Introduction to an Effective Workover Method to Repair Casing Leak

Abstract

Wellbore integrity is very critical in oil and gas industry and needs to be maintained through the entire cycle of well's life. The most important item for well integrity is to set cement between two casings or between casing and formation. A good cement job provides isolation and protection for the well and a poor cement job can have cracks and allows corrosive fluids to migrate through micro channels. Downhole casing repair is a common workover operations worldwide, especially in wells that have been producing over number of years. It is very challenging to control corrosive fluid migration which slowly corrodes casing and tubing over time. An innovative epoxy resin formulations has been developed and tested in the field to repair casing leaks which is extremely easy to handle and very economical. A cost-effective workover program can be developed and implemented depending on the severity of the leak. The improved approach of using innovative resin can be used by mixing with cement blends to repair major casing damage and can also be used as standalone application to fix minor leaks. The system maintains extremely good rheological properties even when mixed with cement. The system has ability to withstand high differential pressure and is also resistant to acid, salts, hydrocarbons and most importantly various corrosive liquids. The precise application is determined by measuring the injectivity of the well. In the low injectivity wells, only epoxy resin solution will be spotted and repair the damaged casing. In the high injectivity wells, the chemical will be mixed with cement and completely seal the damaged zone. The chemical will enhance the mechanical properties of the cement and will be more resilient to extreme down-hole condition. The paper will emphasize the added value and potential of the method in restoring the casing integrity. The paper will also discuss the laboratory test reports and application which will highlight effective and economical outcome.

Reducing oil and gas well leakage: a review of leakage drivers, methane detection and repair options

“…Casing repair technologies include the use of anti-corrosive material, expanding casings and casing repair patches (Sanabria et al 2016, Singh et al 2019, Chartier and Graham 2020. One of the common methods to control external casing corrosion and prevent leakage is cathodic protection (Xu et al 2006, Malekinejad andAlavi 2008).…”

“…To protect against internal casing corrosion, studies have used inner casing polymer coatings and thermal activated resin (Xu et al 2006, Sanabria et al 2016. In addition to anti-corrosion repair strategies, others have used expandable casings, expandable casing repair patches, and cement additives in cement squeeze operations to reduce casing leakage (Storaune and Winters 2005, Singh et al 2019, Chartier and Graham 2020. A comprehensive and detailed review of casing corrosion and repair can be found in Okyere (2018) and others.…”

Methane Emissions from Abandoned Oil and Gas Wells in Alberta and Saskatchewan, Canada: The Role of Surface Casing Vent Flows

“…Well integrity is the ability of wellbore barriers to contain production fluids within the wellbore and prevent uncontrolled subsurface leakage, groundwater contamination, and/or emissions. , Subsurface leakage pathways at oil and gas wells include the production tubing and annular spaces between and outside casings, which can lead to gas in the surface casing and gas migration through soil. , In Canada, surface casings are vented, leading to surface casing vent flows in the presence of subsurface leakage; in the U.S., surface casing vents tend to be closed, causing casing pressures to build up in the presence of leakage . Gas migration represents outside-of-the-casing leakage into subsurface environments, including groundwater, and can lead to gas emissions at the ground surface from soils surrounding the wells. , Gas migration and surface casing vent flows are indicators of wellbore integrity issues and require wellbore treatments such as cement squeezes and casing repair. ,− In contrast, methane emissions from the aboveground wellhead infrastructure often are relatively easy fixes, such as tightening of joints and replacement of parts, and are more likely to originate from the producing formation, indicating that plugging can reduce the emissions. Overall, the presence of surface casing vent flows and gas migration are indicators of well integrity failures, which increase the potential for methane emissions and groundwater contamination. ,,, …”