gas hydrates challenges in oil and gas industry-qatar university-29 june 2011

7/27/2019 Gas Hydrates Challenges in Oil and Gas Industry-Qatar University-29 June 2011

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Gas Hydrates Challenges in Oil and

Gas IndustryProf Bahman Tohidi

Centre for Gas Hydrate ResearchInstitute of Petroleum Engineering

Heriot-Watt University, Edinburgh, EH14 4AS, UK

Contact: Prof Bahman Tohidi, Tel: +44 (0)131 451 3672, Fax: +44 (0)131 451 3127,Email: [email protected], www.pet.hw.ac.uk/research/hydrate

What Are Gas Hydrates? Crystalline solids wherein guest

(generally gas) molecules are trapped incages orme rom y rogen on ewater molecules (host)

They are formed as a result of physicalcombination of water and gas molecules

. .,CuSO4.5H2O) the ratio between waterand gas is not constant


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Hydrogen Bonding

O

O

OO

Hydrate Structure and Thermodynamics The necessary conditions:

Presence of water orice

Suitably sized gas/liquidmolecules (such as C1,

C2, C3, C4, CO2, N2,H2S, etc.)Suitable temperature

and pressure conditions

P

Hydrates

No H drates Temperature and pressure

conditions is a function ofgas/liquid and watercompositions.

T

Hydrate phase boundary


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The Gas Hydrate Structures

Water moleculeMethane, ethane,

carbon dioxide.6

cage

Propane, iso-butane,

natural gas.

512

51262

51264

Structure I

Structure II3

16 8

2

Gas molecule(e.g. methane)

Methane +

neohexane, methane+ cycloheptane.

435663

Structure H

2 1

51268

Hydrates in Subsea/Permafrost Sediments

0

275 285 295 305 315 325 335 345 355T/K

0

275 285 295 305 315 325 335 345 355T/K

5

10

15

20P/MPa

0

5

10

15

20

25

30

35

P/MPa

Depth

5

10

15

20P/MPa

0

5

10

15

20

25

30

35

P/MPa

Depth

hydrates

nohydrates

25

30

35

275 285 295 305T/K

25

30

35

275 285 295 305T/K

y ra es

no hydrates


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Zone of Gas Hydrates in Subsea

Sediments 273 283 293Temperature / K0

Hydrothermal

Sea Floor

Depth/Metre 500

1000

Hydrate Phase

Boundary

Gradient

1500

Zone ofGas Hydrates

in Sediments

GeothermalGradient

The Sediments are saturated with water

Zone of Hydrates in Permafrost273 283 293

T / K0263

Geothermal

Depth of Permafrost

PhaseBoundary

Zone ofGas Hydrates

in PermafrostGeothermal

GradientDepth/M

etre 500

1000

Permafrost

1500

The Sediments are saturated with water


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Hydrate Formation in Porous MediaHydrates

Water

Gas Bubble

Grains

50 Microns

Gas Hydrates in Marine Sediments


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Hydrate Stability Zone in Sediments

Bottom simulating reflector at the base of hydrate stability,Blake Ridge (after Shipley et al., 1979)

Methane Hydrate Discoveries


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Methane Hydrates

Natural Gas (135) Oil (142)

Coal (498)

Gas Hydrates (2171 for 15% recovery factor)

Future Energy Sources (109 TOE)Y. Makogon SPE 77334

Carbon Balance

Hydrate Formers and StructuresAr

Kr N24

6(CH2)3O

C HsII

Hydrogen Hydrates

O2CH4

Xe; H2S

5CO

7

i-C4H10

n-C4H10

sII

sII double

C2H6

C-C3H6

enzene

Adamantane

Methyl Cyclopentane8 Cyclo octanesI

sH (double)


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History of Gas Hydrates Scientific curiosity (1810)

Potential source of energy (1960s)

Some of the current issues: Storage and transportation of natural gas and hydrogen, CO2 capture

and storage, source of energy, wellbore integrity in hydrate bearingse men s, su sea an s es, po en a azar n eepwa er r ng,

separation of oil and gas, global climate change

Potential gas production from hydrates (2016)

Important Properties

Capture large amounts of gas (up to 15 mole%)

Remove light components from oil and gas

Form at temperatures well above 0 C

Generally lighter than water Need relatively large latent heat to decompose

Exclude salts and other impurities

Result from h sical combination of water and as

Hydrate composition is different from the HC phase

Large amounts of methane hydrates exist in nature


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Friend or Foe? Foe Pipeline blockage

Subsea landslides

Deepwater drilling and production (hydrate formation, wellboreintegrity, casing collapse, etc)

Friend Source of energy

Climate change CO2 capture, transport, and storage

Phase change materials

Foe: Dangers to Deepwater Production

uncontrolled gas blowout


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Well Clean-up and Testing

Foe: Gas Hydrates and Seafloor Stability

u sea an s es

can generate tsunamis


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Foe: Gas hydrates and Seafloor StabilitySubsea Land SlidesDissociation ofmarine gas hydratesis believed to beresponsible for hugesubsea landslides.

ome sc en s s

explain themysteries ofBermuda trianglewith gas hydrates.

Foe: Oil and Gas Exploitation

Drillin o eration

Gas hydrates formation could cause serious operational andsafety problems. Some of the scenarios are:

Long tie-backs and deepwaterproduction

Gas expansion and coolingeffect

Start up and shut down Well clean-u and testin Logging operation WAG (Water Alternating Gas)

Injection

Processing


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Avoiding Hydrate Problems Water removal (De-Hydration) Increasing the system temperature Hydrates

Wellhead

conditions Heating

Reducing the system pressure Injection of thermodynamic inhibitors

Methanol, ethanol, glycols

Using Low Dosage Hydrate Inhibitors

Pressure

Downstream

conditions ne c y ra e n ors

Anti-Agglomerants (AA)

Various combinations of the above Cold Flow/HYDRAFLOW

No Hydrates

Temperature

Avoiding Hydrate Problems-Dehydration


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Avoiding Hydrate Problems-Temperature

Hydrates

Wellhead

conditions

Pressure

Reducing Heat Loss, orIncreasing Temperature

Temperature

No HydratesLw-LHC-H-VDownstreamconditions

Avoiding Hydrate Problems-Pressure

No HydratesHydrates

Wellhead

conditions

Pressu

re

Reducing System PressureGenerally not used as apreventive measure

Only used in hydrate plug

Temperature

Lw-LHC-H-V Downstreamconditions

removal


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Avoiding Hydrate Problems-ThermodynamicInhibitors

No Hydrates

Hydrates

Wellhead

conditions

Pressure

Thermodynamic InhibitorInjectionLimitations:- water cut- cost (CAPEX and OPEX)- environmental impact

Temperature

Lw-LHC-H-V

Downstream

conditions- flow regime- operational difficulties- other problems

Avoiding Hydrate Problems-Kinetic HydrateInhibitors (Generally accepted view)

Hydrates Upstream

conditions1800

2000

18

20

Induction Time

Pressure

- - -

Downstream

conditions

T

0

200

400

600

800

1000

1200

1400

P/p

sia

0

2

4

6

8

10

12

14

T/o

P/psia

T/C

min max

Temperature

w HC 0 500 1000 1500 2000Time/min

Induction time should be longer than the residence time!

Test Conditions: Minimum Temperature & Maximum Pressure!!!


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Avoiding Hydrate Problems-Anti-Agglomerants

Hydrates Upstream

conditions

Pressure

Downstream

conditions

T

min max

Temperature

No HydratesLw-LHC-H-V

19 0

20 0

21 0

45

50

50

60PTtor ue

Avoiding Hydrate Problems-Anti-Agglomerants

P/ba

r

80

90

10 0

11 0

12 0

13 014 0

15 0

16 0

17 0

18 0

T/oC

5

10

15

20

25

30

35

40

Torque/

N.cm

10

20

30

40

t ime /h r .

0 2 4 6 8 10 1 2 1 4 1 6 1 8 2 0 2 2 2 4 2 6 2 8 3 0

P/bar

70

80

90

100

110

120

130

140

150160

170

180

190

200

210

T/oC

0

5

10

15

20

25

30

35

40

45

50

Torque/N.cm

0

10

20

30

40

50

60

PTtorque

Water/condensate/gas system (30% water) with 1% AA.Hydrate formation, but very little increase in torque.

t i me /h r .0 2 4 6 8 10 12 14 16 18 20

70 00


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New Approaches in Preventing Gas

Hydrate Problems: Cold Flow No heating No insulation ow ng promo ng y ra e orma on, u preven ng

their agglomeration Providing seeds Using Anti-Agglomerants Natural inhibitors Mechanical meansA combination of the above

Several Institutions are working on Cold Flow SINTEF-BP CSIRO/IFP ExxonMobil Heriot-Watt (HydraFlow)

Heriot-Watt HYDRAFLOW: Concept Convert all or most of the vapour phase into hydrates

(add water if necessary)

inhibitors and/or mechanism of hydrate formation

Transport hydrates as slurry Separate some of the free liquid phase (and chemicals)

and recycle (Loop Concept)

(or transport the gas in the form of hydrates, e.g., dry,hydrates in water or hydrates in oil slurries)


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HYDRAFLOW: Loop Concept Circulating liquid phase plays the role ofcarrier fluid

Gas from Well-1 is converted intohydrates

The same process will continue for otherwells

Hydrate slurry is transported to the hostfacilities

Hydrates, oil and some water are

A suitable fluid mixture is re-circulatedusing a single phase pump on the hostfacilities

HYDRAFLOW: Potential Benefits Reducing/eliminating

Gas hydrate risks

Slugging

Wax

Pipeline pigging requirement

Reducing pipeline costsBare pipes, no heating

No need for subsea and/or multi-phase pumps


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New Approaches: Hydrate Safety Margin

Monitoring and Early Detection Systems Hydrate Safety MarginMonitoring Determinin the actual amount of salt and

Wellhead

conditions

Over

inhibited

Underinhibited

inhibitor (Methanol, Glycol, Ethanol, KHI,and AA) from downstream measurement

Eliminating/reducing risk of human error orequipment malfunction

Automation, adjusting the inhibitorinjection rates

Detecting Early Signs of Hydrate

Pressur

No Hydrates

Temperature

Downstream

conditions

For most systems the initial hydrateformation may not result in pipelineblockage

Detecting the early signs of hydrateformation could result in reducing gashydrate blockage risks

Hydrate risk

Low safety margin

Safe/optimised

Over inhibited

Blockage RemovalIt is not possible to prescribe a general procedure for hydrateblockage removal, as each case needs to be investigated

-

Gas hydrate blockage in the pipeline has some differences within-situ hydrates.

They are initially porous and permeable unlike in-situ hydrates

They may transfer pressure but limited in the transfer of flow

During their formation some free water have been trappedbetween hydrate crystals


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Natural Gas-Water

t = 31 hrs , P=54.9 bar, T=3.4 C t = 94 hrs , P=53.0 bar, T=3.2 C

t = 142 hr s, P=52.1 bar, T=3.2 C t=142 hrs , P=52.1 bar, T=3.2 C

Blockage Removal Through Heating

The objective isto move the Hydratessystem outsidehydrate stability

zone.

The system could Pressu

re Initial

conditions

Final

conditions w- - -V equilibria.

Temperature

No Hydrates

Lw-H-V


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Blockage Removal Through HeatingIt is often difficult to locate apipeline hydrate plug to begin Hydrates

.

Heat must be supplied with caution,beginning from the end andprogressing toward the middle ofthe plug.

If a h drate lu is dissociated in

Pressure

Lw-H-V

Initial

conditions

Final

conditions

the middle, the pressure mightincrease suddenly, resulting inequipment failure, blowouts, orhydrate projectiles in pipelines.

Temperature

Blockage Removal Through Depressurisation The objective is to move thesystem outside the hydrate stability Hydrates

Lw-H-V

. A common misconception is thatdepressurisation alone can causehydrate dissociation, forgettingabout the role of latent heat ofdissociation. When the s stem is

Pres

sure

No Hydrates

Initial

conditions

Final

depressurised, some hydratesremove heat from surrounding anddissociate, resulting in a reductionin the system temperature.

Temperature

con t ons

273


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Blockage Removal Through Depressurisation The thermal gradient will result inheat flow through pipe-wall. Hydrates

Lw-H-V

The system temperature could dropto below zero and ice could form.

The second misconception is thatduring depressurisation, the hydrate

lu dissociate at its end s .

Pressure

No Hydrates

conditions

Final

conditions

In fact although the initial plugdissociation is at its ends, the hydrateplug will dissociate radially resulting inplug dislodge.

Temperature273

Blockage Removal Through DepressurisationQ

Hydrate PlugPipe-Wall

Q

Depressurisation from both endsprojectileice formation

The problem with ice formationlow heat transferprotective layerice will dissociate on temperature rise not pressurereduction


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Blockage Removal Through Inhibitor InjectionInhibitor injection will shift the hydrate phaseboundary to the left, which could result in gashydrate dissociation.

However, gas hydrate dissociation will producefresh water reducing the concentration of theinhibitor.

Also gas hydrate dissociation will result in therelease of gas (possible pressure increase) and areduction in system temperature.

Blockage Removal Through Inhibitor Injection

Initial Inhibitor

Pressu

re

Hydrates

Inhibitor

Injection

Dilution

Initial

Hydrate

Phase

Temperature

No HydratesLw-H-V

Boundary


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Case Studies Hydrates in Gas Lift

H drates in Water In ection Lines

Hydrates in Onshore Natural Gas Production

Pipeline blockage in the North Sea

Hydrate problem during logging operation

Pipeline blockage after an emergency shut-down

Hydrate problems in GOM

Summary Gas hydrates are formed as a result of physical combination

of water and suitably sized molecules

sediments and permafrost regions

They have very interesting properties, with many potentialindustrial applications They had significant impact on the past climate

industries, in particular in offshore and deepwater operation

Novel technologies/techniques are necessary for addressinggas hydrate challenges in deepwater and long tiebacks

Contact: Prof Bahman Tohidi, Tel: +44 (0)131 451 3672, Fax: +44 (0)131 451 3127,Email: [email protected], www.pet.hw.ac.uk/research/hydrate


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Gas Hydrate, Flow Assurance and PVT

Research Activities at Heriot-Watt

Contact:Professor Bahman TohidiDirector, Centre for Gas Hydrate ResearchInstitute of Petroleum EngineeringHeriot-Watt UniversityEdinburgh EH14 4AS, UKDirect Line: +44 (0)131 451 3672Fax: +44 (0)131 451 3127Mobile: +44 (0)776 116 5784Email: [email protected]://www.pet.hw.ac.uk/research/hydrate

CENTRE

FOR GAS

HYDRATE

RESEARCH

Gas hydrates in gas, water and gas water interface, as

viewed through the High Pressure Micromodel

Introduction

Heriot-Watt University is a medium size university inEdinburgh (Capital of Scotland) with some 6,000students

Institute of Petroleum Engineering (IPE) was form in1975 and has some 200 MSc, MPhil and PhD students

Some 70% of the IPE income is from research projects

There several big research groups; such as; Hydrates,Scale, Geophysics, Uncertainty, etc ----


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Background and Areas of Activities BackgroundPVT and Phase Behaviour of Petroleum Reservoir Fluids

Gas hydrate research started in 1986Centre for Gas Hydrate Research Established in Feb 2001Centre for Flow Assurance Research (C-FAR) started in 2007

Areas of Activities

Consultancy, mostly through Hydrafact (www.hydrafact.com)Training (open and in-house courses)

Research Interests PVT and Phase Behaviour of

Reservoir Fluids

Flow Assurance Gas Hydrates

Wax Salt (halite)

Asphaltene

Gas H drates ressure Hydrates

Wellhead

conditions

Hydrates could block subsea pipelines

Flow Assurance

Gas Hydrates in Sediments

Positive/other Applications of GasHydrates

No Hydrates

Temperature

Downstream

conditions

P & T profi le and hydrate phase boundary


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HYDRAFACT Ltd

HYDRAtes and Flow Assurance Consulting and Technologies Construction of equipment

Trainin /short courses

Consultancy

Software (HydraFLASH)

Commercialising novel technologies, e.g.,

(HydraCHEK)Software (HydraFLASH)

HYDRAFLOW

www.hydrafact.com

Current Joint Industry Projects Evaluation of Low Dosage Hydrate Inhibitors

Kinetic Hydrate Inhibitor and Anti-Agglomerant Evaluation

,methodology by Hydrafact (www.hydrafact.com)

One patent has already been filed

Hydrate Monitoring and Early Warning SystemA number of techniques and prototypes have been developed for

monitoring the hydrate safety margin. Two patents have been

filed. One of the devices H draCHEK is bein commercialised b.

Hydrafact

A number of techniques have been developed for hydrate earlywarning. A patent application has been filed

Organising a field trial


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Current Joint Industry Projects Gas Hydrates and Flow Assurance Thermodynamics aspects of hydrates, inhibitor distribution, water content,

salting-out, wax, etc

Solid-liquid equilibria in various glycol-water systems

The developed software (HydraFLASH) is ranked the best by Total and itis being commercialised by Hydrafact

One patent is being filed

Hydraflow: A Wet Cold Flow Solution Converting most of the gas into hydrates and transporting them as slurry

(hydrates, slugging, wax, downhill pressure recovery, reduction in

volumetric flow rate)

A high pressure flowloop has been constructed as well as a unique set oftest facilities.

A patent has been filed which will be commercialised by Hydrafact

Current Joint Industry Projects PVT and Phase Behaviour of Reservoir Flu ids

The lab has been refurbished and equipped with two major Hg-freeequipment (200 C and 15,000 psia) have been purchased

The HPHT (250 C and 30,000 psia) facilities is being equipped with asalt compatible cell (viscosity, density, three phase IFT)

Slim tube is being added to the existing capabilities Some of the topics in the current phase of the project: Viscosity (effect ofmud filtrate contamination), IFT at HPHT, Acoustic Characteristics of

Reservoir Fluids, Phase Behaviour of CO2-Oil systems, Maximum Carbon

Number in GC Analysis, etc

Impact of Aromatics on Acid Gas Injection Project sponsored by the Gas Processing Association

Joint project with Paris School of Mines

Cross-over project between hydrates and PVT project


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Current Joint Industry Projects Impact of Common Impurities on Carbon DioxideCapture, Transport and Storage

CO2 originating from capture processes is generally notpure and can contain impurities such as: H2O, CH4, N2, H2, NOx, H2S, SO2

The main aim of the proposed project is to investigate the phasebehaviour and properties of CO2-rich stream containing impurities

Phase behaviour of Saline water and CO2-rich streams

Other Projects

Towards Zero Carbon Emissions: Novel LowPressure Molecular Natural Gas/CO2/H2Stora e and Se aration usin Semi-ClathratesEPSRC One patent has been filed

Quantifying and monitoring potential ecosystemimpacts of geological carbon storage, NERC We are part of a large consortium

Hydrates in sediments

Methane hydrate formation

in high pressure glass

micromodel

2 sediments

Analysis of existing oceanographic and seismicdata Our work is on effect of hydrates on sediment

properties


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Resources Staff/Students 25 member research team with expertise in Chemical,

Mechanical, Electronic and Petroleum Engineering,Geology/Geochemistry, Physics/Geophysics,Chemistry, Radio-Physics, Polymer with more than 10nationalities.

Experimental Facilities More than 40 versatile experimental rigs, operating

from -80 oC to +350 oC and pressures up to 2,000 bar

Flow loop (1 dia, 40 m long, 200 bar, Moineau pump)in an environmental chamber (-15 to + 20 C)

Software Comprehensive phase behaviour and hydrate

programme, commercial and research versions

Database Wax predictive model

Some of the experimental facilities

gas hydrates challenges in oil and gas industry-qatar university-29 june 2011

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