A system and method for horizontal well with pressure drag fracturing string in oilfield

Abstract

The present application belongs to the technical field of oilfield well horizontal well pressure belt drag fracturing reconstruction, and discloses an oilfield horizontal well pressure belt drag fracturing pipe string system and a use method. The system comprises a tubing plug, an expansion type packer, a closable communication valve, a cup seal packer and a Y211 packer. The tubing plug is fixedly arranged in the horizontal well tubing. One end of the expansion type packer is fixedly connected with a hydraulic anchor arranged on the horizontal section tubing. One end of the closable communication valve is fixedly arranged at the other end of the expansion type packer. One end of the cup seal packer is fixedly connected with the other end of the closable communication valve. The Y211 packer is fixedly arranged at the outlet of the tubing. The expansion type packer and the cup seal packer work simultaneously, and the pressure belt drag pipe string construction is adopted, so that the pressure bearing capacity and the service life of the pipe string are improved. The problems of low construction efficiency caused by the leakage of the blowout tubing and the sand sticking of the pipe string after the repeated reconstruction of the horizontal well are solved.

Description

Technical Field

[0001] This invention belongs to the field of hydraulic fracturing technology for horizontal wells in oilfields, specifically relating to a hydraulic fracturing tubing system and its usage method for horizontal wells in oilfields. Background Technology

[0002] Currently, horizontal wells are widely used in oil and gas field development. However, with the increase in production time, some horizontal wells experience blockage near the wellbore. During the initial stimulation, there was insufficient understanding of the reservoir characteristics, resulting in inadequate stimulation. This leads to a large decline in production and low output of horizontal wells, thus requiring repeated stimulation of horizontal wells.

[0003] Because the wellbore was fully opened during the initial fracturing, and there was leakage in the reservoir, repeated fracturing operations are risky and difficult. Currently, a dual-sealed drag fracturing string is mainly used for construction. The main problems with using this string in the field are as follows: 1. Due to insufficient reservoir energy in the perforated section above the upper packer, the pressure differential during construction is large, making it prone to damage and failure; 2. The use of a large-volume, high-displacement process results in a long blowout period after construction. At the same time, the leakage of sand-carrying fluid from the perforation holes during blowout of the tubing between the two packers is the main reason for the string's easy failure; 3. The reservoir energy in the upper perforated section of the old well is depleted. During blowout, the upper packer is in an unsealed state, and the sand-carrying fluid blown from the reservoir below the upper packer will backflow into the upper reservoir. There is a large amount of gravel in the wellbore, making well cleaning difficult and causing the string to encounter obstruction and jamming. Summary of the Invention

[0004] The purpose of this invention is to provide a pressurized drag fracturing tubing string system and its usage method for oilfield horizontal wells, in order to solve the problems in the prior art;

[0005] To achieve the above technical solution, the present invention provides the following technical solution:

[0006] A hydraulic fracturing string system for horizontal wells in oilfields includes a hydraulic anchor, an expandable packer, a shut-off connecting valve, a cup packer, a Y211 packer, and a tubing plug.

[0007] The hydraulic anchor is connected to one end of the tubing inside the horizontal well;

[0008] The oil pipe plug is detachably connected to the oil pipe;

[0009] One end of the expansion packer is fixedly connected to a hydraulic anchor on the horizontal section of the tubing.

[0010] One end of the shut-off connecting valve is connected to the other end of the expansion packer, and a sliding sleeve for closing the liquid outlet channel by dropping a ball is provided on the shut-off connecting valve;

[0011] One end of the cup packer is fixedly connected to the other end of the shut-off connecting valve;

[0012] The Y211 packer is fixedly installed at the toe of the horizontal well.

[0013] Furthermore, the soluble sealing ball is made of Al2O3 or Al and Mg-based soluble composite materials.

[0014] Furthermore, a sandblasting device is fixedly installed between the leather cup packer and the Y211 packer.

[0015] Furthermore, a one-way valve is provided between the sandblasting and the Y211 packer.

[0016] A method for using a pressurized drag fracturing tubing string system in an oilfield horizontal well includes,

[0017] Connect the hydraulic anchor, expansion packer, shut-off valve, cup packer, sandblaster, check valve and Y211 packer to the tubing in sequence, and after the connection is completed, lower the tubing to the predetermined position and set the Y211 packer.

[0018] A soluble sealing ball is inserted into the wellhead of the horizontal well. Liquid is pumped from the tubing to the soluble sealing ball and then pressurized to close the closable connecting valve.

[0019] After the soluble sealant is dissolved, liquid is pumped from the tubing. Under the action of the cup packer, the pressure in the annulus between the cup packer and the Y211 packer and the tubing increases, causing the expansion packer to set and seal the target end before fracturing operations are carried out.

[0020] After fracturing, a tubing plug is lowered into the wellhead to seal the fluid flow path inside the tubing. The tubing string is then raised to the next target location, where the Y211 packer is set. The tubing plug is then retrieved, and fluid is pumped into the tubing again. Under the action of the cup packer, the pressure inside the tubing increases, causing the expandable packer to set again. After sealing the target end, fracturing is performed. The above process is repeated to complete the fracturing of the entire well.

[0021] Further, once the soluble sealing ball is placed on the shut-off valve, pressure is applied from the wellhead of the horizontal well after the shut-off valve is closed.

[0022] Furthermore, the size of the soluble sealing ball is determined according to the size of the sliding sleeve of the shut-off connecting valve.

[0023] Furthermore, when installing a tubing plug on the horizontal well tubing, a steel wire rope is used to connect to the tubing plug to seal the tubing.

[0024] Furthermore, after plugging the tubing, the tubing is lifted to the next section of the sealing position, and the Y211 packer is set at the same time. The tubing plug is then removed, and fracturing operations are completed at different locations in the horizontal well. The above process is repeated to complete the fracturing operations of the entire well.

[0025] Compared with the prior art, the advantages of the present invention are:

[0026] This invention discloses a pressurized drag-drive fracturing string system for oilfield horizontal wells. It employs an upper packing unit composed of an expandable packer and a cup packer, solving problems such as large pressure loss and severe erosion damage caused by using a choke nozzle to set the expandable packer under high-flow, high-sand conditions. This system improves the overall pressure-bearing capacity and lifespan of the horizontal well string. The cup packer remains sealed after fracturing, resolving the issue of sand-carrying fluid flowing through the annulus after fracturing in older wells. It achieves annular fluid sealing, with tubing plugs used for sealing within the tubing. This system enables pressurized drag-drive fracturing without venting after repeated fracturing in horizontal wells, addressing the problems of tubing leakage and sand jamming caused by venting after repeated fracturing in horizontal wells, which leads to low construction efficiency of the double-seal drag-drive fracturing string and the inability to improve construction efficiency due to sand-carrying fluid flowing through the annulus. Attached Figure Description

[0027] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0028] In the attached diagram:

[0029] Figure 1 This is a schematic diagram of the overall structure of a pressurized drag fracturing tubing system for oilfield horizontal wells according to the present invention;

[0030] Figure 2 This is a schematic diagram of the structure of an oilfield horizontal well pressurized drag fracturing tubing string system for lifting the tubing string after completing the construction and sealing of the fluid outlet channel under pressurization;

[0031] Figure 3 This is a schematic diagram of a hydraulic fracturing string system for horizontal wells in oilfields, according to the present invention, which involves lifting the string to the next construction section to retrieve the tubing plug for construction.

[0032] The components include: 1. tubing; 2. hydraulic anchor; 3. expansion packer; 4. shut-off connecting valve; 5. cup packer; 6. second-stage fracturing fracture; 7. sandblaster; 8. check valve; 9. Y211 packer; 10. first-stage fracturing fracture; 11. tubing plug; 12. wire rope. Detailed Implementation

[0033] The present invention will now be described in detail with reference to the accompanying drawings and embodiments. It should be noted that, unless otherwise specified, the embodiments and features described herein can be combined with each other.

[0034] The following detailed description is exemplary and intended to provide further detailed explanation of the invention. Unless otherwise specified, all technical terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art. The terminology used in this invention is for describing particular embodiments only and is not intended to limit the scope of exemplary embodiments according to the invention.

[0035] This invention provides a pressurized drag fracturing tubing system for horizontal wells in oilfields, such as... Figure 1 , Figure 2 and Figure 3 As shown, the well includes a hydraulic anchor 2, an expandable packer 3, a shut-off connecting valve 4, a cup packer 5, a Y211 packer 9, and a tubing plug 11. The hydraulic anchor 2 is connected to one end of the tubing 1 inside the horizontal well; the tubing plug 11 is detachably connected to the tubing 1; one end of the expandable packer 3 is fixedly connected to the hydraulic anchor 2 on the horizontal section of the tubing 1; one end of the shut-off connecting valve 4 is connected to the other end of the expandable packer 3, and a sliding sleeve is provided on the shut-off connecting valve 4 to close the fluid outlet channel by dropping a ball; one end of the cup packer 5 is fixedly connected to the other end of the shut-off connecting valve 4; and the Y211 packer 9 is fixedly installed at the toe of the horizontal well. This configuration allows the expandable packer 3 and the cup packer 5 to work simultaneously during horizontal well construction, improving the overall pressure-bearing capacity and lifespan of the tubing string. Simultaneously, the structure of the cup packer 5 solves the problems of high pressure loss, severe erosion damage, and easy failure of the expandable packer caused by using a choke nozzle to set the packer under high-volume, high-sand conditions, as well as the problem of sand-carrying fluid flowing through the annulus after fracturing in older wells. It also addresses the issue of low construction efficiency due to tubing puncture and sand jamming caused by blowouts after repeated horizontal well fracturing, which can result in the use of a dual-seal fracturing tubing string.

[0036] Specifically, a soluble sealing ball that is introduced from the outside is fixedly installed on the valve sleeve of the shut-off connecting valve 4. Preferably, the soluble sealing ball is made of Al2O3 or Al and Mg-based soluble composite material.

[0037] Specifically, the oilfield horizontal well pressurized fracturing tubing system of the present invention also includes a sandblaster 7 and a single-phase valve. The sandblaster 7 is disposed between the cup packer 5 and the Y211 packer 9. One end of the check valve 8 is connected to the Y211 packer 9 and the other end is connected to the sandblaster 7. That is, the sandblaster 7, the check valve 8 and the Y211 packer 9 are directly connected in sequence below the tubing 1.

[0038] The present invention discloses a method for using a pressurized drag fracturing tubing string system in an oilfield horizontal well, comprising: sequentially connecting a hydraulic anchor, an expandable packer 3, a shut-off connecting valve 4, a cup packer 5, a sandblaster, and a Y211 packer 9 to the tubing 1; after the connection is completed, lowering the tubing 1 to a predetermined position and setting the Y211 packer; inserting a soluble sealing ball at the wellhead of the horizontal well; pumping liquid from the tubing to the shut-off connecting valve and pressurizing it, then closing the shut-off connecting valve 4; after the soluble sealing ball dissolves, pumping liquid from the tubing. Under the action of the cup packer 5, the pressure inside the tubing increases, causing the expandable packer to set and seal the target end before fracturing operations are performed. After fracturing, the tubing plug 11 is run into the wellhead to seal the fluid flow channel inside the tubing. The tubing string is then pulled up under pressure to the next horizontal well modification location, where the Y211 packer is set. The tubing plug is then retrieved, and fluid is pumped into the tubing again. Under the action of the cup packer 5, the pressure inside the tubing increases, causing the expandable packer to set and seal the target end before fracturing operations are performed. This process is repeated to complete the fracturing of the entire well. Specifically, the use of a pressurized drag fracturing tubing string system in an oilfield horizontal well includes the following steps:

[0039] Step 1: Connect the tools in sequence, lower them into the predetermined positions, and set the Y211 packer;

[0040] Step 2: Insert the soluble sealing ball corresponding to the shut-off connecting valve 4 into the wellhead. When the soluble sealing ball is seated on the sliding sleeve of the shut-off connecting valve 4, pressurize the wellhead to close the shut-off connecting valve 4.

[0041] Step 3: After the soluble sealing ball dissolves, the oil pipe 1 pumps liquid in. Due to the isolation effect of the cup packer 5, the expansion packer 3 sets under the action of the internal and external pressure difference, thus completing the sealing of the construction section.

[0042] Step 4: Perform hydraulic fracturing.

[0043] Step 5: After fracturing, the tubing plug 11 is inserted into the tubing string under pressure using a steel wire rope 12 to seal the fluid outlet channel of the tubing 1.

[0044] Step 6: Since the fluid outlet channel inside tubing 1 is blocked by tubing plug 11, and the channel for sand-carrying fluid to flow between sections in the annulus is blocked by packer 5, the problem of sand-carrying fluid flowing between sections in the annulus after pressure is solved. It is possible to drag the tubing under pressure without releasing the flow after pressure, lift the tubing to the next section sealing position, set packer Y211, remove tubing plug 11, and continue construction.

[0045] Specifically, in step 2, after the soluble sealing ball is dropped from the wellhead, it needs to be pumped at a small displacement until the soluble sealing ball sits on the corresponding sliding sleeve.

[0046] Specifically, after the soluble sealing ball is placed on the shut-off connecting valve 4, and the shut-off connecting valve 4 is closed, pressure is applied from the wellhead of the horizontal well.

[0047] Specifically, such as Figure 1 , Figure 2 and Figure 3 As shown, using this tubing string for drag fracturing operations will result in multiple fractures along the direction of the horizontal well, such as the first fracturing fracture 10 and the second fracturing fracture 6.

[0048] Specifically, when pressurizing the wellhead of a horizontal well, the pressurization should be carried out only after the soluble sealing ball is placed on the shut-off connecting valve 4 and comes into contact with the valve sleeve of the shut-off connecting valve 4.

[0049] Specifically, the size of the soluble sealing ball is determined based on the size of the sliding sleeve of the shut-off connecting valve 4.

[0050] Specifically, when a tubing plug 11 is installed on the horizontal well tubing 1, it is connected to the tubing plug 11 by a wire rope 12 to seal the tubing 1.

[0051] Specifically, after plugging tubing 1, tubing 1 is repeatedly lifted to the next section of the sealing position, while Y211 packer 9 is set, tubing plug 11 is pulled out, and fracturing operations at different locations of the horizontal well are completed. The above process is repeated to complete the fracturing operation of the entire well.

[0052] Specifically, in Figure 1 Based on, combined Figure 2 and Figure 3This invention describes the principle of a pressurized fracturing string system for oilfield horizontal wells. After connecting the expandable packer 3, the shut-off connecting valve 4, the cup packer 5, and the Y211 packer 9 sequentially to the tubing 1, the process string for the horizontal well is lowered to the predetermined modification position, and the Y211 packer is seated. A soluble sealing ball corresponding to the shut-off connecting valve 4 is inserted from the wellhead. When the soluble sealing ball sits on the sliding sleeve of the shut-off connecting valve 4, the wellhead is pressurized, and the shut-off connecting valve 4 is closed. After the soluble sealing ball dissolves, the oil... Fluid is pumped into pipe 1. Due to the isolation effect of the cup packer 5, the expanding packer 3 sets under the pressure difference between the inside and outside, completing the sealing of the construction section and carrying out fracturing. After fracturing, the tubing plug 11 is lowered into the tubing string under pressure via the wire rope 12 to seal the fluid outlet channel of tubing 1. It can be seen that the upper packing unit composed of the expanding packer 3 and the cup packer 5 works simultaneously during fracturing, solving the problem of using a throttle nozzle under conditions of large displacement and large sand volume. The expansion packer setting leads to problems such as large pressure loss at the throttle nozzle and severe erosion damage. Simultaneously, it improves the overall pressure-bearing capacity and lifespan of the tubing string. Furthermore, because the fluid outlet channel inside tubing 1 is blocked by the tubing plug 11, and the annular sand-carrying fluid flow channel is blocked by the cup packer 5, the problem of sand-carrying fluid flowing between annular sections after pressure testing in old wells is solved. This allows for pressure-driven tubing string movement without release of the blowout, lifting the tubing string to the next sealing position, setting the Y211 packer, removing the tubing plug 11, and continuing construction. After the construction is completed, the packer 5 will not be unsealed, which solves the problem of sand-carrying fluid flowing between the annulus and the tubing string after the old well is pressured. It achieves the sealing of the annulus fluid. The tubing 1 is sealed with tubing plug 11, which enables the tubing string to be dragged under pressure without venting after repeated horizontal well modification. This solves the problem of tubing 1 leakage and tubing string sand jamming caused by venting after repeated horizontal well modification, which leads to low construction efficiency of double-sealed drag fracturing tubing string. It also solves the problem of not being able to improve construction efficiency by dragging fracturing tubing string under pressure due to sand-carrying fluid flowing between the annulus and the inability to improve construction efficiency due to sand-carrying fluid flowing between the annulus and the inability to improve construction efficiency.

[0053] As is known from common technical knowledge, this invention can be implemented through other embodiments that do not depart from its spirit or essential characteristics. Therefore, the disclosed embodiments described above are merely illustrative in all respects and are not the only ones. All modifications within the scope of this invention or its equivalents are included in this invention.

[0054] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the specific implementation of the present invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A method for using a pressurized drag fracturing tubing string system in an oilfield horizontal well, characterized in that, include: Connect the hydraulic anchor, expansion packer (3), shut-off connecting valve (4), cup packer (5), sandblaster (7), check valve (8) and Y211 packer (9) to the tubing (1) in sequence, and after the connection is completed, lower the tubing (1) to the predetermined position and set the Y211 packer. The hydraulic anchor (2) is connected to one end of the tubing (1) inside the horizontal well; The oil pipe plug (11) is detachably connected to the oil pipe (1); One end of the expansion packer (3) is fixedly connected to the hydraulic anchor (2) on the horizontal section of the tubing (1); One end of the shut-off connecting valve (4) is connected to the other end of the expansion packer (3), and a sliding sleeve for closing the liquid outlet channel by throwing a ball is provided on the shut-off connecting valve (4); One end of the cup sealer (5) is fixedly connected to the other end of the shut-off connecting valve (4); A soluble sealing ball is inserted at the wellhead of the horizontal well. Liquid is pumped from the tubing to the soluble sealing ball and then pressurized to close the closable connecting valve (4). After the soluble sealing ball dissolves, liquid is pumped from the tubing. Under the action of the cup packer (5), the pressure in the annulus between the cup packer and the Y211 packer and the tubing increases, causing the expansion packer to set and seal the target end before fracturing construction is carried out. After fracturing, a tubing plug (11) is lowered into the wellhead to block the fluid flow channel in the tubing. The tubing string is then lifted under pressure to the next horizontal well modification position, and the Y211 packer is set. At the same time, the high-pressure section in the lower part of the horizontal well is isolated by the Y211 packer. The tubing plug is then retrieved, and fluid is pumped into the tubing again. Under the action of the cup packer (5), the pressure in the annulus between the cup packer and the Y211 packer and the tubing increases, causing the expansion packer to set again. After the target end is sealed, fracturing is carried out. The above process is repeated to complete the fracturing of the entire well.

2. The method of using a pressurized drag fracturing tubing string system for oilfield horizontal wells according to claim 1, characterized in that, The soluble sealing ball is made of Al-based or Mg-based soluble composite material.

3. The method of using a pressurized drag fracturing tubing string system for oilfield horizontal wells according to claim 1, characterized in that, A sandblaster (7) is fixedly installed between the leather cup packer (5) and the Y211 packer (9).

4. The method of using a pressurized drag fracturing tubing string system for oilfield horizontal wells according to claim 3, characterized in that, A one-way valve (8) is provided between the sandblaster (7) and the Y211 packer (9).

5. The method of using a pressurized drag fracturing tubing string system for oilfield horizontal wells according to claim 1, characterized in that, After the soluble sealing ball is placed on the shut-off connecting valve (4), the shut-off connecting valve (4) is closed and pressure is applied from the wellhead of the horizontal well.

6. The method of using a pressurized drag fracturing tubing string system for oilfield horizontal wells according to claim 1, characterized in that, The size of the soluble sealing ball is determined according to the size of the sliding sleeve of the shut-off connecting valve (4).

7. The method of using a pressurized drag fracturing tubing string system for horizontal wells in oilfields according to claim 1, characterized in that, When a tubing plug (11) is installed on the tubing (1) of a horizontal well, it is connected to the tubing plug (11) by a wire rope (12) to seal the tubing (1).

8. The method of using a pressurized drag fracturing tubing string system for oilfield horizontal wells according to claim 1, characterized in that, After sealing the tubing (1), the tubing (1) is repeatedly lifted to the next sealing position, and the Y211 packer (9) is set at the same time. The tubing plug (11) is then removed to complete the fracturing operation at different positions of the horizontal well. The above process is repeated to complete the fracturing operation of the entire well.

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