Code of Practice for coal seam gas well head emissions detection ...

Standard leak classification
The following standard gas leak classification definition has been adopted and requires reportable
leaks to be notified to the P&G Inspectorate.
“A Well Head Reportable Leak” is defined as:
1. An emission due to an unplanned release from a CSG well site facility that, at a
measurement distance of 150mm immediately above (and downwind) and surrounding the
leak source in an open air environment above ground position; gives a sustained LFL
reading greater than 10% of LFL for a 15 second duration.
2. The following incidents/circumstances also fall under the definition and require CSG
operators to notify the P&G Inspectorate:
a. an unplanned hydrocarbon gas release reported by the emergency services, a public
authority or member of the general public;
b. an unplanned hydrocarbon gas release resulting in an incident involving fire or injury;
c. an unplanned hydrocarbon gas release which receives media attention, and
d. an unplanned release with the potential for significant escalation close enough to a
building or other confined space and large enough that gas is likely to enter any
building or confined space.
An unplanned gas release that falls outside of the above parameters will be classified as an
“Internally Reportable Well Head Leak” and will be subject to reporting procedures and
rectification treatment in accordance with an individual company’s leak management plan and
other safety management plan risk-based assessments and requirements in other safety
management plans.
Standard leak detection methodology
A suitably trained and competent field technician will survey for gas leaks by placing the probe of
the gas detector immediately adjacent to but not touching (approximately 10-20mm away) all
potential sources of leakage at the well facility.
Should an indication of gas be found, the field technician will:
1. Record the % LFL or % methane sustained for 15 seconds.
2. After complying with the detector’s manufacturer’s instrument instructions for retest (eg a
purge in clean atmosphere), the field technician shall retest a distance of 150mm from the
leak source in all directions and determine the highest leak zone (potentially immediately
above and in a downwind situation from the source).
3. The highest confirmed % LFL of gas sustained for 15 seconds with the gas probe held at
150mm from the potential source must be recorded.
4. The source of leak must be clearly identified and recorded.
A reportable well head leak is defined in the Standard leak classification section above.
This standard exceeds currently accepted industry standards of detection in higher risk
environments such as large scale semi enclosed gas processing and refining plants.
Code of Practice for CSG well head emissions, detection and reporting - Version 2 June 2011 8