When developing projects that may encounter H2S (sour gas), the AER requires that the applicant do an H2S release-rate assessment. The H2S release-rate assessment is used to determine the emergency planning zone (EPZ) for the proposed project.
Before filing a well licence application, the applicant must assess the sour gas potential of all formations that the well will encounter. For each formation capable of flowing hydrocarbons, a potential release rate must be calculated and incorporated into the H2S release rate assessed for the well.
For category C, D, and E wells (see Directive 056: Energy Development Applications and Schedules, table 7.1), the applicant must complete, as part of the well licence application, schedule 4.3 outlining H2S details for the well. The information provided on schedule 4.3 is the basis for the applicant’s participant involvement program for the proposed well project.
The operator is expected to hold onto the release-rate assessment, including all supporting documents and calculations, in case of emergency or for audit purposes, and it must be produced at any time if requested by the AER.
An applicant may file an H2S release-rate assessment (as a presubmission) with the AER before submitting a well licence application. This is an optional process that allows the applicant to
- obtain feedback on methodology and H2S release-rate assessments,
- verify the EPZ radius to be used which determines the personal consultation and notification radii that apply to the well project, and
- minimize the time it takes to process a well licence application.
Application Submission for Release-Rate Presubmissions
All H2S release-rate presubmissions can be sent by e-mail directly to email@example.com.
Guidance Documents for Release-Rate Presubmissions
H2S Release-Rate Presubmission Checklist
Directive 065, section 7.11.15, Release-Rate Assessments
Review Process Summary for Release-Rate Presubmissions
After the application is received by e-mail, a review process will take place as follows:
- The release-rate file is reviewed for completeness and registered.
- The file is assigned for geological review.
- A geological review is conducted—the review will focus on identifying all potential hydrocarbon-bearing zones; the release rates of those zones must then be calculated and incorporated into the assessment. Sour zones that have been discounted from the release-rate calculation based on geological controls (i.e., facies changes) will be reviewed in detail.
- The submitter may receive a request for additional geological information or supporting evidence.
- When the geological review is complete, the file is assigned for engineering review.
- An engineering review is conducted—this review will focus on selecting appropriate representative H2S concentrations and absolute open flow rates for each potential hydrocarbon-bearing zone; the release rate is then calculated for each zone.
- The submitter may receive a request for additional test information, calculations, or supporting evidence.
- Failure to provide additional requested information after a reasonable period may result in closure of the release-rate file.
- When AER staff are satisfied that the applicant’s release-rate assessment is complete and that it sufficiently addresses H2S potential at the proposed location, the AER will issue an AER operator’s memo.
- The AER operator’s memo must be provided with the Directive 056 well licence application—the operator’s memo is good for one year or until more data becomes available and results in a higher release-rate estimate.
- The operator is responsible for ensuring that the release-rate assessment is updated if any new data becomes available.
- When an operator’s memo is attached, the AER does not re-review the release-rate assessment at the time of application.
- The complete release-rate assessment must be held by the operator and provided at any time if asked to do so by the AER.