Device and method 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. The invention further discloses a method for preventing and controlling annulus pressure of the oil and gas well. The method has the same advantages.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of oil exploitation equipment, in particular relates to a device and method for preventing and treating annular pressure buildup in oil and gas wells. BACKGROUND

[0002] Annular pressure buildup is a common problem in oil wells, which is caused by cement channeling in the casing annulus. The hazards of annular pressure buildup in oil and gas wells are as follows: threatening the safety of downhole operators, if the pressure is too high, operators may face danger when repairing or replacing downhole equipment, increasing the difficulty of downhole operations, especially when the well is deep, the pressure in the annulus is also increased accordingly, making it more difficult to prevent and control, resulting in high costs and economic losses; annular pressure buildup also causes losses in oil and gas production; annular pressure buildup also causes the casing to be under high pressure for a long time, which increases the risk of natural gas channeling into the formation and leaking to the wellhead, and even causes catastrophic accidents, and even leads to well abandonment.

[0003] In the prior art, during the completion stage of the oil and gas well, it is very important to ensure the sealing integrity of the oil well, and the area where the sealing is easily damaged is the annular space between the casings. The annular space between the casings has been sealed by traditional elastic sealing members and cement, but both the elastic sealing members and the cement have a high failure probability, and microcracks may form in the cement, which may cause long-term casing pressure and gas migration problems, so it is necessary to repair these failures and microcracks. At present, cement or resin is generally used to repair in the later stage, but these operations are expensive, difficult and unreliable, and the annular pressure buildup problem causes huge losses, so how to simply and reliably eliminate the annular pressure buildup has become a technical problem to be solved. SUMMARY

[0004] To solve the above problems, the present application provides a device and method for preventing and treating annular pressure buildup in oil and gas wells, which can form a gas-tight seal in the annulus to prevent potential gas migration and annulus pressure, and ensure the effectiveness of the cement ring seal without the need for well repair or cement squeezing operations during the production process of the oil and gas well.

[0005] The device for preventing and treating annular pressure buildup in oil and gas wells provided by the present application comprises a hot melt metal packer connected between adjacent casings, the hot melt metal packer comprises a hot melt metal cylinder, and the annular region of the hot melt metal cylinder has circulation holes for allowing fluid to pass through, wherein 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 to seal.

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

[0007] Preferably, in the device for preventing and treating annular pressure buildup in oil and gas wells, the hot-melt metal packer further comprises a fixed protection member arranged at the end of the hot-melt metal cylinder.

[0008] Preferably, in the device for preventing and treating annular pressure buildup in oil and gas wells, the hot-melt metal packer further comprises a packer short sleeve pipe fixed at the other end of the fixed protection member, and the end of the packer short sleeve pipe is provided with threads for connecting to the casing.

[0009] Preferably, in the device for preventing and treating annular pressure buildup in oil and gas wells, the fixed protection member and the packer short sleeve pipe are fixed by a pin.

[0010] Preferably, in the device for preventing and treating annular pressure buildup in oil and gas wells, the hot-melt metal cylinder comprises a plurality of metal ring monomers arranged in parallel and closely.

[0011] Preferably, in the device for preventing and treating annular pressure buildup in oil and gas wells, the circulation hole comprises four cement slurry circulation channels arranged in the annular region of each metal ring monomer, and uniformly distributed in the annular region, and on the circular upper surface and / or lower surface of the metal ring monomer, there are circular-arc-shaped grooves communicating between adjacent cement slurry circulation channels.

[0012] The present application provides a method for preventing and treating annular pressure buildup in oil and gas wells, comprising:

[0013] Obtaining a hot-melt metal packer, the hot-melt metal packer comprising a hot-melt metal cylinder, connecting the hot-melt metal packer between adjacent casings to form a casing string;

[0014] Lowering the casing string with the hot-melt metal packer into the well to a predetermined depth, and circulating drilling fluid to wait for cementing;

[0015] Injecting cement slurry into the casing and the hot-melt metal packer for cementing until completion;

[0016] During the production of the oil and gas well, when micro-cracks appear in the cement sheath, causing annular pressure buildup, the hot-melt metal cylinder is heated and melted to become a fluid and fill the area to be sealed and expand in volume during solidification to seal.

[0017] Preferably, in the method for preventing and treating annular pressure buildup in oil and gas wells, injecting cement slurry into the casing and the hot-melt metal packer for cementing comprises:

[0018] Injecting bismuth-based alloy micro-particle cement slurry into the casing and the hot-melt metal packer for cementing at the predetermined depth in the well.

[0019] Preferably, in the method for preventing and treating annular pressure buildup in oil and gas wells, the hot-melt metal cylinder is heated, melted, becomes a fluid and is filled into the area to be sealed is:

[0020] The electric heating device is lowered into the well to melt the hot-melt metal cylinder into a fluid and fill it into the area with micro-cracks or gaps.

[0021] As can be seen from the above description, the device for preventing and treating annular pressure buildup in oil and gas wells provided by the present application comprises a hot-melt metal packer connected between adjacent casings, the hot-melt metal packer comprises a hot-melt metal cylinder, and the annular area of the hot-melt metal cylinder has circulation holes for fluid to pass through. After being heated and melted, the hot-melt metal cylinder becomes a fluid and is filled into the area to be sealed and expands in volume during solidification to achieve sealing. Therefore, the fluid formed after being heated and melted can quickly flow into the area to be sealed, and then during solidification, the liquid becomes solid and the volume increases, so that the micro-cracks and migration channels of the cement sheath outside the casing can be more fully filled, effective gas sealing is achieved, the volume can slightly increase during solidification, better sealing effect than traditional elastic sealing, resin and cement can be achieved, up to 69 MPa, a V0 level of gas-tight sealing is formed in the annulus, suitable for various complex formations and well conditions, so that potential gas migration and annular pressure can be prevented. During the production of oil and gas wells, the effectiveness of the cement sheath sealing can be ensured without the need for workover or cement squeezing operations. The method for preventing and treating annular pressure buildup in oil and gas wells provided by the present application has the same advantages. BRIEF DESCRIPTION OF DRAWINGS

[0022] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed to be used in the embodiments or prior art description will be briefly introduced below. Obviously, the drawings in the following description are only embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor on the basis of the provided drawings.

[0023] Figure 1 An embodiment of a device for preventing and treating annular pressure buildup in oil and gas wells provided by the present application is shown in the figure;

[0024] Figure 2 A cross-sectional view of the hot-melt metal cylinder is shown in the figure;

[0025] Figure 3 An embodiment of a method for preventing and treating annular pressure buildup in oil and gas wells provided by the present application is shown in the figure;

[0026] Figure 4 A schematic diagram of using a bismuth-based alloy micro-particle cement slurry system and a hot-melt metal packer to prevent and treat annular pressure buildup is shown in the figure. DETAILED DESCRIPTION

[0027] The core of the present application is to provide a device and method for preventing and treating annulus pressure of oil and gas well, which can form a gas-tight seal in the annulus, prevent potential gas migration and annulus pressure, and ensure the effectiveness of cement sheath during the production process of oil and gas well without the need for workover or cement squeezing operation.

[0028] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the scope of protection of the present application.

[0029] The present application provides an embodiment of a device for preventing and treating annulus pressure of oil and gas well as shown in Figure 1 Figure 1 The present application provides an embodiment of a device for preventing and treating annulus pressure of oil and gas well as shown in Figure 1 The present application provides an embodiment of a device for preventing and treating annulus pressure of oil and gas well as shown in Figure 2 Figure 2 ​​As shown in Fig. 1, the heat-melting metal cylinder 101 is a schematic view of the cross section of the heat-melting metal cylinder, which can be a whole cylinder or a split cylinder, and the annular area of the heat-melting metal cylinder 101 has circulation holes 1011 for fluid to pass through, and adjacent two circulation holes 1011 can be connected by grooves, and the circulation holes 1011 can be through the upper and lower to ensure that the cement slurry can pass through the annulus between the casing and the well wall from the lower part of the well to the upper part of the well to form a circulation, wherein the heat-melting metal cylinder 101 is used to be melted into a fluid after being heated, filled into the area to be sealed, and sealed by volume expansion during solidification. Since the heat-melting metal cylinder is first melted into a fluid by heating, it can flow into the area to be sealed, and then during the process of solidification into a solid, it can expand in volume similar to water turning into ice, and the solid formed after solidification has a larger volume than the liquid state, so that the area to be sealed can be filled more densely, better filling the space of cracks and the like, eliminating the annulus pressure, and it can be clearly seen that the heat-melting metal cylinder 101 itself is part of the casing string of the oil and gas well during the well construction process, and is lowered into the annulus, and its position can be predicted in advance, that is, the position where the annulus pressure phenomenon is likely to occur can be predicted, and the heat-melting metal cylinder 101 can be placed at this position in advance, and the number of such positions can be selected according to actual needs, that is, a plurality of heat-melting metal cylinders 101 can be connected on the casing at different depths, and lowered to the predetermined depth for cementing and completion, and in the production process of the oil and gas well, in order to avoid the annulus pressure (or to eliminate the annulus pressure), the heat-melting metal cylinder 101 on the heat-melting metal packer 1 is melted under the action of the electric heating device, and a dense and airtight sealing effect is formed in the casing annulus, so that the micro-cracks and fluid migration channels on the cement sheath are eliminated, and therefore, the annulus pressure problem can be fundamentally solved, and the sealing effect is better than that of the prior art, and the treatment cost of the annulus pressure can be significantly reduced.

[0030] It should be noted that the hot melt metal packer can be preferably a bismuth-based alloy packer, specifically, the bismuth-based alloy packer can be heated to high temperature by electric heating or any other heating method until the bismuth-based alloy melts, and the melted alloy has similar viscosity to water and 10 times the density of water, so the alloy can flow into a very small area, including the cement microannulus, and after the bismuth-based alloy flows and fills the small space to be sealed, it can be cooled and solidified within 30 minutes, and because the solid bismuth expands in volume compared to the liquid state, it can displace the fluid in the wellbore, and during the solidification of the bismuth, an airtight seal is formed, forming a seamless packer downhole, which improves safety, and does not require special connections, and bismuth is non-corrosive and harmless to the environment, corrosion-resistant, can quickly form a seal and complete a pressure test, and can be applied to various stages of drilling, completion, workover or well shut-in, and is especially suitable for isolation and sealing during oil drilling and completion.

[0031] As can be seen from the above description, the device for preventing and treating annular pressure buildup in an oil and gas well provided by the present application 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 fluid to pass through, wherein the hot melt metal cylinder is used to become a fluid after being heated and melted and to fill the area to be sealed and to expand in volume during solidification to seal, so that the fluid formed after being heated and melted can quickly flow into the area to be sealed, and then during solidification, the liquid becomes solid and the volume increases, so that the casing cement sheath microcracks and migration channels can be more fully filled, effective airtight sealing is achieved, the volume can slightly increase during solidification, a better sealing effect than traditional elastic sealing, resin and cement can be achieved, up to 69 MPa, a V0 level airtight seal is formed in the annulus, suitable for various complex formations and well conditions, so that potential gas migration and annular pressure can be prevented, and during oil and gas well production, the effectiveness of the cement sheath seal can be ensured without the need for workover or cementing operations.

[0032] In one specific embodiment of the device for preventing and treating annular pressure buildup in an oil and gas well, with reference to Figure 1 The hot melt metal packer 1 can further include a fixed protection member 102 arranged at the end of the hot melt metal cylinder, which functions to fix the hot melt metal cylinder in place to facilitate running into the well and protect the hot melt metal cylinder, improving work efficiency, and further with reference to Figure 1The hot-melt metal packer 101 can further comprise a packer short sleeve 103 fixed with the other end of the fixed protection piece 102, and the end of the packer short sleeve 103 is provided with threads for connecting to the casing. It should be noted that the packer short sleeve 103 can have the same diameter as the casing described above to achieve better matching. The packer short sleeve 103 can be connected with the casing described above by using the matching threads 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 herein. Furthermore, the fixed protection piece 102 and the packer short sleeve 103 can be fixed by using a pin, which can ensure that they are not easy to fall off. Of course, other fixation methods such as riveting, welding, etc. can also be used, which are not limited to pin connection.

[0033] In another embodiment of the device for preventing and treating annular pressure buildup in an oil and gas well, with continued reference to Figure 1 The hot-melt metal cylinder 101 can comprise a plurality of metal ring monomers 1012 arranged in parallel and closely, and the number of metal ring monomers 1012 can be reduced or increased according to actual needs. The adjacent metal ring monomers 1012 are not connected but arranged in parallel and closely, and can be fixed at both ends to achieve stable lowering into the well at a predetermined depth. On this basis, the circulation hole 1011 can comprise four cement slurry circulation channels arranged in the annular region of each metal ring monomer 1012 and uniformly distributed in the annular region. In addition, the adjacent cement slurry circulation channels can have a circular-arc-shaped groove communicating with each other on the upper and / or lower circular surface of the metal ring monomer 1012 to achieve mutual communication between the cement slurry circulation channels. Of course, the number of cement slurry circulation channels can be increased or decreased according to actual needs, which are not limited herein, as long as the cement slurry circulation channels in each metal ring monomer 1012 are mutually penetrated to ensure the flow of cement slurry without obstruction.

[0034] The present application provides an embodiment of a method for preventing and treating annular pressure buildup in an oil and gas well as shown in Figure 3 Figure 3 The present application provides an embodiment of a method for preventing and treating annular pressure buildup in an oil and gas well as shown in

[0035] S1: Obtain a hot-melt metal packer, the hot-melt metal packer comprising a hot-melt metal cylinder, connect the hot-melt metal packer between adjacent casings to form a casing string;

[0036] ​It should be noted that the hot-melt metal packer can be the hot-melt metal packer mentioned above, and the casing and the hot-melt metal packer are lowered into the well according to actual needs to form a casing string with the hot-melt metal packer, and one or more hot-melt metal packers can be lowered according to actual needs, which is not limited here.

[0037] S2: Lower the casing string with the hot-melt metal packer into the well to a predetermined depth, circulate the drilling fluid, and wait for cementing;

[0038] The predetermined depth can be predicted in advance, and when it is known that one or more depth positions are prone to annular pressure, the hot-melt metal packer is placed at the corresponding depth position or positions to perform corresponding processing when the annular pressure actually occurs subsequently. After this lowering process is completed, the drilling fluid is circulated and the subsequent cementing process is waited for.

[0039] S3: Injecting cement slurry into the casing and the hot-melt metal packer for cementing until completion;

[0040] That is, the cement slurry is displaced to the annulus outside the casing through the inside of the casing string and the hot-melt packer, and after the cement slurry is solidified to complete the well, the well can be put into production.

[0041] S4: During the production of the oil and gas well, when micro-cracks occur in the cement sheath, causing annular pressure, the hot-melt metal cylinder is heated and melted to become a fluid and fill the area to be sealed and expand in volume during the solidification process to seal.

[0042] Specifically, this step is to lower the electric heating device to melt the hot-melt metal packer on the casing string to fill the micro-cracks or gaps that have occurred to achieve the purpose of preventing and solving the annular pressure during the production of the oil and gas well, as needed before or after the annular pressure occurs.

[0043] In one specific embodiment of the method for preventing and treating annular pressure in the oil and gas well, injecting cement slurry into the casing and the hot-melt metal packer for cementing can further include the following steps:

[0044] At the predetermined depth in the well, inject bismuth-based alloy micro-particle cement slurry into the casing and the hot-melt metal packer for cementing.

[0045] It should be noted that the bismuth-based alloy micro-particle cement slurry can be composed of micro-silica powder, ultra-fine cement, expanding agent, water reducing agent, etc., and bismuth-based alloy metal micro-particles are added. In this case, if cracks or channeling occurs in the cement sheath before or after the annulus pressure appears, the electric heating device can be lowered to melt the bismuth-based alloy micro-particles in the cement sheath to fill the micro-cracks or gaps that have appeared. After the bismuth-based alloy liquid solidifies, it expands in volume, thereby achieving an airtight sealing effect to prevent and solve the problem of annulus pressure.

[0046] In another specific embodiment of the above method for preventing and solving the problem of annulus pressure in an oil and gas well, the hot-melt metal cylinder is heated to melt into a fluid and filled into the area to be sealed, which can be specifically:

[0047] The electric heating device is lowered to melt the hot-melt metal cylinder into a fluid and filled into the area of micro-cracks or gaps that have appeared.

[0048] Of course, other heating methods that can generate high temperatures can also be used. After the heating method is lowered to a certain depth of the hot-melt metal cylinder, the heat generated is transferred to the hot-melt metal cylinder to melt it into a fluid. This fluid will automatically flow and fill into the area of micro-cracks or gaps that have appeared, and after filling, it will solidify. Since the solid after solidification expands in volume relative to the fluid, the micro-cracks or gap area can be filled very tightly, thereby achieving better sealing.

[0049] The above method is illustrated by three examples as follows:

[0050] Example 1:

[0051] In the initial well construction process, the solution is implemented before the problem occurs, and the problem is solved in advance. The bismuth-based alloy micro-particle cement slurry system is used for well cementing. If annulus pressure occurs during oil well production, the electric cable and electric heating device are lowered to the depth of the bismuth-based alloy micro-particle cement slurry system to melt the bismuth-based alloy micro-particles and form a V0-level airtight seal in the annulus.

[0052] Example 2:

[0053] In the initial well construction process, the solution is implemented before the problem occurs, and the problem is solved in advance. The hot-melt metal packer is lowered into the well as part of the original casing string. If annulus pressure occurs during oil well production, the electric cable and electric heating device are lowered to melt the bismuth-based alloy and form a V0-level airtight seal in the annulus. By pre-installing this kind of hot-melt metal packer on the casing, the casing does not need to be perforated to achieve sealing.

[0054] Example 3:

[0055] Example 1 and Example 2 are applied simultaneously in the same well, for example,Figure 4 As shown, Figure 4 The diagram illustrates the simultaneous use of a bismuth-based alloy microparticle cement slurry system and a thermoplastic metal packer to prevent annular pressure. From left to right, the first diagram shows the casing 401 being lowered into the well, with the bismuth-based alloy microparticle cement slurry system 403 and the thermoplastic metal packer 404 placed at specific depths within the annulus. Other sections are treated with conventional cement 402. The second diagram shows the formation of microcracks or migration channels 405 within the well after a period of time. The third diagram shows the installation of a cable and an electric heating device 406 within the well to heat the bismuth-based alloy microparticle cement slurry system and the thermoplastic metal packer. After melting, the liquid flows into the microcracks or migration channels 405 and then solidifies. The volume expands relative to the liquid state, causing the microcracks or migration channels to disappear, achieving an airtight seal. Therefore, it is evident that simultaneously employing these two measures can better prevent and resolve annular pressure problems.

[0056] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A device for preventing annular pressure in oil and gas wells, characterized in that, The device includes a fusible metal packer connected between adjacent sleeves. The fusible metal packer includes a fusible metal cylinder with an annular region having circulation holes for fluid passage. The fusible metal cylinder is used to become fluid after being heated and fill the area to be sealed, and expands in volume during the solidification process to achieve a seal.

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

3. The device for preventing annular pressure in oil and gas wells according to claim 1, characterized in that, The hot-melt metal packer also includes a fixing and protective component disposed at the end of the hot-melt metal cylinder.

4. The device for preventing annular pressure in oil and gas wells according to claim 3, characterized in that, The hot-melt metal packer also includes a packer short sleeve fixed to the other end of the fixed protective member, the end of the packer short sleeve having threads for connection to the sleeve.

5. The device for preventing annular pressure in oil and gas wells according to claim 4, characterized in that, The fixing protective component is fixed to the short sleeve of the packer using pins.

6. The device for preventing annular pressure in oil and gas wells according to claim 1, characterized in that, The hot-melt metal cylinder comprises multiple parallel, closely arranged metal ring units.

7. The device for preventing annular pressure in oil and gas wells according to claim 6, characterized in that, The circulation holes include four cement slurry circulation channels disposed in the annular region of each of the metal ring units and evenly distributed in the annular region. Moreover, on the circular upper surface and / or lower surface of the metal ring unit, adjacent cement slurry circulation channels have interconnected arc-shaped grooves.

8. A method for preventing annular pressure in oil and gas wells, characterized in that, include: A hot-melt metal packer is obtained, the hot-melt metal packer comprising a hot-melt metal cylinder, and the hot-melt metal packer is connected between adjacent sleeves to form a sleeve string; The casing string with the hot-melt metal packer is lowered into the well to a predetermined depth, and the drilling fluid is circulated while waiting for cementing. Cement slurry is injected into the casing and the hot-melt metal packer to cement the well until well completion; During the production process of oil and gas wells, when microcracks appear in the cement sheath, causing pressure in the annulus, the hot-melt metal cylinder is heated and melted, becoming a fluid that fills the area to be sealed. During the solidification process, the volume expands to seal the area.

9. The method for preventing annular pressure in oil and gas wells according to claim 8, characterized in that, Cementing the casing and the hot-melt metal packer by injecting cement slurry includes: At a predetermined depth within the well, bismuth-based alloy microparticle cement slurry is injected into the casing and the hot-melt metal packer for cementing.

10. The method for preventing annular pressure in oil and gas wells according to claim 8, characterized in that, The step of heating and melting the hot-melt metal cylinder to become a fluid and filling it into the area to be sealed is as follows: The electric heating device is lowered in to melt the hot-melt metal cylinder, which then becomes a fluid and fills the microcracks or gaps that have appeared.

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