SPT Gas Condensate vs Oil Wax Deposition

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SPT Gas Condensate vs Oil Wax Deposition

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  • Gas Condensate vs Oil Wax Deposition

    Lauchie Duff Olga Users Group 11 November, 2009

  • OUTLINE

    q Recap from Previous Olga Users Presentationq Gas Condensate Misconceptionsq Fluid Characterisation Introduction Using Oil Mq Fluid Characterisation Using A & B Gas Condensates qWax Introductionq Wax Precipitation vs Wax DepositionqWaxy Condensates vs Waxy Oils Depositionq References

  • Recap Summary: Olga Wax Attack

    q Non Newtonian Rheology & How to Model in Olga

  • Recap: Olga Wax Attack on Non Newtonian Flow

    Steady State Shear & Thermal History EffectsOil Cooldowns : SCDP vs CCDP

    0

    500

    1000

    1500

    2000

    2500

    3000

    3500

    4000

    4500

    20 22 24 26 28 30 32 34 36Temperature (oC)

    Apparent Viscosity (mPas)

    S 1.20 BT 90C: 2kppm PPD, SCDP

    S 1.20 BT 90C: 2kpp PPD, CCDP83% Delta atFinal T

  • Recap: Non Newtonian Flow: Restarts

    Shear & Thermal History Affects on RestartsRestarts Ramps after Shut Down at 16oC: Shear History Effects

    0

    10

    20

    30

    40

    50

    60

    70

    80

    0 10 20 30 40 50 60 70 80 90 100Shear Rate (s-1)

    Shear Stress (Pa)

    No ramping after cooldown ramping

  • WAX / Condensate Misconceptionsq Condensate colour determines contaminationq Subsurface hydrocarbons are homogeneous fluids with no spatial

    variation, unlike petrophysical variations.q Waxes are n alkanes only q Measured WATs and wax contents are more accurate than

    simulatedq Wax Precipitation equals Wax Depositionq Reported GC / HTGC compositions must be right. The lab has

    surely integrated the areas and mass %s correctly?q Condensate compositions terminate around C30-C40q Long compositional heavy tails (of condensates), if they exist, are

    very insignificant (compared to oils)q Reported compositions and associated EOSs are matched to

    measured dew points by regression of critical propertiesq Condensate near well bore banking of heavy ends does not occur in

    high permeability formations

  • Fluid Characterisation is First (and very big) Step in Wax Deposition

    Concepts and Wax Primer: 1 Composition MeasurementsM Oil HTGC vs GC

    C52+ = 1.828%

    C30+ = 15.047 %

    0.0

    2.0

    4.0

    6.0

    8.0

    10.0

    12.0

    14.0

    16.0

    0 10 20 30 40 50 60

    SCN

    Wt%

    HTGC

    GC

  • M Oil Compositionq Lets take the HTGC and extend power and exponential laws

    M Oil HTGC & Manual Extrapolations

    C52+ = 1.828%

    y = 29992290.385621x-4.827528

    R2 = 0.974967

    C52+ = 2.189%

    0.0001

    0.0010

    0.0100

    0.1000

    1.0000

    10.0000

    5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 105 110 115 120 125 130 135 140 145 150

    SCN

    Wt%

    Measured HTGC

    HTGC: Manual Extrapolations

    Exponential

    Power

    Power (HTGC: Manual Extrapolations)

    y = 78.1118e-0.1220xR2 = 0.9583C52+ = 1.525%

  • M Oil Compositionq Lets take the HTGC and extend using PVTSim Characterisations-

    ie Log Wt% vs Molec Wt is LinearM Oil HTGC & Manual Extrapolations

    C52+ = 1.828%

    C100+= 0.0785%

    y = 29992290.385621x-4.827528

    R2 = 0.974967

    C52+ = 2.189%

    0.0001

    0.0010

    0.0100

    0.1000

    1.0000

    10.0000

    5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 105 110 115 120 125 130 135 140 145 150

    SCN

    Wt%

    Measured HTGC

    HTGC: Basis for Manual Extrapolations

    Exponential Extrapolation

    Power Extrapolation

    PVTSim C100+ Characterisation

    y = 78.1118e-0.1220xR2 = 0.9583C52+ = 1.525%

  • WAX: Composition incl n AlkanesqDoes the n alkane a/c for all the wax?

    M Oil HTGC

    0.07850.0000

    1.0000

    2.0000

    3.0000

    4.0000

    5.0000

    6.0000

    5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100

    SCN

    Wt%

    HTGC: PVTSim Characterised C100+

    n alkanes

  • M Oil Composition incl n Alkanes

    0.07850.00

    0.50

    1.00

    1.50

    2.00

    2.50

    3.00

    3.50

    4.00

    4.50

    5.00

    5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100

    SCN

    Wt%

    0

    0.05

    0.1

    0.15

    0.2

    0.25

    0.3

    0.35

    0.4

    0.45

    0.5

    Wax% ?

    HTGC: PVTSim Characterised C100+

    n alkanes as % SCN

  • M Oil Properties: WAT / WDTq Pour Point = 24oCq WAT by 3 different DSCs(45->75oC) / CPM (39-48.8oC)/ Rheology /

    CWDT (51oC) M Oil DSC (Heating Cycle)

    2

    2.5

    3

    3.5

    4

    4.5

    5

    0 20 40 60 80 100 120

    Temperature (oC)

    WDT1 = 67OCWDT 2 = 55OC

    WDT 2 = 44OC

    Heat Capacity

    J/gOC

    Still Melting at >100oC

  • M OIL WAX: WDT vs WATq Note endothermic melting curve vs exothermic xlln curve. Ie end of

    melting approx at beginning of Xlln. This is a very significant result as it reveals the effect of kinetics on WDT / WAT ie WDT-WAT almost zero

  • M WAT SIMULATION BASED ON HTGC

    Simulated M WAT: 52oC

    0

    5

    10

    15

    20

    25

    -30 -20 -10 0 10 20 30 40 50 60

    Temperature (oC)

    Wax Wt%

    Tulsa WAT to C52+

  • M OIL WAX: Conclusion

    qWe have simulated WAT of 52oC vs DSC measured WAT of 63oC & WDT of >100oC. Is this Robust and we can now characterise to these measurements?

  • WAX: M Oil Composition incl n AlkanesqDoes wax content go down as SCN increases?

    0.07850.00

    0.50

    1.00

    1.50

    2.00

    2.50

    3.00

    3.50

    4.00

    4.50

    5.00

    5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100

    SCN

    Wt%

    0

    0.05

    0.1

    0.15

    0.2

    0.25

    0.3

    0.35

    0.4

    0.45

    0.5

    Wax% ?

    HTGC: PVTSim Characterised C100+

    n alkanes as % SCN

  • M OIL : PVTSim CharactersationqPVTSim characterises zero wax after last measured plus

    fraction-but is this correct?PVTSims PARAW Characterised Fractions

    0

    0.1

    0.2

    0.3

    0.4

    0.5

    0.6

    0.7

    0 10 20 30 40 50 60 70 80 90 100

    SCN

    Fraction

    Paraffins

    Napthenes (Branched & Cyclics)

    Aromatics

    Waxes

    Asphaltenes

  • WAX: Composition incl n AlkanesqPVTSim characterises zero wax after last measured plus fraction

    0.07850.00

    0.50

    1.00

    1.50

    2.00

    2.50

    3.00

    3.50

    4.00

    4.50

    5.00

    5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100

    SCN

    Wt%

    0

    0.05

    0.1

    0.15

    0.2

    0.25

    0.3

    0.35

    0.4

    0.45

    0.5

    Wax% ?

    HTGC: PVTSim Characterised C100+

    n alkanes as % SCN

    PVTSims Heavy Characterised Wax %

  • My favourite PhD on WDT vs WAT

    Audrey Taggart 1995, Univ Strathclyde Nucleation, Growth and Habit Modification of n Alkanes etc Ref [3]

    qTerminology: Meta stable zone width = WDT-WAT

    q WDT approaches WAT in the limit of slow cooling

  • My favourite PhD : WDT vs WAT

    MSZW Associated with Crystallite Dissolution & Precipitation from

    C18H38 Melt

    0

    0.1

    0.2

    0.3

    0.4

    0.5

    0.6

    0.7

    0.8

    25 26 27 28 29 30

    Temperature

    Cooling Rate (oC/min)

    WAT WDT

    MSZW

    Tsat (at b =0oC /min)

  • WDT / WAT and Wax Xtal Effects

    MSZWs vs Carbon Chain Lengths

    0

    0.5

    1

    1.5

    2

    2.5

    3

    12 14 16 18 20 22 24 26 28 30 32

    Carbon Chain Length

    Meta Stable Zone Width (oC)

    MONOCLINIC

    TRICLINIC

    ORTHORHOMBIC

  • My favourite PhD on this subject

    WATs for Normal Alkanes (Measured at 5oC /min)

    -5

    5

    15

    25

    35

    45

    55

    65

    75

    85

    95

    105

    10 15 20 25 30 35 40 45 50 55 60Carbon Number

    Temperature (oC)

    0

    30

    60

    90

    120

    150

    180

    210

    240

    Enthalpy of Crystallisation (J/g)

    WATEnthalpy of Crystallisation

    TRICLINIC

    MONOCLINICORTHORHOMBIC

  • WAX PRIMERq Wax is not just n alkanes but many other species. eg Ref [2] determined

    microxlline waxes (mpts>60C) to be 20-40% n alkanes,15-40% iso alkanes and approx 35% cycloalkanes.

    q Macro and microXlline waxes. Microxlline waxes average 1-2 microns.q MicroXlline waxes MWts from 300 to 2500 (C21-C179).q Relatively poorly measured and limitations of measurements not widely

    understood. For example UOP 46 measures wax content at 30C after filtering cold extract through GF filters that retain 1.5 microns (at best) in liquid. CPM measures down to 2 microns at best. Kinetics of cooling affects WAT measurement.

    q WAT is defined as 2 ppm most insoluble (highest MWt) species. No lab measurements capable of measuring to this level.

    q Recent project: Oil. CPM WAT 39-48oC. DSC WAT at least 63oC.q GC / HTGC Measurements. Lack of resolution as Mwt increases and

    Xllinity changes from macro to microXlline.q Recommend best GC / HTGC merged to provide overall fluid

    composition.

  • WAX PRIMER

    q Investigation of n alkane content of macro & microXlline waxes:q AW 034 AND AW050 were microxlline and OFM/CFA macroxlline

  • Must Understand that Micro / Macro Relationship

  • WAX: Simulated WAT of Oil Mq Simulated WATs 52oC-85oC

    Simulated M WATS: 52-85oC

    0

    5

    10

    15

    20

    25

    -30 -20 -10 0 10 20 30 40 50 60 70 80 90

    Temperature (oC)

    Wax Wt%

    PVTSim WAT to C52+

    Tulsa WAT to C98+

    PVTSim (Heavy) WAT

  • PVTSim: Melting (WDT) vs SCNPVTSim SCN vs Melting Points of n Alkanes

    -120

    -100

    -80

    -60

    -40

    -20

    0

    20

    40

    60

    80

    100

    120

    140

    C7 C10

    C13

    C16

    C19

    C22

    C25

    C28

    C31

    C34

    C37

    C40

    C43

    C46

    C49

    C52

    C55

    C58

    C61

    C64

    C67

    C70

    C73

    C76

    C79

    C82

    C85

    C88

    C91

    C94

    C97

    C100

    TM (oC)

    If sample contains no more than

    C52, then require heating sample

    to 90oC in order to melt.

    If sample contains C100, then

    require heating sample to 125oC

    in order to melt.

    Equally, if sample contains C100,

    WDT - WAT = 125-96= 30oC

    If sample only contains C52:

    WDT-WAT = 90- 52 = 38oC

  • GAS CONDENSATE FLUID CHARACTERISATION

    Reasons why your gas condensate fluid characterisation is probably wrong.

    q Sampling below dew point if MDT, sample contaminationq Compositional gradientsq DST-well conditioning / poor separator control = gas / liquid

    entrainmentq Subsampling losing fractionsq Laboratory GC vs HTGC Measurements-improper

    measurement heavy fractions: condensate PVT very sensitive to the small amounts heavy fractions

    q EOS characterisation issues: Heavy fraction extension

  • GAS CONDENSATE FLUID CHARACTERISATION

    Choosing Representative Samplesq Is there such a thing? ie how do reservoir compositional

    gradients affect sample colour for example? Ref [4]

  • GAS CONDENSATE FLUID CHARACTERISATION

    Condensate colourq Ref [6] from onshore Canada describes the asphaltene production as varying from well to well and the condensate colour varies from clear to black between wells in the same field. Ref [6] further describes the condensate discolouration changing from pale yellow at low flow to black at high flow and back to pale yellow when flow is lowered again. Serious asphaltene emulsion and asphaltene fouling occurred during high flow periods. Other wells experienced a permanent shift from clear to dark condensates after absolute open flow tests with compression.q Ref [7] from an onshore Austrian lean gas condensate field also describes the same colouration issues as above being flow related. This reservoir was dew pointed at reservoir conditions (285 bar and 78oC). Plant asphaltene deposition was an issue and the estimated asphaltene content was 5 ppm of the produced liquid phase. The produced, dark coloured condensate streams showed through production testing to have increased colouring at the higher rates, attributed to increased asphaltene uptake.

  • GAS CONDENSATE FLUID CHARACTERISATION

    q Examples of GC vs HTGC and how GC misses heavy fractions Ref [1]

  • GAS CONDENSATE FLUID CHARACTERISATION

    q Examples of GC vs HTGC and how GC misses waxes and other high MWt species

  • GAS CONDENSATE FLUID CHARACTERISATION` North Sea Gas Condensate Example Ref [5]: HTGC inset

  • GAS CONDENSATE FLUID CHARACTERISATION1. Condensate A GC vs HTGC

    n Company A HTGC C100+ = 3.5 wt%n Company B GC C36+ = 0.384 wt%n Company C GC C35+ = 0.03 wt%

  • GAS CONDENSATE FLUID CHARACTERISATION1.

    2. PVT Consequences of Gas Condensate A GC / HTGC Measurements

    n GC based EOS underpredicted two measured dew points by 344 and 690 psi

    n HTGC based EOS exactly matched one and underpredicted the other by 190 psi

  • P Condensate Case History

    P Condensate Propertiesn API 46.7 (0.794 g/cc)n Pour point 21oCn Cloud Point 41oC by AMS 259 (CPM cooling at 0.2oC /min (= WAT?)n CWDT 45oCn Wax content ?

  • P Condensate Case History: PVT

    P Gas Condensate VLE (Company X)

    0

    1000

    2000

    3000

    4000

    5000

    6000

    7000

    8000

    0 50 100 150 200 250 300 350

    Temperature oC

    PSIG

    Measured Dew Point

    Co X Characterisation

    PVTSim C20+ Characterisation

  • P: Reservoir Fluid & TBP GivenReported Compositions: Reservor Fluid P & TBP P

    C38+ = 0.36%

    C20+ = 6.055 %

    0.01

    0.10

    1.00

    10.00

    100.00

    N2 CO2 C1 C2 C3 iC

    4nC

    4iC

    5nC

    5 C6 C7 C8 C9 C10

    C11

    C12

    C13

    C14

    C15

    C16

    C17

    C18

    C19

    C21

    C24

    C28

    C32

    C38+

    SCN

    Wt%

    Condensate TBP

    Reservoir Fluid

  • Flash P Reservoir Fluid to STPn Why stop at C59+?

    "Normal Characterisation" Options: Reservoir STP Flash to C59+

    with 55 C7+ Pcs

    C62+ = 1.2324%

    6.055

    0.01

    0.10

    1.00

    10.00

    100.00

    N2 C2 nC

    4 C6 C9 C12

    C15

    C18

    C21

    C24

    C27

    C30

    C33

    C36

    C39

    C42

    C45

    C48

    C51

    C54

    C57

    C60-

    C62

    SCN

    Wt%

    STP Condensate

    Reservoir Fluid

  • STP P Condensate Compositionn Lets go to C80 being Max PVTSims Normal Characterisation

    " Normal Characterisation" Options: Reservoir STP Flash with 74

    C7+ Pcs to C80

    C80+ = 0.0339%

    1.2324%

    0.39%

    0.00001

    0.00010

    0.00100

    0.01000

    0.10000

    1.00000

    10.00000

    100.00000

    N2 C1 C3 nC

    4nC

    5 C7 C9 C11

    C13

    C15

    C17

    C19

    C21

    C23

    C25

    C27

    C29

    C31

    C33

    C35

    C37

    C39

    C41

    C43

    C45

    C47

    C49

    C51

    C53

    C55

    C57

    C59

    C61

    C63

    C65

    C67

    C69

    C71

    C73

    C75

    C77

    C79

    SCN

    Wt%

    STP Condy Characterised to C80

    STP Condy Characterised to C59+

    Reservoir Fluid

  • STP P Condensate Composition

    nWhy stop at C80? C80+ is still 339 ppmnWe want to go to 1-2 ppm. nWhy?

  • P Condensate Composition

    nWe now need to use PVTSim Heavy Characterisation to go beyond C80.nBut this condensate is not heavy. API =

    46.7nProblem # 1 with PVTSim: Many normal

    waxy fluids have carbon numbers in excess of C100nWe continue with Heavy Characterisation

  • STP P Condensate Compositionn Lets go to C200 being Max PVTSims Heavy Characterisation

    " Heavy Characterisation" Options: Reservoir STP Flash with 74

    C7+ Pcs to C80

    C100+= 0.0874%

    C61+= 1.2324%

    0.0010

    0.0100

    0.1000

    1.0000

    10.0000

    100.0000

    N2 C1 C3nC

    4nC

    5 C7 C9C11C1

    3C1

    5C1

    7C1

    9C2

    1C2

    3C2

    5C2

    7C2

    9C3

    1C3

    3C3

    5C3

    7C3

    9C4

    1C4

    3C4

    5C4

    7C4

    9C5

    1C5

    3C5

    5C5

    7C5

    9C6

    1C6

    3C6

    5C6

    7C6

    9C7

    1C7

    3C7

    5C7

    7C7

    9C8

    1C8

    3C8

    5C8

    7C8

    9C9

    1C9

    3C9

    5C9

    7C9

    9

    SCN

    Wt%

    STP Condy Characterised to C200

    STP Condy Characterised to C80

    STP Condy Characterised to C59+

    Reservoir Fluid

  • P Condensate Heavy vs Normal Charactn Normal

    Heavy vs Normal Characterisation P Condensate 20 C7+ PCs

    0.00

    2.00

    4.00

    6.00

    8.00

    10.00

    12.00

    14.00

    N2

    CO2 C1 C2 C3 iC

    4nC

    4iC

    5nC

    5 C6 C7 C8 C9 C10

    C11

    C12

    C13

    C14

    C15

    C16

    C17

    C18

    C19

    C20-

    C21

    C22-

    C24

    C25-

    C28

    C29-

    C33

    C34-

    C39

    C40-

    C48

    C49-

    C80

    Wt %

    Normal Characterisation

    Heavy Characterisation

  • P Condensate Heavy vs Normal Charactn Heavy

    Heavy vs Normal Characterisation P Condensate 20 C7+ PCs

    0.00

    2.00

    4.00

    6.00

    8.00

    10.00

    12.00

    14.00

    N2

    CO2 C1 C2 C3 iC

    4nC

    4iC

    5nC

    5 C6 C7 C8 C9 C10

    C11

    C12

    C13

    C14

    C15

    C16

    C17

    C18

    C19

    C20-

    C21

    C22-

    C24

    C25-

    C28

    C29-

    C32

    C33-

    C39

    C40-

    C49

    C50-

    C200

    Wt %

    Heavy Characterisation

    Normal Characterisation

  • P Condensate Characterisation Summary

    Fluid CharacterisationC7+ PCs C20+ C38+ C59+ C80+ C100+TBP1 None None 10.96 0.36TBP2 None None 20.8GC Normal 20 26.23GC Heavy 20 24.65GC Normal 55 26.227 8.771 1.779 0.000 0.000GC Normal 74 26.231 8.776 1.784 0.034 0.000GC Heavy 94 24.644 8.164 1.875 0.390 0.087

    Characterisation Summary

  • P Condensate HTGC : What is this saying?n Wax content decreasing as SCN increases?

    " Normal Characterisation" Options: Reservoir STP Flash with 74

    C7+ Pcs to C80

    0.00001

    0.00010

    0.00100

    0.01000

    0.10000

    1.00000

    10.00000

    C20

    C22

    C24

    C26

    C28

    C30

    C32

    C34

    C36

    C38

    C40

    C42

    C44

    C46

    C48

    C50

    C52

    C54

    C56

    C58

    C60

    C62

    C64

    C66

    C68

    C70

    C72

    C74

    C76

    C78

    C80

    SCN

    Wt%

    STP Condy Characterised to C80

    HTGC (n alkanes) of Condy

  • Simulated P WAT v1 based on HTGCn V1 Simulated WAT =36oC vs CPM 41oC or CWDT 45oC?

    P Condensate Simulated WAT v1 = 36oC

    0.0001

    0.001

    0.01

    0.1

    1

    10

    100

    -30 -25 -20 -15 -10 -5 0 5 10 15 20 25 30 35 40

    Temperature oC

    Wax Content %

    v1 WAT

  • P Condensate Distillates Propertiesn 49.2 % Wax for C22+

    API Gravity 31.8Density 15C g/ml 0.866Viscosity 70C cSt 8.697Viscosity 100C cSt 4.736Pour Point C 21Conradson Carbon Residue

    wgt % 0.48

    Ash wgt % 0.045Asphaltenes wgt %

  • P Condensate Distillate Propertiesn UOP 46 C22+ = 49.2% Wax

    n HTGC C22+ = 6.6 % Wax (n alkane = 13% UOP46)HTGC vs UOP Wax Fraction

    0.000

    0.100

    0.200

    0.300

    0.400

    0.500

    0.600

    0.700

    C20

    C22

    C24

    C26

    C28

    C30

    C32

    C34

    C36

    C38

    C40

    C42

    C44

    C46

    C48

    C50

    C52

    C54

    C56

    C58

    C60

    C62

    C64

    C66

    C68

    Wax Fraction

  • Simulated P WAT v2q We need to resimulate reflecting 49% wax content for C22+

    P Condensate Simulated WAT v2 = 74.7oC

    0.0001

    0.001

    0.01

    0.1

    1

    10

    100

    -30 -25 -20 -15 -10 -5 0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80

    Temperature oC

    Wax Content %

    v1 WAT v2 WAT

  • C80+ = 0.034 Wt%We need to keep going down the

    SCNs because WAT is down to 1-2 ppm.

  • P Condensate WAT v3P Condensate Simulated WAT v2 = 85oC

    0.0001

    0.001

    0.01

    0.1

    1

    10

    100

    -30 -25 -20 -15 -10 -5 0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95

    Temperature oC

    Wax Content %

    v1 WAT

    v2 WAT

    v3 Heavy Characterised WAT

  • Simulated v2 P WAT vs CPM / CWDT

    q 75oC vs CPM 41oC and CWDT 45oCq So Simulation Must be Wrong?

    Lets look at some other Information: Melting Points of C80 using PVTSimq C80 MPt (Tf) = 112oC (WAT driven by C80 of

    0.034 wt% = 75oC)q WDT WAT = 37oC. Is this reasonable?

    Conservative?qWDT approaches WAT in the limit of slow cooling

  • PVTSim Melting (WDT) vs SCNPVTSim SCN vs Melting Points of n Alkanes

    -120

    -100

    -80

    -60

    -40

    -20

    0

    20

    40

    60

    80

    100

    120

    140

    C7 C10

    C13

    C16

    C19

    C22

    C25

    C28

    C31

    C34

    C37

    C40

    C43

    C46

    C49

    C52

    C55

    C58

    C61

    C64

    C67

    C70

    C73

    C76

    C79

    C82

    C85

    C88

    C91

    C94

    C97

    C100

    TM (oC)

    If sample contains no more than

    C52, then require heating sample

    to 90oC in order to melt.

    If sample contains C100, then

    require heating sample to 125oC

    in order to melt.

    Equally, if sample contains C100,

    WDT - WAT = 125-96= 30oC

    If sample only contains C52:

    WDT-WAT = 90- 52 = 38oC

  • Are we ready to make P Wax File?Still need viscosity tuned data

    P Condensate Cooldown Viscosity at 60s-1

    0

    10

    20

    30

    40

    50

    60

    5 10 15 20 25 30 35 40 45 50 55

    Temperature oC

    Viscosity (s-1)

  • Are we ready to make P Wax File?Whats happening here?

    P Condensate Cooldown Viscosity from 50 to 25oC

    0

    1

    2

    3

    4

    5

    6

    7

    25 30 35 40 45 50 55

    Temperature oC

    Viscosity (s-1)

  • Its all Upside Down!

  • Visco Tuning Using P WAT v 3

    P Condensate Cooldown Viscosity at 60s-1 : PVTSim Viscosity Tuning

    0

    10

    20

    30

    40

    50

    60

    5 10 15 20 25 30 35 40 45 50 55

    Temperature oC

    Viscosity (s-1)

    Raw Experimental

    Filtered Experimental

    Simulated

    Tuned

  • Wax Deposition in Production System

    Export of Stabilised Condensate through onshore pipeline-15oC Ground Temperature

  • Wax Deposition in Production SystemOnshore STO Condensate Export: 20 Days:

    Oil M vs Condensate P: Single Phase Onshore Pipeline

    82

    82.5

    83

    83.5

    84

    84.5

    85

    85.5

    86

    86.5

    87

    0 5000 10000 15000 20000 25000 30000 35000

    Distance (m)

    WAT (oC)

    0

    0.2

    0.4

    0.6

    0.8

    1

    1.2

    1.4

    1.6

    1.8

    2

    DXWX (mm)

    M Oil WAT

    P Condensate WAT

    M Oil DXWX

    P Condensate DXWX

  • Wax Deposition in Production SystemOnshore STO Condensate Export: 20 Days:

    Oil M vs Condensate P: Single Phase Onshore Pipeline

    0

    10

    20

    30

    40

    50

    60

    70

    80

    90

    0 5000 10000 15000 20000 25000 30000 35000

    Distance (m)

    T (oC) / Viscosity (cp)

    0

    2000

    4000

    6000

    8000

    10000

    12000

    14000

    16000

    QOST bbl/d

    M Oil T P Condensate TM Oil ViscosityP Condensate ViscosityM Oil QOSTP Condensate QOST

  • Wax Deposition in Production SystemOnshore STO Condensate Export: 20 Days:

    Oil M vs Condensate P: Single Phase Onshore Pipeline

    0

    10

    20

    30

    40

    50

    60

    70

    80

    0 5000 10000 15000 20000 25000 30000 35000

    Distance (m)

    Viscosity (cp)

    0

    100

    200

    300

    400

    500

    600

    700

    800

    900

    Shear Rate (s-1)

    M Oil Viscosity

    P Condensate Viscosity

    M Oil Shear Rate

    P Condensate SR

  • CONCLUSIONS

    1. Do not confuse science and the engineering implications of the science. Get the science right first before figuring the engineering consequences

    2. Differences between Reservoir and DST compositions could be due to:

    n analysis techniques employedn heavy end depletion in the near well bore region (condensate banking) n deposition in the production system (downstream WH choke)3. Wax precipitation is a precursor to deposition but

    should not be confused with deposition.4. Gas condensate deposition as simulated by Olga

    requires Reynolds number modification.

  • CONCLUSIONS: Condensate Banking Ref [8]

  • CONCLUSIONS: Condensate Banking

    n Core 1 had a permeability of 256 Md and 17.5% porosity.n Core 2 had a permeability of 39 Md and 18.5% porosity

    n Core 1 had a 10x Reduction in KG due to liquid bankingn Core 2 had a 25% reduction in KG due to liquid banking

  • References1. Zhou, Li et al 2005 Distribution and Properties of High Molecular Weight Hydrocarbons in Crude Oils and Oil Reservoir of Shengli Oil Field, ChinaJ. Pet Science & Eng 2005

    2. Barker et al 1995 The Chromatographic Analysis of Refined and and Synthetic Waxes. In Adlard Ed Chromatography in the Petroleum Industry Journal Chromatography Library Series, vol 56,pp 55-93

    3. Taggert. A 1995 Nucleation, Growth and Habit Modification of n Alkanes and Homologous Mixtures in the Absence and Presence of Flow Improving Additives PhD, University Strathclyde.

    4. Mullins et al 2009 The Impact of Reservoir Fluid Compositional Variation on Flow Assurance Evaluation OTC 20204

    5. Heath et al 1995 Quantification of the C30+ Fraction of North Sea Gas Condensates by HTGC Analytical Proceedings Incl Analytical Comms 1995,32,485

    6. Cosman, F Controlling Asphaltenes in Gas Condensate Systems NL Treating Chemicals Internal Case History from Alberta, Canada. 1970s

    7. Thou, Ruthhammer et al 2002 Detection Asphaltenes Flocculation Onset in a Gas Condensate System SPE 78321

    8. Thomas B 2003 Gas Condensate Reservoirs SPE 101514