Surface casing vent flows (SCVFs) are a persistent challenge across the oil and gas industry. They occur when gas or fluids migrate up the surface casing and escape at the wellhead, typically due to poor cement bonding or casing integrity issues. Beyond safety concerns, SCVFs represent a continuous source of methane emissions that operators are increasingly expected to quantify, control and eventually eliminate.
Figure 1: Image showing the surface casing vent flow and gas migration.
Adapted from Tiago Morais, CC BY-SA 4.0, via Wikimedia Commons
Regulatory Framework in Western Canada
Each province has its own approach to SCVF detection, reporting, and repair:
Alberta:
Governed by AER Directive 087 – Well Integrity Management, which sets clear expectations for SCVF testing, reporting, and classification. “Serious” vent flows, typically those exceeding 300 m³/day, require immediate action.
Saskatchewan:
The Ministry of Energy and Resources (ER) outlines surface casing venting in section 22 of the Oil and Gas Conservations Regulations (OGCR 2012), whereby remedial efforts may be required depending on the severity of the leak. Repair efforts would need to be approved by the ER.
British Columbia:
The BC Energy Regulator addresses SCVF management in its Drilling and Production Regulations & Activity Operations Manual, detailing how operators must detect, measure, and repair gas migration or surface casing vent flows.
Across all provinces, the message is clear: persistent vent flows must be identified, measured, and either repaired or controlled.
Measuring or Estimating SCVF Emissions
Operators can assess SCVFs using two main approaches:
- Direct Measurement: Portable flow meters (ex. Ventbusters Inc.) and gas analyzers measure flow rate and methane concentration at the vent, providing accurate emissions data.
- Estimation: When measurement is not possible, reported flow categories and default emission factors are used to estimate methane release.
Accurate measurement not only supports regulatory compliance but also strengthens emissions reporting under programs such as OGMP 2.0 and corporate ESG frameworks.
Controlling Emissions Prior to Abandonment
When wells cannot be immediately repaired or permanently abandoned, interim abatement systems can play a key role:
- Enclosed Combustors: Capture and cleanly burn vented gas with destruction efficiencies exceeding 98%. They convert methane to CO₂ and water, dramatically lowering greenhouse gas intensity. Our Emission Rx MC-Series Enclosed Combustors are designed to eliminate these emissions safely and effectively.
- Catalytic Methane Abatement Systems: Use specialized catalysts to oxidize methane at lower temperatures without an open flame, ideal for low-BTU gas or sites where continuous flame is undesirable. Our CMAS (Catalytic Methane Abatement System) is designed to eliminate these emissions safely and effectively.
Both solutions help reduce site emissions and keep operations compliant while wells await full remediation.
The Takeaway
Surface casing vent flows may be a small part of a well’s life cycle, but their impact can be significant. By accurately measuring emissions and applying the right control technology, whether through enclosed combustion or catalytic oxidation, operators can reduce environmental impact, improve safety, and stay ahead of tightening regulatory requirements across Alberta, Saskatchewan, and BC.