HYDROGEN SULFIDEIn the Oilfield

OVERVIEWGeneral H2S InformationAPI GuidanceBLM Onshore Order #6Other RegulationsDOTEPA

WHAT IS H2SColorless gasFlammableHeavier than airExtremely toxic Rotten egg smellDeadens sense of smell

WHY DOES H2S OCCURBiological breakdown of organic matter in an anaerobic environment

HEALTH EFFECTSLow concentrations (30ppm) shock, convulsions, coma, death

EXPOSURE LIMITSACGIH TLV (8hr)= 10 ppmOSHA ceiling (15 min)= 20 ppmOSHA peak (instantaneous) = 50 ppmIDLH = 100 ppmATSDR MRL = 0.07 ppm (acute), 0.03 ppm (intermediate)

OTHER PHYSICAL PROPERTIESExplosiveReacts with water to form Sulfuric Acid

TearsLungsReacts with iron/steel to form Iron Sulfide (extremely flammable)

Iron spongeBurns to form Sulfur Dioxide (toxic gas)May lead to metal fatigue

H2S PRODUCTION

AMERICAN PETROLEUM INSTITUTERecommended Practice 49 -Recommended Practice for Drilling and Well Servicing operations Involving Hydrogen SulfideApplies to well drilling, completion, servicing, workover, downhole maintenance and plug & abandonment procedures.Establishes location classificationsAddresses personnel training, monitoring equipment, personal protective equipment, contingency planning and emergency procedures.Also establishes Sulfur Dioxide requirements

LOCATION CLASSIFICATIONSNo Hazard AreaCondition 1 Area low hazard10ppm, 30 ppm

WARNING SYSTEMSCondition 1 Area warning sign with green flag or lightCondition 2 Area - warning sign with yellow flag or light; visual and audio alarmsCondition 3 Area warning sign with red flag or light; visual and audio alarms

MONITORING Equipment Manufacturer certified for H2S and SO2Accurate in a range from well below to well above action levels (H2S = 10 ppm, SO2 = 2 ppm)Mixture of fixed and portable monitors as needed to protect workers

MONITORING EQUIPMENTUsed during all activities where a potential of H2S and SO2 to exceed action levels exists.Located in the following areas:Bell nippleMud return line or shale shakerPipe-trip tankDrillers stationLiving quartersOther areas of potential accumulationCalibrated and functionally tested per manufacturer

WARNING SYSTEM ACTIVATIONTypical 2 level alarm10 ppm20 to 300 ppm

TRAININGAll personnel working in an area with potential of H2S and SO2 to exceed action levels exists.Minimum topics;Hazards, characteristics and exposure symptomsSourcesDetection equipment, warning signs and wind direction awarenessWorkplace procedures, location of safety equipment and location of safe breathing areasPPEEmergency response

CONTINGENCY PLANMay be required by certain federal, state or local agencies.Must contain:Facility specific description and mapsMonitoring equipment locationsSafety equipment locationsSafe breathing area locationsEvacuation routesTraining and drill requirementsEmergency response procedures

BUREAU OF LAND MANAGEMENTOnshore Oil and Gas Order No. 6, Hydrogen Sulfide Operations

APPLICABILITYAll onshore Federal and Indian oil and gas leases.Drilling, completing, testing, reworking, producing, injecting, gathering, storing, or treating operations.Involving zones which are known or could reasonably be expected to contain H2S present in concentrations equal to or greater than 100 ppm.

REQUIREMENTSWritten H2S Drilling Operations Plan submitted with APDWritten Public Protection Plan submitted with APD, notification of production or when radius of exposure criteria are metTraining Program available for review upon requestAll plans and programs available at site

REQUIREMENTSH2S Drilling Operations Plan

Site diagrams showing all safety equipment, topography, exit roads, briefing (safe breathing) areas, flare lines and pitsAppropriate well control equipment, personal protective equipment, H2S monitoring equipment, visual and audio warning system, appropriate mud system, appropriate metallurgical plan and means of communication from wellsite

REQUIREMENTSPublic Protection Plan

Drilling or production site where:The 100 ppm radius of exposure is greater than 50 feet and includes any occupied residence, scholl, church, park, school bus stop, place of business or other are where the public could be reasonably expected to frequent

REQUIREMENTSPublic Protection Plan

Drilling or production site where:The 500 ppm radius of exposure is greater than 50 feet and includes any part of a federal, state, county or municipal road maintained for public use

REQUIREMENTSPublic Protection Plan

Drilling or production site where:The 100 ppm radius of exposure is equal to or greater than 3,000 feet and includes any facility or part of a federal, state, county or municipal road maintained for public use.

RADIUS OF EXPOSUREPasquill-Gifford derrived equation:

X = [1.589)(H2S concentration)(Q)]0.6258

X = radius of exposureH2S concentration = decimal equivalent of the volume fraction of H2S in the gas streamQ = maximum volume of gas determined to be available for escape in cubic feet per day

ESCAPE RATE (Q)Gas production facility = maximum daily absolute open flow gas production rateOil production facility = (gas/oil ratio of production) (maximum daily production rate)Exploration well = use the above from producing wells from the target interval in the area

PUBLIC PROTECTION PLANMust include:

responsibilities of key personnel and institutions for alerting the public and requesting assistance; list of telephone numbers and names of response agencies or contractors, residents, those responsible for occupants of public buildings and those responsible for safety of public roadways; a plat of the 100 ppm and 500 ppm radius of exposure showing all private and public buildings and roads; emergency response measures

PUBLIC PROTECTION PLANMay be required to include: public education seminars, mass alert systems (including telephone, commercial radio or television), and public input allowances

OTHER REGULATIONSOSHAProcess Safety Management DOTPipeline Safety RequirementsEPARisk Management Plan requirementsSARA Title 3 requirementsSTATE SPECIFIC