OIL AND NATURAL GAS CORPORATION LTD., (A Govt. of India...

Risk Assessment Report for Additional Exploratory

Drilling of 15 wells in NELP-I Offshore Block

KG-DWN-98/2, KG Basin, Andhra Pradesh

OIL AND NATURAL GAS CORPORATION LTD.,

(A Govt. of India Enterprise)

Corporate Health Safety and Environment

ONGC, Delhi

2017

TABLE OF CONTENTS

1.0 RISKS AND HAZARDS 1

1.1 Identification of Risks and Hazards in Exploratory Drilling Operations 1

1.2 Major Hazards 5

1.2.1 Blowout 5

1.2.2 Blowout Frequency Analysis 6

1.2.3 Blowout Consequences and Effects 7

1.3 Collisions Involving Drillship (MODU) 8

1.3.1 Consequences and Effects 8

1.4 Helicopter Crashes 8

1.4.1 Consequences and Effects 9 1.5 Control Measures for Major Hazards 9 1.5.1 Blowout 9 2.0 OIL SPILLS AND SPILL CONTINGENCY PLANS 10 2.1 Rupture of Flow Lines / Main Oil Lines / Hoses / Subsea Lines 12 2.2 Accidents Involving Vessels and / or Offshore Installations 12 2.3 Well blowout Incidents 12 2.3.1 Perceived Risk (numerical values given below are Illustrative failure

frequency) 13

2.4 Sabotage or Terrorism 14 2.5 Under Water Damage due to Tsunami Effect 14 2.6 Sub-surface oil Spill Plume 15 2.7 Vessels Collisions 17 2.8 Helicopter Crashes 17 3.0 HYDROGEN SULPHIDE (H2S) 17 3.1 H2S Gas Detection System 18 4.0 LOW FRACTURE GRADIENTS HIGH PRESSURES AND LOW

TEMPERATURES 20

5.0 FIRE FIGHTING FACILITY 21 5.1 Fire Water System 21 5.2 Fire Fighting Equipment at Drilling Rig 22 LIST OF TABLES

Table-1 Major hazards and risks of Oil/Gas well drilling

Table-2 Criteria for the Risk Ranking

Table-3 Risk Categories and Significance of Criteria

Table-4 Location of the firefighting gadgets at drilling rig

Table-5 Identification of various hazards, its consequences and prevention and mitigations measures of exploratory drilling

LIST OF FIGUERS

Fig-1 Risk Ranking Matrix

Fig-2 Sub Surface Oil Spill Plume

Fig-3 Oil / Gas Well Blow-out Communication Flow Chart

Risk Assessment Report for the Proposed Additional Exploratory Drilling in NELP-I Block KG-DWN-98/2,

KG Offshore, Andhra Pradesh

1

Risk Assessment

1. RISKS AND HAZARDS

Hydrocarbon operations are generally hazardous in nature by virtue of intrinsic chemical

properties of hydrocarbons or their temperature or pressure of operations or a

combination of these. Fire, explosion, hazardous release or combinations of these are

the hazardous associated with hydrocarbon operations. These have resulted in the

development of more comprehensive, systematic and sophisticated methods of Safety

Engineering such as Hazard analysis and Risk Assessment to improve upon the integrity,

reliability and safety of hydrocarbon operations.

In the present study, deep water drilling is being taken up in NELP-I block KG-DWN-98/2.

Bathymetry in this area ranges from 300 m - 3100 m and wells of approximate depth of

2000m to 7000 m from the sea surface will be drilled.

These blocks are located at a distance of 28-250 km from the coast. The risk assessment

encompasses identification of risks involved in the drilling process and assessment of

probability that may result in certain consequences and preventive/existing control

measures and the additional control measures required are discussed in detail.

1.1 IDENTIFICATION OF RISKS HAZARDS IN EXPLORATORY DRILLING OPERATIONS

Taking into account the applicability of different risk aspects of the offshore drilling

operations to be undertaken in the block KG-DWN-98/2 major categories of hazards that

can be associated with proposed project has been dealt with in detail. They are as follows:

Table-1: Major hazards and risks of Oil/Gas well drilling

Sl.No. Hazards Risks

1. Blow out Fire, Oil spill

2. Oil Spill Fire, Environmental damage

3. Collision of offshore vessels Damage to Rig, BOP stack, Blow out, oil spill



2

4. Helicopter crash – ditch into sea Loss of life/property damage

5. Presence of H2S Loss of life

Specially for deep water

1. Low fracture Gradients Shallow gas Blowouts

2. Low Temperature and High pressures

Hydrate Problems

All the above mentioned hazards are significant and will have major consequences. In

addition to these, changes in physical parameters of ocean do have significant impact on

offshore deep water drilling. All the causative factors have been evaluated and through

risk ranking criteria detailed below and the risk reduction measures existing and residual

risks of these have been evaluated and detailed in the Table-5 at the end of this chapter.

The following risk ranking matrix has been used for assessing the risks of various activities

of exploratory drilling. All the risks and hazards have been evaluated based on the

likelihood of occurrence and magnitude of consequences. The significance of the risk is

expressed as the product of likelihood and the consequence of the risk event, expressed

as follows: Significance = Likelihood X Consequence, risk matrix Figure-1. Risk ranking

criteria) in three regions that identify the limit of risk acceptability according to the policy

and the strategic objectives of ONGC is given in Table-2. Depending on the position of

the intersection of a column with a row in the risk matrix, hazard prone activities have

been classified as low, medium and high thereby qualifying for a set of risk reduction /

mitigation strategies. Risk ranking methodology has been given in end of this chapter as

Appendix-1.



3

Table-2: Criteria for the Risk Ranking

Severity of incident (or consequences)

FATAL / HIGH POTENTIAL MAJOR

Personnel

Fatality or permanently disabling injury

Man Overboard Environmental-

significant release with serious off-site impact and more likely than not to cause immediate or long term health effect

Property Damage

Blowout/ Explosion / Major Fire

Helicopter Crash Cost (Equipment damage)-major or total destruction to process areas estimated at a cost more than Rs 5,00,000/- (Five lakhs) Shut Down –

More than 24 hours down time

Public image:

National and International

MAJOR Personnel

one or more serious injury/disabling injury

man hour loss more than 500 hrs

Environmental-

significant release with serious off-site impact

Property Damage

Vessel Collision Cost(Equipment damage)-

major damage to process areas; estimated at a cost more than Rs 1,00,000/- (one lakh) up to Rs 5,00,000/- (Five lakhs)

Shut Down / Failure

Critical Equipment

More than 12 hours. Public image: Industry wide

attention Fire:

15 mins and above

Explosion

MINOR Personnel

not severe injury resulting in more than one day off MTC

Environmental-

release which results in agency notification or permit violation

Cost(Equipment damage)-

some equipment damage at an estimated cost > Rs 5000/- (Five thousand) up to Rs 1,00,000/- (One lakh)

Shut Down –

More than 06 hours. Public image:

Area Fire:

Less than 15 mins

SIGNIFICANT Personnel

less than one day off MTC

Environmental-

environmentally reportable event with no agency notification or permit violation


minimal equipment damage at a minimal cost up to Rs 5000 (Five thousand)

Public image:

Confined to installation.

Fire:

Up to 2 mins

RECORDABLE

Personnel First aid incidents Environmental- environmentally recordable event Cost(Equipment damage)- No recordable equipment damage

SCORE 5 4 3 1 1

Prob. of occurrence (or likelihood)

Negligible Low Medium High Frequent

No known occurrences in the industry

Known to have occurred in the industry

Known to have occurred in the company

Known to have occurred in the Asset/Drilling

Services

Known to have occurred on this Rig

GRADE A B C D E



4

RISK MATRIX

Likelihood

Negligible Low Medium High Frequent No known occurrences in the industry

Known to have

occurred in the industry

Occurs in the

company

Occurs in the

Asset/Drilling Services

Occurs on this Rig

Se

ve

rity

People Asset Environment A B C D E

Recordable

First aid incidents

No recordable equipment damage environmentally recordable event 1

Significant Less than one day off MTC

Minimal equipment damage at a minimal cost up to Rs 5000 (Five thousand)

Significant Environmentally Incident

2

Minor not severe injury resulting in more than one day off MTC

Cost(Equipment damage)

Damage cost Rs 5000-1,00,000/- Shut Down

More than 06 hours.

Fire: less than 15 minutes

Release which results in agency notification or permit violation

3

Major One or more serious injury/disabling injury

Man hour loss more than 500 hrs


major damage to rig estimated at a cost more than Rs 1,00,000/- (one lakh) up to Rs 5,00,000/- (Five lakhs)

Shut Down / Failure

Critical Equipment

More than 12 hours. Fire:

15 mins and above

Significant release with serious off-site impact

4

FATAL / HIGH POTENTIAL MAJOR

Fatality or permanently disabling injury Man Overboard

Cost (Equipment damage)

major or total destruction to process areas estimated at a cost more than Rs 5,00,000/- (Five lakhs) Shut Down

More than 24 hours down time

Significant release with serious off-site

impact and more likely than not to

cause immediate or long term health

effect

5

Fig-1: Risk Ranking Matrix



5

Table-3: Risk Categories and Significance of Criterea

1.2 MAJOR HAZARDS

1.2.1 BLOWOUT

A blowout in a hydrocarbon exploration activity can be defined as any uncontrolled flow

of formation fluids from the reservoir to the surface, due to formation pressure exceeding

the hydrostatic pressure of the mud or fluid column and failure of secondary blowout

prevention measures. For an offshore drilling activity, blowout events may occur at the

drill ship level or subsea and may result in pool /jet fires, or sometimes may lead to release

of toxic gases like Hydrogen Sulphide.

Blowouts during offshore operations may be initiated during exploratory drilling phase and

also as a result of external causes viz. earthquakes, ship collision, and structural collapse.

In the context of the proposed project, offshore operations will be limited to exploratory

drilling and testing. Therefore, any incidence of blowout during the aforesaid phases may

occur as a result of loss of well control due to formation fluid entry into well bore, well head

damage or loss of containment. The underlying causes of most of the blowout incidents

(excluding external causes) occurring worldwide can be interpreted as organizational and

managerial. An analysis of blowout causes into such factors attempted for the Marintek

database (NSFI 1985) revealed that the main causal factors were improper maintenance,

operational failures and inadequate supervision. Blowout followed by ignition, which

prevents access to the wellhead is a major hazard.

Contributors to blowout are:

Risk Criteria Definition

Low (Continuous improvement)

The level of risk is broadly acceptable and no specific control measures are required.

Medium (Risk reduction measures)

The level of risk can be tolerable only once a structured review of risk-reduction measures has been carried out.

High (Intolerable risk)

The level of risk is not acceptable and risk control measures are required to move the risk figure to the previous regions.



6

a) Primary

Failure to keep the hole full

Mud weight too low

Swabbing during trips

Lost circulation and

Failure of differential fill-up equipment.

b) Secondary

Failure to detect and control a kick as quickly as possible

Mechanical failure of BOP

Failure to test BOP equipment properly

Damage to or failure of wellhead equipment

Failure of casing; and

Failure of formation or cement bond around casing.

1.2.2 BLOWOUT FREQUENCY ANALYSIS

Blowout frequency estimates are obtained from a combination of incident experience and

associated exposure in a given area over a given time period. Due to limited offshore oil

& gas related data in our country, blowouts that have occurred at other offshore locations

worldwide have been considered for the blowout frequency analysis. Input data for the

frequency analysis of blowout events were taken from World Offshore Accident Database

of DNV1. Review of blowout frequencies from the database reveals a frequency

1.1 X 10-2 per operation per year for drill ships compared to Jack-up Rigs (9.8 X 10-3) and

Fixed Platforms (9.3 X 10-4). This higher frequency for drill ship can be attributed to the

fact that drill ships being utilized for deep sea drilling are often difficult to control because

of required motion compensation, especially, if the weather becomes rough, compared to

fixed offshore installations thereby translating into higher risk for blowouts. Since the

proposed project involves only exploratory drilling, measurement of exposure for blowout

incidents has been determined by considering blowout frequencies during well drilling and

by the rig type. The blowout frequency for the proposed ten wells have been obtained by

multiplying the blowout frequencies per well per year by the number of wells drilled, and

the time taken for drilling each well.



7

Estimated frequency for blowout for the proposed drilling operation in exploratory block –

KG-DWN-98/2 is: Probability for blowout from fifteen drilling operations = 1.1 X 10-2 (prob/

year / drilling operation) X15 (no of drills) X 0.2 (time taken for each drill in yrs) =

3.3 X 10-2.

1.2.3 BLOWOUT CONSEQUENCES AND EFFECTS

A blowout incident can take a variety of different forms, ranging from a minor leak which

can be stopped within minutes, to a major release which continues out of control for days

or even months. The consequences of a blowout event will to a large extent depend on

how the blowout scenario evolves and the following possible scenarios are likely:

Release of oil resulting in a slick or spill on the sea release of drilling fluids and

resulting spill leading to contamination of marine environment.

Release of toxic / flammable gas which may have deleterious effect on the drill ship

personnel.

Ignition of the flammable gas / oil released resulting in a jet fire, pool fire or an

explosion

Ignition of released oil and gas can possibly result in considerable harm, with historical

data showing 40 % blowout such incidences leading to more than significant damage to

the drilling ship / platform (WOAD database) and resulting in associated fatalities amongst

drilling crew and support personnel present on the ship / platform. Also, ignition has been

recorded in about 30% of the blowout cases on an average (SINTEF offshore blowout

database). However, on positive side, with improvement of offshore drilling technology,

number of offshore blowouts occurring has significantly gone down in the last decade.

If the hydrostatic head exerted by the column of drilling fluid is allowed to drop below the

formation pressure then formation fluids will enter the wellbore (this is known as a kick)

and a potential blowout situation has developed. Fast and efficient action by operating

personnel in recognizing the above situations and taking precautionary measure can avert

a blowout.



8

1.3 COLLISIONS INVOLVING DRILL SHIP (MODU)

A collision situation is considered for the risk assessment for the impacts on MODU by

other drill ships or other marine vessels working nearby or passing by it.

The following possibilities have been taken into consideration:

Visiting support vessels which approach the MODU under their own power

and including supply vessels, standby vessels, etc. Collisions Involving

MODU and Passing Vessels.

Collisions with offshore oil structures involving passing vessels are generally

very rare (about 5 % of all reported collisions) but can be potentially very

damaging.

Collisions involving Supply and Other Vessels

1.3.1 CONSEQUENCES AND EFFECTS

The analysis of collision consequences is generally based on the principle of conservation

of energy. However, in the case the collision there is a glancing blow from a support

vessel, where the vessel brushes against the platform, the kinetic energy transfer is

minimal and is expected to cause minimal damage to the MODU. The impact of a full-on

collision may however be more severe and may lead to structural damage to the MODU.

The risk to personnel manning a platform / drill ship from a collision in terms of fatalities

or injuries has been historically found to be very low, if not resulting in a catastrophic

incidence like a blowout. It should be noted that the MODU would be connected to the

drilling apparatus at the sea bottom. A collision involving high energy transfer may lead to

a rupture or leak in the riser resulting in a process leak or a blowout.

1.4 HELICOPTER CRASHES

The journey to and from offshore installations has historically been one of the main

reasons for accidental death or injury to many offshore workers. For the drilling activities,

crew transport to and from the MODU will be by helicopter, due to its speed, convenience

and good operability under rough weather conditions and Frequency Probability.



9

Several approaches exist to analyze probability of helicopter crash risks. A more

reasonable approach involves the use of individual risk approach as a product of three

components:

Frequency of helicopter accidents per flight;

Proportion of accidents which involve fatalities;

Proportion of personnel on board in fatal accidents who become fatalities.

1.4.1 CONSEQUENCES AND EFFECTS

Helicopter crashes involved with offshore oil & gas exploration and production have

happened routinely in the past, especially in the North Sea offshore operations in Europe,

with some resulting in fatalities or injuries to crew members. In addition to the risk posed

to the helicopter occupants, accidents involving helicopters can also cause damage to the

drill ship itself by way of crashing into the ship during take-off or landing or by an accident

when the helicopter is on the helideck. However, the consequence of such risk may be

considered to be small compared to the other risks sources on the MODU.

1.5 CONTROL MEASURES FOR MAJOR HAZARDS

1.5.1 BLOWOUT

The precautionary and control measures used for blowout prevention are discussed

Below:

A. Precaution against Blowout

1. The following control equipment for drilling mud system shall be installed and

kept in use during drilling operations to prevent the blowout:

A tank level indicator registering increase or reduction in the drilling mud

volume and shall include a visual and audio –warning device near the driller

stand.

A device to accurately measure the volume of mud required to keep the well

filled at all times.

A gas detector or explosive meter at the primary shale shaker and

connected to audible or visual alarm near the driller stand.



10

A device to ensure filling of well with mud when the string is being pulled

out.

A control device near driller stand to close the mud pump when well kicks.

2. Blowout prevention (BOP) drill shall be carried out once every week near the

well during drilling.

3. Suitable control valves (Koomy control) shall be kept available near the well

which can be used in case of emergency to control the well.

4. When running in or pulling out tubing, gate valve and tubing hanger shall be

pre- assembled and kept readily available at the well.

B. Precaution after Blowout

On appearance of any sign indicating the blowout of well, all persons, other than

those whose presence is deemed necessary for controlling blowout, shall be

withdrawn from the well. During the whole time while any work of controlling a

blowout is in progress, the following precautions shall be taken:

1. A competent person shall be present on the spot throughout.

2. Area within 500 meters of the well on the down wind direction will be demarcated

as danger zone.

All electrical installations will be de-energized.

Approved safety lamps or torches will only be used within the danger zone.

No naked light or vehicular traffic will be permitted within the danger zone.

3. A competent person shall ascertain the condition of ventilation and presence of

gases with an approved instrument as far as safety of persons is concerned.

4. Two approved type of self-containing breathing apparatus or any other breathing

apparatus of approved type will be made available for use in an emergency.

5. Adequate firefighting equipment will be kept readily available for immediate use.

2.0 OIL SPILLS AND SPILL CONTINGENCY PLANS

As with any hydrocarbon development, oil spill risks are associated with exploraotory

drilling activity. They may vary from a few litres of accidental spill of diesel from offshore

vessels to several thousands of tons of oil during unexpected blow out situations. In line



11

with the standard industry practice and NOSDCP guidelines, ONGC has prepared

continegency plan(Annexure-ii) to mitigate spills. ONGC has developed OSR facilities

for Tier-1. For larger spills (Tier-2 & 3) ONGC has MOU with ICG (Indian Coast Guard)

and international agency like OSRL, Singapore. With industry co-operation and external

intervention. The spill may occur due to leakage at well head or oil wells blow out.

The spill may be: Instantaneous Spills or Continuous Spills. However, it is required to

have a fair understanding of the risks and probability of spills arising out of its operations

and their consequences due to movement and possibility of landing/infecting along the

coast.

The surface or subsurface oil spill consists of slick floating on the water surface, which

partially dissolves in the water and partially evaporates into the atmosphere. There is a

continuous exchange between the suspended and surface oil (floating oil). The

assumption made in deriving the governing equations is that the thickness of the oil layer

is negligible in comparison with the water depth. In addition to the location, size, and

physico-chemical properties of the spill, and other major factors affect the fate of the oil

slick which are governed by complex interrelated transport and weathering processes.

The spilled oil spreads and moves by the forces of winds and currents. A small portions

of hydrocarbons begin to go into solution in the underlying water column, but most of the

oil is lost through evaporation into the atmosphere. In the present model, all these

processes are considered in the transport of Oil Slick.

The oil spill analysis has been carried out using Hydodyn-OILSOFT model. This model

was developed by Environ Sotware (P) Ltd, Bangalore. It is used for predicting the oil spill

trajectory, weathering processes and their charateristics during the following oil spill

scenarois as stated below:

a) Instantaneous Spills:

700 tons (Crude oil spill at the proposed well locations in the Block)

b) Continuous Spills:



12

Leakage of crude oil of 800 m3/day for 1 day (24 hrs) at the proposed well

locations in the Block (due to minor blow out the well location/ accident to

the shuttle tanker)

Leakge of crude oil of 2000 m3/d (24 hrs) at the proposed well locations of

the Block (due to blow out at the wall)

Leakage of crude oil of 366 m3/hr for 15 min at the proposed well locations

of the Block (due to hose leakage)

East coast is enclosed with open sea where tidal forces interact with open ocean water.

The current of the region are tidal driven and the water column is vertically well mixed. A

recent study carried out for the movement of oil spill in the nearby region shows that

movement of oil slick is more governed by:

Wind movement rather than current

Season - An important factor as the wind direction and also current direction

changes

Main spill scenario only have been assessed, as smaller spills of tank over flow, joints and

valves leak etc. will result in lesser spill than the ones listed below. However, the

probabilities of their taking place as per the statistical modeling have also been given:

2.1 RUPTURE OF FLOW LINES/MAIN OIL LINES/HOSES/SUB SEA LINES:

An oil spill from rupture of flow lines of any one of the wells will activate the auto shut off

valves of the concerned well through appropriate control system. In case of auto shut off

not functional and, taking into consideration the rate of oil flow, length and diameter of the

pipe (Length 25 km (Worst case scenario), Diameter 20 cm and reaction time of 15

minutes), it is estimated that a maximum of 360 tons of oil will spill at a flow rate of 90

TPH. (Volume of Spill = 2 Pie X Radius of Pipeline X Length of Pipeline X Flow Volume)

2.2 ACCIDENT INVOLVING VESSELS AND/OR OFFSHORE INSTALLATION:

An oil spill due to collision between a vessel and the installation will result in a spill of

about 500-1000 tons depending upon the size of vessel (capacity of wing tanks of any

vessel) into the sea. The larger vessels are not operating in the ONGC operational area.

2.3 WELL BLOWOUT INCIDENTS:



13

An oil spill due to Well Blow out is possible during deep-water exploratory drilling. Well

Blow out is also possible during any subsequent “Well Intervention” of existing wells for

Work - Over activities. In the event of an unfortunate well blow out, the situation will call

for the immediate services of Well Control specialists. But, adherence to established

drilling procedures which includes proper use of Blow out Preventers (BOPs) of rated

pressures will adequately control the oil spill risk due to well blow outs.

The amount of oil spill in a blow-out can be quantified for different time options at the flow

rate of 960 tons per day, viz 40 TPH, on a higher side. Depending upon the response

time, following amount of oil can spill from the well:

S.N. Response Time Oil Spilled

1 6 hours 240 tons

2 24 hours 960 tons

3 48 hours 1920 tons

The KG basin crude evaporates to the tune of 40 % by volume, and hence only 60 % of

the spilled volume will be on the water surface. This will get emulsified with sea water to

make it four times the oil volume. In this scenario, an initial oil spill of 240 tons will get

reduced to 144 tons, but will emulsify to almost 700 tons, if the blow out is capped within

6 hours. Similarly for a blow-out which takes two days to cap, will spill almost 5000 tons

oil.

These figures have been assumed for cold blow out. In hot blow out, only 25 % of this

oil quantity will spill, and the remaining 75 % will get burnt. This is the reason for taking

three spill scenarios of 100, 700 and 5000 tons for spill tracking models.

Other probabilities of risks are given below:

2.3.1 PERCEIVED RISK (NUMERICAL VALUES GIVEN BELOW ARE ILLUSTRATIVE

FAILURE FREQUENCY)

Operator shall perceive the risk of the oil spill from their operating facilities considering

likely sources of spill, expected quantity and its impact on the environment. A contingency

plan shall include following elements while describing perceived risks:

1) Sources and expected quantity of oil spill



14

2) Pipelines, Hoses and Arms leakage / rupture

Riser failure - Failure frequency

- Above sea portion 20%. (HSE, 10% (DNV)

- Sub-sea portion 47%. (HSE 29%)

- Splash Zone portion 33%. (HSE 52%)

- Riser size 12” <D<16: = 1.47X10-5/year

- Riser size 4”<D<8” = 2.68X10-6/year

- Riser sized>16” = 1.84X10-5/year

Flow line / Hoses / Arms

- Partial rupture = 1.25X10-5/year

- Total rupture = 3.94X10-5/year

Main Oil Line

- Total rupture – 18-24” Oil Line 1.76X10-5/year, 10-16” Oil Line 2.26X10-5/year

Blow Out

- 5X10-3/well year (development and exploratory indicative for onshore and offshore

area)

- 1.4X10-3/well work-over.

Leakage from Coupling / Joints / Valves

- Hose joints = 3.94X10-5/year

- Block valve -3-11” = 1.08X10-4/year, >3” =6.99X10-5/year, <11”=3.95X10-5/year

- Flange Joints 3-11” = 5.56X10-5/year

>3” = 3.95X10-5/year

<11” = 768X10-5/year

Tanker Grounding / Collision / Platform / System failure

Spill depend upon the size and the extent of damage to the ship

MSV 3X 10-3/year,

OSV 1.8X10-4/visit

Passing vessel 11.07X10-4/year (may be applicable for fishing vessel),

2.4 SABOTAGE OR TERRORISM:

Will result in a spill scenario as given in serial a and b

2.5 UNDER WATER DAMAGE DUE TO TSUNAMI EFFECT:



15

After the 2004 Tsunami in addition to the risk quantification, it is also required to have a

fair understanding of the risks and probability of spills arising out of its operations and

their consequences due to movement and landing along the coast.

2.6 SUB SURFACE OIL SPILL PLUME

Average current speed varies from 0.33 m/sec to 0.13 m/sec from surface to bottom

respectively in the east coast. We have assumed that a uniform density of sea water from

bottom to surface and the spill moves to surface with the velocity computed based on the

difference in densities of sea water & oil and vertical velocity. The spill at subsurface will

move to surface and loses its volume due to dissolution and bio-degradation activities.

The final quantity that reaches the surface is considered for subsequent oil spill analysis.

The study areas are very high and water depths are in the range of 600–2000 m

dissolution loss will be high.

Fig-2: Sub Surface Oil Spill Plume



16

Fig-3: Oil / Gas Well Blow-out Communication Flow Chart

OIL/GAS BLOW OUT

Try to control the flow /close the well

Base Radio room/Control room

Rig crew/vessel/person noticing first

Radio room Local/Base

Shift in Charge

Drilling rig/Onshore terminal

Tool pusher /Resident

Engineer

Medical Officer

Fire-fighting vessel

Muster in charges of Life

boats

ON SCENE COORDINATOR/RCMT ECR (Onsite on vessel) I/C Maintenance

I/C HSE & I/C Fire

service

I/C Security

CHIEF EMERGENCY COORDINATOR

ED-AM EOA KAKINADA

Head Eng.Serv.

I/C HR/Medical services

I/C Logistics & OSR Vessel

Indian Coast Guard for SAR

and OSR ECR (Offsite)

I/C Infocom

I/C MM & I/C

Finance

Communication to HQ

Communication to outside ONGC



17

Blow out Control Equipment

The Blow out control Equipment is a critical equipment used to control high pressures

encountered during drilling of deep water reservoirs preventing the flow of well fluids to

surface. The blowout preventer is function tested and pressure tested along with choke

and kill lines. More details are placed in the Annexure-1

2.7 VESSELS COLLISIONS

A Vessel Management Plan will be formulated and implemented to reduce collision risk,

both vessel–vessel and MODU–vessel and will address the following:

Mandatory 500 m safety zone around platform;

Operational restrictions on visiting vessels in bad weather;

Defined vessel no-go areas within safety zone; and Agreed approach procedures

to platform by supply and safety vessels.

2.8 HELICOPTER CRASHES

Following preventive and mitigation measures will be adopted with respect to helicopter

operations:

Air worthiness of helicopter will be checked by competent authority before

helicopter is hired by ONGC. All ONGC operated Helicopters are AS-4

compliant

Adequate training will be ensured to the pilot/pilots operating similar craft.

Effective arrangements for coordination will be developed with air traffic control

room at Base port, as also in the MODU;

Helicopter operations will be restricted during night time and during bad weather

conditions.

All employees who are supposed to travel on helicopters will be given basic

training on rescue and survival techniques in the case of a helicopter crash at

sea.

3.0 HYDROGEN SULPHIDE (H2S)

Hydrogen sulphide gas (H2S) is extremely toxic, even very low concentrations can be

lethal depending upon the duration of exposure. Without any warning, H2S may render



18

victims unconscious and death can follow shortly afterwards. In addition, it is corrosive

and can lead to failure of the drill string or other tubular components in a well. The following

safety measures may become necessary as and when H2S is detected while drilling and

testing a new well in drilling. The Occupational Safety and Health Act (OSHA regulations)

set a 10 ppm ceiling for an eight hourly continuous exposure (TWA limit), a 15 ppm

concentration for short term exposure limit for 15 minutes (STEL) and a peak exposure of

50 ppm for 10 minutes.

3.1 H2S Gas Detection System

A four channels H2S gas detection system will be provided. Sensors will be positioned at

optimum points for detection, actual locations being decided on site but likely to be:

Well Nipple

Rig Floor

Shaker header tank

Substructure cellar

The detection system will be connected to an audio visual (siren and lights) alarm system.

This system will be set to be activated at a concentration of 15 ppm H2S.

The mud logging will have a completely independent detection system which is connected

to an alarm in the cabin. This system will be adjusted to sound an alarm at a concentration

level of 10 ppm H2S as suggested in the Drilling and Production Safety Code for Onshore

Operators issued by The Institute of Petroleum.

A stock of H2S scavenger will be kept at drilling site for emergency use.

a. H2S < 10 ppm

Small levels of H2S (less than 10 ppm) will not activate the well site alarms. Such levels

do not create an immediate safety hazard but could be a first indication of high levels of

H2S to follow.

H2S will cause a sudden drop of mud pH. The mud man will therefore organize and

supervise continuous pH checks while drilling. Checks should be as frequent as possible

and always made following a formation change.



19

Following control measures will be taken in case of small level of detection:

H2S scavenger will be added to mud.

H2S levels will be checked at regular intervals for possible increase.

All personnel of the rig will be informed about the presence of H2S and current wind

direction.

Operations will be commenced in pairs.

Sub base and cellar out-of-bounds will be rendered without further checking levels

in this area.

The workers will be provided with personal H2S detectors along with self-containing

breathing apparatus.

b. H2S >10 ppm

Higher levels of H2S (greater than 10 ppm) do not necessarily cause an immediate safety

hazard. However some risk does exist and, therefore, any levels greater than 10 ppm

should be treated in the same manner. Occurrence of 10 ppm or greater H2S

concentration will sound an alarm in the mud logging unit.

If higher levels of H2S greater than 10 ppm are found, following steps will be taken:

Driller will shut down rotary and pumps, pick-up so that drill pipe in BOP and chain

down the break.

One pre-assigned roughneck will go to doghouse and put on breathing apparatus.

All other rig personnel will evacuate the rig and move in up-wind direction to

designated muster point.

Driller and roughneck will return to the rig floor and commence circulating H2S

scavenger slowly and reciprocating pipe.

The level of H2S will be checked in all work areas. H2S scavenger will be added to

the mud and circulated. If H2S levels drop, drilling will be continued with scavenger

in the mud. Approximately 30 % of hydrogen peroxide (H2O2) solution will

neutralize H2S gas in the mud at 20 gallon of H2O2 per 100 barrels of mud.

The workers will be provided with personal H2S detectors along with self-containing

breathing apparatus.



20

4.0 LOW FRACTURE GRADIENTS HIGH PRESSURES AND LOW TEMPERATURES

The development of deep water and ultra-deep water operations brings new and more

complex technical challenges due to harsh conditions encountered at these depths.

Ranges of temperature and pressures (Temperatures of 2o C and pressure up to 400 bars

are common at the mud line) are extreme.

The drilling fluid while flowing through well and riser length will experience temperatures

ranging from 0oC to 150o C and must keep its properties for this whole range. The mud

rheological properties will strongly depend on temperature and pressure variation and

these variations will be different for different mud formulations.

These temperature and pressure ranges are also favourable conditions for the formation

of gas hydrates in drilling mud. Hydrates are solid structures formed from water and gas.

Water content in drilling mud forms a solid structure with gas molecules under certain

temperature and pressure conditions. Formations of these solid gas hydrates is likely to

plug, kill and choke lines as well as annular spaces, and may cause interruption of drilling

operation and even destruction of rig equipment. Use of thermodynamic inhibitor

additives (mainly salt and glycol additives), displaces the equilibrium point of hydrate

formation.

In this block, water depth ranges from 300m-3100 m. Drilling in these extreme water

depths may require the use of riser less drilling technique. Riser less mud recovery (RMR)

provides a dual gradient drilling setup of the well while capturing the drilling fluids and

returning it to the drill ship. The term dual gradient implies two hydrostatic gradients:

The sea water gradient that begins at sea surface

The drilling mud gradient that begins at the sea floor

Conventional drilling has only one pressure gradient for both sea water and mud that

originates at sea surface. Because dual gradient drilling has much less hydrostatic head

associated with the drilling mud in the borehole, drilling fluids can be properly weighted

allowing drilling to be more easily with in the formation pore pressure and fracture

pressure there by avoiding well bore instability.

Initially a 12¼” investigative hole will be drilled to check any shallow water flows. Any flow

will be killed with Heavy Mud. The 36” conductor casing will be jetted up to 90m below



21

mud line and further drilling with 26” bit will be carried out with Pump and Dump method

after pumping High viscous Sweep displaced with Inhibitive Glycol mud. Casing 20” will

be lowered and cemented.

Low sea bed temperatures and high water depths may lead to the formation of gas

hydrates inside the BOP. The freezing point is suppressed using the salts up to the density

limits, and then with mono-ethylene glycol and PAG ((Poly-Alkylene Glycol). Achievement

of adequate cuttings transport in the long riser section at the relatively low annular

velocity is the critical factor. The mud’s carrying capacity must be maintained. And the

riser flow rate should be boosted wherever possible. Good shear thinning characteristics

are therefore required to minimize the PV. The ECD will be closely monitored to avoid

exceeding the expected low fracture gradients.

In case of any borehole problem environment friendly Synthetic Oil Base Mud will be used.

After lowering Riser and BOP, further drilling will be resumed with RHELIANT Synthetic

Oil Base Mud up to target depth.

5.0 FIRE FIGHTING FACILITY

As per Oil Industry Safety Directorate (OISD) guidelines on fire and explosion risk

assessment and fire protection system for offshore installations will be provided:

Fire water system; and

First aid and fire-fighting system.

5.1 FIRE WATER SYSTEM

Fire water system shall comprise of fire water pumps and distribution piping network along

with deluge system, sprinkler system, hose reels, hydrants and monitors, as the main

components. Sea water is used for fire extinguishments, fire control, cooling of equipment

and for exposure protection of equipment/personnel from heat radiation.

Fire water pumps will be designed to deliver the pressure and flow requirements for the

anticipated manual fire-fighting demand (monitors or monitors plus hose streams) as well

as operation of the largest deluge/water spray system if installed. The pump shall able to

supply adequate pressure and flow, to the hydraulically most demanding area. As a

minimum, the fire water pump will be sized to deliver 180 gpm.



22

Fire water piping will be designed to deliver the required volume and pressure for all

systems, hose streams, and monitors that are reasonably expected to operate

simultaneously. One fire water distribution single line with minimum 4 “size pipe/casing

will be installed at drilling site.

Recommended fire water hoses will be of diameter 1 in. (25 mm) or 1'/2 in. (38.1 mm) for

effective handling by one person. Hose lengths of not more than 100 ft (30.5 m) will be

used. The selection of hoses will be made such that that they are resistant to oil, chemical

deterioration, mildew, rot and exposure to offshore environment.

5.2 FIRE FIGHTING EQUIPMENT AT DRILLING RIG

Portable fire extinguisher will be installed as per IS: 2190 on the drilling rig. The minimum

quantities of fire extinguishers at various locations should be provides as per the following:

Table-4: Location of the firefighting gadgets at drilling rig

Sl. No. Type of Area Portable Fire Extinguisher

1. Drilling Rig floor 2 nos. 10 kg DCP type extinguisher

2. Main Engine Area 1 no. 10 kg DCP type extinguisher for each engine

3. Electrical motor/pumps for water circulation for mud pump

1 no. 10 kg DCP type extinguisher

4. Mud gunning pump 1 no.10 kg DCP type extinguisher

5. Electrical Control Room 1 no. 6.8 kg CO2 type extinguisher for each unit

6. Mud mixing tank area 1 no. 10 kg DCP type extinguisher

7. Diesel storage area 1 no. 50 lit mechanical foam

1 no. 50 kg DCP type extinguisher

2 nos. 10 kg DCP type extinguisher

2 nos. sand buckets or ½ sand drum with spade

8. Lube Storage Area 1 no. 10 kg DCP type extinguisher

1 no. sand bucket

9. Air Compressor area 1 no. 10 kg DCP type extinguisher



23

Sl. No. Type of Area Portable Fire Extinguisher

10. Fire pump area 1 no. 10 kg DCP type extinguisher

11. Near Drill In-charge Office One fire extinguisher/shed with 3 nos. 10 kg DCP type extinguisher and 2 sand buckets

12. Fire bell near bunk house 1 no. 10 kg DCP type extinguisher



24

Activity Hazards Consequences Preventions Mitigations Risk ranking Recommendatio

ns/Comments S L RR

Hot work and Welding activity

Fire And Explosion

Equipment Damage

Damage to the eyes and skin of the welder

Getting burned by

fires and explosions

Elimination / Substitution- Perform hot work in a safe location or fire hazards removed or covered

Control

Permit to work system

Adherence to safe code of practice Vol. 1, Part IV, Section 12 (Welding and cutting)

Monitoring of the LEL shall be continuous until the hot work is completed

To protect the immovable fire hazards

Use guards to confine the heat, sparks, and slag, and

Do not perform hot work where flammable vapors or combustible materials exist. Work and equipment should be relocated outside of the hazardous areas, when possible

PPE (Welding goggles and gloves)

fire-

Make suitable fire -extinguishing equipment immediately available. Such equipment may consist of pails of water, buckets of sand, hose, or portable extinguishers and be trained in its use Activation of ERP

4 D 4D

High

For non- routine jobs JSA is carried out Assign additional personnel (fire watch) to guard against fire while hot work is being Performed. Fire watchers are required whenever welding or cutting is performed in locations Where anything greater than a minor fire might develop.

Drilling ( Prior actions to start of drilling operations)

Physical injury Equipment damage Environment damage

Major injury Loss of property

JSA(Pre-spud) checklist as per OISD-RP-190 Executing check list

--First aid facility --Doctor onboard --Stand by equipment/tools for carrying out activity safely

3 B 3B

Low

Tool box talk and better supervision

Table-5: Identification of various hazards, its consequences and prevention and mitigations measures of exploratory drilling



25

Rig Move (Offshore)

Structural damage to rig

Structural damage to platform Wells damaged Pipeline damage

Loss of company property Production loss Opportunity loss

-- Pre-move meeting/rig move meeting prior to the move in the presence of surveyor --Inspection of OSV/Tow boat prior to move --Updated seabed survey report and pipeline drawings used in rig move planning --Relevant preloading guidelines to be adhered to as per RCP, Volume-I.

Examine the weather forecast of the intended transit time

Pre-move meeting in the presence of rig I/C

Observe daily weather forecasts & monitoring during transit

Availability of anchoring facility

Ensure Rig has enough strength to withstand

--Presence of surveyor at the time of mobilization

- Suspend Rig Move - Release the tow boat - Anchor the rig - Facilities to evacuate the rig

- LSA & FFA

4 D 4D

High

Carrying out JSA before initiating the work

Drilling (Handling of tubular)

Phy Physical injury Equipment damage

Major injury Loss of property - Body contact with moving parts - Bursting of oil line

--Tubular handling appraisal procedure guidelines of IADC --Adherence to SOP as per OISD-187,190 -Safe work practices as per RCP- Vol-I

First aid facility Doctor onboard Stand by equipment/tools for carrying out activity safely

4 B 4B

Low

Tool box talk and better supervision



26

Drilling (Tripping)

Occupational hazard

Blow out Fire

--Possible major structural damage. --Possible multiple personnel injuries or fatalities.

--Possible loss of rig. --Possible environmental impact.

--Equipment damage(Travelling block hitting the crown block/derrick floor)

-Procedures and training. -Surface isolation equipment (BOP,

etc.). -Maintenance and testing of

equipment. -Instrumentation and indication of

well status. -Redundant BOP controls.

-Use of mechanical equipment such as pipe spinner, automatic slips, pipe handling equipment, Kelly spinner or top drive etc. to eliminate the occupational hazard -Ensure that Crown-o-matic/twin stop device is installed and working properly -Adherence to well control policy Special considerations during tripping as per guidelines of OISD-RP-174 -Redundant BOP controls.

Agreement with major well control company for call out services

Follow and activate ERP/RCP

--Emergency response procedure, training and drills. --Hospital on board. --Redundant life-saving /

fire-fighting equipment.

--Ability to evacuate the rig.

ERP/RCP activation

Online Hydrocarbon / Combustible Gas detection system.

Availability of LSA & FFA

Facilities to abandon the rig.

PPE like helmet, safety shoes, safety goggles

5 C 5C

High

Provision of Emergency Escape device

Provide sufficient skilled personnel as per competency policy during planning and operation



27

Helicopter operations

Helicopter Collision at helideck and other than helideck

Possible structural damage to rig. Disruption of operations. Possible fire risk (possible multiple fires). Possible personnel multiple injuries or fatalités. Possible environnemental impact.

--Clear helideck lighting and markings.

--Good communication with helicopter.

--Cranes racked – no one in crane cabins during helideck operations.

--Policies and procedures.

--Helicopter maintenance and flying practices are governed by DGCA a regulatory body. --Adherence to Safe Code of Practice Vol. 1, Part IV, Section 6 Designated HLO & HLA

-Emergency Response Plan.

-Emergency Response crew on station at helideck during Helideck operations. -Fire fighting equipment at helideck. -Multiple escape accesses from helideck. -Hospital on board.

-PPE to protect from ill effects of noise

-Helicopter rescue kit

-SAR operations Training (HUET)

5 B Low Religiously follow the DGCA guidelines including helideck design



28

Crane Operation

Dropped objects and Blocks

Possible personnel injuries and fatalities. Possible equipment or structural damage.

Proper signaling, communication. Proper lifting equipment. Preventative maintenance of crane

and lifting equipment. Proper training of personnel. Proper manifesting. DROPS Program to be

Implemented.

Operating Work Instructions as per Code of Safe Practice Vol. 1, Part IV, Section 11 (Material Handling Operation)

Proper procedure and posture while lifting the materials.

Each operator of a crane or other hoisting device be thoroughly trained and properly licensed to operate.

All crane operations shall be supervised by designated officer

Crane operators shall follow lifting directions ONLY from assigned signalers. However an “emergency stop” signal from any one on the location must be obeyed immediately

All safety devices provided on a crane such as boom stops, boom angle indicators, anti- two blocking switches shall be kept in proper working order

Before attempting any lift with

crane, rig operator shall first determine the weight of the load . No lift shall be attempted if load is beyond crane’s rated lifting

Hospital facility and trained medic on board.

Training Activation of ERP

4 E 4E

High

Insist on crane operators’ valid competency certificate



29

capacity as listed on chart for current boom angle

Cementing activity

Personal injury due to high pressure surge

Severe injury to persons


The cementing head shall be secured to the elevator links with wire rope safety line

All piping systems which will be exposed to either pump or well pressure shall be securely stacked down or secured in such a manner as to prevent any undue whipping of the pipe if a failure occurs


3 B 3B

Low

Material handling manually

Occupational Health Hazard

Lifting heavy load manually Occupational disease like back ache problem

Elimination / Substitution-

Mechanized Lifting equipment to be use where ever possible

Control


Proper procedure and posture while lifting the materials.

Training

4 C 20 (High)

For non-routine jobs JSA is carried out Tool box talk on particular topic before commencement of job



30

Personnel embarking or disembarking to boat

Serious / Fatal injuries

Fall of personnel

Strike against hard object of rig & boat

Elimination / Substitution- Minimize the use of boat for person

transportation Weather limitations should be

followed Control -Basic training -Proper Usage & maintenance of personal transfer basket -Enhance skill of operator -Operating Work Instructions as per -----Code of Safe Practice Vol. 1, Part IV, --Section 10 (Personnel and Material Transfer) --Adherence to Marine procedure including weather conditions specially for personal transfer

PPE like safety shoes, helmets, Life Jacket

4 C 4C

High

Follow Marine procedure religiously

ERP scenario Sabotage / Criminal Act / Riot / War

Fire hazard Equipment /

Property damage

--Physical injury or fatalities

--Loss of property --Disruption of

operations


Not Possible Control

Mock Drills as per ERP

Security & surveillance

Communication Facility

Offshore security coordination meeting

Adherence RCP & CDMP

5 B 5B

Medium

Follow CDMP



31

Spill of toxic chemicals/potentially hazardous materials

Emission /Release of Flammable or Toxic Substances .

Fire and explosion.

Occupational Health hazard

Multiple injuries or fatalities Structural damage due to H2S release


Use of non-toxic chemicals wherever possible

Control

Ensure that current MSDS is available at the rig site for all chemicals that are used

All hazardous materials shall be segregated from normal stores and clearly identified.

Hazardous materials labels shall not be removed from containers.

Fire &Gas Detection System

Preventive Maintenance

Class Certification. Of Rig

Safety Drills --Location surveys. --Monitoring during drilling. --Proper equipment. --Tubular inspections.

Follow ERP

PPE like safety shoes, helmets, safety gloves

Training and procedures. Emergency Response

Procedure. Ventilation shutdowns. PPE. H2S detection system. Ability to abandon rig.

3 B 3B

Low

Use of all motors and electrical equipment

Electrical safety/fire hazard

Damaged cable/junction box short circuiting leading to fire Physical injury Electrical shock


Electrical equipment are provided with automatic shutdown devices in case of short circuiting

Control

Program for inspection of electrical equipment and referring Code of Safe Practice Vol. 1, Part VI, Section 3 (Electrical Installation ( Offshore))

Electric safety audits

PPE like electrical shoe

Usage of proper tools with insulation

CPR facility

First aid training

4 D 4D

High



32

Confined space entry

Exposure to oxygen deficient atmosphere.

Fire due to static charge.

Asphyxiation

Fire hazard

leading to loss of material and pollution.

Fatality

Elimination / Substitution- Work shall be planned so as to prevent entry into a confined space Control

Oxygen test,

Purging of tanks with air.

Instructions as given in Code of Safe Practice Vol. 1, Part V, Section 1 &2 Fire Fighting Equipment and Procedures &

Wear a safety harness with an attached life-line

PPE like SCBA, hand gloves,

Fire Prevention and Control ( Offshore )

4 B 4B

Low

A stand-by man shall be assigned the duty of watching the persons working inside the confined space during the time they are inside. (Duties of stand by man shall be defined.

BOP nipple up and nipple down

- Physical injury - Equipment / Property damage - Fire hazard

- Cradle bolt may shear and BOP could fall - Winch wire may fail


Not Possible Control Normally only BOP winch is used - Crew briefing - Checking of cradle bolt, winch wire etc. - Safe work practices to avoid injury due to swinging or dropping of the blow-out preventer assembly Welding is not permitted on BOPs

- PPE like helmet, safety shoes & goggles

3 B 3B

Low

Possibility of Extra sling may be required.

Proper training to crew members

Logging operations

Radiation/ Exposure of substances. Health hazards

Physical injury Explosion effects on

property Occupational disease

Elimination / Substitution- Avoid manual connections Control Safety briefing prior to logging operations - Only qualified & trained person are entitled to handle RCP- Volume-I

- PPE like helmet, safety shoes & safety goggles

4 C 4C

Medium

Avoid primo card connections in hazardous area



33

ERP Scenario Severe Weather (on location)

Physical injury Equipment

damage Environmental

impact

Possible loss of rig. Possible personnel

injuries or fatalities.

Good monitoring of weather patterns in area.

Twice daily weather reports received.

Ability to suspend operations and

go to storm condition.

Ability to evacuate rig. Stand-by boat available. Emergency Response

Procedures.

4 C 4C

High

Note: Team feels that with good weather reporting and procedures in place that hazard can be considered ALARP.

Severe Weather (in transit).

Physical injury Equipment

damage Environmental

impact

Possible loss of rig. Possible personnel

injuries or fatalities.

Good monitoring of weather patterns in area.

Policies and procedures. Predetermined sheltered water

chosen before transit if possible. All watertight barriers sealed during

transit. Power of towing vessels meets

predetermined rating. Rig movers qualified by third party. Inspection of towing gear.

Ability to evacuate rig. Hospital on board. Stand-by boat would be

one of tow vessels.

5 B 5B (Mod)

Storage and handling of Radioactive materials

Leakage from stored Radioactive materials.

--Possible personnel injury. --Possible environnemental impact.

--Procedures. --Only on board when required. --Stored in isolated area with proper

containment and appropriate markings.

--Permit-To-Work required. --Inventory of radioactive material

available to OIM at all times. --Third Party Rig-Up permits.

Hospital facility on board.

2 B 2B

Low

Follow Explosive and Radioactive Manual

Towing Towing failure. Possible structural damage.

--Policies, procedures, training. PMS. --Accurate weather forecasting. --Certification of towing gear. --Multiple redundant tow boats (3).

Redundant towing lines. Line throwing device to

reconnect tow. Backup towing line. Ability to drop anchors. Ability to jack down the

legs (in calm weather only).

Ability to abandon rig.

3 B 3B

Low



34

Well Testing Major Fire / Explosion during Well Testing.

Possible structural and equipment damage.

Possible personnel injury or fatalities.

--Permit-To-Work. --Pre-tour meetings. --Standby watch during Well Test

operations. --Equipment tested before putting

into operation. --Equipment inspected by OIM prior

to operations. --Third Party Rig-Up permits.

Emergency shutdowns. Hospital and trained

medic on board. Firefighting capability. Stand-by boat available

in field.

5 B 5B

Medium

ERP Scenario Man overboard

.Fatality Severe injury

Possible personnel injury or fatality.

Policies and procedures in place while working over water.

Fall arrest system used when working over water.

Emergency Response Manual.

Fast rescue boat available.

Stand-by boat in field. Man-overboard training

and drills as per HSE Manual.

4 B 4B

Low

Anchoring Cable Break. Possible whip-back and possible personnel injury.

Possible equipment damage.

PMS and inspections. Certifications. Experience and trained personnel. Communications.

Repair and/or replace. Hospital on board.

2 B 2B

Low

Drilling (System)

Draw works Failure (break failure or drill line failure).

--Possibility of dropping block.

--Possible personnel injuries or fatalities. --Possible structural

damage. --Possibility of fire

and explosion. --Inability to hang off

string. --Suspension of

operations.

Preventative maintenance. (Slip and Cut, NDT, etc.)

Spare parts on board. Well control capabilities.

Medical facilities on board.

5 B 5B

Mod



35

Drilling (System)

Drill String failure or failure of lifting equipment (elevator, etc.)

Possibility of drill string or component falling to Drill Floor.

Possible personnel injuries or fatalities.

Possible loss of string down hole.

Possible structural damage.

Possible loss of well.

--Preventative maintenance. --Annual inspections. --Training and procedures.

--Medical facilities on board.

--Medevac capability.

4 B 4B

Low

Drilling (System)

Top Drive failure. (Shaft or component failure)

Dropped string on Drill Floor.

Possible dropped string down hole.


Possible structural damage.

Possible reduction of well control capability.

Possible loss of well.

--Preventative maintenance. --Annual inspections. --Training and procedures.

--Medical facilities on board.

--Medevac capability.

4 A 4A

Low

Drilling (System)

Standpipe manifold failure, Choke & Kill manifold failure.


Possible fire and explosion.

Possible stuck drill string.

Possible loss of well containment.

--Bi-weekly testing. --Preventative maintenance. Training. --Redundant lines, valves and

chokes. --Spares on board. --Isolation valve on system. --Cement manifold and cement unit.


2 B 2B

Low



36

Drilling (System)

PVT failure, Pressure sensor failure, flow indicator failure.

Loss of down hole information.

Preventative maintenance. Training. Manual pit volumes. Redundant pressure sensors. Spare parts on board. Training.

Suspension of operations and repair / replace.

1 B 2D

Drilling (System)

Lack of mud weight.

Possible flowing well. Possible uncontrolled

well flow. Possible loss of well.

Continuous monitoring of mud weight

Reserve mud, Availability of sufficient weighing

materials Training and procedures. Pre-spud meeting. Well program.

Well control equipment.

2 C 2C

Low

Religiously follow GTO

Drilling (System)

Diverter failure. Possible blowout on rig floor. Possible multiple injuries or fatalities. Possible loss of rig. Possible loss of well.

Testing, inspections and maintenance.

Training and drills. Correct engineering and design.

Ability for evacuation of rig.

5 C 5C

High

Hazard ranked ‘High’, but considered to be controlled by team.

Drilling (System)

Control system failure.

Possible loss of BOP control. Reduced well control capability. Possible blowout with possible multiple fatalities and possible loss of rig. Possible loss of well.

Testing, inspections and maintenance.

Redundant control systems. Spare parts on board. Ability to function BOP manually at

Koomey unit.

- 2 C 2C

Low



37

Drilling (System)

Line leak or rupture.

Fuel spillage. Possible fire hazard. Possible environmental impact. Possible shutdown of engine(s). Possible suspension of operations.

PMS. Testing. Procedures.

Emergency Fuel Shutoff system.

Level alarms in tanks. Isolation valves. Firefighting teams and

equipment. Fire detection. Spill kits.

2 C 2C

Low

Drilling

Possible major structural damage. Possible multiple personnel injuries or fatalities. Possible loss of rig. Possible environmental impact.

Procedures and training. Surface isolation equipment (BOP,

etc.). Maintenance and testing of

equipment. Instrumentation and indication of

well status. On line Hydrocarbon / Combustible

Gas detection system. Redundant BOP controls. Training and drills. Ability to evacuate the rig.

Emergency response procedure, Hospital on board.

Redundant life-saving / firefighting equipment.

Ability to divert. Stand-by boat available

in field.

5 B 5B

High

Oil spill due to leak, rupture blow out

Environment Pollution

Environment impact on marine life Loss of resources

Procedure for oil spill prevention, blowout prevention

(Steps as listed above) Procedure for transfer of from

supply vessel to rig. Maintenance of fuel storage tanks.

Oil spill contingency plan Mechanical containment

with the help of booms,

Dispersant spraying equipment

5 B 5B High

H2S release due to rupture, leak or blowout

Health impacts on personnel working on rig

Death or unconscious ness depending on the concentration of gas

Regular maintenance of detectors, alarm system for H2S

Regular H2S drills H2S Kick control procedure

H2S contingency Plan WRP for H2S

Breathing apparatus in working areas

All persons preferably stay upwind direction

5 A 5A Med

Low Fracture Gradients

Lost circulation Bore hole collapse Loss of BOP

Prior Drilling of Investigative hole

Activation of diverter 5 A 5A Med



38

Accidental Riser Disconnect due to loss of power to DPS

Well Activity Blow out Primary & secondary power supply Dead man switch

Blow out contingency Plan

5 A 5A Med



39

Appendix-1

Methodology of Risk Assessment

Identification of Hazards and subsequent risk associated with work activity

has been done through HAZID and HAZOP

Severity is based on the Classification of incidents by OISD and Statutory

norms

Probability of occurrence is based on the Rig cycle, Accident analysis with in

rig, Company and E&P industry for the last Ten years as per the data

available

RISK MATRIX

The Risk Matrix is 5 x 5 with Severity along one axis and Likelihood along the other.

Severity and Likelihood of each hazard is estimated using the appropriate criteria

below. The Severity is divided into three categories: People, Assets, and

Environment.

Severity Rankings (Overall)

Recordable (1) – Hazard may reasonably result in a First Aid Case

Significant (2) – Hazard may reasonably result in a Medical Treatment Case

and smaller losses

Minor (3) – Hazard may reasonably result in a Serious Injury Case and

moderate losses

Major (4) - Hazard may reasonably result in a severe injury or property damage

or Environmental Impact

Fatal/High Potential Major (5) – Hazard may reasonably result in multiple

Fatalities or Major loss of property

Likelihood Rankings7

Negligible (A) – Incident not known to have occurred in the industry

Low (B) – Incident known to have occurred in the industry

Medium (C) – Incident occurs in the company

High (D) – Incident occurs in the Asset/Drilling Services

Frequent (E) – Incident occurs on the given rig

After the Likelihood and Severity Rankings for the Hazard are determined, use the

Risk Matrix to determine the Risk Category. Always use the ‘Highest’ or worse severity

if the Severity Rankings for People, Assets, and/or Environment are different.

Any hazards that have a Risk Category of ‘High’ require a Recommendation unless

considered ALARP.

OIL AND NATURAL GAS CORPORATION LTD., (A Govt. of India...

Documents

Transcript of OIL AND NATURAL GAS CORPORATION LTD., (A Govt. of India...