Ntl Gas 101 & 102 · 2005-02-16 · MEA filtration gas sweetening unit Gases are washed in a...

Natural Gas Natural Gas & Natural Gas Liquids& Natural Gas Liquids

Presented by

Dennis Steffy, DirectorMining and Petroleum Training Service


Purpose:Purpose:

To establish a factual understanding of To establish a factual understanding of

Hydrocarbon GasesHydrocarbon Gases, their properties and , their properties and

some facts pertaining to their production, some facts pertaining to their production,

conditioning, processing and conditioning, processing and

transportationtransportation

Origin of Oil and GasOrigin of Oil and Gas

Oil and gas originated from the remains Oil and gas originated from the remains of microscopic life in shallow marine of microscopic life in shallow marine environmentsenvironments

Fossil Fuels are composed

ofhydrocarbons


The total amount of organic matter stored this way is less than 1% of all the organic matter that has been formed by plants and animals over geologic time


These remains These remains decomposeddecomposed to form to form oil and gasoil and gas

Then migrated upwards until Then migrated upwards until trapped by some sort of trapped by some sort of subsurface geological formationsubsurface geological formation


The rock where oil and gas forms The rock where oil and gas forms is called the “is called the “sourcesource” formation” formation

The rock where the oil and gas is The rock where the oil and gas is found is called the “found is called the “reservoirreservoir””

A reservoir must be both A reservoir must be both porousporousand and permeablepermeable

Oil and Gas ReservoirsOil and Gas Reservoirs

High Porosity and PermeabilityHigh Porosity and Permeability

are goodare good

Porosity is open space in the Porosity is open space in the formation where oil and gasformation where oil and gas

can accumulatecan accumulate


More PorosityMore Porosity= = more room for oil and gasmore room for oil and gas

Permeability is the ability of oil and Permeability is the ability of oil and gas to move through the formationgas to move through the formation

High permeability means easy andHigh permeability means easy andrapid movement of oil and gas to the wellrapid movement of oil and gas to the well


Organic rich limestone - a good source rock

Certain conditions of Certain conditions of pressure and pressure and temperature are temperature are required to create required to create petroleum petroleum -- the the hydrocarbon windowhydrocarbon window

Oil forms in a Oil forms in a source source rockrock like organic shale.like organic shale.It It migratesmigrates until it is until it is trappedtrapped by a by a cap rockcap rock..It resides in a It resides in a reservoir reservoir rockrock like sandstone.like sandstone.

ReservoirsReservoirs should have should have high porosity, permeabilityhigh porosity, permeability

Examples: sandstone, conglomerate, Examples: sandstone, conglomerate, cavernous limestone, highly fractured rocks cavernous limestone, highly fractured rocks

(even granite)(even granite)


In the reservoir:In the reservoir:Water is found on the bottomWater is found on the bottom

-- water is heavier than oil or gaswater is heavier than oil or gas

Oil is found just above the waterOil is found just above the water

Gas is found at the top of the reservoirGas is found at the top of the reservoir

Oil migrates up dip because it is less dense than rockOil floats on water of the saturated zone; natural gas (methane) floats on top of the oil

Faults may themselves seal off migration, or may place impermeable rock against the reservoir to block escape

Angular unconformity traps oil in lower dipping layers

Fossil reefs are bulbous lenses interbedded with normal layers

They trap oil derived from lower source rocks

Sedimentary facies changes create lens-shaped wedges or pinch-outs that may serve as traps insome conditions

Summary of Petroleum TrapsSummary of Petroleum Traps

Prudhoe Bay Oil Fields developed below regional unconformities


Much gas can also be found Much gas can also be found dissolved in the oildissolved in the oil

Associated GasAssociated Gas


Associated gasAssociated gas leaves the oil when the leaves the oil when the pressure is reduced to a certain levelpressure is reduced to a certain level

Associated gasAssociated gas slowly leaves the oil as slowly leaves the oil as the reservoir pressure is reduced the reservoir pressure is reduced through production of fluids from the through production of fluids from the reservoirreservoir


The pressure generated by the gas in The pressure generated by the gas in the formation is the formation is critical critical to moving to moving the oil to the surfacethe oil to the surface

As gas pressure is reduced by As gas pressure is reduced by drawing fluids from the reservoir, drawing fluids from the reservoir, energy must be addedenergy must be added to the to the reservoir to bring oil to the surfacereservoir to bring oil to the surface


Energy can be added to the Energy can be added to the reservoir by:reservoir by:

Gas Injection Gas Injection

Water FloodWater FloodMiscible Flood Miscible Flood


Standard practice:Standard practice:

First: Produce the oil First: Produce the oil

Next: The gas when the energy Next: The gas when the energy provided by the gas is no provided by the gas is no longer neededlonger needed

Secondary RecoverySecondary Recovery

Secondary and even tertiary recovery Secondary and even tertiary recovery methods aid in recovering the methods aid in recovering the maximum maximum amount of oil from the amount of oil from the reservoirreservoir

Secondary RecoverySecondary Recovery

Methods include:Methods include:Down hole pumpsDown hole pumpsGas LiftGas LiftMechanical PumpingMechanical Pumping

Other Gas SourcesOther Gas Sources

MethaneMethane can also be found in can also be found in connection with coal or lignite connection with coal or lignite depositsdeposits

Synthetic methane can be produced Synthetic methane can be produced however at high costhowever at high cost


Decomposition ofDecomposition of

organic material always organic material always

produces methaneproduces methane

Other Gas SourcesOther Gas Sources

Large numbers of CowsLarge numbers of Cows

A burping cow is a polluting cow!

Cows, which have doubled in population in the last40 years to an estimated 1.3 billion worldwide, produce one pound of methane for every two pounds of meat that they yield

Hydrocarbons are composed only of Hydrocarbons are composed only of Hydrogen Hydrogen and and CarbonCarbon

We will deal with rather We will deal with rather simplesimplehydrocarbons in this presentationhydrocarbons in this presentation

The hydrocarbons of interest all end in The hydrocarbons of interest all end in the letters ‘the letters ‘--aneane’’

Petroleum HydrocarbonsPetroleum Hydrocarbons

Physical PropertiesPhysical Properties

40094009+97+97C5H12C5H12PentanePentane

32603260+31+31C4H10C4H10ButaneButane

25172517--4444C3H8C3H8PropanePropane

17701770--127127C2H6C2H6EthaneEthane

931 BTU931 BTU--260 F260 FCH4CH4MethaneMethane

Heating Heating ValueValue

Boiling Boiling PointPoint

FormulaFormulaChemical Chemical NameName

Methane

Ethane

Propane

CH4

C2H6

C3H8

Contaminates in Produced GasContaminates in Produced Gas

North Slope gas may have significant North Slope gas may have significant amounts of undesirable contaminates amounts of undesirable contaminates including:including:

Carbon Dioxide up to 13%Carbon Dioxide up to 13%Hydrogen Sulfide up to 250 ppmHydrogen Sulfide up to 250 ppmWaterWater

Conditioning Natural GasConditioning Natural Gasfor Transmissionfor Transmission

To transport gas in a pipeline, To transport gas in a pipeline,

a “contract” establishes the a “contract” establishes the

maximum amountsmaximum amounts of of

undesirable contaminatesundesirable contaminates


A A conditioning plantconditioning plant must be must be

designed to meet contract designed to meet contract

specifications specifications over the life of the over the life of the

projectproject

Hydrocarbon Dewpoint Control System

ConditioningConditioningNatural Gas for TransmissionNatural Gas for Transmission

Carbon DioxideCarbon Dioxide and and Hydrogen Hydrogen

SulfideSulfide are called “are called “acid gasesacid gases” ”

(often called Sour Gas) because (often called Sour Gas) because

they form acids when in contact they form acids when in contact

with water.with water.


Acid gases cause severe corrosion of Acid gases cause severe corrosion of process equipment and pipelinesprocess equipment and pipelines

Hydrogen Sulfide is an Hydrogen Sulfide is an extremely toxicextremely toxicsubstance, immediately dangerous to life substance, immediately dangerous to life and health at very low levelsand health at very low levels

Conditioning Conditioning Natural Gas for TransmissionNatural Gas for Transmission

The removal of ‘The removal of ‘sour gassour gas’’ from a from a

methane stream is called methane stream is called

““sweeteningsweetening” and is a part of the ” and is a part of the

conditioning of gasconditioning of gas to meet pipeline to meet pipeline

contract specificationscontract specifications

There are many There are many

processes to processes to

sweeten gas, sweeten gas,

however the however the

most common is most common is

the the Amine Amine

systemsystem

This natural gas sweetener is designedto remove H2S to less than 4 vppm

and water to less than 1 vppm

The pictures above illustrate a natural gas sweetener installed at a plant site

Absorber

Sour gas or LPG

Rich Amine

FilterFlash Drum

Flashed Gas

Rich-LeanHeat Exchanger

Cooler

Filters

Lean Amine

Treated gas or LPG

Regenerator

Acid Gas

Condenser

Reboiler

MEA filtration gas sweetening unit

Gases are washed in a counter current washing column and the dissolved H2S separated in a later step using steam

Fines, worn from the piping, collect in the amine solution, which ultimately lead to blocking and foam generation in the column

Filters for clearing these streams and discharging either wet or dry cakes have yield excellent results


Amine TreatmentAmine Treatment can remove can remove

both both Carbon DioxideCarbon Dioxide and and

Hydrogen SulfideHydrogen Sulfide


Carbon DioxideCarbon Dioxide can be recan be re--injected into injected into the formation to maintain pressure the formation to maintain pressure and sweep oil toward the well boreand sweep oil toward the well bore

Removal of Removal of Hydrogen SulfideHydrogen Sulfide can can generate large amounts of elemental generate large amounts of elemental SulfurSulfur


Carbon DioxideCarbon Dioxide can form can form Dry IceDry Ice in in process equipment and plug off process equipment and plug off critical componentscritical components

Dry IceDry Ice must be thawed with heat to must be thawed with heat to remove the plugremove the plug

Frozen natural gas shed

In Canada


Water content must be reducedWater content must be reducedto a very low levelto a very low level

Water can freeze and plugWater can freeze and plugcritical process equipmentcritical process equipment

Water combines with Water combines with MethaneMethane totoform form Hydrates Hydrates that can plug off that can plug off

critical process equipmentcritical process equipment

DehydrationDehydration

The most common large scale process The most common large scale process for removing water from a gas stream for removing water from a gas stream is called “is called “Glycol DehydrationGlycol Dehydration””

Glycol dehydration is used all overGlycol dehydration is used all over

the Slope and the Inletthe Slope and the Inlet

Glycol UnitGlycol Unit

DehydrationDehydration

Cold Glycol can absorb large amounts of water Cold Glycol can absorb large amounts of water vaporvapor

When heated, the Glycol then gives up the When heated, the Glycol then gives up the water vapor and can be cooled and reusedwater vapor and can be cooled and reused

Large equipment would be required to handle Large equipment would be required to handle the amounts of gas contemplated by the the amounts of gas contemplated by the North Slope gas lineNorth Slope gas line

Boiler UnitBoiler Unit

Natural Gas Drying & NH3 Removal

This design is capable of removing moisture and ammonia from natural gas through it's adsorption process

The system is capable of taking saturated feed gas and returning dry gas with less than 0.1 ppmv of water

In addition, NH3 is removed down to less than 0.2 ppmv

The pictures above depict a natural gas dryer prior to shipment

This allows the LNG facility to liquefy excess quantities during periods of low use and store them until they can be vaporized at a time of need

This LNG Prepurifier is designed to remove moisture, CO2, and mercaptans from natural gas taken from a pipeline

Gas Custody Gas Custody and Custody Transferand Custody Transfer

The volume of gas transferred from seller The volume of gas transferred from seller to buyer is measured in to buyer is measured in SCF SCF (Standard (Standard Cubic Feet), measured at 14.7 psi and Cubic Feet), measured at 14.7 psi and 60 degrees F60 degrees F

Alternate specifications are more Alternate specifications are more commonly stated in metric unitscommonly stated in metric units


The The Heating ValueHeating Value of the gas in of the gas in

BTU’s per cubic foot is an BTU’s per cubic foot is an

essential sales parameteressential sales parameter


Pure Methane generates 931 BTUPure Methane generates 931 BTU

Penalties may be assessed when the BTU Penalties may be assessed when the BTU value is below contract specificationsvalue is below contract specifications

The The heating valueheating value is measured in a calorimeter is measured in a calorimeter that burns a carefully measured amount of gasthat burns a carefully measured amount of gasunder controlled conditions and measures the under controlled conditions and measures the heat producedheat produced


Standard Units for Gas MeasurementStandard Units for Gas MeasurementMCFMCF 1000 cubic feet=(10’x10’x10’)1000 cubic feet=(10’x10’x10’)MMCF Million Cubic feet=1000xMCFMMCF Million Cubic feet=1000xMCF

100’x100’x100’100’x100’x100’

BCF Billion Cubic feet=1000XMMCFBCF Billion Cubic feet=1000XMMCF1000’x1000’x1000’1000’x1000’x1000’

TCF Trillion Cubic feetTCF Trillion Cubic feet--1000xBCF1000xBCF10,000’x10,000’x10,000’10,000’x10,000’x10,000’

Stranded GasStranded Gas

Stranded Gas is Gas that is

not yet connected

to a transportation system

ShrinkageShrinkage

Shrinkage is the loss of gas used to process and transport the product

Fuel for power generationFuel for facility heatingFuel for compressors and process equipmentIncidental losses through leaks, flares, carryover, etc.

ShrinkageShrinkage

Typical Shrinkage numbers:

–4% to 5% for pipeline compression, the longer the line the greater the shrinkage, up to 8%

–1% to 4% for gas conditioning, probably greater on the Slope

–14% to 17% for LNG production

Contract PriceContract Price

The price paid forlong-term agreements

or agreements to purchase an established volume of gas over a specific time period

Tied to the standard price per BTU for energy

Spot MarketSpot Market

Prices bid for short term or one-time purchases

Traded as commodities

Prices vary according to amounts in storage, anticipated weather conditions

and international markets

Trading Floor at a Natural Gas Marketing Company

Storage GasStorage GasIn the lower 48 where demand is greater than local supply, gas is stored underground in reservoirs during periods of low demand and retrieved when demand increases above local supply

Suppliers can control amounts of gas sold for storage and influence later prices

Storage GasStorage Gas

Sometimes gas can be purchased at Sometimes gas can be purchased at lowerlower costcost during offduring off--peak times peak times andand stored for stored for laterlater useuse

Storage gas Storage gas maximizes the usemaximizes the use of of longlong distancedistance pipelines that can pipelines that can shipship at full at full capacitycapacity more gas than more gas than isis required, required, andand the excess stored the excess stored againstagainst times of times of increasedincreased demanddemand

Source: Energy Information Administration

Components of Residential Natural Gas Prices

Transmission/Storage 19%Commodity 34%Distribution 47%

Industrial 33.2%Elect. Power 23.8%

Residential 21.5%Commercial 13.7%

O&G Indust Ops 4.9%Pipeline Fuel 2.8%Vehicle Fuel 0.1%

Questions?

Date post:	26-Jul-2020
Category:	Documents
Upload:	others
View:	1 times
Download:	0 times

Ntl Gas 101 & 102 · 2005-02-16 · MEA filtration gas sweetening unit Gases are washed in a...

Documents