Introduction H2S is colorless, toxic, and flammable gas. It’sfound in number of PDO operation area. PDO assets in encounter varyingconcentration and pressures of H2S. Currently harweel ; birba and Al Noor havethe highest concentrations of H2S.Hydrogen sulphide occurs naturally in theearth in crude petroleum, natural gas reservoirs, volcanic gasses and hotsprings, hydrogen sulphide is also produced from the breakdown of human andanimal wastes by bacteria, petrochemical and chemical refineries, waste watertreatment facilities, also tar and asphalt manufacturing plants.
H2S in upstreamoil and gas comes from the original reservoir, as a result of the hydrogensource material and conditions under which it was converted to oil and gas.Prolonged injection of water into a hydrocarbonreservoir may result in ” souring” of the fluids, due to the action ofsulphate reducing bacteria introduced during the injection process. Any H2Swill be produced with the fluids. H2S is extremely toxic within PDO assestsencountered during normal operation ranging from drilling, well testing,flaring, production operation, gas injection through to product export , e.g.
drilling/well works on high level H2S wells, breaking containment on processequipment with H2S in the fluids, confined space entry, maintenance operation,sulphur removal system, water Knock-Outs, and Vaccum truck vents. The operation,maintenance and surveillance of process containing hydrogen sulphide hazardsshall be such as to prevent a potentially hazardous situation from developing.In the event of loss of control hydrogen sulphide hazard, the design andoperation practices should assure the early detection and rectification of thepotentially hazardous situation.Characteristics or properties of hydrogen sulphide(H2S) v It smells like rotten eggsat low concentration and causes you to quickly lose sense of small.
(100ppm). ,typicallycalled sour gasv Colorlessv Explosivev Corrosive. Can causecauses severe stress cracking or other metals v Soluble in water, crudeoil or petroleum fractions.
(natural gas, petroleum ether, gasoline, kerosene,fuel oil, lubricants and asphalt or cokev Slightly heavier than airand may accumulate in low lying areas and confined space v Burns with a blue flame toform sulpher dioxide SO2 which is a toxic gasv Toxic at extremely lowconcentrations v Ventingv Broad spectrum toxin- caninjure most body tissuesv Iron sulpide – pyrophic v High concentration-nervous system impact v Tissues the have highdemand are especially vulnerable v Rapidly stops oxygenaccess for cellular metabolism The flammable range for H2S is between 4.3% and46% of gas by volume in air. When the gas is burned. Such as during flaringoperations, sulpher dioxide is formed which readily combines with water to formsulphuric acid in the atmosphere (acid rain). Factors influencing toxicityThe way in which H2S affects a person dependson the following factors ü Duration- the length oftime the individuals is exposedü Intensity- theconcentration of exposureü Susceptibility- theindividuals physiological make-upü Frequency- how often isexposed At certain (600- 1000 ppm) immediate knockdownoccurs Other factors includeü State of healthü Age of the personü Route of exposureü Workplace environmental factorsü Previous exposure levelExposure to hydrogen sulphide causes death bypoisoning the respiratory system at the cellular level.
Symptoms from repeatedexposure to low concentration usually disappears after not being exposed forperiod of time. Repeated to low concentrations that do not effects eventually maylead to irritation if the exposure are frequent Some individauls can extremely vulnerable toH2S and its by- products.The ability to tolerate exposure is reduced byhealth conditions such as:o Emphysema: disease of the lungs o Bromchial asthma: asthma is a disorder that cause the airways of thelungs to swell and narrow, leading to wheezing, shortness of health, chesttightness, and coughing.o Anemia: a condition in which the body does not have enough healthy redblood. Red blood cells provide oxygen to body tissues o Epilepsy: a brain disorder in which a person has repeated seizures o Angina pectoris or other coronary artery disease: chest pain ordiscomfort that usually occurs with activity or stress.o Progressive or sever hypertension; high blood pressure.Individuals who have consumed alcohol 24 hoursof exposure are known to have been overcome by unusually low concentrations ofH2S
