Causas de daños en la carcasa de aceite

Durante el proceso de producción de pozos de petróleo y gas, a menudo se producen daños en la carcasa de petróleo , lo que afecta en gran medida la vida útil de la carcasa de petróleo. A continuación, Union Steel le presentará en detalle las causas de los daños en las carcasas de aceite.

1. Factores externos

Los llamados factores externos se refieren a las razones del daño a la carcasa causado por las medidas de estimulación de la producción de pozos de petróleo y gas, reparación de pozos de petróleo, etc., después de que el pozo de petróleo y gas se pone en producción. La mayoría de los pozos de petróleo y gas de mi país requieren medidas de estimulación de la producción, como la fracturación o la acidificación, antes de ponerse en producción. Tras un periodo de producción, se procederá a la fracturación y acidificación. Algunos pozos también se someten a refracturamiento. Con la mejora continua de la tecnología de procesos, la escala de la transformación también es cada vez mayor. Estas medidas de transformación afectarán en gran medida la vida útil de la carcasa.

(1) Operaciones de perforación

Perforar es una tarea importante antes de fracturar y acidificar. Una ingeniería u operación inadecuadas también pueden causar daños a la carcasa. Por ejemplo, demasiada densidad de orificios puede reducir la resistencia del revestimiento y las perforaciones pueden hacer que el cemento quede fuera del revestimiento. El anillo se rompe, provocando la ruptura de la carcasa, la profundidad de la perforación es demasiado grande o el diseño es inexacto, y el disparo penetra la capa intermedia de lutita por error, lo que hace que el agua de la lutita se expanda, lo que resulta en cambios en la tensión del suelo, provocando deformación o dislocación de la carcasa.

(2) Operaciones de fracturación y acidificación

En la última década, la gente adoptó medidas de fracturación a gran escala para pozos petroleros y consideró el efecto de transformar capas de petróleo de baja permeabilidad. La presión en la boca del pozo puede alcanzar los 50-70 MPa y la presión de la carcasa de la capa de aceite ha alcanzado los 70-100 MPa. La resistencia a la presión interna de la carcasa N-80 de uso común está diseñada para ser de 64,6 MPa, mientras que la resistencia de la carcasa J55 es de solo 21,93 ~ 28,4 MPa. De esta manera, los acoples del casing y las piezas roscadas, así como las secciones del pozo con mala calidad de cementación, son propensas a romperse. Además, cuando el pozo de petróleo se acidifica, se producirá corrosión de la carcasa porque el ácido no se descarga a tiempo. Algunos pozos se acidifican varias veces, lo que acelera la velocidad de corrosión del revestimiento y provoca perforaciones y fugas.

(3) Transferencia de pozos de petróleo y herramientas de fondo de pozo.

When the oil wells are put into production later, some oil wells will be converted into water injection wells. The original oil well cementing height is only about 200m above the oil layer, while the normal water injection well cementing height is required to reach the wellhead. Transfer wells are quite different from ordinary water injection wells. The cement return height is not high enough. The upper casing is not protected by a cement ring and is completely submerged in the shallow water above. On the one hand, the external corrosion of the pipeline is serious. On the other hand, after water injection, the upper casing is subject to water injection pressure, which promotes corrosion with the outside of the pipe and aggravates the damage of the casing. In addition, the collision damage of downhole tools to the inner wall of the casing will also aggravate the corrosion, especially when there is a packer downhole, the packer will cause extremely serious damage to the inner wall of the casing. Firstly, the strong stress expansion when the packer is seated will cause huge stress damage to the inner wall of the casing; secondly, due to the obstruction of the packer, dirt is easy to accumulate near the packer, causing corrosion under the scale, stress damage and scale Synergy. Under stress, the casing loss rate near the packer will increase significantly. When a packer fails and is unsealed, severe damage to the sealing location will be caused. A large amount of practice has proved that the damage to the casing when the packer is unsealed is extremely serious. Packers can cause extremely severe damage to the inner wall of the casing. Firstly, the strong stress expansion when the packer is seated will cause huge stress damage to the inner wall of the casing; secondly, due to the obstruction of the packer, dirt is easy to accumulate near the packer, causing corrosion under the scale, stress damage and scale Synergy. Under stress, the casing loss rate near the packer will increase significantly. When a packer fails and is unsealed, severe damage to the sealing location will be caused. A large amount of practice has proved that the damage to the casing when the packer is unsealed is extremely serious. Packers can cause extremely severe damage to the inner wall of the casing. Firstly, the strong stress expansion when the packer is seated will cause huge stress damage to the inner wall of the casing; secondly, due to the obstruction of the packer, dirt is easy to accumulate near the packer, causing corrosion under the scale, stress damage and scale Synergy. Under stress, the casing loss rate near the packer will increase significantly. When a packer fails and is unsealed, severe damage to the sealing location will be caused. A large amount of practice has proved that the damage to the casing when the packer is unsealed is extremely serious. The strong stress expansion when the packer is seated will cause huge stress damage to the inner wall of the casing. Secondly, due to the obstruction of the packer, dirt is easy to accumulate near the packer, causing corrosion under the scale. Stress damage and scale work together. . Under stress, the casing loss rate near the packer will increase significantly. When a packer fails and is unsealed, severe damage to the sealing location will be caused. A large amount of practice has proved that the damage to the casing when the packer is unsealed is extremely serious. The strong stress expansion when the packer is seated will cause huge stress damage to the inner wall of the casing. Secondly, due to the obstruction of the packer, dirt is easy to accumulate near the packer, causing corrosion under the scale. Stress damage and scale work together. . Under stress, the casing loss rate near the packer will increase significantly. When a packer fails and is unsealed, severe damage to the sealing location will be caused. A large amount of practice has proved that the damage to the casing when the packer is unsealed is extremely serious. When a packer fails and is unsealed, severe damage to the sealing location will be caused. A large amount of practice has proved that the damage to the casing when the packer is unsealed is extremely serious. When a packer fails and is unsealed, severe damage to the sealing location will be caused. A large amount of practice has proved that the damage to the casing when the packer is unsealed is extremely serious.

2. Internal factors

(1) Corrosion in pipelines

In-pipe corrosion mainly refers to the corrosion of the casing caused by the fluid entering the annulus of the oil casing. It mainly occurs in production wells because crude oil or natural gas contains some corrosive gases such as sulfur, carbon dioxide, chloride ions, and hydrogen sulfide. When these gases enter the oil and casing annulus and mix with water, they will cause varying degrees of corrosion to the casing. Injection wells will also contain some corrosive substances, mainly bacteria. However, compared with production wells, the incoming fluid of injection wells can be processed through the surface, minimizing corrosion of the pipe string.

(2) Corrosion outside the pipe

External corrosion mainly occurs when the cement sheath is damaged or there is no cement sheath in the upper part of the oil well. The casing is in direct contact with formation water. Corrosive gases such as carbon dioxide, chloride ions, and hydrogen sulfide in the formation water cause certain corrosion to the casing. When there are corrosion products or scale and any medium containing O2, H2S, Cl- and CO2, galvanic cell corrosion can occur under scale. Taking oxygen corrosion as an example, many oxygen atoms are easily adsorbed on the surface of corrosion products. The difference in oxygen concentration promotes cathode depolarization on the metal surface and accelerates corrosion of the metal surface.

En resumen, las causas de los daños al aceite y a la carcasa se dividen en factores externos y factores internos. En el uso real, debemos prestar atención para evitar estos problemas y extender la vida útil de la carcasa de aceite. Si tiene alguna otra pregunta, comuníquese con: sales@union-steels.com