Advancements in Tracer Flow Testing; Development of Real-Time ...

Advancements in Tracer Flow Testing; Development of Real-Time Technology for

Flow and Enthalpy Measurements

USC Center for Geothermal StudiesDistinguished Speaker Program

USC Center for Geothermal Studies 27 February 2012 © Thermochem, Inc

Flow and Enthalpy Measurements

Tracer Flow Testing-Core Principles

What is Tracer Flow Testing (TFT)?Tracer Flow Testing is the measurement of single- or multi-phase fluid flow by the injection and dilution of phase-specific chemical tracers.specific chemical tracers.

Its primary application in the geothermal industry is monitoring enthalpy and mass flowrate of vapor and liquid at each stage in the power generation process, from production well, to power plant, to reinjection.

USC Center for Geothermal Studies 27 February 2012

Tracer Flow Testing- Core Principles



Mass rate of liquid (Q L) and vapor (Q V) is given by:

QL,V = QT / CT

Q = Mass Rate of Fluid (Liquid or Vapor)QL,V = Mass Rate of Fluid (Liquid or Vapor)

QT = Tracer Injection Mass Rate

CT = Tracer Concentration by Weight



Tracer Flow Testing (TFT) is a “steady state” method in which tracer is metered into the process flow path on a continuous basis and simultaneously sampled downstream of the injection point.

TFT is not a “time of flight” method in which the bul k velocity of the fluid is determined by injecting a pulse of tracer and then monitoring its arrival time at various sample points along the pro cess flow path.



What is Continuous Tracer Flow Testing (CTFT)?

Continuous tracer flow testing (CTFT) is the measurement of mass flow rate and enthalpy in real time. The real -time process is time. The real -time process is made possible by the use of in-field tracer analysis technology.

CTFT utilizes standard TFT tracers, injection equipment and sampling equipment and therefore maintains the advantages inherent to that system.


Tracer Flow Testing- CTFT Tracers

Tracer Selection Criteria for CTFT

� Each tracer must partition completely into its resp ective phase:The liquid-phase tracer must be highly soluble in w aterThe gas-phase tracer must have high volatility to f acilitate vaporization

� The tracers must be thermally and chemically stable under process conditions

� Quantitative, precise analytical methods with wide linear ranges must be available

� Natural background concentrations of the tracers mu st be relatively low and stable or nonexistent.

� The cost of the tracers must be reasonable for the quantities to be injected

� Non-radioactive and non-toxic



� Fluoride (as KF)

� Bromide (as NaBr)

� Fluorescein dye

The liquid-phase tracers that have been evaluated f or CTFT are:

high detection limit, reactive

high detection limit, no field analysis

pH dependence, temperature limitations� Fluorescein dye

� Sodium benzoate

� Rhodamine WT dye

� 1,5-naphthalene disulfonate

� 2,7-naphthalene disulfonate

� Proprietary ThermoTrace

pH dependence, temperature limitations

high detection limit, interferences

pH dependence, temperature limitations

low frequency wavelength emission, interferences

low frequency wavelength emission, interferences



� Propane

� Freon-12

� Helium

The Vapor-phase tracers that have been evaluated ar e:

high detection limit

no longer available

high detection limit, no field analysis� Helium

� Isopropanol

� Perfluorcarbons

� Sulfur hexafluoride (SF 6)

high detection limit, no field analysis

high detection limit, partitioning

cost, required for HP-TFT



The optimal CTFT Tracers are:

ThermoTrace Sulfur Hexafl uoride

� > 50% solubility in water

� Detection limit of < 1 ppb

� Heat stability > 250°C

� Mixture pressures of 2900 psi

� Detection limit of < 0.005 ppb

� Thermally stable and inert below 500°C


Tracer Flow Testing- Field Ops

• The TFT measurement process does not disrupt plant or injection systems nor does it cause production loss.


production loss.

• No modifications or expensive installations needed on pipelines. Only small ports required for injection and sampling.

Tracer Flow Testing- Field Ops

Applicable over a wide range of conditions –� Steam fraction: 1 to 99 %� Pressure: 0 to 5000 psig� Flowrate: 0.5 to 5000+ KPH

True average flowrates integrated over a desired ti me interval –True average flowrates integrated over a desired ti me interval –� Not affected by flow and pressure surges

Enthalpy and Mass Flowrates (Steam Fraction) based on Fundamental Principles and Traceable to Primary St andards -� Not an empirical correlation

No Radioactive or Toxic Chemical Tracers Used


Tracer Flow Testing- Injection System Original Tracer Metering Systems were truck-mounted skids……


Tracer Flow Testing- Injection System

The gas tracer is metered by the MicroMFC , a high-precision mass flow controller that accurately meters the gas tracer (+/- 1.5%).

MicroMod Tracer Metering System

meters the gas tracer (+/- 1.5%).

The liquid tracer is metered by the MicroLDS , a high-precision liquid delivery system that accurately meters the liquid tracer (+/- 0.5%).


Tracer Flow Testing- Tracer Sampling

Two-Phase Sampling in Wellfield


Tracer Flow Testing- Tracer Sampling

Sample Bottles and Cooler


Tracer Flow Testing- Tracer Analysis

Liquid Tracer Analysis On-site Lab

Vapor Tracer Analysis On-site Lab


Tracer Flow Testing- Real Time Analysis

MicroMod Continuous Brine Monitor (CBM)

• Real-time analysis of liquid phase tracer by custom LED flow-through fluorescence detector.

• Automated data logging, temperature correction and output for real-time applications.


Tracer Flow Testing- Real Time Data

Field SF 6 Analyzer(Prototype)

• Automated pre-treatment of vapor to remove H2O, CO2, H2S. Not to remove H2O, CO2, H2S. Not affected by total NCG levels.

• Automatic sample injection and analysis by Electron Capture Detection (ECD) method.

• Automated data processing and output for real-time applications.



Field SF 6 Analyzer(in development)

• Flow-through sample chamber • Flow-through sample chamber and analysis by infrared absorption

• True real-time SF6 measurement

• Automated data processing and output for real-time applications.



Well 1067Thermotrace Injection Rate and Measured ppb TT in B rine

200

300

ppb

TT

in B

rine

60

TT

Inje

ctio

n R

ate

(gra

ms/

min

)

ppb TT in Brinegrams/min TT Injection Rate

Injection

0

100

200

9:43 10:04 10:26 10:48 11:09 11:31Time

ppb

TT

in B

rine

0

20

40

TT

Inje

ctio

n R

ate

(gra

ms/

min

)

Injection start(~16 gr/min)

Increase injection rate(~30 gr/min)

Injection stop


Tracer Flow Testing- Real Time DataWell 5 Brine Flow

Discrete Sample Data

250

300

350

400Discrete Sample Data

Discrete Sample Data:Avg. Brine Flow Rate = 40.9 KPH

0

50

100

150

200

11:48 12:17 12:46 13:14 13:43Time

KP

H


Tracer Flow Testing- Real Time DataWell 5 Brine Flow

CTFT Data vs. Discrete Sample Data

250

300

350

400Discrete Sample DataCBM Data

Discrete Sample Data:Avg. Brine Flow Rate = 40.9 KPH

CBM Data:Avg. Brine Flow Rate = 31.0 KPH

0

50

100

150

200

11:48 12:17 12:46 13:14 13:43Time

KP

H


Tracer Flow Testing- Data Flowchart

Mass flow of each phase

(QL,V = QT / CT)

Mass Flow Controller

SF6 mass injection rate (Q )

Continuous Steam Monitor

SF6 concentration in steam (C )

Total Fluid Enthalpy)H(Q)H(Q

H LLVV ×+×=

Tracer Injection Tracer Analysis

injection rate (QT)

Liquid Delivery System

TT mass injection rate (QT)

in steam (CT)

Continuous Brine Monitor

TT concentration in brine (CT)

Steam Separator

Steam Enthalpy

(HV)

Brine Separator

Brine Enthalpy

(HL)

)Q(Q)H(Q)H(Q

HLV

LLVVT +

×+×=


Tracer Flow Testing- Real Time Data2-Phase Flow Rates and Fluid Enthalpy for Well-2 (C TFT vs. TFT)

600

800

1000

KP

H M

ass

Flo

w

400

500

600

700

Total Fluid Enthalpy

Tot

al fl

uid

Ent

halp

y (B

TU

/lb)

0

200

400

600

11:15 12:27 13:39 14:51 16:03 17:15Time

KP

H M

ass

Flo

w

0

100

200

300

400

Brine Flow Rate

Steam Flow Rate

Tot

al fl

uid

Ent

halp

y (B

TU

/lb)


Tracer Flow Testing- Future Development

�Reducing detection limits for brine and steam

tracers

�Reducing cost of tracers to < $100/year�Reducing cost of tracers to < $100/year

�Downhole TFT for vertical profiling of steam

and brine mass flow


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