothly.

[0003] However, with the deepening of oil field development, large-scale fracturing is often used to develop tight oil, and the amount of fracturing sand injection has increased significantly. At the same time, severe sand return often occurs after fracturing wells are produced. Fracturing sand returns from the formation into the wellbore. Not only can the silt component in it not be filtered out by the sand screen, causing sand jamming problems, but more seriously, the fracturing sand returns and buries the sand screen and the oil pump, causing the oil pump to completely fail to lift. At the same time, the dynamic liquid level of the oil well rises, and the oil pump sampling is empty. During the operation, the pipe string is stuck by the fracturing sand, and conventional operations cannot be lifted or cause the pipe string to fall off, requiring major repairs, which increases the cost of oil well operations.

[0004] The current sand control technology after oil well fracturing mainly uses sand control screens, but it only filters out the fracturing sand in the oil and does not filter out the silt sand. At the same time, it cannot solve the problem of pump lifting failure caused by the phenomenon of sand returning after fracturing burying the sand control screens and pumps. Summary of the invention

[0005] In order to overcome the shortcomings of the existing oil well fracturing that sand returns after fracturing, causing sand jamming, burying the sand control screen and the oil pump, and thus causing the oil pump lifting failure, the present invention provides a four-stage sand sealing and filtering screen and an oil well post-fracture sand control process. The four-stage sand sealing and filtering screen can filter out the fracturing sand and silt sand generated after fracturing, avoid the returned sand burying the sand control screen and the oil pump, and ensure the normal operation of the oil pump.

[0006] The technical solution of the present invention is: a four-stage sand sealing and filtering screen pipe, comprising an upper screen pipe and a lower screen pipe, the bottom of the upper screen pipe is connected to the middle screen pipe, the bottom of the middle screen pipe is connected to the packer, and the bottom of the packer is connected to the lower screen pipe; a plurality of ceramic filter element assemblies are arranged inside the upper screen pipe.

[0007] The packer comprises a packer core tube, and the outer parts of both ends of the core tube are respectively connected with an upper guide shoe and a rubber tube lower pressure cap, and a rubber tube is arranged between the upper guide shoe and the rubber tube lower pressure cap.

[0008] The ceramic filter element assembly comprises a filter element outer shell and a filter element inner shell, with a ceramic filter element arranged therebetween; the filter element outer shell is provided with a filter element outer shell liquid inlet slit, and the filter element inner shell is provided with a filter element inner shell liquid outlet slit.

[0009] The liquid inlet slit of the filter element outer shell is located above the liquid outlet slit of the filter element inner shell.

[0010] The filter element inner shell is conical, the liquid outlet gap of the filter element inner shell is located at the large diameter end of the filter element inner shell, and the liquid inlet gap of the filter element outer shell corresponds to the small diameter end of the filter element inner shell.

[0011] The middle section screen tube comprises an inner core tube, an outer filter cartridge is arranged outside the inner core tube, a middle section screen tube inner cartridge liquid outlet hole is opened on the inner core tube, and a middle section screen tube outer cartridge liquid outlet gap is opened on the outer filter cartridge.

[0012] The present invention has the following beneficial effects: (1) The four-stage sand-sealing and sand-filtering screen pipe not only has the sand-control effect of other sand-control pipe columns, but also has the effect of blocking the fracturing sand returning into the wellbore and filtering out the silt components in the oil, and will not cause other sand-control technologies to be buried by the fracturing sand returning from the formation and cause the oil pump to fail. (2) The packer in the four-stage sand-sealing and sand-filtering screen pipe has the function of blocking the annular space of the oil casing and preventing the fracturing sand returning from the formation from moving up and burying the screen pipe and the oil pump. (3) The lower end screen pipe and the middle section screen pipe part of the four-stage sand-sealing and sand-filtering screen pipe can filter the fracturing sand carried in the oil, and allow the oil to pass through the packer to form a stable dynamic liquid surface above the packer, thereby ensuring the normal production of the oil pump. The lower screen is not afraid of being buried by fracturing sand and can filter out the fracturing sand carried in the oil; the packer blocks the fracturing sand under the rubber tube, allowing the oil to move upward from its center tube to the middle screen, preventing the fracturing sand from moving upward and burying the middle screen, the upper screen and the pump; the middle screen can allow the oil to flow from the internal channel to the annular space of the casing. The oil flow direction of the middle screen is opposite to that of the conventional sand-proof screen, and it mainly plays the role of connecting the upper and lower annuli of the rubber tube, so that a stable dynamic liquid surface is formed above the rubber tube of the packer to ensure the pumping efficiency of the pump. (4) The upper screen in the four-stage sand-sealing sand filter can filter out the very small amount of silt in the oil and prevent sand from getting stuck in the pump. A multi-stage ceramic filter assembly is arranged in the upper screen, and each stage of the ceramic filter assembly can filter the oil in three layers. The structure of the ceramic filter element assembly has three core innovations: first, the ceramic filter element is used to filter out the very small amount of silt remaining in the oil; second, the design of the filter element outer shell and inner shell allows the oil to enter from the top and exit from the bottom. After the oil enters the ceramic filter element assembly from the liquid inlet gap of the upper screen tube ceramic filter element outer shell, it passes through the ceramic filter element and then enters the oil pump liquid inlet channel from the liquid outlet gap of the upper screen tube ceramic filter element inner shell; third, the inner cone design of the ceramic filter element and the filter element inner shell, combined with the setting of the liquid inlet gap of the upper screen tube ceramic filter element outer shell and the liquid outlet gap of the upper screen tube ceramic filter element inner shell, the flow rate of the oil suddenly increases when it flows through the top of the filter element inner shell, and the pressure suddenly decreases when it enters the upper-level ceramic filter element assembly. This effect will drive the flow of oil in the ceramic filter element assembly, accelerate the suction and periodic impact of the liquid outlet gap of the upper screen tube ceramic filter element inner shell, and thus prevent the ceramic filter element from being blocked. (5) The four-stage sand-sealing filter screen seals the fracturing sand returned from the formation to the wellbore within a certain range above the perforated layer. The oil can pass through the sealing layer and form a stable dynamic liquid surface in the oil casing annulus above the sealing layer. The silt components carried by the oil are completely filtered out before entering the oil well pump, ensuring the normal and stable production of the oil well pump without problems of sand burial and sand jamming. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 It is the appearance diagram of the present invention;

[0014] Figure 2It is a schematic diagram of the structure of the present invention;

[0015] Figure 3 Schematic diagram of the structure of the packer;

[0016] Figure 4 It is a schematic diagram of the structure of the middle screen tube;

[0017] Figure 5 It is a schematic diagram of the structure of the upper screen tube;

[0018] Figure 6 It is a structural schematic diagram of a ceramic filter element assembly.

[0019] In the figure, A-inlet hole of the upper screen outer tube, B-inlet gap of the filter element outer shell, C-outlet gap of the filter element inner shell, D-annular space of the casing, E-outlet hole of the middle screen inner tube, F-outlet gap of the middle screen outer tube, G-oil channel in the packer, H-oil channel in the lower screen, I-inlet gap of the lower screen, J-oil in the wellbore, K-inlet channel of the oil pump, 1-upper screen, 2-middle screen, 3-packer, 4-lower screen, 5-thread plug, 101 -Oil pipe coupling, 102-upper joint, 103-outer tube, 104-ceramic filter element assembly, 105-lower joint, 201-middle screen tube inner joint, 202-inner core tube, 203-outer filter cartridge, 301-packer inner joint, 302-packer core tube, 303-upper guide shoe, 304-rubber cartridge, 305-rubber cartridge lower pressure cap, 601-housing upper cover, 602-filter element outer shell, 603-ceramic filter element, 604-filter element inner shell, 605-housing lower cover. DETAILED DESCRIPTION

[0020] The present invention will be further described below in conjunction with the accompanying drawings:

[0021] Depend on Figures 1 to 6As shown, a four-stage sand-sealing sand filter screen comprises an upper screen 1 and a lower screen 4. The bottom of the upper screen 1 is connected to the middle screen 2, the bottom of the middle screen 2 is connected to the packer 3, the bottom of the packer 3 is connected to the lower screen 4, and the bottom of the lower screen 4 is connected to a wire plug 5. The upper screen 1 comprises an upper joint 102 and a lower joint 105, wherein the upper end of the upper joint 102 is connected to the upper oil pipe through an oil pipe coupling 101, and the lower joint 105 is a solid joint. An outer cylinder 103 is connected between the upper joint 102 and the lower joint 105, and a plurality of upper screen outer cylinder liquid inlet holes A are opened on the outer cylinder 103. A plurality of ceramic filter element assemblies 104 are arranged inside the outer cylinder 103, and the upper joint 102 and the lower joint 105 restrict the ceramic filter element assembly 104 inside, and two adjacent ceramic filter element assemblies 104 are crimped. The ceramic filter assembly 104 includes a filter shell 602 and a filter inner shell 604, between which a ceramic filter 603 is arranged, and the filter shell 602 and the filter inner shell 604 are respectively connected to the housing upper cover 601 and the housing lower cover 605 at both ends, so that the ceramic filter 603 is enclosed between the inner and outer housings. The filter inner shell 604 is conical, with a small inner diameter at the upper end and a large inner diameter at the lower end. The filter shell 602 is provided with a filter shell liquid inlet gap B, and the filter inner shell 604 is provided with a filter inner shell liquid outlet gap C, and the filter shell liquid inlet gap B is located above the filter inner shell liquid outlet gap C, that is, the filter inner shell liquid outlet gap C is located at the large diameter end of the filter inner shell 604, and the filter shell liquid inlet gap B corresponds to the small diameter end of the filter inner shell 604.

[0022] The middle screen tube 2 comprises an inner core tube 202, the upper end of the inner core tube 202 is connected to the lower joint 105 on the upper screen tube 1 through the middle screen tube inner joint 201, an outer filter cartridge 203 is arranged outside the inner core tube 202, a middle screen tube inner tube liquid outlet hole E is opened on the inner core tube 202, and a middle screen tube outer tube liquid outlet gap F is opened on the outer filter cartridge 203. The side wall of the lower screen tube 4 is provided with a lower end screen tube liquid inlet gap I.

[0023] The packer 3 is located at the lower part of the middle screen 2 and the upper part of the lower screen 4, and includes a packer internal joint 301 and a packer core tube 302. The upper part of the internal joint 301 is connected to the thread below the inner core tube 202 inside the middle screen 2 by a threaded buckle, and the lower part is connected to the upper thread of the packer core tube 302. The lower part of the packer core tube 302 is connected to the top of the lower screen 4 by a threaded connection. The outer part of the packer core tube 302 is connected to the upper guide shoe 303 and the rubber tube lower pressure cap 305 by a thread, and the rubber tube 304 is set between the upper guide shoe 303 and the rubber tube lower pressure cap 305. The main function of the packer rubber tube 3 is to seal the fracturing sand in the oil casing space D below the rubber tube 304.

[0024] The working principle of the four-stage sand sealing and filtering screen is as follows: when the fracturing pump is lowered after the oil well fracturing is completed, the four-stage sand sealing and filtering screen is connected to the lower part of the oil pump, and then the pumping operation is performed; after the operation is completed and the normal production of the oil well is restored, the oil J in the wellbore is blocked by the rubber tube 304 of the packer 3 in the annular space of the oil casing, but can enter the four-stage sand sealing and filtering screen through the liquid inlet gap I in the lower end screen tube, and the fracturing sand carried in the oil is blocked outside the lower end screen tube 4. The oil moves upward along the oil channel H in the lower end screen tube, reaches the middle section screen tube 2 through the oil channel G in the isolation rubber tube, is blocked upward by the lower joint 105, and flows through the liquid outlet hole E of the inner tube of the middle section screen tube and the liquid outlet gap F of the outer tube of the middle section screen tube to the annular space D of the oil casing above the rubber tube 304, thereby forming a stable dynamic liquid surface to ensure the pumping efficiency of the oil pump. The oil in the annular space D of the oil casing enters the ceramic filter element 603 through the upper screen tube outer cylinder liquid inlet hole A and the filter element shell liquid inlet gap B and continues to move upward, and enters the oil pump liquid inlet channel K through the filter element inner shell liquid outlet gap C. In this process, the oil is filtered five times. The first filtration is to filter out the fracturing sand carried in the oil at the lower screen tube 4, but the oil still contains a small amount of extremely fine sand. The second filtration is at the middle screen tube 2, and the third to fifth filtrations are at the upper screen tube 1. The very small amount of extremely fine sand carried in the oil is filtered out by the filter element shell liquid inlet gap B, the ceramic filter element 603, and the filter element inner shell liquid outlet gap C, and the oil in the oil pump liquid inlet channel K no longer contains fracturing sand. If the oil well needs to be operated again for other reasons, the lifting operation is the same as the conventional operation, and no additional procedures are added.

Claims

1. A four-stage sand sealing and filtering screen pipe, comprising an upper screen pipe (1) and a lower screen pipe (4), characterized in that: The bottom of the upper screen tube (1) is connected to the middle screen tube (2), the bottom of the middle screen tube (2) is connected to the packer (3), and the bottom of the packer (3) is connected to the lower screen tube (4); a plurality of ceramic filter element assemblies (104) are arranged inside the upper screen tube (1); The packer (3) comprises a packer core tube (302), the outer parts of both ends of the packer core tube (302) are respectively connected with an upper guide shoe (303) and a rubber tube lower pressure cap (305), and a rubber tube (304) is provided between the upper guide shoe (303) and the rubber tube lower pressure cap (305); The ceramic filter element assembly (104) comprises a filter element outer shell (602) and a filter element inner shell (604), with a ceramic filter element (603) disposed therebetween; the filter element outer shell (602) is provided with a filter element outer shell liquid inlet slit (B), and the filter element inner shell (604) is provided with a filter element inner shell liquid outlet slit (C); the filter element inner shell (604) is conical, the filter element inner shell liquid outlet slit (C) is located at the large diameter end of the filter element inner shell (604), and the filter element outer shell liquid inlet slit (B) corresponds to the small diameter end of the filter element inner shell (604).

2. The four-stage sand sealing and filtering screen pipe according to claim 1 is characterized in that: The middle screen tube (2) comprises an inner core tube (202), an outer filter cartridge (203) is arranged outside the inner core tube (202), a middle screen tube inner cartridge liquid outlet hole (E) is opened on the inner core tube (202), and a middle screen tube outer cartridge liquid outlet slit (F) is opened on the outer filter cartridge (203).

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