Metal packer device based on carbon-based composite phase change material and using method

Abstract

The invention relates to the technical field of petroleum and natural gas exploration and development, in particular to a metal packer device based on a carbon-based composite phase change material and a using method, and the metal packer device comprises a headstall, a magnetic locator, a weighting rod, a conversion short section, an excitation short section and a phase change packer which are sequentially connected together from top to bottom. The device is reasonable and compact in structure, when the device is used, the phase-change metal sleeve is put into a target position, the phase-change metal sleeve is changed from a solid state to a liquid state by exciting the short section and then is filled in a sleeve annulus, and then the phase-change metal sleeve is changed from the liquid state to the solid state to form plugging of the sleeve annulus, so that the reliability of plugging of the sleeve annulus is improved, and the service life of the sleeve annulus is prolonged. The phase change metal casing pipe plugging device has the advantages of being high in pressure bearing capacity, easy, convenient and rapid to operate, resistant to acid corrosion and wide in application range, and can effectively solve the problems that a packer is difficult to unblock due to sand production of a shaft, poor in long-time working reliability and capable of bringing potential safety hazards to construction under severe conditions.

Description

Technical Field

[0001] The present invention relates to the technical field of oil and gas exploration and development, and is a metal packer device based on a carbon-based composite phase change material and a using method thereof. Background Art

[0002] In the process of oil and gas exploration and development, the packer, as a downhole tool for sealing the annulus between the casing and tubing, plays a crucial role and is widely used in drilling, cementing, testing, well completion, water injection, and downhole operations. Currently, the packers used mainly make the rubber cylinder on the packer expand through hydraulic drive or the up-and-down movement of the pipe string, so as to seal the annulus between the casing and tubing.

[0003] With the increasing domestic demand for oil and gas, the development of oil and gas fields has entered a new stage. High-temperature, high-pressure, and high-sulfur complex oil and gas reservoirs are gradually being explored and developed, which puts higher requirements on downhole tools and requires them to ensure long-term reliability in more demanding environments. Most of the currently used packers for sealing the annulus between the casing and tubing are of the slip and rubber cylinder sealing structure or the pure rubber cylinder sealing structure. In case of sand production in the wellbore, it is difficult or impossible to recover and release the slips of the packer, and its sealing element is a rubber cylinder, and the material of the rubber cylinder is mainly rubber. Under harsh conditions (high temperature, high pressure, and high sulfur content), the relevant properties of such materials will change. High temperature will cause changes in the physical properties of rubber, such as changes in hardness and a decrease in tensile strength; hydrogen sulfide in the wellbore will also react with the internal structure of rubber, resulting in embrittlement and degradation, bringing potential safety hazards to on-site construction.

[0004] In addition, during the exploration and development of oil and gas wells, such situations are often encountered: when a new well is just put into production, the downhole packer has good sealing performance. After a period of production, the downhole packer begins to lose its seal, and the annulus starts to be under pressure. Currently, the main solutions to such problems are as follows: 1) Kill the well and pull out the pipe string to replace the packer; 2) Without pulling out the pipe string, use a plugging agent to plug the leakage point; 3) Periodically relieve the pressure in the annulus to ensure that the annulus pressure is within an acceptable range. The first solution can fundamentally solve the problem of the packer losing its seal, but at the same time, two new problems are also generated: one is that the kill well operation will pollute the reservoir, especially for gas wells, and the production may drop sharply after the kill; the other is that pulling out the pipe string during the kill well operation belongs to workover operations, which not only increases costs but also brings safety risks. The second solution is theoretically feasible, but from the perspective of on-site implementation, the success rate is not high. The main reasons are as follows: the plugging agent is easily affected by the annulus fluid during injection, resulting in mud mixing, and the strength cannot be guaranteed after curing; the position where the packer is located is generally deep, and the corresponding temperature is also high, which is also a great challenge to the temperature resistance of the plugging agent; the downhole fluid environment is complex, such as salinity, acidity, etc., which pose challenges to the performance of the plugging agent. The third solution is only a temporary disposal measure and does not solve the actual problem. Summary of the Invention

[0005] The present invention provides a metal packer device based on a carbon-based composite phase change material and a usage method thereof, which overcomes the deficiencies of the above-mentioned prior art and can effectively solve the problem that the performance of existing oil casing packers changes under harsh conditions and poses potential safety hazards to construction.

[0006] One of the technical solutions of the present invention is achieved by the following measures: a metal packer device based on a carbon-based composite phase change material and a usage method thereof, including a pony head, a magnetic locator, a weight rod, a conversion sub, an activation sub, and a phase change packer connected together in sequence from top to bottom. The phase change packer includes an upper snap ring, a lower snap ring, a connecting pipe, and a phase change metal casing. The lower end of the activation sub is sleeved with the upper end of the connecting pipe. An upper snap ring is detachably and fixedly installed on the outer side of the upper part of the connecting pipe, and a lower snap ring is detachably and fixedly installed on the outer side of the lower end of the connecting pipe. A phase change metal casing is sleeved on the outer side of the connecting pipe corresponding to the position between the upper snap ring and the lower snap ring. The phase change metal casing can be changed from a solid state to a liquid state when the activation sub is energized, and the phase change metal casing can be changed from a liquid state to a solid state when the activation sub is de-energized.

[0007] The following is a further optimization or / and improvement of one of the above-mentioned invention technical solutions: The above may further include a flow collector umbrella. A flow collector umbrella is sleeved on the outer side of the connecting pipe corresponding to the position between the lower end of the phase change metal casing and the lower snap ring. The flow collector umbrella expands outwards when the phase change metal casing changes from a solid state to a liquid state.

[0008] The above may further include a ground control unit and a connecting cable. The ground control unit is connected to the upper end of the pony head through the connecting cable.

[0009] A plurality of vertically through grooves may be evenly distributed at intervals along the circumference on the outer side of the above-mentioned phase change metal casing, and the cross section of the groove is in the shape of a trapezoid with a wider outer side and a narrower inner side.

[0010] Chamfers may be provided on the outer sides of the upper end and the lower end of the above-mentioned phase change metal casing.

[0011] Another technical solution of the present invention is achieved by the following measures: a usage method of a metal packer device based on a carbon-based composite phase change material, including the following steps: Step 1: Install the phase change packer on the outer side of the lower end of the completion string, and then lower the completion string into the well. Step 2: Calibrate the depth after the phase change packer is lowered to the target position. Step 3: Lower the pony head into the casing through a cable winch and a connecting cable. The ground control unit starts to collect the depth data of the activation sub. When the activation sub reaches above the phase change packer, calibrate the depth of the activation sub, and then slowly lower the activation sub so that the depth of the activation sub is consistent with the depth of the phase change packer. Step 4: After the excitation short section is energized, it starts to work, the current collecting umbrella expands outward, and the phase change metal casing changes from solid to liquid and then flows downward to the upper end of the current collecting umbrella to fill the annular space between the outer side of the connecting pipe and the inner side of the casing; Step 5: After the excitation short section works for a certain period of time, the power is turned off and the work is stopped, and the phase change metal casing changes from liquid to solid, sealing the annulus between the outer side of the connecting pipe and the inner side of the casing; Step six, lift up the bridle, remove the excitation short section, and complete the casing annulus sealing operation.

[0012] The following is a further optimization and / or improvement of the second technical solution of the above invention: The second step is to calibrate the depth after the phase change packer is lowered to the target position, then place the tubing hanger, and finally install the wellhead and the Christmas tree.

[0013] The above also includes step seven, starting production after the casing annulus is sealed. If the phase-change metal casing leaks during the production process causing the casing annulus to be pressurized, steps three to six are repeated.

[0014] The invention has a reasonable and compact structure. When in use, the phase-change metal casing is lowered into the target position, and the phase-change metal casing is changed from solid to liquid by stimulating the short section and then filled in the casing annulus. Then, the phase-change metal casing is changed from liquid to solid to form a seal for the casing annulus, and the limited space required for sealing is completely filled, especially including the corrosive well section, so as to improve the reliability of the casing annulus sealing and reduce the restriction of the well condition change on the phase-change metal casing sealing construction. The invention has the advantages of high pressure bearing capacity, simple and fast operation, acid corrosion resistance and wide application range, and can effectively solve the problems of difficulty in unsealing the packer due to sand production in the wellbore, poor reliability of long-term operation and potential safety hazards caused to the construction under harsh conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Attached Figure 1 It is a schematic diagram of the main structure of Embodiments 1 to 6.

[0016] Attached Figure 2 For attachment Figure 1 Schematic diagram of the left view of the phase change packer.

[0017] Attached Figure 3 For attachment Figure 1 Schematic diagram of the main cross-sectional structure of the phase change packer.

[0018] Attached Figure 4 For attachment Figure 1 Schematic diagram of the main cross-sectional structure of the mid-phase change packer being lowered into the target position.

[0019] Attached Figure 5 For attachment Figure 1 Schematic diagram of the main cross-sectional structure of the mid-phase change packer after it is set.

[0020] The codes in the attached drawings are respectively: 1 is a horse head, 2 is a magnetic locator, 3 is a weight rod, 4 is a conversion sub, 5 is an excitation sub, 6 is an upper snap ring, 7 is a lower snap ring, 8 is a connecting pipe, 9 is a phase change metal sleeve, 10 is a current collection umbrella, 11 is a ground control unit, 12 is a connecting cable, and 13 is a groove. Specific embodiments

[0021] The present invention is not limited by the following embodiments, and specific implementation manners can be determined according to the technical solution of the present invention and the actual situation.

[0022] In the present invention, for the convenience of description, the description of the relative position relationship of each component is carried out according to the layout mode of the attached Figure 1 drawing of the specification. For example, the position relationships such as front, rear, upper, lower, left, and right are determined according to the layout direction of the attached drawing of the specification.

[0023] The present invention will be further described below in conjunction with the embodiments and the attached drawings: Embodiment 1: As shown in the attached Figures 1 to 5 drawing, the metal packer device based on the carbon-based composite phase change material includes a horse head 1, a magnetic locator 2, a weight rod 3, a conversion sub 4, an excitation sub 5, and a phase change packer connected together in sequence from top to bottom. The phase change packer includes an upper snap ring 6, a lower snap ring 7, a connecting pipe 8, and a phase change metal sleeve 9. The lower end of the excitation sub 5 is sleeved with the upper end of the connecting pipe 8. An upper snap ring 6 is detachably and fixedly installed on the outer side of the upper part of the connecting pipe 8, and a lower snap ring 7 is detachably and fixedly installed on the outer side of the lower end of the connecting pipe 8. A phase change metal sleeve 9 is sleeved on the outer side of the connecting pipe 8 corresponding to the position between the upper snap ring 6 and the lower snap ring 7. The phase change metal sleeve 9 can be changed from a solid state to a liquid state when the excitation sub 5 is energized, and the phase change metal sleeve 9 can be changed from a liquid state to a solid state when the excitation sub 5 is de-energized.

[0024] According to requirements, the material of the phase change metal sleeve 9 is a well-known carbon-based metal phase change material in the prior art. The excitation sub 5 is a well-known technology in the prior art, such as a heater. The upper and lower ends of the connecting pipe 8 and the upper snap ring 6 and the lower snap ring 7 are detachably and fixedly installed together by a plurality of set screws evenly distributed along the circumference. During use, the phase change metal sleeve 9 is lowered to the target position. By the excitation sub 5, the phase change metal sleeve 9 is changed from a solid state to a liquid state and then fills the casing annulus. Then, the phase change metal sleeve 9 is changed from a liquid state to a solid state to form a plug for the casing annulus, completely filling the defined space to be plugged, especially including the corroded well section, improving the reliability of the casing annulus plugging, reducing the limitation of the well condition change on the plugging construction of the phase change metal sleeve 9, and having the advantages of high pressure-bearing capacity, simple and quick operation, acid corrosion resistance, and wide application range. It can effectively solve the problems of poor reliability of the packer due to long-term operation under harsh conditions and potential safety hazards brought to the construction.

[0025] According to actual needs, the above metal packer device based on carbon-based composite phase change materials can be further optimized and / or improved as follows: Embodiment 2: As an optimization of the above embodiment, as shown in the appendix Figures 1 to 5 As shown, it further includes a flow collector umbrella 10. A flow collector umbrella 10 is sleeved outside the connecting pipe 8 at the position between the lower end of the corresponding phase change metal casing 9 and the lower snap ring 7. The flow collector umbrella 10 expands outwards when the phase change metal casing 9 changes from a solid state to a liquid state. According to requirements, the flow collector umbrella 10 is a known technology in the art. During use, by setting the flow collector umbrella 10, it is possible to avoid the phenomenon that the phase change metal casing 9 flows downward after changing from a solid state to a liquid state and cannot seal the casing annulus, and improve the sealing efficiency of the casing annulus.

[0026] Embodiment 3: As an optimization of the above embodiment, as shown in the appendix Figure 1 As shown, it further includes a ground control unit 11 and a connecting cable 12. The ground control unit 11 is connected to the upper end of the master sub 1 through the connecting cable 12. According to requirements, the ground control unit 11 is a known technology in the art. In the present invention, by energizing the firing nipple 5 through the ground control unit 11 and the connecting cable 12, the operation of sealing the casing annulus can be realized without other power sources, and it can effectively solve the problems existing in traditional packers, such as various specifications and sizes, high requirements for the inner wall of the casing, poor sealing of the corrosion section or inability to set, unsealing under harsh conditions, and the use of pyrotechnic devices.

[0027] Embodiment 4: As an optimization of the above embodiment, as shown in the appendix Figures 1 to 4 As shown, a plurality of upper and lower through grooves 13 are evenly distributed along the circumference outside the phase change metal casing 9. The cross section of the groove 13 is a trapezoid with a wider outer width and a narrower inner width. During use, through such a setting, after the phase change metal casing 9 changes from a solid state to a liquid state, it can flow downward quickly, so that the thickness of the phase change metal casing 9 is uniform when sealing the inner wall of the casing after becoming liquid, and the stability after sealing the casing annulus is improved.

[0028] Embodiment 5: As an optimization of the above embodiment, as shown in the appendix Figures 1 to 4 As shown, chamfers are provided on the outer sides of the upper end and the lower end of the phase change metal casing 9. During use, through such a setting, it is possible to avoid rubbing between the phase change metal casing 9 and the wellbore wall during the process of entering the well, so that the phase change metal casing 9 can be smoothly lowered to the target position.

[0029] Embodiment 6: As an optimization of the above embodiment, as shown in the appendix Figures 1 to 5 As shown, the usage method of the metal packer device based on carbon-based composite phase change materials includes the following steps: Step 1: Install the phase change packer on the outside of the lower end of the completion string, and then lower the completion string into the well; Step 2: Calibrate the depth after the phase change packer is lowered to the target position; Step 3: Lower the horsehead 1 into the casing through a cable winch and a connecting cable 12. The ground control unit 11 starts to collect the depth data of the firing sub 5. When the firing sub 5 reaches above the phase change packer, correct the depth of the firing sub 5, and then slowly lower the firing sub 5 to make the depth of the firing sub 5 consistent with the depth of the phase change packer. Step 4: After the firing sub 5 is powered on and starts to work, the current collecting umbrella 10 expands outwards. After the phase change metal casing 9 changes from solid state to liquid state, it flows downward to the upper end of the current collecting umbrella 10 and fills the annulus between the outer side of the connecting pipe 8 and the inner side of the casing. Step 5: After the firing sub 5 works for a certain period of time, power off and stop working. The phase change metal casing 9 changes from liquid state to solid state, sealing the annulus between the outer side of the connecting pipe 8 and the inner side of the casing. Step 6: Lift the horsehead 1 and retrieve the firing sub 5 to complete the casing annulus setting operation.

[0030] Step 2: After the phase change packer is lowered to the target position, correct the depth, then set the tubing hanger, and finally install the wellhead and the Christmas tree.

[0031] It further includes Step 7: After the casing annulus is set, start production. If the phase change metal casing 9 leaks during production, resulting in pressure in the casing annulus, repeat Steps 3 to 6.

[0032] First, connect the phase change packer to the completion string and lower it into the well together with the completion string. After the phase change packer reaches the position, correct the depth of the completion string, set the tubing hanger, and install the wellhead and the Christmas tree.

[0033] Then, lower the tool string assembled with the horsehead 1, the magnetic locator 2, the weight rod 3, the adapter sub 4, and the firing sub 5 into the casing through a cable winch and a connecting cable 12. The ground control unit 11 collects the depth information of the tool string through the magnetic locator 2. When the firing sub 5 reaches above the phase change packer, correct the depth of the firing sub 5 through the magnetic locator 2, and then slowly lower the firing sub 5 to make the depth of the firing sub 5 consistent with the depth of the phase change packer, and the firing sub 5 contacts the inner side of the connecting pipe 8.

[0034] Subsequently, the ground control unit 11 supplies power to start the firing sub 5. The firing sub 5 starts to work. After the current collecting umbrella 10 expands outwards and fits against the inner wall of the casing, the phase change metal casing 9 changes from solid state to liquid state and flows downward to the upper end of the current collecting umbrella 10 and fills the annulus between the outer side of the connecting pipe 8 and the inner side of the casing. After a certain period of time, the ground control unit 11 stops supplying power, the firing sub 5 stops working, and the phase change metal casing 9 changes from liquid state to solid state, sealing the annulus between the outer side of the connecting pipe 8 and the inner side of the casing.

[0035] Lift the master sub 1 by the cable winch and the connecting cable 12, pull out the firing sub 5, and complete the casing annulus setting operation.

[0036] After the tubing setting operation is completed, production starts. If, after the well has been producing for some time, the casing annulus is pressurized due to leakage of the phase change metal casing 9, then, without moving the tubing string, the tool string assembled by the master sub 1, the magnetic locator 2, the heavyweight rod 3, the adapter sub 4, and the firing sub 5 can be lowered into the casing again through the cable winch and the connecting cable 12. At the phase change metal casing 9, the firing sub 5 is energized again through the ground control unit 11, and the phase change metal casing 9 can be converted again between "solid - liquid - solid" phases, realizing the resetting of the packer and solving the problem of casing annulus pressurization. Compared with traditional treatment measures, this solution can not only quickly solve the problem of annulus pressurization caused by packer leakage, but also reduce the construction cost, simplify the construction process, and avoid the high - risk operation of killing the well and pulling out the tubing string.

[0037] The above - mentioned technical features constitute the embodiments of the present invention, which have strong adaptability and implementation effects. Non - essential technical features can be added or reduced according to actual needs to meet the requirements of different situations.

Claims

1. A metal packer device based on a carbon-based composite phase change material, characterized in that it includes a gooseneck, a magnetic locator, a weight rod, a transition sub, an excitation sub and a phase change packer connected together in sequence from top to bottom. The phase change packer includes an upper snap ring, a lower snap ring, a connecting pipe and a phase change metal casing. The lower end of the excitation sub is sleeved on the upper end of the connecting pipe. An upper snap ring is detachably and fixedly installed on the outer side of the upper part of the connecting pipe, and a lower snap ring is detachably and fixedly installed on the outer side of the lower end of the connecting pipe. A phase change metal casing is sleeved on the outer side of the connecting pipe corresponding to the position between the upper snap ring and the lower snap ring. The phase change metal casing can be changed from a solid state to a liquid state when the excitation sub is electrified, and the phase change metal casing can be changed from a liquid state to a solid state when the excitation sub is powered off.

2. The metal packer device based on a carbon-based composite phase change material according to claim 1, characterized in that it further includes a flow collector umbrella. A flow collector umbrella is sleeved on the outer side of the connecting pipe corresponding to the position between the lower end of the phase change metal casing and the lower snap ring. The flow collector umbrella expands outwards when the phase change metal casing changes from a solid state to a liquid state.

3. The metal packer device based on a carbon-based composite phase change material according to claim 1 or 2, characterized in that it further includes a ground control unit and a connecting cable. The ground control unit is connected to the upper end of the gooseneck through the connecting cable.

4. The metal packer device based on a carbon-based composite phase change material according to claim 1 or 2, characterized in that a plurality of vertically penetrating grooves are evenly distributed at intervals along the circumference on the outer side of the phase change metal casing, and the cross section of the groove is a trapezoid with a wider outer side and a narrower inner side.

5. The metal packer device based on a carbon-based composite phase change material according to claim 3, characterized in that a plurality of vertically penetrating grooves are evenly distributed at intervals along the circumference on the outer side of the phase change metal casing, and the cross section of the groove is a trapezoid with a wider outer side and a narrower inner side.

6. The metal packer device based on a carbon-based composite phase change material according to claim 1 or 2 or 5, characterized in that chamfers are provided on both the outer side of the upper end and the outer side of the lower end of the phase change metal casing.

7. The metal packer device based on a carbon-based composite phase change material according to claim 3, characterized in that chamfers are provided on both the outer side of the upper end and the outer side of the lower end of the phase change metal casing.

8. The metal packer device based on a carbon-based composite phase change material according to claim 4, characterized in that chamfers are provided on both the outer side of the upper end and the outer side of the lower end of the phase change metal casing.

9. A method for using the metal packer device based on a carbon-based composite phase change material according to any one of claims 1 to 8, characterized in that it includes the following steps: Step 1, install the phase change packer on the outer side of the lower end of the completion string, and then lower the completion string into the well; Step 2, correct the depth after the phase change packer is lowered to the target position; Step 3, lower the gooseneck into the casing through the cable winch and the connecting cable. The ground control unit starts to collect the depth data of the excitation sub. When the excitation sub reaches above the phase change packer, correct the depth of the excitation sub, and then slowly lower the excitation sub so that the depth of the excitation sub is consistent with the depth of the phase change packer; Step 4: After the firing sub is energized and starts to work, the flow collector umbrella expands outwards, and the phase change metal sleeve changes from solid state to liquid state and then flows downward to the upper end of the flow collector umbrella to fill the annulus between the outside of the connecting pipe and the inside of the sleeve; Step 5: After the firing sub works for a certain period of time, it is powered off and stops working. The phase change metal sleeve changes from liquid state to solid state, sealing the annulus between the outside of the connecting pipe and the inside of the sleeve; Step 6: Lift the master valve head and remove the firing sub to complete the operation of setting the sleeve annulus.

10. The method for using the metal packer device based on the carbon-based composite phase change material according to claim 9, characterized in that Step 2 is that after the phase change packer is lowered to the target position, the depth is corrected, then the tubing hanger is set, and finally the wellhead and the Christmas tree are installed; and / or, it further includes Step 7. After the sleeve annulus is set, production starts. If the sleeve annulus is pressurized due to leakage of the phase change metal sleeve during production, repeat Steps 3 to 6.

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