Device for preventing and controlling annulus pressure of oil and gas well

Abstract

The device comprises a hot melting metal packer connected between adjacent sleeves, the hot melting metal packer comprises a hot melting metal cylinder, the annular area of the hot melting metal cylinder is provided with a circulation hole used for allowing fluid to pass through, and the annular area of the hot melting metal cylinder is provided with a circulation hole used for allowing fluid to pass through. The hot melting metal cylinder is used for being heated and melted into fluid, filling the fluid into a to-be-sealed area and conducting sealing through volume expansion in the curing process. According to the device, potential gas migration and annulus pressure can be prevented, and the effectiveness of cement sheath sealing can be ensured on the basis that well repairing or cement squeezing operation is not needed in the oil and gas well production process.

Description

Technical Field

[0001] The utility model belongs to the technical field of oil extraction equipment, and particularly relates to a device for preventing and controlling annulus pressure in oil and gas wells. Background Technique

[0002] Annulus pressure is a common problem in oil wells, which is caused by cement channeling in the casing annulus. The hazards of annulus pressure in oil and gas wells are as follows: threatening the safety of downhole operators. If the pressure is too high, operators will face risks when repairing or replacing downhole equipment, increasing the difficulty of downhole operations. Especially when the well depth is relatively deep, the pressure in the downhole annulus also increases accordingly, making it more difficult to prevent and control, resulting in high costs and economic losses; annulus pressure will also cause losses to oil and gas production; annulus pressure will also cause the casing to bear high pressure for a long time, there is a risk of natural gas leaking into the formation and leaking to the wellhead, even triggering catastrophic accidents, and even leading to well abandonment.

[0003] In the prior art, during the completion stage of oil and gas wells, it is very important to ensure the sealing integrity of the oil wells, and the area where the sealing performance is easily damaged is the annular space between the casings. Currently, traditional elastic seals and cement have been used to seal this annular space between the casings, but both the elastic seals and cement have a relatively high failure probability, and microcracks will also form in the cement, which may all lead to problems such as long-term casing pressure and gas migration. Therefore, it is necessary to repair these failures and microcracks. Currently, it is generally repaired by squeezing cement or resin in the later stage, but these operations are all expensive, difficult and unreliable operations, and this annulus pressure problem has brought huge losses. Therefore, how to simply, reliably and low-cost eliminate annulus pressure has become an urgent technical problem to be solved. Summary of the Utility Model

[0004] To solve the above problems, the utility model provides a device for preventing and controlling annulus pressure in oil and gas wells, which can form an airtight seal in the annulus to prevent potential gas migration and annulus pressure, and during the production process of oil and gas wells, without the need for well workover or cement squeezing operations, it can ensure the effectiveness of the cement sheath seal.

[0005] A device for preventing and controlling annulus pressure in oil and gas wells provided by the utility model includes a hot-melt metal packer connected between adjacent casings. The hot-melt metal packer includes a hot-melt metal cylinder, and the annular region of the hot-melt metal cylinder has a circulation hole for allowing fluid to pass through. Among them, the hot-melt metal cylinder is used to become a fluid after being heated and melted and fill the area to be sealed, and expand in volume during the curing process for sealing.

[0006] Preferably, in the above device for preventing and controlling annulus pressure in oil and gas wells, the hot-melt metal packer is a bismuth-based alloy packer.

[0007] Preferably, in the above device for preventing and controlling annulus pressure in oil and gas wells, the hot-melt metal packer further includes a fixed protection member disposed at the end of the hot-melt metal cylinder.

[0008] Preferably, in the above device for preventing and controlling annulus pressure in oil and gas wells, the hot-melt metal packer further includes a packer short casing fixed to the other end of the fixed protection member, and the end of the packer short casing has a thread for connecting to the casing.

[0009] Preferably, in the above device for preventing and controlling annulus pressure in oil and gas wells, the fixed protection member and the packer short casing are fixed by pins.

[0010] Preferably, in the above device for preventing and controlling annulus pressure in oil and gas wells, the hot-melt metal cylinder includes a plurality of metal ring monomers arranged in parallel and closely.

[0011] Preferably, in the above device for preventing and controlling annulus pressure in oil and gas wells, the circulation holes include four slurry circulation channels provided in the annular region of each metal ring monomer, and are evenly distributed in the annular region. Moreover, on the circular upper surface and / or lower surface of the metal ring monomer, there are arc-shaped grooves communicating with each other between adjacent slurry circulation channels.

[0012] As can be seen from the above description, in the device for preventing and controlling annulus pressure in oil and gas wells provided by the present utility model, since it includes a hot-melt metal packer connected between adjacent casings, the hot-melt metal packer includes a hot-melt metal cylinder, and the annular region of the hot-melt metal cylinder has circulation holes for allowing fluids to pass through. Among them, the hot-melt metal cylinder is used to become a fluid after being heated and melted and fill the area to be sealed, and its volume expands during the curing process for sealing. Therefore, the fluid formed after being heated and melted can quickly flow into the area to be sealed. Then, during the curing process, the liquid becomes solid and its volume will become larger, so that the micro-cracks and migration channels of the cement sheath outside the casing can be more fully filled, realizing effective gas sealing. During the curing process, the volume can slightly increase, forming a better sealing effect than traditional elastic seals, resins and cements, up to 69 MPa, forming a V0-level airtight seal in the annulus, applicable to various complex formations and well conditions. Therefore, it can prevent potential gas migration and annulus pressure. During the production process of oil and gas wells, it can ensure the effectiveness of the cement sheath seal without the need for workover or squeeze cement operations. Description of the Drawings

[0013] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only the embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained according to the provided drawings.

[0014] Figure 1 Schematic diagram of an embodiment of a device for preventing and controlling annulus pressure in oil and gas wells provided by the present invention;

[0015] Figure 2 Cross-sectional schematic diagram of a hot-melt metal cylinder. Detailed implementation manners

[0016] The core of the present invention is to provide a device for preventing and controlling annulus pressure in oil and gas wells, which can form an airtight seal in the annulus to prevent potential gas migration and annulus pressure. During the production process of oil and gas wells, without well workover or cement squeezing operations, the effectiveness of the cement sheath seal can be ensured.

[0017] The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of them. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0018] An embodiment of a device for preventing and controlling annulus pressure in oil and gas wells provided by the present invention is as Figure 1 shown. Figure 1 Schematic diagram of an embodiment of a device for preventing and controlling annulus pressure in oil and gas wells provided by the present invention. This device for preventing and controlling annulus pressure in oil and gas wells can be connected to a casing string composed of multiple casings. Such casings are common ordinary casings, so Figure 1 they are not shown in the figure. During the general casing running process, multiple casings are successively run into the well. The device further includes a hot-melt metal packer 1 connected between adjacent casings. The hot-melt metal packer 1 can include a hot-melt metal cylinder 101. Refer to Figure 2 , Figure 2It is a schematic cross-sectional view of a hot-melt metal cylinder. As long as it is cylindrical, whether it is an integral cylinder or a split cylinder is fine. The annular region of the hot-melt metal cylinder 101 has circulation holes 1011 for fluid passage. There can be grooves connecting adjacent two circulation holes 1011. Such circulation holes 1011 can penetrate up and down to ensure that the cement slurry can pass through. It can reach the upper part of the well from the annulus between the casing and the wellbore at the lower part of the well, forming a kind of circulation. Among them, the hot-melt metal cylinder 101 is used to become a fluid after being heated and melted and fill into the area to be sealed, and expand in volume during the curing process for sealing. Exactly because the hot-melt metal cylinder is first heated and melted into a fluid, it can flow into the area to be sealed. Then, during the process of curing into a solid, it can be similar to the volume expansion after water turns into ice. The solid formed after curing has a larger volume than the liquid state. In this way, the area to be sealed can be filled more densely, better filling spaces such as cracks, eliminating annulus pressure. It can be clearly seen that this kind of hot-melt metal cylinder 101 itself is, during the construction of an oil and gas well, as a part of the casing string of the oil and gas well, lowered into the annulus interior. Its position can be predicted in advance. That is to say, if it is predicted which depth is likely to have annulus pressure phenomenon, the hot-melt metal cylinder 101 can be placed in advance at this position. The number of such positions can be selected according to actual needs. That is to say, several hot-melt metal cylinders 101 can be connected to the casing at different well depths and lowered to the predetermined depth for cementing and well completion. During the production process of the oil and gas well, to avoid the occurrence of annulus pressure (or if annulus pressure has already occurred), under the action of the electric heating device, the hot-melt metal cylinder 101 on the hot-melt metal packer 1 is melted, forming a dense gas-tight effect in the annulus outside the casing, thus eliminating the micro-cracks and fluid migration channels on the cement sheath. Therefore, this method can fundamentally solve the problem of annulus pressure, without having to use cement and resin to flow from the outside to the inside to fill internal cracks like the existing technology. Thus, a better sealing effect can be obtained, and the treatment cost of annulus pressure can be significantly reduced.

[0019] It should be noted that the hot-melt metal packer can preferably be a bismuth-based alloy packer. Specifically, the bismuth-based alloy packer can be heated at a high temperature by electric heating or any other heating method until the bismuth-based alloy melts. When melted into a liquid state, it has a viscosity similar to that of water and a density 10 times that of water. Therefore, this alloy can flow into very small areas, including the cement micro-annulus. After the bismuth-based alloy flows and fills the tiny space to be sealed, it can then cool and solidify within 30 minutes. Since the solid state of bismuth expands in volume compared to the liquid state, it can displace the fluid in the wellbore and expand during the solidification process of bismuth to form an airtight seal, forming a packer with a seamless downhole seal. This improves safety and does not require special connections. Bismuth is non-corrosive, harmless to the environment, and corrosion-resistant. It can quickly form a seal and complete a pressure test, and can be applied to various stages of drilling, well completion, workover, or well sealing, especially suitable for isolation and sealing during oil drilling and well completion processes.

[0020] As can be seen from the above description, in the embodiment of the device for preventing and controlling annulus pressure in oil and gas wells provided by the present utility model, it includes a hot-melt metal packer connected between adjacent casings. The hot-melt metal packer includes a hot-melt metal cylinder, and the annular region of the hot-melt metal cylinder has a circulation hole for allowing fluid to pass through. Among them, the hot-melt metal cylinder is used to become a fluid after being heated and melted, fill the area to be sealed, and expand in volume during the solidification process for sealing. Therefore, the fluid formed after being heated and melted can quickly flow into the area to be sealed. Then, during the solidification process, the liquid becomes a solid and its volume will increase, so that the micro-cracks and migration channels of the cement sheath outside the casing can be filled more fully, realizing effective gas sealing isolation. During the solidification process, the volume can increase slightly, forming a better sealing effect than traditional elastic seals, resins, and cements, up to 69 MPa, forming a V0-level airtight seal in the annulus, suitable for various complex formations and well conditions. Therefore, it can prevent potential gas migration and annulus pressure. During the production process of oil and gas wells, it can ensure the effectiveness of the cement sheath seal without the need for workover or cement squeezing operations.

[0021] In a specific embodiment of the above device for preventing and controlling annulus pressure in oil and gas wells, continue to refer to Figure 1 , the hot-melt metal packer 1 can also include a fixed protection part 102 arranged at the end of the hot-melt metal cylinder. The function of this fixed protection part 102 is to fix the hot-melt metal cylinder in place to facilitate lowering it into the well and protect the hot-melt metal cylinder, improving work efficiency. Further, continue to refer to Figure 1, the hot-melt metal packer 101 may further include a packer short casing 103 fixed to the other end of the fixed protection member 102. The end of the packer short casing 103 has threads for connecting to the casing. It should be noted that the packer short casing 103 may have the same diameter as the above-mentioned casing to achieve better matching. By using the mutually matching threads, the packer short casing 103 can be connected to the above-mentioned casing together to achieve firm fixation and ensure that it does not fall off in the well. Of course, other connection methods can also be selected according to actual needs, which are not limited here. Moreover, further, the fixed protection member 102 and the packer short casing 103 can preferably be fixed by pins. Such pins can ensure that the two are not easily separated. Of course, other fixing methods can also be used, such as riveting, welding, etc., which can all be adopted here and are not limited to pin connection only.

[0022] In another specific embodiment of the above device for preventing and controlling annulus pressure in oil and gas wells, continue to refer to Figure 1 , the above-mentioned hot-melt metal cylinder 101 may include a plurality of metal ring monomers 1012 arranged in parallel and closely. Of course, the number of metal ring monomers 1012 can also be reduced or increased according to actual needs. There is no need to connect between adjacent metal ring monomers 1012. They are just arranged in parallel and closely together. After being fixed at both ends, they can be stably lowered to the preset depth position in the well. On this basis, the circulation holes 1011 may include four cement slurry circulation channels provided in the annular region of each metal ring monomer 1012 and evenly distributed in the annular region. Moreover, on the circular upper surface and / or lower surface of the metal ring monomer 1012, there may be arc-shaped grooves communicating with each other between adjacent cement slurry circulation channels to achieve the mutual connection between these cement slurry circulation channels. Of course, the number of such cement slurry circulation channels can also be increased or decreased according to actual needs, which are not limited here, as long as the cement slurry circulation channels in each metal ring monomer 1012 are all interconnected, so as to ensure that the flow of the cement slurry is not blocked.

[0023] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be obvious to those skilled in the art. The general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to these embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A device for preventing and controlling annular pressure in oil and gas wells, characterized in that: The invention comprises a hot-melt metal sealer connected between adjacent casings, wherein the hot-melt metal sealer comprises a hot-melt metal cylinder, and an annular area of ​​the hot-melt metal cylinder has a circulation hole for allowing fluid to pass through, wherein the hot-melt metal cylinder is used to become a fluid after being melted by heat and fill the area to be sealed and expand in volume during the solidification process to perform sealing.

2. The device for preventing and controlling annular pressure in oil and gas wells according to claim 1 is characterized in that: The hot-melt metal packer is a bismuth-based alloy packer.

3. The device for preventing and controlling annular pressure in oil and gas wells according to claim 1 is characterized in that: The hot melt metal packer further comprises a fixing protection member arranged at the end of the hot melt metal cylinder.

4. The device for preventing and controlling annular pressure in oil and gas wells according to claim 3 is characterized in that: The hot melt metal packer further comprises a packer short sleeve fixed to the other end of the fixing protection member, and an end of the packer short sleeve has a thread for connecting to the sleeve.

5. The device for preventing and controlling annular pressure in oil and gas wells according to claim 4 is characterized in that: The fixed protection piece and the short casing of the packer are fixed by pins.

6. The device for preventing and controlling annular pressure in oil and gas wells according to claim 1 is characterized in that: The hot-melt metal cylinder comprises a plurality of metal ring monomers which are closely arranged in parallel.

7. The device for preventing and controlling annular pressure in oil and gas wells according to claim 6 is characterized in that: The circulation hole includes four cement slurry circulation channels arranged in the annular area of ​​each metal ring monomer and evenly distributed in the annular area. Moreover, on the circular upper surface and / or lower surface of the metal ring monomer, adjacent cement slurry circulation channels have interconnected arc-shaped grooves.

Images