A tubular string

Abstract

The application discloses a pipe column and belongs to the technical field of steam thermal recovery of oil, which comprises a pump, a first sleeve and a sliding sleeve. The outer periphery of the first sleeve is provided with a liquid outlet, the outer shaft of the first sleeve is provided with a valve, the valve is arranged above the liquid outlet of the first sleeve, the first sleeve is arranged outside the outer surface of the oil pipe of the pump, and the lower end of the first sleeve is in sealing connection with the outer side of the oil pipe. The sliding sleeve is arranged in the first sleeve in the axial direction, so that the liquid outlet and the valve in the first sleeve are switchable in communication with the cavity in the first sleeve, and the sliding sleeve is arranged outside the oil pipe of the pump. The application can realize the three stages of fracturing sand prevention, steam injection and production at the same time, does not need to replace the pipe column when the next stage operation is performed, reduces operation cost, improves production efficiency, does not produce hot sewage at the same time, avoids the pollution problem of the near-wellbore zone of the formation, and can realize the integration of acidification, steam injection and production and the integration of plugging adjustment, steam injection and production at the same time.

Description

Technical Field

[0001] This invention belongs to the field of steam thermal oil recovery technology, and specifically relates to a tubing string. Background Technology

[0002] Steam injection is a method for increasing the production of heavy oil by first injecting a certain amount of steam into the oil well, shutting the well in for a period of time, and then opening the well to produce oil after the heat energy of the steam has diffused into the oil layer. It is the main method for heavy oil extraction in my country, and about 80% of the country's heavy oil production is obtained through steam injection.

[0003] Currently, heavy oil huff and puff wells are generally in the mid-to-late stages of development, exhibiting problems such as high huff and puff cycles and severe sand production. The conventional solution is to perform three stages before steam injection in the huff and puff well: fracturing and sand control, steam injection, and production commissioning. However, the existing process has several problems: First, it uses three sets of tubing for fracturing and sand control, steam injection, and production commissioning, requiring an operation for each set of tubing replacement, resulting in high operating costs. Second, well control operations are required during the installation of the steam injection tubing and production tubing. Although the well control fluid is mainly hot wastewater (70-80℃), it still has a certain cooling and pollution effect on the near-wellbore area of ​​the formation. Third, the installation of these three sets of tubing requires two separate operations, resulting in long well shutdown times and reduced well productivity. Summary of the Invention

[0004] To solve the above-mentioned technical problems, the present invention provides a tubing string that can simultaneously realize the three stages of fracturing and sand control, steam injection and production. It eliminates the need to replace the tubing string when performing the next stage of operation, thereby reducing operating costs and improving production efficiency. At the same time, it does not generate hot wastewater, avoiding pollution problems in the formation near the wellbore. In addition, it can also realize the integration of acidizing, steam injection and production, as well as the integration of plugging, steam injection and production.

[0005] The technical solution of this invention is as follows:

[0006] This invention provides a tubular column, the tubular column comprising:

[0007] Oil pump;

[0008] The first sleeve has a liquid outlet on its circumferential surface that communicates with the interior of the first sleeve. The first sleeve also has a valve on its circumferential surface that communicates with the interior of the first sleeve. The valve is located above the liquid outlet of the first sleeve. The first sleeve is fitted around the outside of the oil pipe of the oil pump. The lower end of the first sleeve is sealed to the outside of the oil pipe.

[0009] A sliding sleeve is slidably disposed within the first sleeve along the axial direction, so that the liquid outlet in the first sleeve and the valve can be switched to communicate with the interior of the first sleeve. The sliding sleeve is fitted outside the oil pipe of the oil pump.

[0010] Furthermore, the sliding sleeve and the first sleeve are connected by a pin that can be melted at high temperature. The first sleeve is provided with a first protrusion for supporting the first sleeve, and the first protrusion is located below the liquid outlet of the first sleeve.

[0011] Furthermore, the pin includes a body and rubber wrapped around the body.

[0012] Furthermore, the sliding sleeve is provided with a stepped hole that cooperates with the pin. The larger hole in the stepped hole of the sliding sleeve is located near the axis, and the smaller hole in the stepped hole of the sliding sleeve is located near the first sleeve. One end of the pin is threaded into the larger hole of the sliding sleeve, and the other end of the thread is inserted into the inner wall of the first sleeve through the smaller hole of the sliding sleeve.

[0013] Furthermore, the sliding sleeve and the first sleeve are connected by a plurality of pins.

[0014] Furthermore, the valve includes a valve core and an elastic element. The first sleeve has a valve hole communicating with the interior on its wall. A sealing part is provided in the valve hole of the sleeve. The elastic element, the valve core, and the sealing part are arranged in sequence. One end of the elastic element is fixed, and the other end of the elastic element is disposed in the valve hole and connected to the valve core. The valve core can be operably pressed against or separated from the sealing part of the sleeve.

[0015] Furthermore, the sleeve has an annular second protrusion inside the valve hole to form the sealing part, the valve core is spherical, and the outer periphery of the valve core can be operably pressed against or separated from the second protrusion.

[0016] Furthermore, a support rod is provided on the outside of the first sleeve, and one end of the elastic element is fixed on the support rod.

[0017] Furthermore, multiple valves are provided.

[0018] Furthermore, the first sleeve has multiple liquid outlets.

[0019] Furthermore, the oil pump includes the oil pipe, plunger, and cylinder, wherein:

[0020] The lower end of the oil pipe is disposed in the cylinder, the plunger has a chamber, the lower end of the plunger has an openable oil inlet, the lower end of the oil pipe is connected to the plunger, the plunger is slidably disposed in the cylinder along the axial direction, the upper end of the cylinder is connected to the lower end of the sleeve, and the lower end of the cylinder has an openable oil inlet.

[0021] Furthermore, a first valve ball is provided inside the cylinder, and a second valve ball is provided inside the plunger.

[0022] Furthermore, a screen tube is connected to the lower end of the cylinder, and multiple screen holes are provided on the outer periphery of the screen tube, with the lower end of the screen tube being closed.

[0023] Furthermore, a plug is connected to the lower end of the screen tube.

[0024] Furthermore, the upper end of the first sleeve is connected to a heat insulation pipe, and the oil pipe of the oil pump is inserted into the heat insulation pipe.

[0025] Furthermore, the heat insulation pipe is fitted with a packer.

[0026] Furthermore, the tubing string includes a second sleeve, and the packer, the first sleeve, the oil pump, the screen tube, and the plug are all disposed inside the second sleeve.

[0027] The beneficial effects of the present invention include at least the following:

[0028] The present invention provides a tubing string comprising an oil pump, a first sleeve, and a sliding sleeve. The first sleeve has an outlet on its outer side and a valve on its outer side, positioned above the outlet. The first sleeve is fitted over the oil pipe of the oil pump, with its lower end sealed to the outer side of the oil pipe. The sliding sleeve is axially slidable within the first sleeve, allowing the outlet and valve within the first sleeve to be switchably connected to the cavity within the first sleeve. The sliding sleeve is fitted over the oil pipe of the oil pump. When fracturing, sand control, steam injection, and production are required for heavy oil wells, fracturing fluid is first injected into the sliding sleeve. The pressurized fluid moves downwards in the space between the sliding sleeve and the oil pump tubing, flows out through the outlet of the first sleeve, and enters the formation for fracturing and sand control. After the fracturing and sand control operation is completed, the sliding sleeve is slid, connecting the valve of the first sleeve with the cavity inside the first sleeve. The outlet of the first sleeve is closed, and steam is introduced into the first sleeve. The steam moves out through the valve on the side of the first sleeve, thereby increasing the formation temperature. After the steam stage is completed, the storage tank of the first casing is closed, and the valves are closed. By operating the oil pump, the heavy oil in the formation can be sent out of the slurry well to complete oil production. This structure can simultaneously realize the three stages of fracturing and sand control, steam injection and production, without the need to replace the tubing string when carrying out the next stage of operation, which reduces operating costs and improves production efficiency. At the same time, it does not generate hot wastewater and avoids the pollution problem in the near-wellbore area of ​​the formation. In addition, it can also realize the integration of acidizing, steam injection and production, as well as the integration of plugging, steam injection and production. Attached Figure Description

[0029] Figure 1This is a schematic diagram of the structure of a tubular column according to this embodiment;

[0030] Figure 2 for Figure 1 A schematic diagram of the structure of the first set of tubes.

[0031] Explanation of reference numerals in the attached drawings: 1-Oil pump, 101-Oil pipe, 102-Plunger, 103-Cylinder, 104-First valve ball, 105-Second valve ball, 2-First sleeve, 201-Outlet, 202-First protrusion, 203-Valve hole, 204-Second protrusion, 3-Valve, 301-Valve core, 302-Elastic element, 4-Sliding sleeve, 401-Stepped hole, 5-Pin, 6-Screw tube, 7-Plug, 8-Insulation tube, 9-Packer, 10-Second sleeve, 11-Oil layer. Detailed Implementation

[0032] To enable those skilled in the art to better understand this application, the technical solution of this application will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0033] Figure 1 This is a schematic diagram of a tubular column according to this embodiment. Figure 2 for Figure 1 The structural diagram of the first set of pipes in the middle, combined with Figure 1 as well as Figure 2 This invention provides a tubing string, which includes an oil pump 1, a first sleeve 2, and a sliding sleeve 4.

[0034] The first sleeve 2 has a liquid outlet 201 on its circumference that communicates with the interior of the first sleeve. The first sleeve 2 also has a valve 3 on its circumference that communicates with the interior of the first sleeve 2. The valve 3 is located above the liquid outlet 201 of the first sleeve 2. The first sleeve 2 is sleeved on the outer side of the oil pipe 101 of the oil pump 1. The lower end of the first sleeve 2 is sealed to the outer side of the oil pipe 101. The sliding sleeve 4 is slidably disposed inside the first sleeve 2 along the axial direction so that the liquid outlet 201 and the valve 3 inside the first sleeve 2 can be switched to communicate with the interior of the first sleeve. The sliding sleeve 4 is loosely sleeved outside the oil pipe 101 of the oil pump 1.

[0035] When fracturing, sand control, steam injection, and production are required for heavy oil wells, fracturing fluid is first injected into the sliding sleeve 4. The pressurized fluid moves downward in the space between the sliding sleeve 4 and the oil pump tubing 101, flows out through the outlet 201 of the first sleeve to the outside of the first sleeve, and enters the formation for fracturing and sand control. After the fracturing and sand control operation is completed, the sliding sleeve 4 is slid, so that the valve 3 of the first sleeve 2 is connected to the cavity inside the first sleeve, the outlet 201 of the first sleeve 2 is closed, and steam is introduced into the first sleeve. The steam moves out of the first sleeve through the valve 3 on the side of the first sleeve, thereby improving the formation. The temperature of the formation; after the steam injection stage is completed, the storage tank of the first casing 2 is closed and the valve 3 is closed. By operating the oil pump 1, the heavy oil in the formation can be sent out of the spit-and-pour well to complete the oil production; this structure can realize the three stages of fracturing and sand control, steam injection and production at the same time. It does not require the replacement of the tubing string when carrying out the next stage operation, which reduces the operating cost and improves the production efficiency. At the same time, it does not generate hot wastewater and avoids the pollution problem of the formation near the well. In addition, it can also realize the integration of acidizing, steam injection and production, as well as the integration of plugging, steam injection and production.

[0036] Acidification is achieved by adding acidic solutions such as hydrochloric acid or sulfuric acid to the formation through the outlet 201 of the first sleeve.

[0037] Furthermore, combined Figure 2 In this embodiment, the sliding sleeve 4 and the first sleeve 2 are connected by a pin 5 that can shrink in volume at steam temperature. The first sleeve 2 has a first protrusion 202 for support, located below the liquid outlet 201 of the first sleeve 2. When steam is injected into the sliding sleeve 4, the high-temperature steam causes the pin 5 to shrink, preventing it from locking the sliding sleeve 4 and the first sleeve 2. The sliding sleeve 4 then slides down onto the first protrusion 202 of the first sleeve 2, blocking the liquid outlet 201. The first protrusion 202 can be annular or consist of multiple protrusions, as long as it can support the sliding sleeve 4; no limitation is made here.

[0038] Specifically, in this embodiment, the pin 5 may include a body and a rubber covering the body. The rubber may be nitrile rubber, which melts at 150°C, so that the pin 5 is reduced to the body under the action of high-temperature steam, allowing the sliding sleeve 4 to slide down; of course, other rubber materials may also be used, and this is not limited here.

[0039] Specifically, in combination Figure 2In this embodiment, the sliding sleeve 4 is provided with a stepped hole 401 that mates with the pin 5. The larger hole in the stepped hole 401 of the sliding sleeve 4 is located near the axis, and the smaller hole in the stepped hole 401 of the sliding sleeve 4 is located near the first sleeve. One end of the pin 5 is threaded into the larger hole of the sliding sleeve 4, and the other threaded end is inserted into the inner wall of the first sleeve through the smaller hole of the sliding sleeve 4. The threaded connection can ensure the connection strength between the first sleeve and the sliding sleeve 4 during the injection of pressurized liquid; when steam is introduced, it can also ensure that the pin 5 can melt and fall out of the sliding sleeve 4.

[0040] To improve the connection strength between the first sleeve and the sliding sleeve 4, in this embodiment, the sliding sleeve 4 and the first sleeve 2 can be connected by multiple pins 5. The number of pins 5 can be set to 2, 3, or other numbers, which is not limited here. The height of the pins 5 can be higher than the valve 3, or lower than the valve 3, which is also not limited here.

[0041] Furthermore, combined Figure 2 In this embodiment, valve 3 may include valve core 301 and elastic element 302. A valve hole 203 communicating with the interior is provided on the wall of the first sleeve 2. A sealing part is provided inside the valve hole 203 of the sleeve. The elastic element 302, valve core 301, and sealing part are arranged sequentially. One end of the elastic element 302 is fixed, and the other end of the elastic element 302 is disposed inside the valve hole 203 and connected to the valve core 301. The valve core 301 can be operably pressed against or separated from the sealing part of the sleeve. During the steam introduction process, the pin 5 is melted and detached by the high-temperature steam, and the sliding sleeve 4 slides down, causing valve 3 to leak. The continuously injected high-temperature steam increases the pressure inside the first sleeve. Under the action of the high-pressure steam, the valve core 301 moves away from the axis, causing the elastic element 302 to be pressed tightly. A gap is created between the valve core 301 and the sealing part of the sleeve, allowing steam to pass through. Steam moves along the gap from the valve hole 203 to the outside of the first sleeve 2. After the steam injection ends, the pressure inside the first sleeve drops, and under the action of the restoring force, the valve core 301 and the sealing part of the sleeve are pressed together to form a seal.

[0042] The elastic element 302 can be a spring. To improve the corrosion resistance of the spring and the valve ball, a coating can be added to the spring and the valve core 301 to improve corrosion resistance and extend service life.

[0043] More specifically, in this embodiment, an annular second protrusion 204 may be provided inside the valve hole 203 of the sleeve to form a sealing part. The valve core 301 is spherical, and the outer periphery of the valve core 301 can be operably abutted against or separated from the second protrusion 204. The valve core 301 may also be frustoconical, with the external dimensions of the valve core 301 decreasing sequentially along the direction close to the axis. One end of the valve core 301 near the axis can be inserted into the circular hole formed by the second protrusion 204, and the outer side of the valve core 301 abuts against the inner wall of the circular hole formed by the second protrusion 204 to achieve a seal. Preferably, the diameter of the circular hole formed by the second protrusion 204 decreases sequentially along the direction close to the axis.

[0044] Specifically, in this embodiment, a support mesh covering the valve hole 203 can be provided on the outer side of the first sleeve 2, and one end of the elastic element 302 is fixed to the support mesh. The support mesh serves several purposes: firstly, it secures the elastic element 302; secondly, it allows steam to pass through while preventing heavy oil from entering the valve hole 203; and thirdly, it acts as a sand-blocking device. The mesh size of the support mesh can be flexibly adjusted according to actual needs and is not limited here.

[0045] Furthermore, in this embodiment, multiple valves 3 can be provided. Preferably, two valves 3 can be provided. Too many valves 3 should not be provided, as this will cause the heavy oil to form wax blocks and crystals on the outside of the valves 3, resulting in the valves 3 not closing tightly and reducing the sealing performance.

[0046] Furthermore, in this embodiment, the first casing 2 can be provided with multiple outlets 201, which can improve the injection rate of fracturing fluid and improve production efficiency; the multiple outlets 201 can be arranged radially along the outer periphery of the first casing 2.

[0047] Furthermore, combining Figure 1 In this embodiment, the oil pump 1 may include an oil pipe 101, a plunger 102, and a cylinder 103, wherein:

[0048] The lower end of the oil pipe 101 is located inside the cylinder 103. The plunger 102 has a chamber and the lower end of the plunger 102 has an openable oil inlet. The lower end of the oil pipe 101 is connected to the plunger 102. The plunger 102 is slidably located inside the cylinder 103 along the axial direction. The upper end of the cylinder 103 is connected to the lower end of the sleeve. The lower end of the cylinder 103 has an openable oil inlet.

[0049] When the plunger 102 slides upward along the axial direction, the pressure inside the cylinder 103 decreases, and the heavy oil enters the cylinder 103 from the oil inlet at the lower end of the cylinder 103. Then, under the action of pressure, the heavy oil in the cylinder 103 enters the plunger 102 from the oil inlet at the lower end of the plunger 102, and is then sent to the ground along the oil pipe 101.

[0050] Specifically, in combination Figure 1 In this embodiment, a first valve ball 104 is provided inside the cylinder 103, and a second valve ball 105 is provided inside the plunger 102. When the plunger 102 slides upward along the axial direction, both the first valve ball 104 and the second valve ball 105 rise under pressure, opening the oil inlet of the cylinder 103 and the oil inlet of the plunger 102. Conversely, when the plunger 102 moves downward along the axial direction, the first valve ball 104 and the second valve ball 105 descend under pressure, closing the oil inlet of the cylinder 103 and the oil inlet of the plunger 102.

[0051] Furthermore, combined Figure 1 In this embodiment, the lower end of the cylinder 103 can be connected to a screen tube 6. The screen tube 6 has screen holes on its outer periphery and the lower end of the screen tube 6 is closed to perform preliminary filtration of the heavy oil coming from the oil layer 11.

[0052] Specifically, in this embodiment, combined with Figure 1 A plug 7 can be connected to the lower end of the screen tube 6 to achieve a closed setting at the lower end of the screen tube 6.

[0053] To avoid heat loss due to steam temperature drop during the steam injection process, in this embodiment, combined with Figure 1 The upper end of the first casing 2 can be connected to a heat insulation pipe 8, and the oil pipe 101 of the oil pump 1 is inserted into the heat insulation pipe 8; of course, the heat insulation pipe 8 can also keep the heavy oil extracted during the production process warm, so as to avoid excessive temperature drop, high viscosity, poor fluidity, and difficulty in sending it to the outside of the well.

[0054] Furthermore, in this embodiment, combined with Figure 1 A packer 9 can be fitted over the heat insulation pipe 8. The packer 9 is a downhole tool used to seal the annular space between the tubing 101 and the oil and gas well casing or open hole wall. Those skilled in the art can choose flexibly as needed, and no specific limitation is made here.

[0055] Furthermore, in this embodiment, combined with Figure 1 The tubing string may also include a second sleeve 10, and the packer 9, the first sleeve 2, the oil pump 1, the screen pipe 6 and the plug 7 are all located inside the second sleeve 10.

[0056] In addition, during the specific implementation process, the packer 9 can be set above the production well section, so that all oil layers 11 in the heavy oil well can be thermally recovered.

[0057] The tubular column provided by this invention has at least the following effects:

[0058] (1) To achieve integrated pressure protection-steam injection-production, integrated tubing acidification, steam injection and production, and integrated plugging, steam injection and production;

[0059] (2) Reduce operations, save costs, and improve production efficiency;

[0060] (3) No need to circulate water after steam injection, which can avoid the problem of heat loss in the formation and the impact on heat diffusion in the formation caused by circulating water in traditional operations, thus making full use of steam heat.

[0061] (4) It will not produce hot wastewater, thus avoiding pollution problems in the near-well zone of the formation.

[0062] Although preferred embodiments of this application have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments as well as all changes and modifications falling within the scope of this application.

[0063] Obviously, those skilled in the art can make various modifications and variations to this application without departing from the spirit and scope of this application. Therefore, if such modifications and variations fall within the scope of the claims of this application and their equivalents, this application also intends to include such modifications and variations.

Claims

1. A tubular string, characterized in that, The tubular column includes: An oil pump includes an oil pipe, a plunger, and a cylinder, with the lower end of the oil pipe disposed within the cylinder; The first sleeve has a liquid outlet on its circumference that communicates with the interior of the first sleeve. The first sleeve also has a valve on its circumference that communicates with the interior of the first sleeve. The valve is located above the liquid outlet of the first sleeve. The first sleeve is fitted over the outer circumference of the oil pipe. The lower end of the first sleeve is sealed to the outer side of the oil pipe. The lower end of the first sleeve is connected to the upper end of the cylinder. The first sleeve has a first protrusion located below the liquid outlet inside. A sliding sleeve is slidably disposed within the first sleeve along the axial direction, so that the liquid outlet in the first sleeve and the valve can be switched to communicate with the interior of the first sleeve. The sliding sleeve is fitted outside the oil pipe of the oil pump. The sliding sleeve and the first sleeve are connected by a pin that can reduce its volume at steam temperature, so that the sliding sleeve slides down to the first protrusion. The pin includes a body and a rubber covering the body.

2. The tubular string according to claim 1, characterized in that, The sliding sleeve is provided with a stepped hole that mates with the pin. The larger hole in the stepped hole of the sliding sleeve is located near the axis, and the smaller hole in the stepped hole of the sliding sleeve is located near the first sleeve. One end of the pin is threaded into the larger hole of the sliding sleeve, and the other end of the thread is inserted into the inner wall of the first sleeve through the smaller hole of the sliding sleeve.

3. A tubular string according to claim 2, characterized in that, The sliding sleeve and the first sleeve are connected by a plurality of pins.

4. A tubular string according to claim 1, characterized in that, The valve includes a valve core and an elastic element. The first sleeve has a valve hole communicating with the interior on its wall. A sealing part is provided in the valve hole of the first sleeve. The elastic element, the valve core, and the sealing part are arranged in sequence. One end of the elastic element is fixed, and the other end of the elastic element is provided in the valve hole and connected to the valve core. The valve core is operable to abut against or separate from the sealing part of the first sleeve.

5. A tubular string according to claim 4, characterized in that, The valve hole of the first sleeve is provided with an annular second protrusion to form the sealing part. The valve core is spherical, and the outer periphery of the valve core can be operably abutted against or separated from the second protrusion.

6. A tubular string according to claim 4, characterized in that, The first sleeve has a support mesh covering the valve hole on its outer side, and one end of the elastic element is fixed to the support mesh.

7. A tubular string according to claim 4, characterized in that, The valve is provided in multiple ways.

8. A tubular string according to claim 1, characterized in that, The first sleeve has multiple liquid outlets.

9. A tubular string according to any one of claims 1-8, characterized in that, The plunger has a chamber, and the lower end of the plunger has an openable oil inlet. The lower end of the oil pipe is connected to the plunger. The plunger is slidably disposed in the cylinder along the axial direction. The lower end of the cylinder has an openable oil inlet.

10. A tubular string according to claim 9, characterized in that, A first valve ball is provided inside the cylinder, and a second valve ball is provided inside the plunger.

11. A tubular string according to claim 9, characterized in that, The lower end of the cylinder is connected to a screen tube, and the screen tube has multiple screen holes on its outer periphery. The lower end of the screen tube is closed.

12. A tubular string according to claim 11, characterized in that, The lower end of the sieve tube is connected to a plug.

13. A tubular string according to claim 12, characterized in that, The upper end of the first sleeve is connected to a heat insulation pipe, and the oil pipe of the oil pump is inserted into the heat insulation pipe.

14. A tubular string according to claim 13, characterized in that, The heat insulation pipe is fitted with a packer.

15. A tubular string according to claim 14, characterized in that, The tubing string includes a second sleeve, and the packer, the first sleeve, the oil pump, the screen tube, and the plug are all disposed inside the second sleeve.

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