cr fpp 170 h2s policy rev 02

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Company Rule CR FPP 170

H2S Policy

Exploration & Production Rev: 02 Date: 19/05//2004 Page: 2 of 28

Table of Contents

1. RECAP OF RULES............................................................................................... 5

2. FOREWORD ......................................................................................................... 7

2.1 Indicator................................. ............................. ............................ ............................... 7

2.2 Glossary ........................... ............................ ............................. ............................ ........ 7

2.3 Introduction...... ............................. ............................ ............................ ........................ 8

3. H2S CHARACTERISTICS ..................................................................................... 8

4. SAFETY PLANNING........................................................................................... 10

4.1 H2S toxicity........................... ............................ ........................... ........................... ..... 10

4.2 H2S occurrence........................... ............................ ............................ ........................ 12

5. CONTROLLED DRILLING ENVIRONMENT (CDE)............................................ 13

5.1 Definition ........................ ............................. ............................ ............................ ........ 13

5.2 CDE achievement .......................... ............................ ............................. .................... 13

5.3 Limitation.............................. ............................ ............................. ............................ .. 16

6. REQUIREMENTS FOR OPERATIONS............................................................... 17

6.1 Requirements for drilling or WO operations....... ............................. ....................... 17

6.2 Requirement for a light intervention............ .............................. ............................. .. 25

6.3 Ignition of a blow out containing H 2S ....................................................................... 26

7.

REQUIREMENTS FOR MATERIAL.................................................................... 27

7.1 Casing/Tubing Material .......................... ............................ ............................ ............ 27

7.2 Wellhead, Xmas Tree, MLS and Downhole Equipment ......................... ................. 27

7.3 Drill Through Equipment................................. ............................. ............................ .. 27

7.4 Drill String .......................... .............................. ............................. .............................. 28

This document is the property of Total. It must not be stored, reproduced or disclosed to others without written authorisation from the Company.

CR FPP 170 H2S policy rev 02.doc


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Reference documents

Unless otherwise stipulated, the applicable version of the reference documents listed below,including relevant appendices and supplements, is the latest revision published.

Standards

Reference Title

NACE MR 01 75 Rev.03

API RP 49 2nd edition API RP 13 B1 & B2

API SPEC 6A16 th edition

API SPEC 16A1st edition

SSC resistant metallic materials for oil field equipment

RP for safe drilling of wells containing H 2SField testing for drilling fluids

Specifications for WH & Xmastree equipment

Specifications for drill through equipment

Professional Documents

Reference Title

DFP ManualEMF 93 #1

Blowout Contingency Plan chapter FManual Selection of materials for well equipment

Regulations

Reference Title

Not applicable

Codes

Reference Title

Not applicable

Other documents

Reference Title

Not applicable




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Other Total documents

Reference Title

CR FPS 110

CR FPP 150

CR FPP 225

CR FPP 310

GS COR 170

CR FPP 245

CR FPP 246

Bridging document

Casing and Tubing

Casing Design

Tubing calculation

Material for sour service Specification for design

surface wellhead, surface X-mas tree and MLS

subsea wellhead and X-mas tree




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1. RECAP OF RULES

Rule 1 : Each operation programmed under the FPs responsibility must be classifiedaccording to H 2S occurrence levels. For drilling, each phase shall beconsidered separately.

Rule 2 : H2S occurrence level must be systematically reassessed according to drilling,mud logging and electrical logging data collected prior to formation testing.

Rule 3 : CDE in water based mud means the 3 following actions are conductedsimultaneously:

PH of mud maintained above 11 Global sulfides in mud and filtrate monitored Soluble sulfides in mud eliminated using scavengers

Monitoring of sulfide content is made by:

Lead acetate paper (Qualitative)

G.G.T. (Quantitative)

Rule 4 : CDE is a normal objective and of normal practice when H 2S is foreseen.When H 2S occurrence is level 1 or 2, sour service material for casing andwell control equipment must be selected.

Rule 5 : Should H 2S be encountered above the foreseen occurrence level withconsequently no more valid H 2S procedures, operation progress must stopimmediately.

Rule 6 : For H 2S occurrence level #2, an H 2S and safety/protection equipmentdedicated training shall be systematically delivered to all personals comingon the rig site.

Rule 7 : Independently of H 2S occurrence level, an oxygen resuscitator kit shall bekept permanently operational on the rig (sickbay). For H 2S occurrence level

#2, an oxygen resuscitator kit shall be made available on each dedicatedstand-by boat during all H 2S operations.




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Rule 8: In case of H 2S occurrence #2, all specific H 2S procedures should be detailed ina dedicated contingency plan, jointly approved by drilling and safetydepartments, the drilling contractors and, if applicable, the productiondepartment and H 2S company.

Rule 9: As soon as the sour environment criteria can be foreseen, typically H 2Soccurrence level 1 (possible) and level 2, all parts of the first confining barrier(casing, wellhead and BOP) must be sour service.

Rule 10 : For each well with the potential for Hydrogen Sulfide (H 2S), the ignition or notof a blow out containing H 2S shall be stated in the BOCP and in the wellprogramme based on the local conditions and H 2S/SO 2 dispersion studies.

Rule 11: If an H 2S trim BOP is required, it is imperative to verify that the installedshear/blind blades are H 2S proof.

Rule 12: Drill strings shall never be used for acidification or drill stem tests (DSTs) onwells where H 2S risk is identified (H 2S occurrence #2).




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2. FOREWORD

2.1 Indicator

Rule which needs derogation

Main recommendation or useful information

2.2 Glossary

BHA Bottom hole assembly

BOCP Blow Out Contingency Plan

BOP Blowout preventer

CDE Controlled Drilling Environment

CT Coil Tubing

DST Drill stem test

HIC Hydrogen Induced Cracking

HRC Hardness Rockwell

GGT Garret Gas Train

GOR Gas/Oil ratio

LCM Lost circulating material

MLS Mud Line Suspension

NDE Non Destructive Examination

OBM Oil Base Mud

PH Alkalinity

Pm Total alkalinity of the mud including hydroxides, carbonates and bicarbonates

SABA Supplied Air Breathing Apparatus (10 minutes autonomy)

SCBA Self-Contained Breathing Apparatus (45 minutes autonomy)

SSC Sulfide Stress Cracking

WBM Water Base Mud

WO Work-Over




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2.3 Introduction

Hydrogen Sulfide is one of the critical problems that can be encountered while drilling orperforming well interventions. The presence of this gas will affect:

Personnel due to the extreme toxicity of this gas, Equipment because of sulfide stress cracking phenomena affecting most high

strength steels.

The document takes into account the official recommendations issued by:

The American Petroleum Institute (API RP 49, 2nd

Edition, April 15,1987) : "Recommended Practices for safe drilling of wells containing HydrogenSulfide".

The National Association of Corrosion Engineers (NACE Standard MR-01-75,1993 Revision): "Sulfide Stress Cracking Resistant Metallic Materials for Oil FieldEquipment".

Note : Reference is not made to the ISO 15156 standard, this document being notfinalized at this time. It must be kept in mind that sour service criteria mentioned in thisfuture standard will slightly differ from current NACE requirements.

3. H 2S CHARACTERISTICS

Naturally occurring H 2S has two main origins: a bacterial origin and a chemical one.

Bacterial origin is linked to areas that are considered petroliferous and containevaporite beds (anhydrite, gypsum).

Chemical origin (degradation of organic sulfur) is linked to carbonate source bedsfavorable for such a reaction. This explains why most of the gas depositscontaining high H 2S percentages are in carbonate reservoirs (Lacq with 15% H 2Sor Devonian deposit in Alberta with 88% H 2S).

However, H 2S can also be the result of some operations performed during drilling,testing or completion of a well such as:

Decay of lignosulfonates or other fluid additives into sulfides, which can lead toH2S generation

Introduction of sulfate reducing bacteria in drilling fluids that can cause H 2Sgeneration in non active mud pits (LCM pills or kill mud pits) or in reservoirssusceptible to extensive losses

Acid attack of insoluble sulfides, present in the formation or formed by most H 2Sscavengers with H 2S, during an acid job




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For various reasons (poor treatment, reaction with pyrites, etc), water injection forsecondary recovery may also generate H 2S.

Volume of H 2S generated during these operations is generally limited. Nevertheless thedanger remains and all personnel must be aware of these potential origins. It is alwaysof benefit to understand the source of the H 2S in the event of an H 2S alarm.

The main physical properties of H 2S are:

Colorless gas, extremely poisonous, strong nauseating odor in weakconcentrations

Heavier than air: specific gravity (gas @ 15 C, 1 atm) = 1.19 (1 for air) Explosive at concentrations between 4.3% and 45% (5% 15% for Methane) Spontaneous combustion occurs at 260C (500F), compared to 537C (1000F)

for Methane Burns with a blue flame and produces Sulfur dioxide (SO 2), which is also toxic but

much less Soluble in water and very soluble in oil Make some steels brittle under certain temperature conditions Contaminates water based drilling mud: main effects are a drop in pH level, a

strong amplification of rheological properties and a visual darkening of mud H2S density = 1.54 g/l.

Notes:

1) 1 ppm H 2S is equivalent to 1.54 mg H 2S / m 3 or 1*10 -4 % H 2S

or

1 % H 2S is equivalent to 15.4 g H 2S / m3 or 10000 ppm H 2S

2) The H 2S partial pressure is equal to the mole fraction of H 2S in gas phasemultiplied by the global system pressure:

For example: If the concentration of H 2S in gas phase = 100 ppm and if theGlobal pressure = 3000 psi, then

H2S partial pressure 100* 10 -6 * 3000 = 0.3 psi




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4. SAFETY PLANNING

4.1 H 2S toxicity

The extreme toxicity of H 2S for human life is reminded in the next table. The main pointsto remember are:

Very unpleasant odor at very low concentration but this gas affects rapidly thesense of smell

10 ppm in air is the maximum concentration for continuous work on a tour period(but local legislation may be more severe); exposure levels exceeding this valuerequire use of personnel protective breathing equipment

50 ppm is the ceiling limit for short exposure periods: eyes irritation appearsquickly

H2S poisoning by successive short exposures is not cumulative

Reminder: Anybody, which has accidentally inhaled air with high H2S concentration,must be immediately brought in the breathing area and artificially

ventilated.




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4.2 H 2S occurrence

As soon as an operation is programmed (drilling/completion, W.O. or light intervention),risks of encountering H 2S during operations must be systematically assessed andclearly recorded in the common geological & drilling well program or other interventiontechnical program. Three levels of risks can be typically foreseen:

H2S occurrence #0 : No H 2S risks; the geological basin is well known and no H 2Shas never been recorded.

H2S occurrence #1 : H 2S risk is reduced but cannot be totally ignored: Presence of natural sulfides which can be transformed by acid Operations on appraisal or development wells crossing water levels whichmay contain some shows of H 2S Drilling of exploration wells in areas theoretically free of H 2S but bottompressure is greater than 5000 psi

H2S occurrence #2 : Unquestionable risks of H 2S:

All operations on exploration wells in areas known as potential H 2S bearing All operations on delineation or development wells through formations

known to be H 2S bearing W.O. or interventions on wells in communication with reservoirs containingH2S Formation Testing on layers where H 2S has been identified during drillingoperations.

Rule 1 : Each operation programmed under the FPs responsibility must be classifiedaccording to H 2S occurrence levels. For drilling, each phase shall beconsidered separately.

Rule 2 : H2S occurrence level must be systematically reassessed according to drilling,mud logging and electrical logging data collected prior to formation testing.




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5. CONTROLLED DRILLING ENVIRONMENT (CDE)

5.1 Definition

A Controlled Drilling Environment (CDE) means that, even if some reservoirs containingH2S are drilled through:

No gaseous H 2S can appear at surface

No atomic hydrogen is formed at any depth within the wellFor that, H 2S must be neutralized as soon as it can enter the well. The role of drillingfluid is of course essential.

5.2 CDE achievement

5.2.1 In WBM (Water Base Mud) : The first step in achieving a CDE is to maintain the pH (Alkalinity) of the mud high

enough (10-11) to allow H 2S dissociation while minimizing the presence of atomichydrogen at the source of SSC. In such environment soluble sulfides are producedif H2S is present. But if mud pH drops for any reason, these sulfides canrecombine immediately to form gaseous H 2S that can lead to a dangeroussituation. Sufficient alkalinity provision in the mud should avoid this risk (Pm > 3).

The second step in achieving a CDE is then to eliminate the soluble sulfides inmud using sulfides scavengers. Numerous scavengers exist for WBM; the most

popular is the ironite sponge (iron oxides) but zinc based scavengers are alsoavailable. Whatever the type of scavenger used, insoluble metal sulfides areformed. The constraint is that gaseous H 2S will be produced from metal sulfides incase of acidification; consequently acid spots is not recommended if drill string isstuck.




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The list of common chemicals used as scavenger is given below:

Trade Name Type Company

MILGARD H2S extractor - Basic zinc carbonate BAKER

MILGARD L Liquid zinc chelate BAKER

IRONITE SPONGE Solide H2S scavenger IRONITE

SAFE SCAF HS Soluble H2S scavenger M.I.

SS10 H2S remover OSCA

SOURSCAV H2S remover BAROID

ZINC CARBONATE All companies

ZINC OXYDE Zinc source for OBM -H2S removal All companies

The following figures give respectively:

The repartition of different sulfides function of the medium pH (Figure 1)

Fig. 1

DANGER




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Possible H 2S concentration in air above mud function of total sulfides in mud(Figure 2)

10

pH = 9

pH = 10

pH = 8

pH = 11

pH = 12

100 1.0001

10

100

1.000

H2S (ppm) in air

Global sulfidesdissolved in mud

Collapse uncon sciousness death

Loss of sense of smell

Maximum safe working level

Fig. 2

Rule 3 : CDE in water based mud means the 3 following actions are conductedsimultaneously:

pH of mud maintained above 11 Global sulfides in mud and filtrate monitored Soluble sulfides in mud eliminated using scavengers

Monitoring of sulfide content is made by:

Lead acetate paper (Qualitative) G.G.T. (Quantitative)




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5.2.2 In OBM (Oil base mud) :

With OBM, risks of SSC are minimized as the oil phase coats and protects metalsurfaces; but on a other hand, H 2S is highly soluble in oil and sulfide detection in such amud is a little more difficult; in addition scavengers efficiency is reduced.

Mud characteristics are affected by H 2S influx (Emulsion stability, HP/HT filtrate, andrheology). Free lime is often used in OBM to neutralize H 2S influx. ZnO can also beadded as complementary scavenger; but H 2S influxes not totally neutralized when

entering the well will dissolve in OBM and liberate gaseous H 2S on surface. Moreattention should therefore be paid to surface detection system and crew reactivity.

Then if possible, OBM should be avoided if H 2S bearing levels are foreseen.

5.3 Limitation

To keep the return fluid pH at the right value may be questionable during a kick andeven in CDE, free H 2S may appear. SSC can therefore be a concern and sour servicematerial must be selected for the structural well barrier. Regarding drill string, risks offailure exist but workload can eventually be monitored and first of all, consequencesshall be more limited. Therefore only specific drilling cases (shallow acid gas wells withhigh risks of kick, abnormal string breaks, etc) can justify sour service drill pipes.

Rule 4 : CDE is a normal objective and of normal practice when H 2S is foreseen.When H 2S occurrence is level 1 or 2, sour service material for casing andwell control equipment must be selected.




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6. REQUIREMENTS FOR OPERATIONS

6.1 Requirements for drilling or WO operations

Equipment and procedures must be adapted to each previous H2S occurrence levels.

Requirements apply to the following parts:

Safety

Tubular, wellhead and well control equipment material CDE Rig equipment

The first point should be integrated to the contingency plan relating to the foreseenoperations.

Rule 5 : Should H 2S be encountered above the foreseen occurrence level withconsequently no more valid H 2S procedures, operation progress must stopimmediately.

The well must be either temporarily secured so as to allow compliance with dedicatedrequirements, or definitely plugged and abandoned, should the former option beimpossible.

Cost cannot be taken into consideration for such a decision.

6.1.1 Safety

Rule 6 : For H 2S occurrence level #2, an H 2S and safety/protection equipmentdedicated training shall be systematically delivered to all personnel comingon the rig site.

Rule 7 : Independently of H 2S occurrence level, an oxygen resuscitator kit shall bekept permanently operational on the rig (sickbay). For H 2S occurrence level#2, an oxygen resuscitator kit shall be made available on each dedicatedstand-by boat during all H 2S operations.




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6.1.1.1 In case of H 2S occurrence #0

Detection:

One fixed H 2S alarm system with alarm set at 5 ppm in air; alarm should raise in the drillfloor area, mud logging cabin (if installed) and tool pushers office.

Electronic sensors are installed :

On mud logging unit degasser (if installed) On flow line On return mud pit On rig floor

Reminder: H 2S detectors must be carefully protected against water projection, regularlycalibrated and tested to be sure they are fully operational.

One electronic portable detector shall be permanently available at hand in the drillmaster cabin and in living quarters.

Protection:

No protective equipment is required. However and firstly if reservoirs coring and/or

sampling are foreseen, a minimum set of escape masks equipped with H 2S filtrationcartridge and/or SABA should be available on the rig floor.

Reminder: Protective equipment must be checked and crew be trained on the use ofmasks before the critical foreseen operation.

Communication:

No specific transmission system in addition of basic rig intercom system.

Procedures:

No specific procedures excepted general instructions in case of H 2S alarm.




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Detection:

One complete H 2S alarm system with alarm set at 5 ppm in air; alarm should raise inthe drill floor area, shale shakers, mud logging cabin, mud pits / pump area and toolpushers office.

Electronic sensors are installed:

On mud logging unit degasser

On flow line On return mud pit On rig floor One independent alarm at air intakes of living quarters

Portable detectors available in dog house, mud room and living quarters.

Protection:

Escape masks with H 2S filtration cartridge and/or SABA available in dog house, mudroom and mud logging cabin (in sufficient number for working shift personnel).

4 self-contained breathing apparatus of medium capacity (45 minutes) available inoffices or living quarters (with adequate air refilling system).

Communication:

An efficient intercom system should exist between all strategic/work points of the rig.

A phone link should be operational onshore between camp and rig.

Procedures:

Procedures and responsibilities in the event of an H 2S alarm must be clearly definedand joined to the operation program.

Specific procedures and special care when opening a sampler or when recovering acore at surface.

Rig evacuation drills without change.

Periodic briefing on perfect maintenance and use of escape masks and portablebreathing systems.

Normal and emergency communication systems on rig and between rig and stand byboat must periodically be tested.




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All specific equipment needed must be kept in perfect working conditions and regularlytested. It is highly recommended to hire this equipment from a H 2S Services Companyalong with the services of an H 2S Supervisor. The latter will take care of onsitecontinuous people training and awareness, equipment maintenance, air refillingoperations, H 2S and SO 2 monitoring.

Of course material and crew should be fully operational prior H 2S problems can beencountered.

Detection:

Two independent fixed H 2S alarm systems (from mud logging company, drilling rigcontractor or H 2S services company,) with alarm set down at 10 ppm in air. Alarmshould raise in the drill floor area, shale shakers, mud logging cabin, mud pits / pumparea and tool pushers office.

Electronic sensors are installed:

On mud logging degasser On flow line On shale shakers On return mud pit On cellar deck On rig floor On any critical place where H 2S, heavier than air, can accumulate (will depend on

rig configuration and ventilation).

An independent H 2S detection system shall be installed offshore at air intakes of livingquarters (may be considered onshore at the rig camp).

Dedicated portable H 2S detectors given to tool pusher, mud engineer, mud logger,company man, barge master, supply captains.

Two portable tubes gas detector pumps with H 2S and SO 2 detector tubes.

Lead acetate paper.

For well testing with H 2S, the detection system needs to be adapted to the well testingset up. In particular, SO 2 detection should be installed at the well test area and at airintakes of living quarters.




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Protection:

Two breathing areas are prepared onshore, each sides of rig, prevailing windsconsidered.

Offshore, one breathing area/muster point will be prepared; helideck shall often remainthe best muster point if H 2S is a concern.

All personnel equipped with one dedicated SABA; at least 50 % POB spare SABAavailable on rig (dispatched at main critical areas).

As soon as an H 2S formation level can be met, this mask must be wear at all time whenon rig location (onshore) or outside of the living quarters (offshore).

A minimum set of SCBA of medium capacity (45 minutes) should be available on rig:typically 12 on an offshore rig, 6 on a land rig.

Cascade breathing air system for a long-term work in H 2S environment : each workplace should be equipped with air plugs manifold (including cranes). It is alsorecommended to equip the muster point and the life boats platforms with plugsmanifolds on small drilling unit (jackup, compact rig). Air compressors (2 minimum) shallbe located at the breathing area. This complete system (compressors, accumulators,regulators and plugs manifold) shall be designed according to operations andevacuation plan.

An assessment on lifeboats capacity, taking into account the expected air breathingsystem embarked, has to be done.

Supply vessels need SCBA capacity for the deck crew so as to be able to disconnectmooring lines and move up wind in case of an H 2S alarm on the rig.

Communication:

In addition of an efficient rig intercom system (and camp/rig phone link onshore) apublic address system connected on backup power supply shall be installed.

Chalkboards or notepads shall be available to assist communication.

Appropriate caution signs and flags shall be placed onshore at all possible locationentrances. Additional wind direction devices should be visible from any work andbreathing areas.




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Procedures:

Rule 8: In case of H 2S occurrence #2, all specific H 2S procedures should be detailed ina dedicated contingency plan, jointly approved by drilling and safetydepartments, the drilling contractors and, if applicable, the productiondepartment and H 2S company.

Drilling or W.O. programs should systematically remind and refer to relating points inapplicable H 2S contingency plan.

Two classifications must be done prior to set up an H 2S contingency plan: An H 2S rig areas classification, typically:

H 2S 0 area : areas where H 2S should not be encountered (due to wind,relative height or pressurization) ; should of course be periodically checked. H 2S 1 area : areas normally safe but should be systematically checked ;escape masks has to be carried. H 2S 2 area : areas with potential danger once H 2S alarm has beenactivated; in that case their access should only be permitted to dedicatedpersonnel, equipped with SCBA and never alone.

An H 2S operating conditions classification, typically: NO ALERT LEVEL if H2S is not detected in the atmosphere, sulfides mayhave been detected in mud and/or H 2S may have been detected in extractedgas. ALERT LEVEL 1 if H2S concentration in the atmosphere is below or equal to10 ppm somewhere on the rig. ALERT LEVEL 2 if H2S concentration in the atmosphere is exceeding 10ppm somewhere on the rig.

H2S contingency plan content:

In addition of previous classifications, an H 2S contingency plan will include at least:

The list and assignment of essential personnel (people which stay on board in theevent of a partial evacuation)

The specific H 2S training The organization and periodicity of safety drills The responsibilities and duties of individual according to operating conditions

classification The breathing apparatus policy The rig evacuation policy H2S specific procedures for normal conditions (alert level 0) : tripping, coring, kick

control, WL operations, sampling, well testing The emergency procedures alert level 1 The emergency procedures alert level 2This document is the property of Total. It must not be stored, reproduced or disclosed to others without written authorisation from the Company.



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The environmental limitations versus operations Stand-by vessels communication and safety procedures Neighboring rigs or platforms communication and safety procedures The platform evacuation procedures The local population communication and evacuation plan (onshore).

6.1.2 Casings/Tubings, Wellhead and Xmastree

H2S occurrence #0 : Standard equipment can be chosen. If H 2S is detected and sourenvironment possible, operation must be stopped immediately and well plugged.Operations will resume only if H 2S service equipment can be installed and anyinadequate casing part be covered by a suitable string.

H2S occurrences #1 or #2: The first confining envelop must be sour service within theexpected operational conditions.

Rule 9: As soon as the sour environment criteria can be foreseen, typically H 2Soccurrence level 1 (possible) and level 2, all parts of the first confining barrier(casing, wellhead and BOP) must be sour service.

6.1.3 Controlled Drilling Environment (CDE)

H2S occurrence #0: No specific requirement

H2S occurrence #1: Sulfides detector (GGT or mud duck) will be operational onsite and mud engineer aware of its maintenance and procedures. In case of waterbase mud, a minimum corrosion inhibitor storage will be available on site as wellas the required Na(OH) 2 to rise the PH of the mud if necessary.

H2S occurrence #2: Probable occurrence of H 2S will affect the mud program andspecific mud engineer training. Sulfides detection will stay active during all thecritical phases and sulfides inhibition process ready to be put on stream; enoughscavenger storage should be kept on site. Monitoring of global sulfides in mud andfiltrate will be clearly recorded. Mention that, in case of BHA stuck, acidic slugmust be prohibited.




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6.1.4 Drilling/WO Rig

In any case and independently of the considered H 2S occurrence level:

Rig components should be arranged on location (onshore) or rig correctly oriented(offshore) to take advantage of prevailing winds and keep living quarters, camp,engines and helideck upwind from any source of vented gas; a windsock isinstalled and correctly lighted, easily visible from the drillers position and helideck.

Escape ways must be properly indicated, lighted and kept free from obstruction. Gas exhaust from atmospheric degasser is lined to crown block; a direct

overboard line stays present.

The Specific requirements are:

H2S occurrence #0 : No specific requirement

H2S occurrence #1:

Well control equipment must be H 2S service and BOP arrangement conformto specifications given in CR FPP 160 . Operational mud logging equipment and staff

H2S occurrence #2: In addition of occurrence #1 requirements, the followingarrangement is strongly recommended:

Cascade air breathing system with accumulators and plugs manifolds rightlysized The derrick vertical exhausts from atmospheric and vacuum degassers shallbe diverted on request to horizontal lines; this diversion must be clearlyindicated. Offshore flarebooms (floating rigs, jackups) will be permanently deployed onboth side of the rig (excepted DP rigs) fitted with a positive ignition source.Diverted lines from poor boy and vacuum degasser are directed to theflarebooms. Depending on the vessel installation and prevailing winds onlyone boom may be sufficient on a jacket assisted by a tender vessel. Shouldflarebooms not be available, specific horizontal exhaust lines shall be fixed. Large explosion proof blowers or fans should be installed as a protectionagainst low wind (drill floor, shale shakers) or any open location badlyventilated where H 2S may accumulate. Inside ventilation system should be correctly designed; differential ofpressures between rooms must be periodically measured (idem OBM drillingrequirement). Air system in accommodation quarters shall be on a closedinternal circuit with possibility to close external air intakes and vents. Onshore camp should be installed at 1000m minimum upwind from rig.




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6.2 Requirement for a light intervention

In case of a light intervention classified H 2S occurrence #2 with or without any drillingor W.O. rig on site, intervention program should clearly mention:

The logistical and safety means insuring adequate work in H 2S environment, safebreathing area and possibilities for a prompt escape if any.

The verification of H 2S suitability of all equipment (directly used and back-up). The working limitations that all foreseen equipment (coil tubing, Wire line) can

have in H 2S environment (rating, working cycles number). The users procedures to limit SSC occurrence and consequences (inhibitor use,

high pH fluid injection). This needs the presence of an H 2S supervisor in charge of the training of all

personnel (technical and supporting), arrangement and maintenance of alldetection, protection and communication equipment.

Relating program should be jointly approved by:

Drilling/Completion department, Production department, Contractor in charge of the operation,

H2S company if any.




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6.3 Ignition of a blow out containing H 2S

Rule 10 : For each well with the potential for Hydrogen Sulfide (H 2S), the ignition or notof a blow out containing H 2S shall be stated in the BOCP and in the wellprogramme based on the local conditions and H 2S/SO 2 dispersion studies.

The recommended method to ignite a blow out is with a flare gun used from a safe areaon the upwind side. Several flare guns with spare flares should be available on site, withadequate SCBAs for the ignition team. Flares that fit in a shot gun will give more range.Specific training/drills to use the flare gun should be done on site at a regular basis.

However a back up solution should exist adapted to the specific case.




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7. REQUIREMENTS FOR MATERIAL

7.1 Casing/Tubing Material

Refer to CR FPP150: casing and tubing chapter 4.

Nota : Material selection is defined with respect to severity regions from 0 to 3, definedby reference to ISO 15156. These severity regions are defined versus two corrosion

related parameters : the H 2S partial pressure and the pH. It must be considered thatthere is no formal equivalence between the H 2S occurrence # 0 to 3 (related to humanHeath and Safety criteria) and the severity regions from 0 to 3 (related to corrosioncriteria), although both are linked to the H 2S concentration.

7.2 Wellhead, Xmas Tree, MLS and Downhole Equipment

Refer to CR FPP245: surface wellhead, surface X-mas tree and MLS and CR FPP 246:subsea wellhead and X-mas tree.

7.3 Drill Through Equipment

Further information is provided in CR FPP 160 Well Control Equipment.

Specifications for Drill Through Equipment are covered by API SPEC 16A which statesthe following:

"With the exception of shear blades, all metallic materials which come in contact withthe well fluid shall meet the requirement of NACE Standard MR-01-75 for sour service."

Formely shear blades were made of high strength steels, which were not alwaysmanufactured to be compatible with H 2S. But nowadays special super trim shear/blindrams are currently in use.

Rule 11: If an H 2S trim BOP is required, it is imperative to verify that the installedshear/blind blades are H 2S proof.

With regard to marine drilling risers, CDE may be effective on the main tubular as anykick will be evacuated through the choke line. In addition this riser does not justify high

strength steel excepted on specific component (ball joint). Kill and choke lines shall bespecified as H 2S service.




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H2S Policy


7.4 Drill String

Generally drill string components are for use in controlled drilling environment andtherefore conventional API SPEC 5D grades (E, X95, G105 and S135) may be usedeven if not SSC resistant.

Non-API SSC resistant drill pipes with grades up to 110Ksi are available for specificapplications if foreseen problems justify their use (unbalanced works, probability of H 2Skicks, etc.). It should be verified in addition that relevant tool joints are not susceptible toH2S. Real mechanical properties of these pipes must be assessed.

The following can improve the work with standard drill strings in a CDE:

Use of correct make-up torques to avoid excessive stress, Use of corrosion inhibitors, Increase in the frequency of BHAs inspections.

If an H 2S service drill string is required, all crossovers and specific joints inserted instring up to surface should be compatible with H 2S. As previously stated, due to

reduced yield strengths, this can result in lower capacities than standard equipment.

Rule 12: Drill strings shall never be used for acidification or drill stem tests (DSTs) onwells where H 2S risk is identified (H 2S occurrence #2).