PETROLEUMCHE252 INDUSTRIAL PROCESS

Introduction1859 first well was drilled in Penn Sylvania, USA1897 first well was drilled offshore in California, USA1910 first well was drilled in Malaysia (well Miri No.1 in Sarawak)

PetroleumA form of bitumen composed principally of hydrocarbons which exists in the gaseous or liquid state in its natural reservoirs.Petroleum = hydrocarbon compound + non hydrocarbon compoundHydrocarbon = organic compounds of carbon (C) & hydrogen (H) onlyNon-hydrocarbon = compound that contain some sulphur, oxygen and nitrogen atoms besides C & HThe principal forms of petroleum are:Crude oilNatural gasCondensateAsphalt

Crude OilA mixture of HC that exists in the liquid phase in natural underground reservoirs and remains liquid at atmospheric pressure after passing through surface separating facilitiesAppearance: dark brown to yellowish brownDensity: ranges from very dense denser than water to very lightViscosity: ranges from solid to liquid

Natural gasA mixture of HC compounds and small quantities of various non-HC (eg. N2 and CO2) existing in the gaseous phase or in solution with oil in natural underground reservoirs at reservoir conditionsMain HC component: methane (CH4)Dry gas contains 90-100% CH4Wet gas contains greater proportions of ethane, propane, butane etcCO2, H2S & N2 also presentSweet and sour gases refer to the low and high content of H2S respectivelyApplication: power generation, industrial feedstock eg. Fertilizers or liquefied into LNG for efficient transportation

Natural gas classificationAssociated gas:- free natural gas, commonly known as gas-caps which overlies and in contact with crude oil in the reservoirDissolved gas:- Natural gas which is in solution with crude oil in the reservoir at reservoir conditionsNon associated gas:- Free natural gas not in contact with crude oil in the reservoir

WaterGas Non - associated gas reservoirWater

CondensateHCs which are in the gaseous state under reservoir conditions but become liquid either in passage up the hole or at surface due to the reduced pressure conditions.Composed mainly of compounds in which molecules contain at least 5 C atomsColour: yellowish to colorless

AsphaltThick brownish or black substance derived from the same crude oil which produces kerosene, gasoline and vinyl.Composed of at least 80% carbon, which explains its deep black color. Sulphur is another ingredient found in the tar-like asphalt, as well as some trace minerals. Application: sealant for rooftops and a durable surface for roads, airport runways, playgrounds and parking lots.

Origin of petroleumIn general, 2 theories exist:Inorganic theories - reaction of CO2 with H2O under suitable conditions- assumes oil form from the reduction of primordial carbon or its oxidized form at high temperatures deep in the earth

2.Organic theories - remains of plants and animals (most widely accepted)- accumulation of HC from living things - generation of HC by heat action on biogenically formed organic matters

Reservoir rockMost important types: sandstones and carbonatesA petroleum reservoir is the part of rock that contains the pool of oil or gasAny rock with interconnected pores and sufficient permeability to allow oil or gas phase production

Sequence of activities in petroleum industryAcquisition of Right

EXPLORATION

APPRAISAL

DEVELOPMENT

PRODUCTION

Export or Processing

Acquisition of right to obtain permission from government or relevant agency before drilling of exploration wellExploration to search for oil and gasAppraisal to determine commercial significance of discovery & to shape the field initial development planDevelopment to formulate the field development plan, install platforms, to drill and complete the development wells

Production to bring oil/gas from subsurface to surface and to separate between gas/oil/water before the oil is stored and gas is processedTransportation to bring oil from storage to refinery and gas to gas processing plant either by pipeline or floating tankerRefining/gas processing to manufacture petroleum products from crude oilMarketing to distribute the petroleum products to customers

Seismic data acquisitionSeismic method involves generation of elastic vibration causing ground motion which can be detected by geophones

Exploration drilling:Petroleum accumulations can only be discovered by drilling i.e. there is no direct method of locating a pool of petroleum without first drilling test wellsDrilling also serves as a source of subsurface dataPurpose of drilling finding and producing oil

Questions to be answeredWhere, how deep is the reservoir?How thick is it?What kind of rock is it?What is the porosity of this rock?What does it contain (water, oil or gas)?What will it produce?What is its areal extent?

What is a field development plan?Highlight the planned development activities in the fieldAddresses the following:- geology of the field- oil and gas original in place, reserve and production forecast- schedule of field development- no. of platforms and wells - methods for improving oil recovery- well completion design- production facilities aspects- gas utilisation and conservation schemes- project cost and project economic

Types Of Offshore Drilling Rigs

Oil Production System

Tubing a small pipe of diameter 3 inch installed in the well to handle the fluid flow from the reservoirChristmas tree assembly of valves on a final casing to control the rate of oil productionchoke a removable steel orifice device fitted to a well flowline to restrict fluid flowFlowline a pipeline that connects the well to the separatorSeparator vessel for separating mixtures of oil, gas and waterStorage tank a tank in which oil is stored

Purpose of refiningThe refinery is designed to process several different types of crude oil to produce useful petroleum products

Diff. prodts at diff. temp

Refining crude oil is carried out in 3 main stages: separation to split crude oil into groups of HCs using distillation process conversion breaking down of large HC molecules into smaller ones at temp higher than used in distillation treatment to remove impurities

SeparationProcess to split crude oil into groups of HCs according to size of diff moleculesMolecular size determined according to no. of carbon atoms presentThe larger and more complex molecules, the higher the boiling pt. and temp. to vaporizeWhen crude oil heated, lightest HC boil off first and heaviest last. As vap. cooled, they condensed back to liquids reverse order distillation process (to separate HCs into fractions or groups wt similar boiling pts.In refinery, fractional distillation takes place in tower (fractionator) wt temp 340oC at baseTemp gradually decrease towards the top 110oCColumn internals divided by intervals by horizontal trays: perforated or valve traysValve trays more common since they can accommodate wider vapor load than perforated trays Vap load, no of valves open on each tray also increaseEach tray cooler than the one below it providing temperature gradient on which separate vapors can condense

Crude oil first heated by furnace, then passed into the lower part of the columnSince most fractions in the oil is already boiling, they vaporize and rise up column thru valve traysAs each fraction condenses and chges back to liquid on separate trays, they are drawn offThis distillation proc. is continuous wt hot curde oil flowing in near the base of column and separate fractions flowing out at each level1st distillation carried out at atm. press. & separate crude oil into gases, light distillates, middle distillates & residueThe very lightest fraction: refinery gas in vap phase, used as fuel in refinery1st prodt fraction: LPG C3 & C4Light distillates: gasoline & naphtha major feedstock for petrochemical industryMiddle distillates: kerosene aviation fuel, gas oil heating fuel and for blending in diesel fuelsResidue used for fuel oil or further processed into lubricating oils, waxes & bitumenDepending on crude oil being processed, a single atm. DC not sufficient to separate out req. range of prodts. EfficientlyOften a series of DC is used

ConversionDist. proc rarely yield prodts in proportions required by marketHence, a variety of conversion techniques used to enable yield of prodts to be reshaped to match market demandConversion processes depend on types of crude to be processed & requirements of the market

CrackingThermal crackinghydrocrackingCat-crackingSteamcrackingvisbreakingBreaking down of large HC molecules into smaller valuable ones at temp.Higher than in DCCracking usg catalyst Prod. Components for Blending into high octane motor gasoline, diesel fuel Components, C3-C4 gasesHeat & pressurealone was the original method of obtaining greater amounts of motor gasolineCatalyst and hydrogen gas present at high pressureLPG or light distillates broken down in presence of steam at high T and low PUsed to improve quality of heavy fuel oils & to make diesel fuel componentsalkylationreformingLinking or changing arrangement of molecules to obtain additional quantities of high octane motor gasolineLight distillates containing HC molecules reformed by heat & P into more useful molecules of same size and boiling range usg catalyst eg platinum(Platformer)

TreatmentTo remove impurities of prodts from distillation proc., feedstocks & prdts of conversion proc.Why? Reduce efficiency of conversion proc., prdts become corrosive or unpleasant for customer to handleMain impurity: sulphur found in nearly all crude oils to some extentCrude oils categorized by sulphur contentSweet crude: small amts of sulphurSour crude: large amts of sulphurMercaptans: organic sulphur compoundHow to remove sulphur? Pass the untreated prdts wt a stream of H2 thru a bed of catalyst, converted to H2S gas then addition of chemicals, extracted and converted to liquid or solid sulphur for saleOthers: N2, O2 and various metallic compds which needed removal

BlendingMost fuels and lubricants are blends of limited no. of basic grades fr refineryContain additives designed for particular usesCarried out in batching tanks complete wt stirrer or circulating pumps or by in-line blending