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

Flow and Enthalpy MeasurementsUSC Center for Geothermal Studies

Distinguished 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 (QL) and vapor (QV) 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 bulk velocity of the fluid is determined by injecting a pulse of tracer and then monitoring its arrival time at various sample points along the process 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 TracersTracer Selection Criteria for CTFT

Each tracer must partition completely into its respective phase:The liquid-phase tracer must be highly soluble in waterThe gas-phase tracer must have high volatility to facilitate 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 must 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


Tracer Flow Testing- CTFT Tracers

Fluoride (as KF)

Bromide (as NaBr)

Fluorescein dye

The liquid-phase tracers that have been evaluated for 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


Tracer Flow Testing- CTFT Tracers

Propane

Freon-12

Helium

The Vapor-phase tracers that have been evaluated are:

high detection limit

no longer available

high detection limit, no field analysis Helium

Isopropanol

Perfluorcarbons

Sulfur hexafluoride (SF6)

high detection limit, no field analysis

high detection limit, partitioning

cost, required for HP-TFT


Tracer Flow Testing- CTFT TracersThe optimal CTFT Tracers are:

ThermoTrace Sulfur Hexafluoride

> 50% solubility in water Detection limit of < 1 ppb Heat stability > 250C

Mixture pressures of 2900 psi Detection limit of < 0.005 ppb Thermally stable and inert below 500C


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 OpsApplicable 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 time interval True average flowrates integrated over a desired time interval Not affected by flow and pressure surges

Enthalpy and Mass Flowrates (Steam Fraction) based on Fundamental Principles and Traceable to Primary Standards - 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 SamplingSample 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 DataField SF6 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.


Tracer Flow Testing- Real Time Data

Field SF6 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.


Tracer Flow Testing- Real Time DataWell 1067

Thermotrace Injection Rate and Measured ppb TT in Brine

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ppb TT in Brinegrams/min TT Injection Rate

Injection

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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

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400Discrete Sample Data

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

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K

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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

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

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Tracer Flow Testing- Data FlowchartMass flow of each phase

(QL,V = QT / CT)Mass Flow ControllerSF6 mass

injection rate (Q )

Continuous Steam Monitor

SF6 concentration in steam (C )

Total Fluid Enthalpy)H(Q)H(QH LLVV +=

Tracer Injection Tracer Analysis

injection rate (QT)Liquid Delivery

SystemTT 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(QH

LV

LLVVT +

+=


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

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

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Brine Flow Rate

Steam Flow Rate

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Tracer Flow Testing- Future Development

Reducing detection limits for brine and steam

tracers

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

Downhole TFT for vertical profiling of steam

and brine mass flow


www.thermochem.com

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