Hazard and Operability & Safety Integrity Level Case Study for FGGS-OIL.

Oil India Limited entrust iFluids Engineering to carryout HAZOP & SIL Study for Field Gas Gathering Station at Baghjan field in Upper Assam, India.

Oil India Limited (OIL), a Navaratna company under ministry of Petroleum and natural Gas, desires to construct a Modular Field Gas Gathering Station (FGGS), for augmenting natural gas production facility. Baghjan oilfield is located about 25 KMs to the northwest of Makum oilfield and was discovered in year 2000. The production from the field is reasonable with ample reserve of crude oil and natural gas. Presently, production is carried out from 6 Nos. of wells through an EPS (Early Production Setup). The Baghjan field is having huge amount of Non-Associated Gas (NAG) potential and the expected gas production from this area in 7.5 MMSCMD. To explore these resources one modular Field Gas Gathering Station (FGGS) having the facilities for production of natural gas is to be created. The proposed FGGS shall have Non-Associated Gas (NAG) processing facility for 5.0 MMSCMD (2 trains x 2.5 MMSCMD) and provision to feed Associated Gas (AG) of 0.5 MMSCMD along with the NAG to a Glycol based Dehydration facility (5.0 MMSCMD) for achieving water dew point less than or equal to (0) Zero Deg C. The facility shall include Production and Test Manifolds, Gas /Condensate/Water Separators, Gas Heaters, Gas Dehydration, Flare system and Effluent Treatment and disposal system along with all the required utilities and auxiliary systems. HAZOP & SIL studies are carried out for the above mentioned systems and the methodology followed is described below.

HAZOP (Hazard & Operability) study is an aid in managing project risk through early identification of hazards and operability problems and to reduce the probability and consequences of an incident that would have a detrimental impact to the PEAR (People, Environment, Assets and Reputation). Usually, this assessment focuses more on the process of the plant itself. The process flow is divided into few sections identified as nodes and thorough analysis is carried out by using the Guide Words (No, Less, More, Reverse for parameters like Flow, Pressure, Temperature, Level, Concentration) for each section to study the possibility of the deviations happening in each of the nodes and identifying the consequences of the risk, safeguarding the risk and providing appropriate recommendations in order to minimize the risk.

Safety Integrity Level more usually referred to “SIL” or “SIL level”, is a unit of measurement for quantifying risk reduction. Layers of Protection Analysis (LOPA) is a powerful analytical tool for assessing the adequacy of protection layers used to mitigate process risk. LOPA builds upon well-known process hazards analysis techniques, applying semi-quantitative measures to the evaluation of the frequency of potential incidents and the probability of failure of the protection layers. It is a simple tool and identifies the Independent Layer of Protection to be considered for risk Classification and risk reduction. As per the scope of this SIL Classification study, safety instrumented functions (SIFs) were identified in the P&IDs and the C&E matrices relevant to project having the main objectives to:

  • Identify potential risks to the people, environment and assets due to failure of Safety Related Systems and associated facilities in the plant to operate on demand.
  • Define the basic performance requirements of all Safety Related Instrumented systems to reduce the above risks to “As Low as Reasonably Practicable”.

SIL identifies all the hazards of a process and estimates the risks inherently involved and determines if that risk is tolerable/acceptable. All instruments/devices in a SIF loop must work together to meet the SIL requirement. A SIL Assessment or SIL Study is a formal documented method that enables a team of suitably qualified and experienced engineers to determine a SIL level, based on relevant criteria and analyses for any particular control or safety loop.