Downhole Fluid Sampling, Contamination Estimation

Tariq Mattar RDC, Snr.PE

10 Mar 2021

Downhole Fluid Sampling, Contamination Estimation

CORING AND CORE ANALYSIS: CHALLENGES AND BEST PRACTICESVirtual Workshop Series (Feb, Mar & Apr 2021)

SPWLA SAUDI ARABIA CHAPTER (SAC)9th Topical Workshop

Agenda

2 SPWLA SAC WORKSHOP - CORING AND CORE ANALYSIS: CHALLENGES AND BEST PRACTICES

Basic Theory of Optical Density

DFA (Down Hole Fluid Analysis); Main Measurements

OCM (Oil Contamination Monitoring) Theory

WCM (Water Contamination Monitoring) Theory

Cases

Q&A

Objective


TM

“To Understand the Down Hole Fluid Analysis Physics of Measurements & Fundamentals of Optical Contamination Monitoring & Water Contamination Monitoring to enable assessment of the Sample Quality & the Hydrocarbon / Water Characteristics InSitu Conditions”

4

SPWLA SAC WORKSHOP - CORING AND CORE ANALYSIS: CHALLENGES AND BEST PRACTICES

Wireline Formation Tester

Down Hole Fluid Analysis is an Application within the Formation Tester

Sampling / Downhole Fluid Analysis (DFA):

o To confirm the presence of Hydrocarbon / Water bearing zones (clear any OH logs & Gradients uncertainties)

o PVT Studies (Reservoir Simulations, SARA, FDP, Facilities, Flow Assurance etc..)

o Determine Hydrocarbon / Water Type and Characteristics

o Determine Fractions of Fluid

o Assess Vertical & Lateral Communication (Composition, GOR, RFG)

o Estimate Contamination to Determine Sample Quality & Accurate Fluid Characteristics InSitu Conditions

TM

5


MRSMS – Multi-sample (carries 6 Bottles)

Fluid Analyzer Main

Pump Out Standard

Pump Out H/X/XX

Fluid Analyzer 2

Dual Packer

Saturn

Sample Chamber (pH)

Single Probe

Pow

er Cartlidge

Formation Tester ModulesBasic DFA/Sampling

String

Inlet Port

Pump Out

Power Cartlidge

Carrier SC/MS

Advanced Sampling String

2 Press Gauges3 Temp GaugesResistivity Cell

TM

Fluid Analyzer Main

Fluid Analyzer Main

Entry

Ports

Entry

Ports

Entry

Ports

6


Formation Testing ModulesFluid Analyzer; EYES Downhole

Fluid A

nalyzerF

luid Analyzer

To wellbore

TM

7


Formation Testing ModulesFluid Analyzer; Optical Density Spectrometry

Fluid A

nalyzerF

luid Analyzer

0

10logI

IOD

TM

8


Formation Tester ModulesFluid Analyzer; Optical Density Spectrometry

Fluid A

nalyzerF

luid Analyzer

C1

C2C3-C5

C6+

C1C3-C5

C6+

C1

C6+

CO2C3-C5C2

TM

8

9


Formation Tester ModulesFluid Analyzer; Fluorescence, Resistivity, Gas Detection, H2S & DV

Fluid A

nalyzerF

luid AnalyzerGas Detection Density-Viscosity RodH2S Coupons

TM

ResistivityFluorescence

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Formation Tester ModulesSpectroscopic pH Determination

Fluid A

nalyzerF

luid Analyzer

TM

0.8

0.6

0.4

0.2

0.0

OD

700600500400

Wavelength (nm)

pH > 9 base only

6 <pH < 9acid-base mixture

pH < 6acid only

1.2

1.0

0.8

0.6

0.4

0.2

0.0

OD

700600500400

Wavelength (nm)

1.2

1.0

0.8

0.6

0.4

0.2

0.0

OD

700600500400

Wavelength (nm)

experimentpredicted

pH=7.4

A B

pH Sensitive Dye

Accuracy ~ 0.1 unitRange extended by using dye mixturespKa’ is function of T, P and IS

Optical Contamination Monitoring OCM

SPWLA SAC WORKSHOP - CORING AND CORE ANALYSIS: CHALLENGES AND BEST PRACTICES 11

12


Fluid Miscibility; Fluid Fractions Vs Contamination

Miscibility is the property of liquids to mix in all proportions, forming a homogeneous solution

Miscible fluids− OBM filtrate & oil − OBM filtrate & gas Condensate − WBM filtrate & formation water

Immiscible fluids− OBM filtrate & water− WBM filtrate & oil − WBM filtrate & gas condensate− WBM filtrate & dry gas

OCM is not applicable to immiscible fluids Fluid fraction or fluid cut is more applicable

when sampling/DFA immiscible fluids

TM

13

SPWLA SAC WORKSHOP - CORING AND CORE ANALYSIS: CHALLENGES AND BEST PRACTICES TM

-0.1

0.9

1.9

2.9

3.9

4.9

500 700 900 1100 1300 1500 1700 1900

Clean up monitoring: 15 mins (after Mud)OBM & Oil

Formation Tester

Flowline

Fil

trate

Filtr

ate

Early Time

Crude Oil

Light Color

Formation Tester

Flowline

Filtr

ate

Filtr

ate

Late Time

Fo

rmati

on

Crude Oil

Dark Color

Fo

rmati

on

Methane Channel

Oil Peak/OBM

Wavelength (nm)

Optical Density

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-0.1

0.9

1.9

2.9

3.9

4.9

500 700 900 1100 1300 1500 1700 1900

Clean up monitoring: 1 hr

Wavelength (nm)

Optical Density

15


2.9

3.9

4.9

1500 1700 1900-0.1

0.9

1.9

500 700 900 1100 1300

Wavelength (nm)

Optical Density

Clean up monitoring: 2 hrs

16


3.9

4.9

-0.1

0.9

1.9

2.9

500 700 900 1100 1300 1500 1700 1900

Wavelength (nm)

Optical Density


17


4.9

2.9

3.9

1100 1300 1500 1700 1900-0.1

0.9

1.9

500 700 900

Wavelength (nm)

Optical Density

Clean up monitoring: 3.5 hrs

18


4.9

3.9

-0.1

0.9

1.9

2.9

1500500 700 900 1100 1300 1700 1900

Wavelength (nm)

Optical Density


19


-0.1

0.9

1.9

2.9

3.9

4.9

500 700 900 1100 1300 1500 1700 1900

Wavelength (nm)

Optical Density


20


-0.1

0.9

1.9

2.9

3.9

4.9

500 700 900 1100 1300 1500 1700 1900

Wavelength (nm)

Optical Density


21


-0.1

0.9

1.9

2.9

3.9

4.9

500 700 900 1100 1300 1500 1700 1900

Wavelength (nm)

Optical Density


22


-0.1

0.9

1.9

2.9

3.9

4.9

500 700 900 1100 1300 1500 1700 1900

Wavelength (nm)

Optical Density


23


-0.1

0.9

1.9

2.9

3.9

4.9

500 700 900 1100 1300 1500 1700 1900

Wavelength (nm)

Optical Density


Flowline

Filtr

ate

Filtr

ate

Early Time

Crude Oil

Light Color

Flowline

Filtr

ate

Filtr

ate

Late Time

Form

ati

on

Crude Oil

Dark Color

TM


Beer – Lambert Law of Mixing Fluids

TM

25


Linear relationship between absorbance and concentration of species

In the color region the OD of filtrate is normally zero

oilfil ODODOD ,, 1

- contamination

oilfil

oil

ODOD

ODOD

,,

,

Beer – Lambert Law of Mixing Fluids

26


0, filOD

oilfil

oil

ODOD

ODOD

,,

,

oilOD

OD

,

1

aOD oil ,

12/5)(

v

bavOD

Single Channel OCM

2/3

27


Color

ac bc

1.88 44.10

Methane

am bm

0.14 1.93

Fitting Methane & Color Channels

Color Channel

Methane Channel

Volume

Colo

r Channel / M

eth

ane C

hannel

12/5)(

v

bavOD

OD meas 1.65

OD meas0.128

28


88.11 OD

Color

ac bc

1.88 44.10

14.01 OD

Methane

am bm

0.14 1.93

oilOD

OD

,

1

Contamination plotting

Color (12%)

Methane (8%)

No Correction to methane

1.65

0.128

29


-0.1

0.9

1.9

2.9

3.9

4.9

500 700 900 1100 1300 1500 1700 1900

Wavelength (nm)

Optical Density

Linear relation between channels

OD filtrate @ methane channel ≠ 0

Methane Channel offset: 15 mins

OD filtrate @ color channel is often 0

30


When Ch4 (Color) = 0Ch0 (Methane) = 0.051Filtrate OD = 0.051

Cross Plot between Methane & Color

Meth

ane C

hannel

Color Channel

31


oilfil

oil

ODOD

ODOD

,,

,

88.11 OD

Color

ac bc

1.88 44.10

Methane

am bm

0.14 1.93 14.0051.0

14.0

OD

Color (12%)

Methane (8%)

Methane Corrected (11%)

1.65

0.128

Water Contamination Monitoring WCM

SPWLA SAC WORKSHOP - CORING AND CORE ANALYSIS: CHALLENGES AND BEST PRACTICES 32

33


Density (�) and Conductivity (C) change linearly with contamination (h)

• h =��

��, density mixing rule at constant P & ~T

• h =��,��

��,��,��, Conductivity mixing rule

Mixing rules for Downhole WCM

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Exponent selection:• Single probe : = 5/12th

• Radial probe : = 2/3rd

Fluid property changes with cleanup can be modeled with a power law:

� = �� + ��

�� = ��,�� + ��

� → ∞

Formation fluid property determination

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Volume (cm3)

Densi

ty [

g/cc

]Conduct

ivit

y [m

S/m

]

Flow regime identification

From regression:�� = �� + ��

Assume:�� = ��

�� = �� + ��

log��

��= − � log �

�� = 1.0125+ 6.2��/�

��,�� = 16470+ 1422134��/�

Example 2

Paper #27291 • Adriaan Gisolf

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0.2

[g/cc]

End point plotting & QC

Filtrate end point can be achieved from:

• Surface measurement

• Conductivity Vs Density Cross plot

Measured fluid properties all:

• Vary linearly with contamination

• Vary linearly together

Any properties cross-plotted

• Should generate a straight line

• Linear function can be fitted

• End point should fall on the linear fit

Paper #27291 • Adriaan Gisolf

Measured data

Data eliminated from regression

Linear regression

Conductivity [mS/m]D

ensi

ty [

g/cc

]

10,000 [mS/m]

Filtrate

Formation water

h =��

��h =

��,��

��,��,��

Summary

Accurate Contamination Estimation is crucial for Sampling Quality which affects PVT studies, FDP, Facilities Design etc..

Determining Contamination in Real time saves unnecessary Pumping hours & rig time

Using all sensors available & accurate modeling will minimize the contamination uncertainty

37


Thank You

www.spwla-saudi.org

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Downhole Fluid Sampling, Contamination Estimation

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