Risk management and assessment for business Advances in Process Control 9 20 September 2011, York, United Kingdom

risk management and assessment for business

Advances in Process Control 920 September 2011, York, United Kingdom

Advances in Process Control 9 Jasjeet Singh

APC 9

Are Blowout Preventers and Fire & Gas Systems ready to be classified as Safety Instrumented Systems on offshore installations?

Presented By:

Jasjeet Singh MCMI, AMIChemE, MBA, BE (Chemical)

Senior Engineer, Risktec Solutions Limited


APC 9Objectives

Introduce briefly to Blowout Preventer (BOP), and Fire and Gas Systems (FGS) in offshore oil & gas installation context;

Simplistically evaluate the Safety Integrity Level (SIL) these systems would be expected to achieve; and,

Discuss if these systems should be designated as Safety Instrumented Systems (SIS);

Discuss “challenges” in upgrading BOP and FGS to SIS status.


APC 9Functional Safety Definition

What is Functional Safety?

The industry standard IEC 61511 defines it as “Functional safety is part of the overall safety that depends on a system or equipment operating correctly in response to its inputs.”

Example:

An over-temperature protection device, using a thermal sensor in the windings of an electric motor to de-energise the motor before they can overheat, is an instance of functional safety.

Specialised insulation to withstand high temperatures is not an instance of functional safety (although it is still an instance of safety and could protect against exactly the same hazard).


APC 9Basic SIS Configuration

Detect

Decide

Execute

Sensor Elements Pressure Temperature Flowrate Composition

Logic Control Safety PLC Relay Logic

Final Elements Valve Assemblies Circuit Breakers Power Drives Secondary Systems


APC 9Systems under the Scanner

Blow Out Preventer Fire and Gas System


APC 9Blow Out Preventer

A Blow Out Preventer (BOP) is a combination of several valves installed at the wellhead.

Function: Prevention of escape of well fluids from primary containment

BOP Typical Location: Beneath the rig for land rigs; At the water’s surface on jack-up rigs; On the seafloor for floating offshore rigs.

What is a Blow Out Preventer?


APC 9What a BOP Looks Like…


APC 9Simplistic LOPA on a BOP System

ScenarioUnexpected release of high pressure gas in the reservoir into the well causing abnormal and sudden increase in riser pressure. Potential for release of high pressure oil / gas jet at the platform from the well (Blow-Out).

Consequences Multiple fatalities from fire & explosion on the installation; MATTE

Target Frequency Factor 6 (equivalent to 10-6 per year)

Initiating Event Unexpected well pressure due to accumulated gas

Initiating Event Frequency Factor 3 (equivalent to 1 in 1000 well sites)

Conditional Modifiers Ignition Control – 0 (No credit)

Exposure – 0 (No credit)


APC 9Simplistic LOPA on a BOP System

Independent Protection Layers Risk Reduction Factor

BPCS Indication of pressure in the control room and process shut down 1

Alarms Linked to the BPCS system – Not Independent 0

Mitigated Event Factor (6) – (3) – (1) 2

Required SIL for chosen SIF 2

Hence the “BOP System” may be required to meet SIL 2 requirements.


APC 9BOP Control System

Primary Functions: To ensure that sufficient hydraulic pressure is conveyed to the BOP assembly when a

demand is placed; Ensure that the sequence of valve activation is executed as per design;

Elements: Pressure measurement devices (an array of pressure transmitters / switches at

different strategic locations) Logic Control (Sub sea modules and on Topsides) Final Elements (The BOP assembly - Actuators & Valves) Support Elements (Hydraulic Power Unit)


APC 9Typical BOP System


APC 9Challenges in upgrading BOP to SIS Status

Technical Challenges: Complex System – An array of devices including multiple sensors Manufacturing high integrity equipment for subsea environment

Operation and Maintenance Challenges: Proof Testing as per requirements of the Standard

• “End to End” tests in operation are not feasible - Destructive nature of final elements

• Maintenance of equipment under harsh & corrosive environment

Compliance / Standards related Challenges: Human in the loop – limited reliability issues Same Equipment – Different Requirements

LOOP, LOOP AND THE WHOLE LOOP, NOTHING BUT THE LOOP


APC 9

PHAS

E 11

– S

afet

y Li

fe C

ycle

Str

uctu

re a

nd P

lann

ing

(IEC

6151

1-1

Clau

se 6

.2)

PHASE 1

Hazard and Risk Assessment

PHASE 2

Allocation of Safety Functions to Protection Layers

PHASE 3

SIS Safety Requirements Specifications

PHASE 4

SIS Design & Engineering

PHASE 5

SIS Installation, Commissioning & Validation

PHASE 6

SIS Operation & Maintenance

PHASE 7

SIS Modification

PHASE 8

SIS Decommissioning

IEC 61511-1 Clause 8


IEC 61511-1 Clause 10, 12

IEC 61511-1 Clause 11, 12

IEC 61511-1 Clause 14, 15



IEC 61511-1 Clause 18PHAS

E 10

– S

IS F

uncti

onal

Saf

ety

Asse

ssm

ent (

IEC

6151

1-1

Clau

se 5

)

PHAS

E 9

– SI

S Ve

rifica

tion

(IEC

6151

1-1

Clau

se 7

, 12.

4 an

d 12

.7)

STAGE 1: Analysis Stage

STAGE 2: Realization Stage STAGE 4: Management and Planning Stage

STAGE 3: Operations and Maintenance Stage

SIS Safety Life Cycle –Where will a BOP cause issues

?

?

?

?


APC 9Regulator’s Position

United Kingdom

HSE Offshore Division’s Guide GASCET (April 2006) includes BOP as one of the devices for which a functional safety assessment is recommended using:

UKOOA Guidelines for Instrument Based Protective Systems

IEC 61508

IEC 61511

Norway United States

Australia Middle East -

South Asia -

?

?

?


APC 9Fire and Gas System

Fire and Gas ‘Detection’ SystemsThree principal types of detectors commonly in use on off-shore installations:

Heat, Flame & Smoke Flammable Gas Toxic Gas

Fire and Gas System – ‘Final Elements’ HVAC System Emergency Shut Down Sequence Initiation Shut Off / Isolation Valves Blowdown and Depressurisation System


APC 9Simplistic LOPA on a FGS

Scenario Release of flammable gas. Potential for jet fire / VCE.

Consequences Multiple fatalities from fire & explosion on the installation

Target Frequency Factor 6 (equivalent to 10-6 per year)

Initiating Event 10” gas pipeline failure due to vessel impact

Initiating Event Frequency Factor 3

Conditional Modifiers Ignition Control – 0 (No credit)

Exposure – 0 (No credit)


APC 9Simplistic LOPA on a FGS

Independent Protection Layers Risk Reduction Factor

BPCS Process shut down. Isolation of pipeline from nearest isolation valves. 1

Alarms Non - Independent Alarms 0

SRPS Temporary refuges & escape crafts 1

Mitigated Event Factor (6) – (3) – (1) 1

Required SIL for chosen SIF 1

Hence the “FGS” may be required meet SIL 1 requirements.


APC 9Challenges in upgrading FGS to SIS Status

Technical Challenges: FSG is also a complex system and is linked with the Emergency Shutdown System FSG is a combination of a number of loops – multiple SIFs with different SIL requirements

Operation and Maintenance Challenges: A large amount of kit to be maintained

Compliance / Standards related Challenges: Usual suspects

LOOP, LOOP AND THE WHOLE LOOP, NOTHING BUT THE LOOP


APC 9BOP and FGS as SIS – The Two Sides

Against ForField devices and technologies are fundamentally different …

But the devices are available, and are being developed…

Not be considered performing a critical safety function…

They do. ESD is only part of the overall safety & risk control…

IEC 61508 is not applicable… Covers all E/E/PE systems...

Too costly… Not more than cost of an accident…

Difficult to materialise … Effort should be made – necessity is mother of invention…

Regulator does not want this… Post DwH, they do…mostly…

Industry has been operating this way – Why now? Continuous improvement …


APC 9Recommendations

Oil and gas industry should explore the possibility of upgrading the BOP and FGS to SIS.

IEC, Industry and Regulators should red-define / amend the relevant requirements to clarify the issue.

Design engineers and safety consultants should be aware of the issue and endeavour to improve the safety system .


APC 9Closing Remarks

Not all safety systems are created equal and every installation has different performance, risks and financial goals to meet.

Small regional operators are much less likely to make this step change in the way the BOP and the FGS are managed due to limited resources. It is up to global organisations to take this initiative, and raise standard of best practice in managing these systems.


APC 9

Thank You for Your Attention

Documents

Risk management and assessment for business Advances in Process Control 9 20 September 2011, York, United Kingdom