Establishing Baselines, Continuous Monitoring through P&A/Mitigation Restoration, and Wellbore Integrity Validation
SUMMARY
The Ventbuster® is built-for-purpose and is the most technologically advanced precision emissions metering device for Casing Vent Flow (CVF) testing and evaluation. Its patented flow channel enables users to obtain the most accurate, intuitive, repeatable, and continuous, real-time emissions quantification and reporting. The Ventbuster® performs in full compliance with the Alberta (AER), British Columbia (BCER), and Saskatchewan (MER) Energy Regulators in Canada, the Department of Energy (DOE), the Department of Interior (DOI) in the USA, and the Department of Resources (DOR) Energy Regulator in QLD, Australia.
SYNOPSIS
Detrimental hydrocarbons, saline water, or other greenhouse gas (GHG) emissions from a surface casing or other annular wellhead vents must be detected, then monitored, flow and pressure tested, and reported to jurisdictional energy regulators. If a vent leak is deemed serious, it must be repaired immediately. If deemed non-serious, it must be repaired at the time of well plugging and abandonment or decommissioning.
A CVF indicates that downhole containment or zonal isolation of wellbore fluids and pressures has failed. This condition is often referred to as a wellbore integrity failure. CVF testing is conducted on oil, gas, injection, and disposal wells to monitor and report unrestrained vertical migration of fluids from the well, manifesting as a surface leak from the vent assembly. This wellbore integrity failure condition is typically a result of poor primary cementing or simply a lack of cement in the annular space between casing strings. Indirectly, a positive CVF can result from a production casing, intermediate casing, or liner leak, wellhead seal failure, or, on occasion, decaying organics trapped within the casing vent assembly.
CLIENT BENEFITS
Establishes precise baseline testing and reporting of methane (CH4) and greenhouse gases (GHG) venting to the atmosphere to assist in enabling sound engineering, planning, and cost-effective well integrity restoration.
Continuous real-time wellhead vent monitoring with the Ventbuster® during Plug and Abandonment (P&A) and leak mitigation operations has proven to enhance the success and proficiency of wellbore integrity restoration.
Continuous 24/7, post-leak mitigation monitoring is proof positive of a successful and permanent repair, providing undisputed assurance to Regulators for clearance to cut and cap the well.
PRECEDENCE
Establishing the Baseline CVF Emissions
Record wellhead pressures and probe to determine the presence of hydrocarbon gases, H2S, and CO2. Collect gas sample(s) for analysis.
Install the Ventbuster® and conduct and record the stabilized flow rate, flow pressure, flow temperature, and stabilized shut-pressure test. Collect a post-test gas sample(s) for analysis.
Continuous Monitoring Through P&A and Leak Repair
Once the rig and associated equipment are rigged up over the well to commence downhole operations, re-install the Ventbuster® for continuous monitoring of the CVF throughout the P&A operation to ensure there is no wellbore integrity failure or to live-stream the ongoing intervention to verify that each stage of the repair operation is effecting positive change downhole and verifying continued procedures.
Upon completion of P&A and mitigation operations, rig out all equipment and continue monitoring the wellhead vent(s) to confirm wellbore integrity restoration.
Validation of Well Integrity Repair
Before cutting off the wellhead, capping the wellbore, and commencing surface restoration, re-install the Ventbuster® as proof of a successful and permanent repair with undisputed assurance to Regulators for clearance to cut and cap the well.
FOOTNOTES
CH4 is the primary gas emitted from CVF leaks. It is an extremely potent GHG, trapping as much as 80 times as much atmospheric heat as carbon dioxide (CO2) over the first 20 years and 28 times more potent over a one-hundred-year timescale.
With a positive CVF, jurisdictional regulators will dictate whether the vent should be left open to atmosphere or closed.
If the vent assembly is to be left in an open position, appropriate precautions must be adhered to, ensuring that there is no imminent danger or risk to the public, animals, property, or the environment.
If the vent assembly is left in a closed position, appropriate precautions must be taken to ensure that there will not be an excessive pressure build-up in the casing annulus, which may cause a mechanical wellbore failure. To assess this risk, a stabilized shut-in pressure build-up test is critical.