What do facility operators do with output SO2 (sulfur dioxide) from short-term gas releases? If you operate a petroleum-industry facility and it undergoes testing, servicing, cleanup, underbalanced drilling or various blowdowns resulting in planned temporary flaring, it will need appropriate permits from one or more of the governing agencies.
The hierarchy you use for decision-making should be quite straightforward, or even familiar: avoid or at least reduce flaring by justifying and minimizing volumes (if possible) or else meet minimum performance requirements (if not). To reduce incidents of odours, no raw venting should be allowed if the gas can burn.
In-line testing is strongly preferred and plants must consider any feasible choices for using this option. Otherwise, licensees need to design their programs to keep output SO2 emissions at a minimum and comply with regional ambient air quality standards. Since this industry dominates in Alberta, Canada, we will use references to the governing bodies and regulations in this region, such as the Alberta Ambient Air Quality Objectives (AAAQO).
Testing procedure shall follow details outlined in the Alberta Energy Regulator (AER) Directives 56, 60 (Section 3) and 71 if emergencies are involved. If the facility intends to sweeten gas, it will probably require an Alberta Environment and Parks (AEP) sour gas plant approval even if it eliminates output SO2.The AER has placed limits on flaring durations corresponding to facility type:
Temporary flaring permits involve a different process. See Figure 4, included in Section 3.3 of AER Directive 60. When is one of these needed?
Now, how to determine that threshold. AER Directive 60 outlines three tiers - Tier 1 at 600,000 m3 or less, Tier 2 at 400,000 m3 or less and Tier 3 at 200,000 m3 or less.
The permit request must include information about the activity used to fill the AERflare.xls and AERincin.xls worksheets, include a cover letter with the permit request (listing objections or concerns from the public), Lahee classifications and maps, comparisons of testing options, type of unit, reason for the request, dispersion modeling and an air quality management plan if exceedences of the AAAQO beyond those allowed in the AER low-risk criteria are expected.
Sites should keep air dispersion modelling assessments on file for at least a year afterward. Please call Barry at Calvin Consulting, (403-547-7557) if you need this work completed.
Companies like to employ underbalanced drilling techniques when it is safe to do so. It means the pressure near the drill is lower than the pressure in the formation below. This way they can reduce water pollution in the formation, drill faster, conserve mud and still reduce friction but the method can result in dangerous kicks and blowouts and incur higher safety costs.
The AER has special information requirements for this situation, especially if flaring exceeds the Volume Allowance Thresholds. How did the company determine the flaring rates? How long will the drilling take? How much testing time is required?
Refer to AER https://www.aer.ca/rules-and-regulations/directives/directive-036 for additional regulatory information regarding underbalanced drilling.
Well Flaring - What are the Performance Requirements? Section 7 states that facilities need to use eliminate output SO2 flaring equipment in accordance with the rules provided; engineering and design must be completed properly and adhered to afterwards.
Official methods exist for determining H2S concentrations; they include gas chromatography and/or Tutwiler gas analysis apparatus. One important thing is to suspend operations if an H2S concentration of greater than 5% is found. You are to prevent raw sour gas from escaping to the atmosphere and follow AER Directive 55 for proper storage maintenance regulations.
Facilities shall submit reports and information regarding flaring and testing as outlined in Section 3.10. It refers the reader to requirements in AER Directive 40 as well as other bulletins and documents. Section 3.11 sets out provisions for temporarily setting up a well with no output SO2 flaring prior to the start of production, with some exceptions for emergencies.
Calvin Consulting Group Ltd. specializes Alberta ESRD and AER applications and dispersion modelling. If your facility needs professional assistance with these matters, please call Barry J. Lough at Calvin Consulting Group Ltd. at at 403-547-7557 for help with questions you might have. See a bit more about Calvin services here:
How shall your gas processing facility handle temporary flaring and the SO2 gas that results from it?
Alberta AER gives guidance in Directive 60.
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