A sealing and filtering integrated pipe and a sand control process after oil well fracturing

Abstract

The present invention relates to an integrated sealing and filtering pipe and a sand prevention process after oil well fracturing. The invention mainly solves the problem that the sand returned after the existing oil well fracturing causes sand jamming, burying the sand prevention 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 integrated sealing and filtering pipe can filter out the fracturing sand and silt sand generated after fracturing, prevent the returned sand from burying the sand prevention 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 sealing and filtering integrated pipe and a sand control process after oil well fracturing. Background Art

[0002] Oil well fracturing is a key measure for increasing oilfield production. After fracturing a well is commissioned or resumed, sand flow typically occurs. Fracturing sand flows from the formation into the wellbore along with the oil. To prevent fracturing sand from entering the wellbore pump and causing sand jams, which could affect the pump's lift, a sand-control screen is typically installed below the pump to filter out the fracturing sand. This ensures the pump remains unaffected by the fracturing sand and maintains normal, stable operation.

[0003] However, with the deepening of oilfield development, large-scale fracturing is often used to develop tight oil, resulting in a significant increase in the amount of fracturing sand injected. Simultaneously, severe sand return is frequently observed after fracturing wells are put into production. Fracturing sand is returned from the formation into the wellbore, where not only is the silt content unable to be filtered out by the sand screens, causing sand jams, but more seriously, the fracturing sand can bury the sand screens and the wellbore pump, causing the pump to completely fail. Simultaneously, the dynamic fluid level in the well rises, and the pump cannot sample anything. During operations, the string becomes stuck in the fracturing sand, preventing conventional lifting or causing the string to fall off, requiring major repairs and increasing well operating costs.

[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, and at the same time cannot solve the fracturing problem. Summary of the Invention

[0005] In order to overcome the shortcomings of the existing oil well fracturing caused by sand returning after fracturing, which causes sand jamming, burying the sand control screen and the oil pump, and thus causing the oil pump lifting failure, the present invention provides an integrated sealing and filtering pipe and an oil well post-fracture sand control process. The integrated sealing and filtering pipe can filter out the fracturing sand and silt generated after fracturing, prevent the returned sand from 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 sealing and filtering integrated pipe, including 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 provided inside the upper screen pipe.

[0007] 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.

[0008] The liquid inlet slit of the filter element outer shell is located above the liquid outlet slit of the filter element inner shell.

[0009] 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.

[0010] The packer includes a packer core tube, the outer thread of the packer core tube is connected to a rubber tube nut, a plurality of circumferentially evenly distributed sliders are provided on the upper part of the rubber tube nut, a plurality of radially arranged springs are provided between the inner wall of the slider and the packer core tube; a rubber tube is provided at the bottom of the rubber tube nut.

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

[0012] A post-fracture sand control process for oil wells using the integrated filter and seal pipe comprises the following steps: during the post-fracture pumping operation, the integrated filter and seal pipe is lowered to a designed depth; the oil tubing string is rotated clockwise to set the packer in the integrated filter and seal pipe; and normal production is resumed after the operation is completed.

[0013] Furthermore, during normal production, the oil moves upward in the wellbore and is blocked by the packer. The oil enters the integrated filter and seal pipe along the lower screen and moves upward, blocking the fracturing sand returning to the wellbore from the formation under the packer. The oil passes through the packer and is blocked by the upper screen, flows from the middle screen to the annular space of the oil casing above the packer and continues to move upward, forming a stable dynamic liquid surface to ensure the pumping efficiency of the oil well pump; as the oil well pump sucks and lifts the oil from the upper screen into the liquid inlet channel of the oil well pump, the very small amount of silt carried in the oil is filtered outside the upper screen.

[0014] The present invention has the following beneficial effects: (1) The integrated sealing and filtering pipe not only has the sand control effect of other sand control pipe strings, but also has the effect of blocking the fracturing sand returning to the wellbore and filtering out the silt components in the oil, which 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 integrated sealing and filtering pipe can achieve the effect of rotary sealing and lifting and unsealing, and has the function of sealing the annular space of the oil casing to prevent the fracturing sand returning from the formation from moving up and burying the screen pipe and the oil pump; the sealing method is simple, without the need for complicated operations such as throwing balls and positive pressure, and the sealing can be completed by rotating the pipe string clockwise. (3) The lower end screen pipe and the middle section screen pipe part in the integrated sealing and filtering 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 packer rubber tube, allowing the oil to move upward from its center tube to the middle screen tube, preventing the fracturing sand from moving upward and burying the middle screen tube, the upper screen tube and the oil pump; the middle screen tube can flow the oil from the internal channel to the annular space of the oil casing. The oil flow direction of the middle screen tube is opposite to that of the oil flow in the conventional sand control screen tube. It mainly plays the role of connecting the upper and lower oil casing annuli of the packer rubber tube, allowing a stable dynamic liquid surface to be formed above the packer rubber tube to ensure the pumping efficiency of the oil pump. (4) The upper screen tube in the integrated sealing and filtering pipe can filter out the very small amount of silt in the oil and prevent the oil pump from getting stuck. A multi-stage ceramic filter assembly is set in the upper screen tube, 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 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 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 oil flow rate suddenly increases when flowing through the top of the filter element inner shell, and the pressure suddenly decreases when entering 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 integrated sealing and filtering pipe 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

[0015] Figure 1 It is an outline diagram of the present invention;

[0016] Figure 2 It is a structural schematic diagram of the present invention;

[0017] Figure 3 Schematic diagram of the packer structure;

[0018] Figure 4 This is a schematic diagram of the structure of the middle sieve tube;

[0019] Figure 5 It is a structural diagram of the upper screen tube;

[0020] Figure 6 It is a structural diagram of the ceramic filter element assembly.

[0021] In the figure, A-inlet hole of the upper end screen tube 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 oil casing, E-outlet hole of the middle section screen tube inner tube, F-outlet gap of the middle section screen tube outer tube, G-oil channel in the packer, H-oil channel in the lower end screen tube, I-inlet gap of the lower end screen tube, J-oil in the wellbore, K-inlet channel of the oil pump, 1-upper end screen tube, 2-middle end screen tube, 3-packer, 4-lower end screen tube, 5-plug, 101-tubing 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-slider nut, 304-slider shaft bracket, 305-slider, 306-spring, 307-rubber cartridge nut, 308-rubber cartridge, 309-spacer ring, 310-rubber cartridge inner tube, 311-pin, 312-sleeve, 601-housing cover, 602-filter element outer shell, 603-ceramic filter element, 604-filter element inner shell, 605-housing lower cover. DETAILED DESCRIPTION

[0022] The present invention will be further described below in conjunction with the accompanying drawings:

[0023] Depend on Figures 1 to 6As shown, a sealing and filtering integrated pipe includes an upper screen tube 1 and a lower screen tube 4. 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, the bottom of the packer 3 is connected to the lower screen tube 4, and the bottom of the lower screen tube 4 is connected to a wire plug 5. The upper screen tube 1 includes an upper joint 102 and a lower joint 105. The upper end of the upper joint 102 is connected to the upper oil pipe via a tubing coupling 101, and the lower joint 105 is a solid joint. An outer tube 103 is connected between the upper joint 102 and the lower joint 105. The outer tube 103 is provided with a plurality of upper screen tube outer tube liquid inlet holes A. The outer tube 103 is provided with a plurality of ceramic filter element assemblies 104. The upper joint 102 and the lower joint 105 confine the ceramic filter element assemblies 104 inside, and adjacent ceramic filter element assemblies 104 are crimped together. The ceramic filter assembly 104 includes a filter outer shell 602 and a filter inner shell 604, with a ceramic filter 603 disposed therebetween. The outer shell 602 and the inner shell 604 are connected at both ends to the housing upper cover 601 and the housing lower cover 605, respectively, enclosing the ceramic filter 603 between the inner and outer shells. The inner shell 604 is conical, with a smaller inner diameter at the upper end and a larger inner diameter at the lower end. The outer shell 602 is provided with a filter housing liquid inlet slit B, and the inner shell 604 is provided with a filter inner shell liquid outlet slit C. The outer shell liquid inlet slit B is located above the inner shell liquid outlet slit C, i.e., the inner shell liquid outlet slit C is located at the larger diameter end of the inner shell 604, and the outer shell liquid inlet slit B corresponds to the smaller diameter end of the inner shell 604.

[0024] The middle sieve tube 2 includes an inner core tube 202, the upper end of which is connected to the lower joint 105 on the upper sieve tube 1 via a middle sieve tube inner joint 201. An outer filter cartridge 203 is provided on the outer surface of the inner core tube 202. The inner core tube 202 has a middle sieve tube inner tube liquid outlet hole E, and the outer filter cartridge 203 has a middle sieve tube outer tube liquid outlet slit F. The side wall of the lower sieve tube 4 has a lower sieve tube liquid inlet slit I.

[0025] The packer 3 includes a packer core tube 302, the upper end of the packer core tube 302 is connected to the inner core tube 202 of the middle section screen tube 2 through the packer internal joint 301, the outer thread of the packer core tube 302 is connected to a rubber tube nut 307, and there is a gap between the upper end of the rubber tube nut 307 and the packer core tube 302, and two sections of slider shaft frames 304 are provided in the gap, and a number of circumferentially uniformly distributed sliders 305 are provided between the two sections of slider shaft frames 304, and a number of radially arranged springs 306 are provided between the inner wall of the slider 305 and the packer core tube 302, and the end of the slider shaft frame 304 at the upper end is connected to the slider nut 303, which can limit the outward movement of the slider 305, and the elastic action of the spring 306 is conducive to the slider 305 always fitting with the inner wall of the external casing 312. A rubber inner tube 310 is provided between the bottom of the rubber nut 307 and the core tube 302 of the packer. Several rubber tubes 308 are provided on the outside of the rubber inner tube 310, and spacer rings 309 are provided between adjacent rubber tubes 308 to transmit axial pressure. A pin 311 is connected between the side wall of the rubber inner tube 310 and the core tube 302 of the packer. The casing 312 is the original structure of the oil well, which mainly serves to accommodate the original well pipe string, the oil pump and the integrated filter pipe, and at the same time forms an oil casing annular space D. The main function of the packer 3 is to seal the oil casing annular space, prevent the fracturing sand carried in the oil from moving upward, and seal the fracturing sand below the rubber tube 308 of the packer 3 above the perforated layer section, so as to prevent the fracturing sand from returning and burying the middle screen pipe 2, the upper end screen pipe 1 and even the oil pump, thereby preventing the oil pump from failing.

[0026] The post-fracture sand control process of the oil well using the integrated sealing and filtering pipe has the following operating steps: when the fracturing pump is lowered after the oil well fracturing is completed, the integrated sealing and filtering pipe is connected to the lower part of the oil well pump, and then the pump is lowered; when the oil well pump is lowered to the designed depth (generally about 70 meters above the perforated layer), the oil pipe is rotated clockwise, and the core pipe 302 of the new type of packer 3 in the integrated sealing and filtering pipe rotates clockwise, so that the rubber tube nut 307 moves downward and compresses the rubber tube 308. Since the rubber tube inner tube 310 is connected to the packer core pipe 302 by the pin 311, it can prevent the rubber tube 308 from moving downward, thereby further compressing the rubber tube 308 so that it is tightly expanded on the inner wall of the casing 312, thereby achieving the purpose of isolating the lower oil casing annular space, thereby realizing the setting of the packer, and in this way, the fracturing return sand is blocked within a certain range above the perforated layer. After the operation is completed and normal production resumes at the well, the oil J in the wellbore is blocked by the rubber sleeve 308 of the packer 3 in the casing annular space. However, it can enter the integrated sealer and filter pipe through the lower screen inlet slit I. The fracturing sand carried by the oil is blocked outside the lower screen 4. The oil then moves upward along the oil channel H in the lower screen, through the oil channel G in the packer, into the middle screen 2. It is then blocked upward by the lower joint 105, and flows through the middle screen inner tube outlet hole E and the middle screen outer tube outlet slit F into the casing annular space D above the rubber sleeve 308, thereby forming a stable dynamic liquid level to ensure pumping efficiency. Within the casing annular space D, the oil enters the ceramic filter 603 through the upper screen outer tube inlet hole A and the upper screen ceramic filter shell inlet slit B, continues upward, and enters the oil pump inlet channel K through the upper screen ceramic filter shell outlet slit C. During this process, the oil is filtered five times. The first filtration is at the lower end screen pipe 4, where the fracturing sand carried in the oil is filtered out. However, the oil still contains a small amount of extremely fine sand. The second filtration is at the middle end screen pipe 2. The third to fifth filtrations are at the upper end screen pipe 1. The very small amount of extremely fine sand carried in the oil is filtered out by the liquid inlet gap B of the upper end screen pipe ceramic filter shell, the ceramic filter element 603, and the liquid outlet gap C of the upper end screen pipe ceramic filter inner shell. The oil in the oil pump inlet channel K no longer contains fracturing sand and silt. If the oil well needs to be re-operated for other reasons, the original wellbore string is pulled up, causing the packer core tube 302 to also move upward. Since the rubber tube 308 is tightly swollen against the inner wall of the casing 312, the rubber tube inner tube 310 cannot move upward. The packer core tube 302 breaks the pin 311, causing the packer core tube 302 to move upward. When the pin 311 breaks, the axial control of the rubber tube inner tube 310 is lost. The elasticity of the rubber tube pushes the rubber tube inner tube 310 downward, thereby restoring the rubber tube 308 to its original size and releasing the packer. When the string is further pulled up, the rubber tube inner tube 310 falls on the lower end screen 4 and is pulled out of the wellhead together with the sand control screen 4.

Claims

1. A sealing and filtering integrated pipe, comprising an upper sieve pipe (1) and a lower sieve 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 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) arranged between the two; a filter element outer shell liquid inlet slit (B) is formed on the filter element outer shell (602), and a filter element inner shell liquid outlet slit (C) is formed on the filter element inner shell (604); the filter element outer shell liquid inlet slit (B) is located above the 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); The packer (3) comprises a packer core tube (302), the outer thread of the packer core tube (302) being connected to a rubber tube nut (307), a plurality of circumferentially evenly distributed sliders (305) being provided on the upper part of the rubber tube nut (307), a plurality of radially arranged springs (306) being provided between the inner wall of the slider (305) and the packer core tube (302); and a rubber tube (308) being provided at the bottom of the rubber tube nut (307).

2. The sealing and filtering integrated tube according to claim 1, characterized in that: There is a gap between the rubber tube nut (307) and the packer core tube (302), and two sections of slider shaft frames (304) are arranged in the gap. The slider (305) is located between the two sections of slider shaft frames (304).

3. The sealing and filtering integrated tube according to claim 2, characterized in that: A rubber tube inner tube (310) is provided between the bottom of the rubber tube nut (307) and the packer core tube (302), a plurality of rubber tubes (308) are provided outside the rubber tube inner tube (310), and spacer rings (309) are provided between adjacent rubber tubes (308).

4. The sealing and filtering integrated tube according to claim 1, 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).

5. A post-fracture sand control process for oil wells using the sealing and filtering integrated pipe according to any one of claims 1 to 4, characterized in that: During the pumping operation after fracturing, the integrated sealing and filtering pipe is lowered to the designed depth, and the oil pipe string is rotated clockwise to seal the packer (3) in the integrated sealing and filtering pipe. After the operation is completed, normal production is resumed.

6. The post-fracture sand control process for oil wells according to claim 5, characterized in that: During normal production, the oil moves upward in the wellbore and is blocked by the packer (3). The oil moves upward along the lower screen pipe (4) into the integrated filter and seal pipe, blocking the fracturing sand in the formation returning to the wellbore below the packer (3). The oil passes through the packer (3) and is blocked by the upper screen pipe (1). The oil flows from the middle screen pipe (2) to the oil casing annular space (D) above the packer (3) and continues to move upward, forming a stable dynamic liquid surface that ensures the pumping efficiency of the oil pump. As the oil pump sucks and lifts the oil from the upper screen pipe (1) into the oil pump inlet channel (K), the very small amount of silt contained in the oil is filtered outside the upper screen pipe (1).

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