A method for preventing corrosion damage to oil and gas well casings using magnetic anode materials

Abstract

The application discloses a method for preventing corrosion damage of a casing of an oil and gas well by using a magnetic anode material, and comprises the following steps: (1) preparing magnetic anode particles: a magnetic material and a density adjusting material are respectively adhered to two ends of an anode material to prepare the magnetic anode particles; (2) in a cementing process, the magnetic anode particles are added into cement slurry and then pumped together with the cement slurry; and (3) under the action of an applied magnetic field, the magnetic anode particles are adsorbed on the outer wall of the casing. According to the method, the magnetic anode particles can be uniformly adsorbed on the outer wall of the casing, a protective layer is formed after cement solidification, and the protective layer plays a corrosion prevention role when the outer wall of the casing contacts a corrosive medium, so that the service life of the casing is greatly prolonged, the purpose of preventing corrosion failure of the casing is achieved, the construction period is short, and the cost is low.

Description

Technical Field

[0001] This invention belongs to the field of casing corrosion prevention technology, specifically relating to a method for preventing corrosion damage to oil and gas well casings using magnetic anode materials. Background Technology

[0002] In oil and gas field development, casing corrosion damage from formation water is common, stemming from the formation of corrosion galvanic cells when the steel casing comes into contact with formation water. During this reaction, the casing loses electrons and oxidizes. To inhibit electron migration from the casing surface, sacrificial anode cathodic protection technology is commonly used. Current sacrificial anode cathodic protection technology often involves connecting block anode materials to the casing surface via welding or splicing, in conjunction with an epoxy protective layer. The process involves first removing rust and polishing the outer surface of the casing, installing the anode material, keeping it clean and dry, and applying an epoxy protective primer to the casing surface before rust reappears. After 4-6 hours, epoxy cold-applied tape is wrapped around the casing surface, followed by a topcoat. The casing can only be lowered into the well after both the topcoat and primer have fully cured. This process is complex, difficult, requires a large amount of anode material, is costly, and the anode material is prone to falling off during casing insertion. Replacing the worn-out anodes is expensive and difficult. Therefore, there is an urgent need to find a new method to prevent corrosion damage to oil and gas well casings. Summary of the Invention

[0003] To address the shortcomings of existing technologies, this invention provides a method for preventing corrosion damage to oil and gas well casings using magnetic anode materials. This method involves adding magnetic anode particles to traditional cementing cement. The anode particles are inserted during cementing, and under the influence of a magnetic field, they are adsorbed onto the outer wall of the casing. As the cement solidifies, the anode particles are fixed to the outer wall of the casing, thus providing corrosion protection.

[0004] A method for preventing corrosion damage to oil and gas well casing using magnetic anode materials includes the following steps:

[0005] (1) Preparation of magnetic anode microparticles: magnetic material and density adjustment material are respectively attached to both ends of the anode material to prepare magnetic anode microparticles;

[0006] (2) During the cementing process, the magnetic anode particles are added to the cement slurry and then pumped in together with the cement slurry;

[0007] (3) Under the action of an external magnetic field, the magnetic anode particles are adsorbed onto the outer wall of the sleeve.

[0008] Preferably, the density of the magnetic anode particles is the same as the density of the cement slurry during the cementing process.

[0009] Preferably, the anode material is cylindrical with a diameter of 0.1mm-2mm and a length of 0.1mm-3mm.

[0010] Preferably, the magnetic material is a ring magnet, the inner diameter of which is the same as the diameter of the anode material, the outer diameter is 0.5mm-1mm larger than the inner diameter, and the length is 0.1mm-1mm.

[0011] Preferably, the density adjusting material is a ring-shaped foam plastic, and the inner and outer diameters of the density adjusting material are the same as those of the magnetic material. The length of the density adjusting material is adjusted according to the density of the magnetic anode particles.

[0012] Preferably, the density adjusting material is polyethylene foam, polypropylene foam, or polystyrene foam.

[0013] Preferably, the magnetic material and the density adjusting material are respectively bonded to both ends of the anode material with 502 glue.

[0014] Preferably, in step (2), the mass ratio of the magnetic anode particles to the cement slurry is 1:(20-100).

[0015] Preferably, the attractive force of the external magnetic field is 50kg-100kg.

[0016] Preferably, the magnetic material is a magnet, and the anode material is a zinc anode material.

[0017] Preferably, the external magnetic field is generated by a pulsed high magnetic field generator.

[0018] Advantages of this invention:

[0019] (1) The construction steps are simple. The magnetic anode particles are added during the cement injection process and are firmly connected to the casing.

[0020] (2) By means of the present invention, magnetic anode particles can be uniformly adsorbed on the outer wall of the casing. After the cement solidifies, a protective layer is formed. When the outer wall of the casing comes into contact with the corrosive medium, it plays a role in corrosion prevention, thereby greatly extending the service life of the casing and ultimately achieving the purpose of preventing casing corrosion failure.

[0021] (3) No external current is required, and no additional external power supply equipment is needed;

[0022] (4) No need to replace the anode later, the construction cycle is short, the construction can be completed in a few hours, and the cost is low. Detailed Implementation

[0023] Example 1

[0024] For a low-density cement slurry system with a density of 1.60 g / mL (cement slurry formulation: 36% G-grade cement + 10% fly ash + 2.5% microsilica + 1% phosphate + 0.5% polyvinyl alcohol + 50% water):

[0025] A method for preventing corrosion damage to oil and gas well casing using magnetic anode materials includes the following steps:

[0026] (1) Preparation of magnetic anode microparticles: Prepare a cylindrical zinc anode material with a diameter of 1 mm and a length of 1 mm, a ring magnet with an inner diameter of 1 mm, an outer diameter of 1.5 mm and a length of 0.2 mm, and a ring polyethylene foam with an inner diameter of 1 mm and an outer diameter of 1.5 mm. Attach the ring magnet and the ring polyethylene foam to both ends of the cylindrical zinc anode material with 502 glue to prepare magnetic anode microparticles. Adjust the density of the magnetic anode microparticles to 1.60 g / mL by controlling the length of the ring polyethylene foam.

[0027] (2) During the cementing process, the magnetic anode particles are added to the cement slurry at a mass ratio of 1:20, and then the magnetic anode particles are pumped in together with the cement slurry.

[0028] (3) The pulsed strong magnetic field generator is lowered into the inner wall of the sleeve to generate an external magnetic field with an attraction force of 96 kg, which adsorbs the magnetic anode particles onto the outer wall of the sleeve.

[0029] Example 2

[0030] For a low-density cement slurry system with a density of 1.30 g / mL (cement slurry formulation: 30% G-grade cement, 10% vitrified microspheres + 3% fly ash + 0.5% microsilica + 0.5% polyvinyl alcohol + 0.5% kaolinite + 0.5% aluminum sulfate + 55% water):

[0031] A method for preventing corrosion damage to oil and gas well casing using magnetic anode materials includes the following steps:

[0032] (1) Preparation of magnetic anode microparticles: Prepare a cylindrical zinc anode material with a diameter of 0.8 mm and a length of 1 mm, a ring magnet with an inner diameter of 0.8 mm, an outer diameter of 1.8 mm and a length of 0.2 mm, and a ring polyethylene foam with an inner diameter of 0.8 mm and an outer diameter of 1.8 mm. Attach the ring magnet and the ring polyethylene foam to both ends of the cylindrical zinc anode material with 502 glue to prepare magnetic anode microparticles. Adjust the density of the magnetic anode microparticles to 1.30 g / mL by controlling the length of the ring polyethylene foam.

[0033] (2) During the cementing process, the magnetic anode particles are added to the cement slurry at a mass ratio of 1:30, and then the magnetic anode particles are pumped in together with the cement slurry.

[0034] (3) The pulsed strong magnetic field generator is lowered into the inner wall of the sleeve to generate an external magnetic field with an attraction force of 52 kg, which adsorbs the magnetic anode particles onto the outer wall of the sleeve.

[0035] Example 3

[0036] For a low-density cement slurry system with a density of 1.30 g / mL (the cement slurry formulation is the same as in Example 2):

[0037] A method for preventing corrosion damage to oil and gas well casing using magnetic anode materials includes the following steps:

[0038] (1) Preparation of magnetic anode microparticles: Prepare a cylindrical zinc anode material with a diameter of 0.1 mm and a length of 0.1 mm, a ring magnet with an inner diameter of 0.1 mm, an outer diameter of 0.6 mm and a length of 0.02 mm, and a ring polystyrene foam with an inner diameter of 0.1 mm and an outer diameter of 0.6 mm. Attach the ring magnet and the ring polystyrene foam to both ends of the cylindrical zinc anode material with 502 glue to prepare magnetic anode microparticles. Adjust the density of the magnetic anode microparticles to 1.30 g / mL by controlling the length of the ring polystyrene foam.

[0039] (2) During the cementing process, the magnetic anode particles are added to the cement slurry at a mass ratio of 1:50, and then the magnetic anode particles are pumped in together with the cement slurry.

[0040] (3) The pulsed strong magnetic field generator is lowered into the inner wall of the sleeve to generate an external magnetic field with an attraction force of 50 kg, which adsorbs the magnetic anode particles onto the outer wall of the sleeve.

[0041] Example 4

[0042] For a low-density cement slurry system with a density of 1.30 g / mL (the cement slurry formulation is the same as in Example 2):

[0043] A method for preventing corrosion damage to oil and gas well casing using magnetic anode materials includes the following steps:

[0044] (1) Preparation of magnetic anode microparticles: Prepare a cylindrical zinc anode material with a diameter of 2 mm and a length of 3 mm, a ring magnet with an inner diameter of 2 mm, an outer diameter of 2.5 mm and a length of 0.5 mm, and a ring polystyrene foam with an inner diameter of 2 mm and an outer diameter of 2.5 mm. Attach the ring magnet and the ring polystyrene foam to both ends of the cylindrical zinc anode material with 502 glue to prepare magnetic anode microparticles. Adjust the density of the magnetic anode microparticles to 1.30 g / mL by controlling the length of the ring polystyrene foam.

[0045] (2) During the cementing process, the magnetic anode particles are added to the cement slurry at a mass ratio of 1:100, and then the magnetic anode particles are pumped in together with the cement slurry.

[0046] (3) The pulsed strong magnetic field generator is lowered into the inner wall of the sleeve to generate an external magnetic field with an attraction force of 100 kg, which adsorbs the magnetic anode particles onto the outer wall of the sleeve.

[0047] Comparative Example 1

[0048] The existing impressed current cathodic protection method is adopted:

[0049] The bushing cathodic protection system mainly consists of an external power supply, an anode ground bed, a reference electrode for the protected body (bushing), connecting cables, and insulating joints. The protected bushing is connected to the negative terminal of the external power supply, and the anode ground bed is connected to the positive terminal of the protected bushing. The bushing is protected by current supplied by the external power supply.

[0050] Comparative Example 2

[0051] The existing sacrificial anode cathodic protection method is adopted:

[0052] The sacrificial anode material is cast and machined into short sections. The installation process is as follows: First, the outer surface of the casing is derusted and polished, and then blast-blasted to achieve Sa2.5 grade, keeping it clean and dry. The short section anode material is then installed, and painting must be done before any rust reappears. Next, the primer is applied to the casing surface using a coating tool. After 4-6 hours, epoxy cold-applied tape is wrapped around the casing surface, and a topcoat is applied. After the finished product has been left to cure for 7 days, allowing the topcoat and primer coatings to fully cure, it is then lowered into the well for installation.

[0053] Construction comparison:

[0054] The construction period for Comparative Example 1 was 15-20 days, and the construction period for Comparative Example 2 was 7-10 days. According to the provisions of the standard GB175-2007 General Portland Cement for setting index of Portland cement, the construction period for Examples 1, 2, 3, and 4 was 1-10 hours; it can be seen that the construction period of the present invention is significantly reduced.

[0055] In addition, in Comparative Example 2, the anode is very easy to fall off due to impact and friction during downhole construction. In Examples 1, 2, 3, and 4, the anode material is added after the casing is lowered into the well, so there will be no falling off. Moreover, it is injected along with the cement, making construction simple.

Claims

1. A method for preventing corrosion damage to oil and gas well casing using magnetic anode materials, characterized in that: Includes the following steps: (1) Preparation of magnetic anode microparticles: magnetic material and density adjustment material are respectively attached to both ends of the anode material to prepare magnetic anode microparticles; (2) During the cementing process, the magnetic anode particles are added to the cement slurry and then pumped in together with the cement slurry; (3) Under the action of an external magnetic field, the magnetic anode particles are adsorbed onto the outer wall of the sleeve; In step (2), the mass ratio of the magnetic anode particles to the cement slurry is 1:(20-100).

2. The method for preventing corrosion damage to oil and gas well casing using magnetic anode materials according to claim 1, characterized in that: The density of the magnetic anode particles is the same as the density of the cement slurry during the cementing process.

3. The method for preventing corrosion damage to oil and gas well casing using magnetic anode materials according to claim 2, characterized in that: The anode material is cylindrical, with a diameter of 0.1mm-2mm and a length of 0.1mm-3mm.

4. The method for preventing corrosion damage to oil and gas well casing using magnetic anode materials according to claim 3, characterized in that: The magnetic material is a ring magnet, with an inner diameter the same as the diameter of the anode material, an outer diameter 0.5mm-1mm larger than the inner diameter, and a length of 0.1mm-1mm.

5. The method for preventing corrosion damage to oil and gas well casing using magnetic anode materials according to claim 4, characterized in that: The density adjusting material is a ring-shaped foam plastic. The inner and outer diameters of the density adjusting material are the same as those of the magnetic material. The length of the density adjusting material is adjusted according to the density of the magnetic anode particles.

6. The method for preventing corrosion damage to oil and gas well casing using magnetic anode materials according to claim 5, characterized in that: The density adjusting material is polyethylene foam, polypropylene foam, or polystyrene foam.

7. The method for preventing corrosion damage to oil and gas well casing using magnetic anode materials according to claim 6, characterized in that: The magnetic material and density-adjusting material are respectively bonded to both ends of the anode material with 502 glue.

8. The method for preventing corrosion damage to oil and gas well casing using magnetic anode materials according to claim 7, characterized in that: The attraction force of the external magnetic field is 50 kgf-100 kgf.

9. The method for preventing corrosion damage to oil and gas well casing using magnetic anode materials according to claim 1, characterized in that: The magnetic material is a magnet, and the anode material is a zinc anode material.