The successful construction of any well depends upon employing leading standards and best practices in design and drilling processes to provide for operational safety and environmental protection. In British Columbia, permit holders must observe relevant legislation and mandated specifications, and are responsible for being compliant with any permit conditions the Commissions considers necessary.
Permit holders must also look beyond the initial construction of a well, and take measures to maintain its long-term integrity. As per the Drilling and Production Regulation (DPR), well equipment must be designed and maintained to operate safely under the conditions anticipated during the life of a well. Permit holders must adhere to good engineering practices and, if required, apply technical solutions to eliminate or minimize any adverse effects to the environment.
When a well is drilled, it must be cased with steel pipe to provide stability to the wellbore and to ensure fluids are contained within the well. Multiple casings are used within a well, and the depths to which they are set are determined by regulations and the geological conditions present in the wellbore. The shallowest casing is called the surface casing. The purpose of installing surface casing is to isolate usable groundwater from the well and to stabilize the well for the remaining drilling program. After the casing is installed, cement is pumped in the space between the casing and the geological materials that surround the wellbore in order to achieve a seal.
Surface Casing Vent Flow and Gas Migration
Surface casing vent flows and gas migration can occur at some oil or gas wells due to imperfections within well seals. These imperfections may result from drilling or cementing conditions, or from methods practiced at older wells not constructed to present day standards.
Surface Casing Vent Flow, or SCVF, involves the movement of gas between the surface casing and the next string of casing upward out of the surface casing vent assembly. In rare instances, a liquid could also follow the same flow path.
Gas Migration, or GM, is the flow of gas outside the surface casing of a well. When GM occurs, there is potential for migration to enter the groundwater and this may cause changes to groundwater chemistry in the vicinity of the well.
Regulating SCVF and GM
Casing and Cementing
Section 18 of the DPR outlines well casing and cementing requirements, including sufficient casing strengths and depths to ensure the casings and cement will be suitable for maintaining well control and containment during the service life of the well. These standards are in place for safety and environmental protection.
SCVF: A permit holder must check for evidence of SCVF at key points throughout the life of a well including at the completion of drilling, before and after hydraulic fracturing and prior to final decommissioning of the well. A bubble test is one way to determine if gas is present at the surface casing vent. This procedure is described in section 9.7.3 of the Commission’s Oil and Gas Operations Manual (the Manual).
GM: Testing for GM may be done using a soil vapour survey - a screening tool that analyzes soil for the presence of methane. Observation at the ground surface outside the surface casing may also confirm the presence of gas. There may be visual, auditory, olfactory or other evidence of possible GM, such as stressed vegetation near the well.
SCVF: If a SCVF is detected that does not present an immediate safety or environmental concern, the permit holder must test the flow rate and buildup pressure, and submit a SCVF/Gas Migration Form to the Commission within 30 days. Once a SCVF is identified, flow tests are recommended annually for a minimum of five years, and the Commission reserves the right to order specific test measures as required.
Should significant SCVF be detected, permit holders must manage and report the issue in accordance with section 41 of the DPR. They are required to take immediate steps to eliminate the hazard, promptly notify the Commission, and submit without delay a report outlining the steps taken to eliminate the hazard.
The criteria for classifying a SCVF are outlined in section 9.7.3 of the Manual.
GM: Reporting and Assessment of GM are specified in Section 41(4.1) of the DPR. If GM is detected, the permit holder must notify the Commission within 72 hours by completing and submitting a SCVF/Gas Migration Form. After notifying the Commission, the permit holder has 90 days (or less, if an earlier deadline is applied by the Commission) to evaluate the cause and source, and submit a robust risk assessment reporting their findings. The full assessment must be completed under the direction of a qualified professional possessing an appropriate combination of formal education and experience, and who is familiar with all applicable regulations, operating standards, and protocols. Based on a review of the report, the Commission can require further investigation, monitoring, mitigation, risk management, and/or further reporting requirements.
SCVF: For non-serious SCVFs, repair may be deferred until final well decommissioning. There are measures a permit holder may take to minimize venting volumes in the interim, and in some instances, permit holders may be permitted to explore the option of capturing SCVFs for production. These are described in section 9.7.4 of the Manual.
Permit holders of wells determined to have significant SCVF are to contact the Commission as soon as possible to discuss repair and management requirements.
GM: GM may be required to be repaired at any time based on the Commission's discretion. Due to safety and environmental considerations, some GM incidents are repaired at the time of final well decommissioning, with monitoring and risk management approaches employed until the time repair work occurs.
Improving Our Approach to SCVF and GM
The Commission has, and will continue to make changes to improve our understanding and management of SCVF and GM. In 2013, the Commission initiated an investigation of northeast B.C. wells in order to expand its understanding of GM frequency, causes and impacts. Using the findings from that investigation, action has been taken both internally and externally to audit and improve the Commission’s regulatory responsibilities and processes. There are several projects and initiatives either complete or currently underway:
- The DPR was amended to expedite the time in which a permit holder must notify the Commission of a discovery of GM, and for the permit holder to submit to the Commission without delay a report respecting the evaluation and risk assessment of the GM.
- The DPR was amended to require permit holders to submit findings from any surface casing flow gas analysis to the Commission.
- Last year, the Commission created a Risk Assessment Framework for Wellsites with Gas Migration (Table 9F in the Manual). Permit holders use this framework to tabulate GM risks and identify the degree of potential effects to safety, health, and the environment. The framework situates a permit holder to identify mitigation and management measures best-suited for addressing their specific wellsite.
- The Risk Assessment Framework was updated in 2017 to include the Groundwater Review Assistant (GWRA). The GWRA assists users in retrieving groundwater related information when conducting a hydrogeological review or assessment. As a result, groundwater monitoring programs have been developed and implemented at selected well sites.
- The Commission is working with several government bodies on the development of provincial methane reduction regulations that would meet or exceed both provincial and federal regulatory targets.
- By way of Industry Bulletins and Directives, the Commission shares industry findings and outlines recommendations on how to better manage SCVF through improved field practices.
- Under the DPR, for each well completion, a permit holder must maintain a record of the well control equipment on site, and assess its performance regularly following the completion of the well.
Partnerships and Independent Studies
The Commission continues to support independent research and partners directly with academia to undertake initiatives with the goal of reducing the incidences of GM, SCVFs and methane emissions in the province. From this work, recommendations are developed, refined practices are implemented, and discoveries are shared with environmental organizations, government and industry.
- The Commission is now in the process of establishing a Methane Research Collaborative for B.C. with other partners.
- The Commission is participating in studies with post-secondary institutions to address key aspects of natural gas development including cementing and fracture propagation and assessments of groundwater sampling.
- The Northeast Air Monitoring Project has been a collaborative initiative with participants from across government with the goal of capturing air quality data. Information about this project including current data from specific air monitoring stations is available online.
The Commission is collaboratively supporting research at the University of British Columbia to revisit the investigative report of 2013 to ensure scientific and statistically defensible analysis and interpretation is completed using relevant Commission data, which will provide an updated and scientific basis for continued regulatory and process enhancements related to well integrity.
- The Commission has a mobile Air Monitoring Environmental Laboratory (CAMEL) with sensory equipment to measure air quality and investigate odour reports raised by the public. These units measure air pollutants and atmospheric conditions, data that is shared with the community in order that improvements may be made to the way oil and gas activities are managed in the province.
- The Commission also has a highly advanced infrared optical gas detection system to improve capabilities to detect and monitor GM related to oil and gas activities. This system improves productivity and safety and operates in a variety of environmental conditions.
- A project is underway to test the efficiency of drones equipped with methane detection units for applications in assessing the presence or absence of GM in the field.
- A site-specific case study is under development, using detailed instrumentation and environmental monitoring to learn more about the impacts of GM.
- During 2013, Commission staff undertook field inspections to screen for evidence of GM, and confirmed there had been no negative impacts on any domestic sources of groundwater. Since a Commission study undertaken at that time, the Commission has increased its number of field inspections on wells identified as experiencing GM.
- In 2016, Commission hydrogeology staff conducted field inspections of wells with GM to inform development of technical guidance for industry related to gas migration risk assessment requirements of the DPR.
- A recent aerial survey of abandoned wells was conducted to assess new technological capabilities in detecting methane emissions at decommissioned well sites. More information is available in Information Bulletin 2017-01.
Data Submission and Management
- Internally, the Commission has taken steps to improve processes that expedite, track and address reported instances of GM. Reports of GM are now flagged and Commission engineering and hydrogeology staff are notified in order to conduct preliminary reviews.
- Externally, permit holders must retain testing and repair information for the life of the well, and provide records to the Commission upon request.
Wherever Commission technical guidance can be improved as a result of the above mentioned work, the Commission revises its manual, guidelines and forms. All documentation is freely available via the Commission website with revisions updated monthly.
If you have any questions regarding well integrity, please contact the Commission at OGC.Communications@bcogc.ca.