Device for enhancing strength of well cementation cement sheath and well cementation process

Abstract

The invention relates to the field of rock salt mine well drilling water solution mining, in particular to a device for enhancing the strength of a well cementation cement sheath, which comprises a connecting pipe arranged at the bottom of a production casing; a woven spring is arranged in the spring box, and the spring box is fixed at the bottom of the connecting pipe; the spring laying mechanism comprises a first elastic piece, a second elastic piece, an anchor rod and a trigger device, wherein the first elastic piece and the second elastic piece are fixed to the outer side of the connecting pipe. The first elastic piece is connected with the triggering device, the triggering device can be started according to the diameter change of well cementation, the second elastic piece is released after the triggering device is started, and the second elastic piece pushes the anchor rod and fixes the anchor rod to the inner wall of a drilling well; when well cementation is conducted through the device, the thickness of the outer ring space of the production casing of the ore-bearing section can be increased, a cement sheath with the high overall structural strength can be formed after springs are automatically arranged and cement is automatically poured in the hole expanding section, and the production casing of the ore-bearing section is prevented from being damaged. And the service life of the production sleeve is further prolonged.

Description

Technical Field

[0001] The invention relates to the technical field of rock salt mine drilling and water-soluble mining, and in particular to a device for enhancing the strength of cement ring and a cementing process. Background Art

[0002] The salt layers in my country's rock salt mines generally present the characteristics of thin layers and multiple interlayers. The first salt layer mined by drilling water solution mining is generally selected at the bottom salt layer of the salt-bearing section. The brine in the dissolution cavity develops very quickly due to the phenomenon of gravity differentiation and the general law of dissolution, especially the rapid dissolution near the casing. In the middle and late stages of brine production, the casing in the buried depth range of the salt-bearing layer section is suspended in the dissolution cavity. Under the influence of multiple factors, the production casing is easy to break at weak places. One of the main reasons is that when water is injected, the fluid flows out at the casing mouth, and the reaction force formed by the water flow pushes the suspended part of the casing to swing back and forth; in addition, the surrounding rock strata of some rock salt mines contain gas. During mining, gas will gather at the top of the dissolution cavity. When the casing mouth is at the gas-liquid interface, the gas enters the casing through the casing mouth. The high-pressure gas expands in volume as the pressure decreases, and the flow rate accelerates, which also causes the swing of the suspended part of the casing. Due to the effect of gravity differentiation, the concentration of brine in the dissolution cavity gradually increases from top to bottom. After the casing is broken, the brine returned to the upper part of the dissolution cavity has a low concentration, and the quality of the brine may even fail to meet production requirements.

[0003] The back-and-forth swinging of the casing will not only cause casing damage, but also have another major harm, which is to damage the cement outside the casing at the top of the dissolution cavity, thereby destroying the tight structure between the casing and the formation. The fresh water at the top of the dissolution cavity quickly floats up along the cracks in the broken cement ring outside the casing, causing the dissolution cavity to dissolve upward too quickly, lengthening the length of the suspended part of the casing, and further aggravating the occurrence of casing damage and breakage accidents. In this way, it is difficult to advance the dissolution of the dissolution cavity in the horizontal direction, the planar dissolution range cannot be opened, and the recovery rate of the controlled resources of the well group cannot be improved.

[0004] The breaking and detachment of production casing and the damage of cement ring outside casing will affect the development and utilization of rock salt resources, resulting in the inability to fully exploit a large amount of rock salt resources controlled by the well group and increasing the investment in rock salt mine construction costs. Summary of the invention

[0005] 1. Technical issues to be resolved

[0006] The invention provides a device for enhancing the strength of cementing cement ring, aiming to solve the problem of production casing breaking due to swing caused by lack of protection of production casing due to insufficient strength of cement ring in ore layer.

[0007] (II) Technical solution

[0008] In order to achieve the above-mentioned object, the present invention proposes a spring box for enhancing the strength of the cement ring of casing cementing, comprising: a connecting pipe, arranged at the bottom of the production casing; a spring box, in which a braided spring is arranged, and fixed to the bottom of the connecting pipe; a spring arrangement mechanism, comprising a first spring sheet and a second spring sheet fixed to the outside of the connecting pipe, an anchor rod and a trigger device;

[0009] The first spring piece is connected to the trigger device, and can be activated according to the diameter change of cementing. After the trigger device is activated, the second spring piece is released, and the second spring piece pushes the anchor rod and fixes the anchor rod to the inner wall of the well; the anchor rod is connected to the braided spring, and when the production casing continues to be pushed downward, the anchor rod will pull the braided spring to surround the production casing.

[0010] A further technical solution is that the trigger device comprises a plurality of hinge support rods and pin pull bars, pins and pin pull ropes;

[0011] A plurality of hinged support rods are arranged around the connecting tube, and each of the hinged support rods has a notch on the top and is hinged to the spring box at the bottom, and the anchor rod is inserted into the notch; one end of a plurality of pin pull rods is connected to the plurality of hinged support rods one by one, and the pin holes on the other end are overlapped and the pins are inserted therein, and the pins are connected to the first elastic sheet through the pin pull rope, and the first elastic sheet can pull the pin pull rope to drive the pin to come out of the pin hole.

[0012] A further technical solution is that the first spring piece has a shuttle-shaped structure, which is sleeved on the outside of the connecting pipe and can expand to match the diameter of the drilling well; the inner side of the shuttle-shaped structure has a plurality of threading protrusions, and the pin pull rope passes through the first wire holes on the plurality of threading protrusions in sequence and then passes through the second wire hole on the connecting pipe to be connected to the pin.

[0013] A further technical solution is that the top of the anchor rod is provided with a barb, which is away from the connecting tube and directed downward; when the pin is inserted into the pin hole, the top end of the hinge support rod leans against the connecting tube and compresses the second spring sheet, and the hinge support rod drives the top end of the anchor rod toward the connecting tube; when the pin is disengaged from the pin hole, the second spring sheet is reset, and the hinge support rod drives the barb at the top end of the anchor rod to insert into the inner wall of the wellbore.

[0014] A further technical solution is that the pin pull rod and the hinge support rod are rotatably connected; or the pin pull rod is flexible and connected to the hinge support rod via a threaded adjustment structure, which can pre-adjust the starting angle of the hinge support rod.

[0015] A further technical solution is that it also includes a slender clamp, one end of which can extend into the connecting pipe and insert the pin into the pin hole.

[0016] A further technical solution is that a conversion joint is provided between the connecting pipe and the production casing, a through hole is opened on the side of the conversion joint for passing concrete; and the spring box and the connecting pipe are fixedly connected by an annular plate.

[0017] A further technical solution is that the braided spring includes a braided rope and a spring; multiple braided ropes are evenly distributed around the spring and respectively correspond to multiple anchor rods; one end of each braided rope is braided along the axial direction of the spring, and the other end is connected to the anchor rod.

[0018] A further technical solution is that the diameter of the spring box is larger than the diameter of the production casing, and the diameter of the production casing is larger than the diameter of the connecting pipe.

[0019] The cementing process using the device for enhancing the strength of cement sheath as described above specifically includes:

[0020] S1: Determine the length of the spring box, the number of coils of the spring and the overall length of the spring arrangement mechanism according to the wellbore diameter, expansion diameter, wellbore structure and well depth range;

[0021] S2: Assemble the spring arrangement mechanism, including:

[0022] The connecting pipe and the spring box are fixed by an annular steel plate;

[0023] The spring is braided with a braided rope and then spirally pressed into the spring box;

[0024] Using a hinged support rod to install a barbed anchor rod on the top of the spring box, and fixing the end of the braided rope on the anchor rod;

[0025] The first spring sheet and the second spring sheet are fixedly mounted on the connecting pipe, and after pre-compression, the trigger device is dynamically adjusted;

[0026] S3: Drilling with a brine well construction drill and expanding the hole with a reamer in the mining section;

[0027] S4: The production casing is installed on the top of the assembled spring deployment mechanism, and the spring deployment mechanism is pushed into the well using the production casing. When the expansion section is reached, the first spring sheet expands, and the second spring sheet is released through the trigger device. The second spring sheet pushes the anchor rod into the inner wall of the well, and the production casing is continuously pushed in. The anchor rod continuously pulls out the braided spring through the braided rope and surrounds the production casing until the production casing reaches the designed position and stops.

[0028] S4: Inject cement slurry for cementing.

[0029] (III) Beneficial effects

[0030] The cementing device of the present invention can increase the thickness of the outer ring space of the production casing in the ore-bearing section, and the spring is automatically arranged in the expansion section, which can further form a high-strength cement ring for cementing. This cement ring structure enhances the bonding strength between the production casing and the formation, so that fresh water is not so easy to go up through the outer ring gap of the production casing. The addition of springs as a skeleton in the cement ring can enhance the strength of the cement ring, so that the suspended production casing will not be damaged during the swinging process. Furthermore, when the production casing is suspended, the cement ring can still firmly wrap the production casing, multiplying the weight of the suspended part of the production casing. When the production casing is injected with the same flow rate and flow rate of the medium, the swing amplitude of the production casing will be very small, which is more conducive to maintaining the stability of the production casing, reducing the speed of dissolution development, and maintaining high concentration of brine, which is very beneficial to improving the recovery rate of the well group. Secondly, the cement ring structure also reduces the probability of the outer ring gap of the production casing at the top plate of the dissolution cavity being squeezed and damaged, prolongs the life of the suspended part of the production casing, and reduces the speed of dissolution development in the dissolution cavity, which is very beneficial to brine production. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 A schematic diagram of the overall structure of a device for enhancing the strength of cement sheath;

[0032] Figure 2 for Figure 1 Schematic diagram of the cross section at AA in the middle;

[0033] Figure 3 for Figure 1 Schematic diagram of the cross section at the middle BB;

[0034] Figure 4 for Figure 1 Schematic diagram of the cross section at C in the middle;

[0035] Figure 5 for Figure 1 Schematic diagram of the cross section at D in the middle;

[0036] Figure 6 Schematic diagram of the unfolding of the braided spring.

[0037] [Description of Reference Numerals]

[0038] 1: production casing; 2: connecting pipe; 3: spring box; 4: braided spring; 41: braided rope; 42: spring; 5: spring arrangement mechanism; 51: first spring piece; 511: threading protrusion; 52: second spring piece; 53: anchor rod; 531: barb; 54: trigger device; 541: hinged support rod; 542: pin pull strip; 543: pin; 544: pin pull rope; 6: conversion joint; 61: through hole; 7: annular plate; 8: first line hole; 9: second line hole. DETAILED DESCRIPTION

[0039] In order to better explain the present invention and facilitate understanding, the present invention is described in detail below through specific implementation modes in conjunction with the accompanying drawings.

[0040] Take a rock salt mine as an example. Its salt layer is buried 2400m deep, the thickness of the salt-bearing section is 50m, and the surrounding rocks at the top of the salt layer are dolomite and limestone. The diameter of the second drilling hole of the brine well is 215.9mm, and the specification of the production casing is 177.8×9.19mm. Five years after the new well group of the salt mine was put into production, the brine concentration suddenly decreased and could not meet the requirements of the salt production system for brine concentration. The new brine well under construction needs to solve the problem of short effective service life of the brine well. The new brine well needs to enhance the cementing quality of the ore-bearing section and delay the time when the production casing in the dissolution cavity is suspended.

[0041] This embodiment provides a device for enhancing the strength of cement sheath. Figure 1-Figure 3 As shown, it includes

[0042] The connecting pipe 2 is arranged at the bottom of the production casing 1. Specifically, the connecting pipe 2 is connected to the production casing 1 through a drillable joint, and both ends of the drillable joint are respectively connected to the production casing 1 and the connecting pipe 2 through threads. This connection method is convenient for on-site installation.

[0043] The spring box 3 is provided with a braided spring 4 and is fixed to the bottom of the connecting tube 2. Specifically, the spring box 3 and the connecting tube 2 can be connected by welding to ensure reliable connection. The braided spring 4 specifically refers to the spring wire being bundled in sequence along the axial direction of the spring 42 by a braided rope 41.

[0044] The spring arrangement mechanism 5 includes a first spring piece 51 and a second spring piece 52 fixed to the outside of the connecting pipe 2, an anchor rod 53 and a trigger device 54. Specifically, the first spring piece 51 is connected to the trigger device 54, and the first spring piece 51 can start the trigger device 54 according to the diameter change of the cementing. After the trigger device 54 is started, the second spring piece 52 is released, and the second spring piece 52 pushes the anchor rod 53 and fixes it to the inner wall of the cementing; the anchor rod 53 is connected to the braided spring 4, and when the production casing 1 continues to move downward, the anchor rod 53 will pull the braided spring 4 to surround the production casing 1. Among them, the first spring piece 51 and the second spring piece 52 are connected to the outside of the connecting pipe 2 by welding or clamping.

[0045] The use of the above-mentioned device for cementing can increase the thickness of the outer ring space of the production casing 1 in the ore-bearing section, and a high-strength cement ring structure is formed by arranging an elastic support body in the expansion section. The cement ring structure makes it difficult for fresh water to flow upward through the outer ring gap of the production casing 1. The addition of a spring 42 as a skeleton in the cement ring can enhance the strength of the cement ring, so that the suspended production casing 1 will not be damaged during the swinging process. When the production casing 1 is suspended, the cement ring can still firmly wrap the production casing 1, multiplying the weight of the suspended part of the production casing 1. When the production casing 1 is injected with a medium of the same flow rate and velocity, the swing amplitude of the production casing 1 will be very small, which is more conducive to maintaining the stability of the production casing 1, reducing the development speed of the upper dissolution, and maintaining a high concentration of brine, which is of great benefit to improving the recovery rate of the well group.

[0046] In this embodiment, the trigger device 54 includes four hinged support rods 541 and four pin pull strips 542, a pin 543 and a pin pull rope 544. The four hinged support rods 541 are arranged around the connecting pipe 2, and each hinged support rod 541 has a notch at the top, and the bottom is hinged to the spring box 3, and the anchor rod 53 is inserted into the notch. Specifically, the four hinged support rods 541 are rotatably connected to the top of the spring box 3, allowing the hinged support rods 541 to have a certain range of motion while maintaining the reset capability. The notch on the hinged support rod 541 is square, and the bottom of the corresponding anchor rod 53 is an adapted square. Such a setting will prevent the anchor rod 53 from rotating during the swinging process.

[0047] One end of the four pin pull strips 542 is connected to the four hinge support rods 541 one by one, and the pin 543 holes at the other end are overlapped and inserted into the pin 543. The pin 543 is connected to the first elastic piece 51 through the pin pull rope 544. The first elastic piece 51 can pull the pin pull rope 544 to drive the pin 543 to disengage from the pin 543 hole.

[0048] Specifically, the first spring piece 51 has a shuttle-shaped structure, which is sleeved on the outside of the connecting pipe 2 and can expand to match the diameter of the cementing well; the inside of the shuttle-shaped structure has a plurality of threading protrusions 511, which are located at the position where the diameter of the shuttle-shaped structure is the largest, so as to better start the trigger device 54. Figure 4 and Figure 5 As shown, the pin pull rope 544 passes through the first wire holes 8 on the plurality of threading protrusions 511 in sequence and then passes through the second wire hole 9 on the connecting tube 2 to be connected to the pin 543. Preferably, a ceramic ring is arranged inside the first wire hole 8, which can effectively reduce the friction of the pin pull rope 544.

[0049] Specifically, the top of the anchor rod 53 has a barb 531, which faces away from the connecting pipe 2 and toward the inner wall of the well, and has an oblique downward angle with the connecting pipe 2, so as to be better inserted and riveted to the inner wall of the well. When the pin 543 is inserted into the pin 543 hole, the top of the hinge support rod 541 leans against the connecting pipe 2 and compresses the second elastic sheet 52, and the hinge support rod 541 drives the top of the anchor rod 53 to lean against the connecting pipe 2; when the pin 543 is disengaged from the pin 543 hole, the second elastic sheet 52 is reset, and the hinge support rod 541 drives the barb 531 at the top of the anchor rod 53 to insert into the inner wall of the well.

[0050] In this embodiment, the pin pull bar 542 and the hinge support rod 541 are rotatably connected to ensure that the pin pull bar 542 will not interfere with the connecting tube 2 during the rotation of the hinge support rod 541. Of course, the pin pull bar 542 can also be provided with a larger activity space by increasing the through hole of the pin pull bar 542 on the connecting tube 2, or using a pin pull bar 542 with a certain flexibility. Preferably, the pin pull bar 542 and the hinge support rod 541 are connected by a threaded adjustment structure, and this design can pre-adjust the starting angle of the hinge support rod 541.

[0051] In this embodiment, a slender clamp is also included, one end of which can extend into the connecting pipe 2 and insert the pin 543 into the pin 543 hole. The head of the slender clamp can be magnetically attracted, and the magnetic attraction method can quickly insert and release the pin 543.

[0052] In this embodiment, a drillable conversion joint 6 is arranged between the connecting pipe 2 and the production casing 1. A through hole 61 is opened on the side of the conversion joint 6. The through hole 61 is long and is used to pass concrete. The spring box 3 and the connecting pipe 2 are fixedly connected by an annular plate 7.

[0053] In this embodiment, combined with Figure 6 As shown, the braided spring 4 includes a braided rope 41 and a spring 42; the specific braided rope 41 is made of flexible thin steel wire, and there are four of them. The four braided ropes 41 are evenly distributed around the spring 42 and correspond to four anchor rods 53 respectively; one end of each braided rope 41 is braided along the axial direction of the spring 42, and the other end is connected to the anchor rod 53.

[0054] It should be noted that in this embodiment, the diameter of the spring box 3 is larger than the diameter of the production casing 1 , and the diameter of the production casing 1 is larger than the diameter of the connecting pipe 2 .

[0055] Using the above-mentioned device for enhancing the strength of cementing cement ring, the specific cementing construction process is as follows:

[0056] First, a 3mm diameter elastic steel wire made of 316 material is used to be bent into a spring 42. The middle diameter of the spring 42 is 255mm and the helix angle is 5.6°. The depth range of the cement ring outside the production casing 1 of the brine well that needs to be reinforced is the ore-bearing section and 10m above the top of the ore layer, a total of 60m. A 3mm elastic steel wire is used as the spring wire, which is unfolded in the reinforcement section at a spacing of 30mm. The number of turns of the spring 42 required is 2000. Four braided ropes 41 are used to braid the elastic steel wires one by one at a symmetrical angle to form a spring 42, and a 177.8mm spring box 3 with a length of 8m is made. It should be noted here that the middle diameter of the spring 42 is determined by the interval between the borehole diameter and the production casing 1, which is generally less than 20mm of the borehole diameter. The spring 42 is spirally compressed and placed in the spring box 3 to reduce the middle diameter of the spring 42. After the device is lowered to the expansion depth, the braided rope 41 can pull the spring 42 out of the casing, and the spring 42 automatically restores its original middle diameter and is set outside the production casing 1.

[0057] Then, use the circular steel plate to weld and fix the connecting pipe 2 and the spring box 3. Press the braided elastic steel wire braided spring 4 spirally into the spring box 3, insert the four anchor rods 531 with barbs into the notches on the hinge support rod 541, and bind the braided rope 41 at the end of the braided spring 4 to the anchor rod 531 with barbs. Tie the second spring piece 52 with a rope, and bring the anchor rod 531 with barbs toward the connecting rod. Use one end of the pin pull rope 544 to string the four first spring pieces 51 together, and extend the other end into the connecting rod through the first wire hole 8 on the connecting rod. Use a slender clamp to remove the first wire from the connecting rod. Pull out the pin pull rope 544 from the top and tie up the pin 543, adjust the four pin pull strips 542 so that the pin 543 holes at the ends of the four pin pull strips 542 overlap, send the pin 543 into the pin 543 hole through a slender clamp, immediately untie the rope on the second spring piece 52, and at the same time tie the first spring piece 51 with a strip so that the outer diameter is smaller than the outer diameter of the production casing 1, and adjust the length of the pin pull rope 544. The specific length should be able to pull out the pin 543 when the device passes through the well section of drilling and reaming.

[0058] The depth range of the cement ring outside the production casing 1 of the brine well that needs to be reinforced is the ore-bearing section and 10m above the top of the ore layer, with a total length of 60m. According to the length of the spring layout mechanism 5 for cementing, a pocket of at least 10m needs to be set at the bottom of the borehole. The second opening of the brine well is drilled to the depth below the production casing 1 with a 215.9mm drill bit or maintained vertically to drill down to a depth of 10m to ensure the pocket length required for open hole logging and the spring layout mechanism 5 for cementing. Then the drill tool is equipped with a YK216-280 hydraulic reamer to expand the ore-bearing section including the top of the ore-bearing layer within a depth range of 10m. The hole can be expanded multiple times to ensure the quality of the expansion. It should be noted here that the purpose of expanding the hole is to increase the gap between the casing and the formation so that the spring box 3 has enough space to evenly release the spring 42 and keep the spring 42 evenly distributed. At the same time, it can also increase the thickness of the cement ring, which is conducive to enhancing the bonding strength between the production casing 1 and the formation. Increasing the weight of the suspended production casing 1 can increase the stability of the production casing 1 and reduce the shaking caused by water injection recoil. It also reduces the integrity of the cement ring outside the steel casing at the top of the dissolution cavity and slows down the dissolution rate. Further explanation: a hydraulic stabilizer is set for every 3 production casings 1 in the expansion section to ensure that the production casing 1 is centered in the borehole, and the spring 42 and cement ring are evenly distributed around the casing to increase the structural strength of the cement ring and the cementing quality. After expansion, the annular gap between the production casing 1 and the formation is large, and the conventional stabilizer can no longer keep the production casing 1 centered, so a hydraulic stabilizer is used.

[0059] After the hole enlargement operation is completed, the borehole is cleaned and the production casing 1 with the spring arrangement mechanism 5 for cementing is prepared to be lowered. The automatic arrangement device for elastic steel wire for cementing can be lowered into the well by connecting the production casing 1 with the drillable conversion joint 6. When the first spring piece 51 just enters the surface casing or the intermediate casing, the strip binding rope on the first spring piece 51 should be loosened, and then the strips are added to the production casing 1 one by one. At this time, the first spring piece 51 is close to the hole wall. After being lowered to the hole enlargement section, the four first spring pieces 51 are unfolded outward, and the pin pull rope 544 is pulled out to pull the pin 543 out of the pin pull rope 542 hole. The four hinged support rods 541, under the action of the second force spring piece, pull the four barbed 53 The anchor rod 53 is pressed against the well wall. The barbs 531 on the four barbed anchor rods 531 will penetrate into the formation after contacting the well wall and finally be riveted to the well wall. The barbed anchor rod 531 is detached from the hinge support rod 541 and pulls the braided rope 41 to gradually pull the braided spring 4 out of the spring box 3 until the bottom of the production casing 1 is lowered into the designed position and stops. Since the connecting pipe 2 is hollow and the side of the conversion joint 6 is a long strip hole structure, the device does not affect the normal injection of cement slurry cementing. The drillable conversion joint 6 is drilled out when the cement plug is swept. Preferably, the production casing 1 is slowly lowered 2m before entering the expansion section. To ensure that the first spring piece 51 is fully deployed at the moment of entering the expansion section, the pin pull rope 544 is pulled out to pull the pin 543 out of the pin 543 hole.

[0060] The application of the above cementing technology to the construction of brine wells can ensure that the recovery rate of the controlled resources of the well group reaches more than 70%, and the service life of the brine well can generally reach more than 15 years, especially for thick and large brine production salt layers, which is conducive to the full exploitation of rock salt resources. According to the calculation of the underground casing mouth distance of 200m and the dissolution radius of 50m of the well group, the controlled NaCl resource reserves of the well group are 2.5 million tons, and the designed recoverable NaCl volume is 1.75 million tons. The well group has a brine return volume of 100m3 / h, a NaCl brine concentration of 300g / l, and an annual production time of 8000h. The well group can produce 240,000 tons of brine per year. The well group can reach the level of full extraction of rock salt resources after 8 years of normal production and operation, which is completely controlled within the service life of the well group.

[0061] It should be noted that all directional indications in this embodiment (such as up, down, left, right, front, back, etc.) are only used to explain the relative position relationship, movement status, etc. between the components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0062] In addition, in the present embodiment, the descriptions involving "first", "second", etc. are only for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" or "second" may explicitly or implicitly include at least one of the features. In the description of the present embodiment, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0063] In this embodiment, unless otherwise clearly specified and limited, the terms "connection", "fixation", etc. should be understood in a broad sense. For example, "fixation" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in this embodiment can be understood according to specific circumstances.

[0064] It should be understood that the above description of the specific embodiments of the present invention is only for illustrating the technical route and features of the present invention, and its purpose is to enable those skilled in the art to understand the content of the present invention and implement it accordingly, but the present invention is not limited to the above specific implementation methods. Any changes or modifications made within the scope of the claims of the present invention should be included in the protection scope of the present invention.

Claims

1. A device for enhancing the strength of cement sheath, characterized in that: include: A connecting pipe (2) is arranged at the bottom of the production casing (1); A spring box (3) containing a braided spring (4) and fixed to the bottom of the connecting tube (2); A spring arrangement mechanism (5) comprising a first spring sheet (51) and a second spring sheet (52) fixed to the outside of the connecting tube (2), an anchor rod (53) and a trigger device (54); The first spring piece (51) is connected to the trigger device (54), and can be activated according to the diameter change of the cementing well. After the trigger device (54) is activated, the second spring piece (52) is released, and the second spring piece (52) pushes the anchor rod (53) and fixes the anchor rod (53) to the inner wall of the well. The anchor rod (53) is connected to the braided spring (4), and when the production casing (1) continues to be pushed downward, the anchor rod (53) will pull the braided spring (4) to surround the production casing (1).

2. The device for enhancing the strength of cement sheath of cementing as claimed in claim 1, characterized in that: The trigger device (54) comprises a plurality of hinge support rods (541), a pin pull strip (542), a pin (543) and a pin pull rope (544); A plurality of hinge support rods (541) are arranged around the connecting pipe (2), and each hinge support rod (541) has a notch at the top and is hinged to the spring box (3) at the bottom, and the anchor rod (53) is inserted into the notch; One end of the plurality of pin pull strips (542) is connected to the plurality of hinge support rods (541) one by one, and the pin (543) holes provided at the other end are overlapped and inserted into the pin (543), and the pin (543) is connected to the first elastic sheet (51) through the pin pull rope (544), and the first elastic sheet (51) can pull the pin pull rope (544) to drive the pin (543) to come out of the pin (543) hole.

3. The device for enhancing the strength of cement sheath of cementing as claimed in claim 2, characterized in that: The first elastic piece (51) has a shuttle-shaped structure, is sleeved on the outside of the connecting pipe (2), and can expand to match the diameter of the well; The inner side of the shuttle-shaped structure has a plurality of threading protrusions (511), and the pin pull rope (544) passes through the first thread holes (8) on the plurality of threading protrusions (511) in sequence and then passes through the second thread hole (9) on the connecting tube (2) to be connected to the pin (543).

4. The device for enhancing the strength of cement sheath of well cementing as claimed in claim 2, characterized in that: The top of the anchor rod (53) is provided with a barb (531), and the barb (531) faces away from the connecting pipe (2) and is directed downward; When the pin (543) is inserted into the pin (543) hole, the top end of the hinge support rod (541) is close to the connecting tube (2) and compresses the second elastic sheet (52), and the hinge support rod (541) drives the top end of the anchor rod (53) to be close to the connecting tube (2). When the pin (543) is disengaged from the pin (543) hole, the second elastic piece (52) is reset, and the hinge support rod (541) drives the barb (531) at the top end of the anchor rod (53) to be inserted into the inner wall of the well.

5. The device for enhancing the strength of cement sheath of well cementing as claimed in claim 2, characterized in that: The pin pull rod (542) and the hinge support rod (541) are rotatably connected; or the pin pull rod (542) is flexible and connected to the hinge support rod (541) via a threaded adjustment structure, which can pre-adjust the starting angle of the hinge support rod (541).

6. The device for enhancing the strength of cement sheath of well cementing as claimed in claim 2, characterized in that: It also comprises a slender clamp, one end of which can extend into the connecting pipe (2) and insert the pin (543) into the pin (543) hole.

7. The device for enhancing the strength of cement sheath of well cementing as claimed in claim 1, characterized in that: A conversion joint (6) is provided between the connecting pipe (2) and the production casing (1), and a through hole (61) is provided on the side of the conversion joint (6) for passing concrete; the spring box (3) and the connecting pipe (2) are fixedly connected via an annular plate (7).

8. The device for enhancing the strength of cement sheath of well cementing as claimed in claim 1, characterized in that: The braided spring (4) comprises a braided rope (41) and a spring (42); The plurality of braided ropes (41) are evenly distributed around the spring (42) and are respectively arranged corresponding to the plurality of anchor rods (53); One end of each braided rope (41) is braided along the axial direction of the spring (42) and the other end is connected to the anchor rod (53).

9. The device for enhancing the strength of cement sheath of well cementing as claimed in claim 1, characterized in that: The diameter of the spring box (3) is greater than the diameter of the production casing (1), and the diameter of the production casing (1) is greater than the diameter of the connecting pipe (2).

10. A cementing process, using the device for enhancing the strength of cement sheath according to claims 1 to 9, characterized in that: include: S1: Determine the length of the spring box (3), the number of turns of the spring (42) and the overall length of the spring arrangement mechanism (5) according to the wellbore diameter, the expansion diameter, the wellbore structure and the well depth range; S2: Assembling the spring arrangement mechanism (5), including: The connecting pipe (2) and the spring box (3) are fixed by using an annular steel plate; The spring (42) is braided with a braided rope (41) and then spirally pressed into the spring box (3); Using a hinged support rod (541), an anchor rod (53) with barbs (531) is installed on the top of the spring box (3), and the end of the braided rope (41) is fixed on the anchor rod (53); The first spring sheet (51) and the second spring sheet (52) are fixedly mounted on the connecting pipe (2), and after pre-compression, the trigger device (54) is dynamically adjusted; S3: Drilling with a brine well construction drill and expanding the hole with a reamer in the mining section; S4: The production casing (1) is installed on the top of the assembled spring arrangement mechanism (5), and the spring arrangement mechanism (5) is pushed into the well using the production casing (1). When the expansion section is reached, the first spring sheet (51) expands, and the second spring sheet (52) is released in linkage through the trigger device (54). The second spring sheet (52) pushes the anchor rod (53) into the inner wall of the well, and the production casing (1) is continuously pushed in. The anchor rod (53) continuously pulls out the braided spring (4) through the braided rope (41) and surrounds the production casing (1), until the production casing (1) reaches the designed position and stops; S4: Inject cement slurry for cementing.

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