A differential sand washing tool for workover of oil fields comprising an inflatable packer

Abstract

The application provides an oil field workover differential sand washing tool comprising an expansion packer and relates to the field of oil field workover tools. The oil field workover differential sand washing tool comprising an expansion packer comprises a backflush valve, the inner middle part of the backflush valve is provided with a differential mandrel, the inner wall of the backflush valve is fixedly connected with expansion packers on the upper side and the lower side, the inside of the differential mandrel is slidably connected with a taper head, one end of the differential mandrel is fixedly connected with a nozzle, the right side of the backflush valve is fixedly connected with a guide head, and the outside of the differential mandrel is provided with a reset spring. The differential sand washing tool can greatly improve the efficiency of sand washing and well washing, reduce sand washing operation time, and prevent the reflow of sand in the wellbore into the bottom layer, so that sand washing is complete. The working state of the tool is controlled only by the displacement and pressure change of a pump truck, and the conversion between the two working states is fast and simple.

Description

Technical Field

[0001] This invention relates to the field of oilfield workover tools, specifically to a differential sand flushing tool for oilfield workover that includes an expandable packer. Background Technology

[0002] Currently, oilfield sand flushing and well washing mainly uses well washing valves with self-sealing packers (i.e., cup packers). Due to its own design characteristics, the sealing element of this packer—the cup—is always in close contact with the oil well casing during the drilling process, which makes it very easy to wear and damage. Often, the cup is severely worn when it reaches the operating depth. In the actual sand flushing process, some or even most of the sand flushing and well washing power fluid leaks out from the cup. This not only greatly reduces the sand flushing efficiency and prolongs the sand flushing operation time, but the leaked power fluid also washes the sand that should have been flushed out of the surface back into the formation, forming quicksand, which then flows back into the wellbore during subsequent oil well production. Summary of the Invention

[0003] To address the shortcomings of existing technologies, this invention provides a differential sand flushing tool for oilfield well workover that includes an expandable packer. This tool solves the problem of most of the sand flushing fluid leaking from the rubber cup, which not only greatly reduces sand flushing efficiency and prolongs sand flushing operation time, but also causes the leaked fluid to backwash the sand that should have been flushed to the surface back into the formation, forming quicksand, which then flows back into the wellbore during subsequent oil well production.

[0004] To achieve the above objectives, the present invention provides the following technical solution: a differential sand flushing tool for oilfield well workover including an expandable packer, comprising a backflush valve, a differential mandrel disposed in the inner center of the backflush valve, expandable packers fixedly connected to the upper and lower sides of the inner wall of the backflush valve, a cone head slidably connected inside the differential mandrel, a nozzle fixedly connected to one end of the differential mandrel, a guide head fixedly connected to the right side of the backflush valve, and a return spring disposed outside the differential mandrel.

[0005] Preferably, the differential mandrel is provided with filling holes at both the upper and lower parts.

[0006] Preferably, the filling hole is connected to the negative pressure zone.

[0007] Preferably, a method for using an oilfield workover differential sand flushing tool including an expandable packer includes the following steps:

[0008] Step 1: After the differential sand flushing tool reaches the sand flushing depth, start the pump truck to flush with low pressure and low displacement. The sand will be flushed and mixed with the power fluid and flow to the top of the expansion packer. Then, the flushing pipe can be lowered while flushing until the planned depth is reached. The sand flushing depth refers to the position of the sand surface.

[0009] Step 2: The pump truck starts with high pressure and high displacement. Under the action of pressure difference, the differential spindle compresses the return spring and moves downward. After it moves to the bottom, the cone closes the nozzle. At the same time, the flushing hole opens and liquid is injected to expand and set the seal. The backflush valve opens and backflush begins.

[0010] Step 3: Continuous high-pressure, high-volume backflush until all the sand above the expander packer is circulated out of the wellbore;

[0011] Step 4: Reduce the power fluid displacement to a certain value, and the tool will switch from the backflush state to the forward flush state. The return spring will spring open, causing the differential mandrel to move upward. The filling hole will then connect with the negative pressure zone, and the liquid in the expansion packer will be discharged, causing the expansion packer to contract.

[0012] Step 5: Close the backflush valve and the power fluid will spray out from the nozzle. Repeat the above operation to flush out the dust and sand from the entire wellbore.

[0013] Preferably, an application of an oilfield workover differential sand flushing tool including an expandable packer is described below.

[0014] Preferably, in the S1 forward flushing state: when the power fluid is at low pressure and low flow rate, the expandable packer contracts, the backflush valve on the tool closes, and the power fluid is sprayed out from the nozzle at the front end of the tool, which can disperse the sand in the wellbore and mix it with the power fluid, making it easier for the sand flushing string to descend. At the same time, the sand particles flow to the top of the expandable packer. In the forward flushing state, a negative pressure zone will be formed behind the nozzle, and the filling hole is connected to this negative pressure zone at this time, so that the expandable packer will be reliably in the contracted state.

[0015] S2, Backflush State: When the power fluid is under high pressure and has a large displacement, the backflush valve on the tool opens, the expansion packer expands and sets, the nozzle closes, and the power fluid is sprayed upward from the backflush valve, flushing the sand particles out to the ground through the annulus. In this state, the inlet of the expansion packer is connected to the filtered power fluid. The higher the power fluid pressure, the higher the expansion pressure inside the expansion packer, thus ensuring that the expansion packer is in a reliable setting state.

[0016] This invention provides a differential sand flushing tool for oilfield well workover, including an expandable packer. It offers the following advantages:

[0017] 1. In this invention, after the differential sand flushing tool reaches the sand flushing depth, the pump truck is activated for low-pressure, low-displacement forward flushing. The sand is dispersed and mixed with the motive fluid, flowing above the expansion packer. Then, forward flushing continues while the sand flushing string is lowered until the planned depth is reached. The pump truck then activates high-pressure, high-displacement operation. Under the pressure difference, the differential mandrel compresses the return spring and descends. Once it reaches the bottom, the cone closes the nozzle. Simultaneously, the flushing hole opens and fluid is injected to expand and set the packer. The backflush valve opens to begin backflushing, continuing with high-pressure, high-displacement backflushing until the expansion packer is reached. Once all the sand above the packer is circulated out of the wellbore, and the power fluid discharge is reduced to a certain value, the tool will switch from backflushing to forward flushing. The return spring will spring open, causing the differential mandrel to move upward. The filling hole will then connect with the negative pressure zone, discharging the liquid from the expanding packer. The expanding packer will then contract, the backflushing valve will close, and the power fluid will spray out from the nozzle. Repeating the above operations can flush out the dust and sand from the entire wellbore, thereby greatly improving the efficiency of sand flushing and well washing, reducing the sand flushing operation time, and preventing the sand in the wellbore from flowing back into the bottom layer, ensuring thorough sand flushing.

[0018] 2. This invention controls the working state of the tool by changing the pump truck's displacement and pressure, and the transition between the two working states is quick and easy. Attached Figure Description

[0019] Figure 1 This is a diagram of the internal structure of the present invention.

[0020] Among them, 1. backflush valve; 2. differential spindle; 3. expansion packer; 4. cone head; 5. return spring; 6. nozzle; 7. guide head; 8. filling hole. Detailed Implementation

[0021] 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 some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0022] Example 1:

[0023] like Figure 1As shown, this embodiment of the invention provides an oilfield workover differential sand flushing tool including an expandable packer. It includes a backflush valve 1, a differential mandrel 2 disposed in the inner center of the backflush valve 1, expandable packers 3 fixedly connected to the upper and lower sides of the inner wall of the backflush valve 1, a cone 4 slidably connected inside the differential mandrel 2, a nozzle 6 fixedly connected to one end of the differential mandrel 2, a guide head 7 fixedly connected to the right side of the backflush valve 1, and a return spring 5 disposed outside the differential mandrel 2. After reaching the sand surface position at the sand flushing depth using the differential sand flushing tool, the pump truck is activated for low-pressure, low-displacement forward flushing, dispersing the sand and mixing it with the power fluid, which then flows above the expandable packer 3. Then, forward flushing can continue while lowering the sand flushing string until the planned predetermined depth is reached. The pump truck is then activated for high-pressure, high-displacement operation. Under the pressure differential, the differential mandrel 2 compresses and returns to its original position. The spring 5 descends, and after it reaches its lower position, the cone 4 closes the nozzle 6. At the same time, the flushing hole 8 opens and injects fluid to expand and set the seal. The backflush valve 1 opens and begins backflushing. High-pressure, high-volume backflushing continues until all the sand above the expandable packer 3 is circulated out of the wellbore. The power fluid discharge pressure is reduced to a certain value, and the tool switches from backflush to forward flushing. The return spring 5 springs open, causing the differential mandrel 2 to move upward. The filling hole 8 then connects with the negative pressure zone, and the liquid inside the expandable packer 3 is discharged and extracted. The expandable packer 3 contracts, the backflush valve 1 closes, and the power fluid is sprayed out from the nozzle 6. Repeating the above operation can flush out the dust and sand in the entire wellbore, thereby achieving zero leakage of the well washing power fluid, greatly improving the efficiency of sand flushing and well washing, reducing the sand flushing operation time, and preventing the sand in the wellbore from flowing back into the bottom layer. The sand flushing is thorough.

[0024] The differential mandrel 2 is provided with filling holes 8 at both the upper and lower parts.

[0025] The filling hole 8 is connected to the negative pressure zone.

[0026] Example 2:

[0027] A method for using an oilfield workover differential sand flushing tool including an expandable packer includes the following steps:

[0028] Step 1: After the differential sand flushing tool reaches the sand flushing operation depth, start the pump truck to flush with low pressure and low displacement. The sand will be flushed and mixed with the power fluid and flow to the top of the expansion packer 3. Then, the flushing pipe can be lowered while flushing until the planned depth is reached. The sand flushing operation depth refers to the position of the sand surface.

[0029] Step 2: The pump truck starts with high pressure and high displacement. Under the action of pressure difference, the differential spindle 2 compresses the return spring 5 and moves downward. After it moves to the bottom, the cone head 4 closes the nozzle 6. At the same time, the flushing hole 8 opens and injects liquid to expand and set the seal. The backflush valve 1 opens and starts backflush.

[0030] Step 3: Continuous high-pressure, high-volume backflush until all the sand above the expander packer 3 is circulated out of the wellbore;

[0031] Step 4: Reduce the power fluid displacement pressure to a certain value, and the tool will switch from the backflush state to the forward flush state. The return spring 5 will spring open, causing the differential spindle 2 to move upward. The filling hole 8 will then connect with the negative pressure zone, and the liquid in the expansion packer 3 will be discharged, causing the expansion packer 3 to contract.

[0032] Step 5: Backflush valve 1 is closed, and the power fluid is sprayed out from nozzle 6. Repeating the above operation can flush out the dust and sand in the entire wellbore.

[0033] Example 3:

[0034] An application of an oilfield workover differential sand flushing tool including an expandable packer, combined with... Figure 1 It can be explained that this invention can be applied to different working states, such as forward and reverse applications, including the following two applications:

[0035] Preferably, in the S1, positive flushing state: when the power fluid is at low pressure and low flow rate, the expandable packer 3 contracts, the backflush valve 1 on the tool closes, and the power fluid is sprayed out from the nozzle 6 at the front end of the tool, which can disperse the sand in the wellbore and mix it with the power fluid, making it easier for the sand flushing string to descend. At the same time, the sand particles flow to the top of the expandable packer 3. In the positive flushing state, a negative pressure zone will be formed behind the nozzle 6, and the filling hole 8 is connected to this negative pressure zone at this time, so that the expandable packer 3 will be reliably in the contracted state.

[0036] S2, Backflush State: When the power fluid is under high pressure and high displacement, the backflush valve 1 on the tool opens, the expansion packer 3 expands and sets, the nozzle 6 closes, and the power fluid is sprayed upward from the backflush valve 1, flushing the sand particles out to the ground through the annulus. In this state, the inlet of the expansion packer 3 is connected to the power fluid that has been filtered and contains no sand or impurities. The higher the pressure of the power fluid, the higher the pressure of expansion inside the expansion packer 3, thus putting the expansion packer 3 in a reliable setting state. The working state of the tool is controlled by the pump truck displacement and pressure changes. The transition between the two working states is quick and easy.

[0037] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for using a differential sand flushing tool for oilfield well workover, including an expandable packer, characterized in that: This method of use is based on an oilfield workover differential sand flushing tool using an expandable packer. The oilfield workover differential sand flushing tool using an expandable packer includes: a backflush valve (1), a differential mandrel (2) is provided in the middle of the backflush valve (1), an expandable packer (3) is fixedly connected to both the upper and lower sides of the inner wall of the backflush valve (1), a cone head (4) is slidably connected inside the differential mandrel (2), a nozzle (6) is fixedly connected to one end of the differential mandrel (2), a guide head (7) is fixedly connected to the right side of the backflush valve (1), and a return spring (5) is provided on the outside of the differential mandrel (2); a filling hole (8) is provided at both the upper and lower parts of the differential mandrel (2); the filling hole (8) is connected to the negative pressure zone. The usage method includes the following steps: Step 1: After the differential sand flushing tool reaches the sand flushing operation depth, start the pump truck to flush with low pressure and low displacement. After the sand is flushed and mixed with the power fluid, it flows to the top of the expansion packer (3). Then, the flushing pipe can be lowered while flushing until the planned depth is reached. The sand flushing operation depth refers to the position of the sand surface. Step 2: The pump truck is turned on with high pressure and large displacement. Under the action of pressure difference, the differential spindle (2) compresses the return spring (5) and moves downward. After it moves to the bottom, the cone (4) closes the nozzle (6). At the same time, the filling hole (8) opens and injects liquid to expand and set the seal. The backflush valve (1) opens and starts backflush. Step 3: Continuous high-pressure, high-volume backflush until all the sand above the expansion packer (3) is circulated out of the wellbore; Step 4: Reduce the power fluid displacement pressure to a certain value, and the tool will switch from the backflush state to the forward flush state. The reset spring (5) will spring open, causing the differential spindle (2) to move upward. The filling hole (8) will then connect with the negative pressure zone, and the liquid in the expansion packer (3) will be discharged, causing the expansion packer (3) to contract. Step 5: Close the backflush valve (1), and the power fluid will be sprayed out from the nozzle (6). Repeat the above steps to flush out the dust and sand in the entire wellbore.

2. The method of using an oilfield workover differential sand flushing tool including an expandable packer as described in claim 1, characterized in that: Including the following applications: S1, Positive flushing state: When the power fluid is at low pressure and low flow rate, the expansion packer (3) contracts, the backflush valve (1) on the tool is closed, and the power fluid is sprayed out from the nozzle (6) at the front end of the tool, which can disperse the sand in the wellbore and mix it with the power fluid, making it easier for the sand flushing string to go down. At the same time, the sand particles flow to the top of the expansion packer (3). In the positive flushing state, a negative pressure zone will be formed behind the nozzle (6), and the filling hole (8) is connected to the negative pressure zone at this time, so that the expansion packer (3) will be reliably in the contracted state. S2, Backflush state: When the power fluid is under high pressure and has a large displacement, the backflush valve (1) on the tool is opened, the expansion packer (3) expands and sets, the nozzle (6) is closed, the power fluid is sprayed out from the backflush valve (1) and rises, and the sand particles are flushed out to the ground through the annulus. In this state, the liquid inlet of the expansion packer (3) is connected to the filtered power fluid. The higher the power fluid pressure, the higher the expansion pressure inside the expansion packer (3), so that the expansion packer (3) is in a reliable setting state.

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