Fire, Gas Dispersion, Explosion Analysis (FGDEA) and Hazardous Area Classification (HAC) for the Wells in the Kauther Gas Lift Project

Elixir Engineering was awarded to perform Fire, Gas Dispersion & Explosion Analysis (FGDEA) and Hazardous Area Classification (HAC) for the Wells in the Kauther Gas Lift Project. 

Project Summary

• KGP fields are rich retrograde condensate gas reservoirs.
• There was a need to extend well life to reduce deferment and improve UR by improving well outflow and reducing OPEX and flaring associated with unloading restoration operations.
• Gas lift combined with Velocity string VS was determined to be the best solution for kick-off and for continuous lifting purposes.
• Accordingly, Rock International intended Elixir Engineering to perform Fire, Gas Dispersion & Explosion Analysis (FGDEA) and Hazardous Area Classification (HAC) for wells in the Kauther Gas Lift Project.

What is HAC

Hazardous Area Classification (HAC) is a method used to evaluate and categorize sections of a facility based on the presence and concentration of flammable substances. Its main purpose is to identify areas prone to fire or explosion risks and to ensure the selection of appropriate equipment and safe installation practices, thereby distinguishing these hazardous zones from non-hazardous ones.

Hazardous Area Classification (HAC) Methodology

• The evaluated separation of a facility into hazardous and non-hazardous regions, as well as the segmentation of the hazardous sections into zones, is known as area classification.
• A hazardous area is characterized as a three-dimensional place where it is reasonable to assume the presence of a flammable atmosphere at frequencies that necessitate extra care in the design and construction of equipment as well as the management of other potential sources of ignition.
  • Zone Classification: Hazardous areas are divided into zones based on the likelihood of occurrence and duration of a flammable atmosphere.
  • Zone 0: That portion of a dangerous location where there is a constant or prolonged presence of combustible air.
  • Zone 1: The portion of a dangerous location where flammable air is most likely to occur during regular operations.  
  • Zone 2: That part of a hazardous area in which a flammable atmosphere is not likely to occur in normal operation and, if it occurs, will exist only for a short period.
• Non-hazardous areas: Areas not covered by any of the aforementioned.
  • Grade and source of release: A source of release is any location from which a flammable gas, vapor, or liquid may be released into the atmosphere for the purposes of area classification. Based on their expected frequency and duration, three release grades are determined.
  • Continuous grade release: A release that happens regularly and at brief intervals, or that is almost continual.
  • Primary grade release: A release that is anticipated to happen in operational procedures that is likely to happen regularly or periodically throughout normal operation.
  • Secondary grade release: A release that is unlikely to happen during regular operations and, in any case, will only happen occasionally and briefly.

Fluid Categories:

Vent Dispersion Study

What is Vent Dispersion Study

A vent dispersion study assesses how gases or vapors released from a vent disperse into the atmosphere. This study helps determine safe distances and operational limits to prevent hazardous concentrations from reaching areas where they could pose health or explosion risks. By modeling the dispersion patterns, it ensures that released substances remain within safe, acceptable limits, safeguarding people, equipment, and the environment.

• The objectives of the FGDEA are to carry out dispersion and thermal radiation assessment to ensure the distance from the wellhead/RMS manifold and the vent heights to the fence is adequate.
• The following leak sources are considered for the modeling
  • Well head and RMS manifold
  • Drain Pit Vent
  • RV Vents

Overview

• The FGDEA is a structured and systematic study to identify and assess credible fire and explosion hazards and ensure the facility layout eliminates the potential for escalation as far as reasonably practicable.
• This involves performing physical effects modeling (PEM) to assess the impact of credible leaks and assess the potential for escalation as per PDO SP-1258 (Quantitative Risk Assessment (QRA) Specification).
• The study quantifies the physical effects of hydrocarbon releases, as defined by the potential sources of leakage (PSLs), and assesses the potential for impact on personnel due to flammable releases.
• The physical effects modeling carried out as part of the FGDEA will be used to optimize the safe distance as per project scope to mitigate escalation and achieve an inherently safe plot, as far as practicable, based on PDO SP-1127.
• Steps
  • Vent modelling
    • Calculate the required fence distance and vent height to achieve the heat radiation criteria (5 Kw/m2 at the property fence) using the Gas Jet Flame Module.
    • For the vent height calculated in Step-1, carry out flammable gas and H2S dispersion analysis to ensure that the calculated height also meets the gas exposure limits at the facility fence to ensure that personnel working inside the fence are not exposed to flammable or toxic gas.
  • Leak Modelling
    • Obtain composition and flowrates from Process for the RMS and Wellhead for new wells
    • Carry out leak modeling for the 22mm.
    • Analyze flammable dispersion for 100% LFL to assess whether the required distance to the fence is safe from the source of leak.

Deliverables:

Hazardous Area Classification Report compiled with zone maps, documentation of Hazardous Materials, Safety Recommendations. FGDEA Report compiled with Vent Design Recommendations, Contour Maps, Emergency Response Guidelines, Mitigation Measures, and Risk Assessment.