Tor Bjørnstad 1

Tor Bjørnstad

Institute for Energy Technology (IFE)Kjeller, Norway

Heavy Oil Reservoirs: Fluid Tracing Challenges

Tor Bjørnstad12.04.23 Tor Bjørnstad 2

Established 1948About 600 employeesTurnover: MNOK 750Main activity areas

Nuclear technology Petroleum research Energy and

environmental technology

Research under contract

Institute for Energy Technology (IFE)

Tor Bjørnstad

Purpose of my visit here:

1. Offer to Pemex services with state-of-the-art technology within reservoir description (tracer technology), corrosion, flow assurance and pipeline transportation developed in our own laboratories.

2. Invite Pemex as an industrial participant along with other major oil companies into our various and ongoing Joint Industry Programs (JIPs) on R&D and technology development.

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Contents

About tracers Conventional use of tracers in reservoirs Tracer types, sampling, analysis and

modelling Heavy oil recovery methods – tracing

challenges Outlook – new functional tracers

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Visionary thinking

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Reservoir characterization

Geological(or static)reservoir

model

Geological(or static)reservoir

model

Well logsWell logs

BiostratigraphyBiostratigraphy

SedimentologySedimentology

GeochemistryGeochemistrySeismicsSeismics

Reservoir modellingReservoir modelling

Tracer dataTracer data

Production dataProduction data

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Tracer Technology:Definitions

Tracer Technology:Definitions

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What is Tracer Technology?

Tracer Technology may roughly be defined as a monitoring technology of physical, chemical or biological processes whereby a tracer species, which can be readily analysed on-line (in-stream, in-vivo) or off-line (in vitro), is added to the process in order to follow the process development and describe its mechanisms.

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Tracer category 1: Passive tracers

Passive or conservative (or also, less precisely, called ideal) tracers:

The requirement is that the tracer shall passively follow the fluid phase or phase fraction into which it is injected without any chemical or physical behaviour different from that of the traced component itself. In addition, the tracer must not perturb the behaviour of the traced phase in any way, -neither must the fluid phase or its components perturb the tracer behaviour.

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Tracer category 2: Active tracers

Active (also, less precisely, called non-ideal or reacting) tracers:

The tracer is taking active part in the process in qualitatively predictable ways, and is used to measure a property of the system in which it is injected. The degree of the active part-taking is a quantitative measure of the property to be determined.

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There are various tracer types

It is found to be practical to divide oilfield tracers into three types (not kinds!) based on their principally different production, treatment and analysis:

Molecules with special Stable-Isotope Ratios (D, 13C etc) Non-radioactive chemical species Radioactive atoms or molecules

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The “IFE Tracer Club”-different phases

Tracer Technologydevelopment sponsored by major oil companies.

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Tracers in reservoirs:Reservoir description and

flow-field mapping

Tracers in reservoirs:Reservoir description and

flow-field mapping

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Water expels oil

8 km

2 km

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Injection wellInjection well

ProductionwellProductionwell

Stratified reservoirStratified reservoir

Tracing of injection fluids

Tracing of injection fluids Preferential flow

directionsHorizontal and vertical communication between wellsPermeability strataSweep volumesLarge-scale hetero-geneities

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Field tracer production profiles

Production curves for HTO in various production wells also illustrating how break-through has been missed in two casesDesign of experi-ment done with ECLIPSE on existing reservoir model 0 0.4 0.8 1.2 1.6 2 2.4

(Thousands)

TIME FROM FIRST INJECTION (DAYS)

2.6

2.4

2.2

2

1.8

1.6

1.4

1.2

1

0.8

0.6

0.4

0.2

0

FROM WELLS IN A NORTH SEA RESERVOIR

INJ.

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North Sea field example

Use of well-to-well TT on the SNORRE-field showed surprising fluid flow directions of water and gas.

This resulted in a partly new stratigraphic model which again changed the reservoir model. Infill wells can be placed with increased reliability.

Injectionwell

Productionwell

Water tracer

Gas tracer

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North Sea oil reservoir – FAWAG process

Flow pattern from I1, I2 and I3

· Overlap of gas- contacted areas

· Development of gas caps both from I1 and I2

P1

P2

P3

P4 P5

P7

P8

P10

P9

P11

I1

I2

I3

P6

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Tracer response after WAG

PMCH

P4P4 P5P5

P7P7

P8P8

P9

I2I2

I3

P6P6

PMCH responses from I2

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Tracer Types, Sampling, Analysis and Modeling

Tracer Types, Sampling, Analysis and Modeling

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Isotopic ratio tracers

Example: Ratio of 12C and 13C which varies in different fluids and C-containing matter.

The standard is an established reference, such as ocean water.

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Radioactive tracers for IWTT

Organic molecules:

CH2TOH, 14CH3OH

CH314CHOHCH3, CH3CTOHCH3

Inorganic molecules:

HTO, 22Na+, 125I-, (131I-), (82Br-), 36Cl-, 35SCN-, S14CN-, (35SO4

2-), 56Co(CN)63-,

57Co(CN)63-, 58Co(CN)6

3-, 60Co(CN)63-

Co(CN)5(14CN)3-

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Non-radioactive polyfluorinated interwell water tracers

H

F

COOHH

HH

H

F

COOHH

H H

F

H

COOHF

H H

H

H

COOHF

F H

H

H

COOHH

F F

H

F

COOHH

H F

H

F

COOHF

F F

H FCOOH

HH H

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“Water” samples from flow line

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Non-radioactive gas tracers

Perfluorinated cyclic hydro-carbons with coordinated light hydrocarbon (methyl) groups are excellent gas tracers

PMCP PMCH

CARBON

FLUORINE

1,2,4-PTMCH

PDCB

1,3-PDMCH

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Gas Tracer sample container

General version, pressurized

General version, pressurized

New, for PFC-New, for PFC-tracers, non-tracers, non-pressurizedpressurized

New, for PFC-New, for PFC-tracers, non-tracers, non-pressurizedpressurized

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GC-MS/MSGC-MS/MS

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HPLC spectrometerHPLC spectrometer

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Gullfakswater

IFE-WTN-1,3

IFE-WTN-1,3,6

Fluorescein

Tap water

Heidrunwater

IFE-WTN-2,7

Emission wavelength (nm)

Exi

tatio

n w

avel

engt

h (r

el)

Nornewater

Fluorescense of Fluorescense of produced produced

waters and waters and tracerstracers

Fluorescense of Fluorescense of produced produced

waters and waters and tracerstracers

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Isotope mass spectrometerIsotope mass spectrometer

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LSC scintillation vial

12 mL scintillation cocktail+

8 mL distilled sample

intimately mixed

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Liquid scintillation counting - analysis of HTO in produced water

HTO spectrum, sample 1: 82 ± 4 Bq/l

HTO spectrum, sample 2: 10 ± 2 Bq/l

Background spectra

Channel number (Energy)

Co

un

tin

g r

ate

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Heavy Oil Production – Tracing Challenges

Heavy Oil Production – Tracing Challenges

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Oil Classification

Type API gravityDensity (kg/m3)

Viscosity (cP)

Bitumen << 10 1000 ++ > 10.000

Extra heavy oil < 10 1000 + > 1000

Heavy oil 10 – 22.3 920 - 1000 > 100

Medium oil 22.3 – 31.1 870 - 920 10 - 100

Light oil > 31.1 < 870 < 10

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Cyclic Steam Stimulation (CSS)

Steam injection

Steam soaking

Backpro-duction

Backpro-duction

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Tracers for CSS

Requirement: Tracers stable at temperatures of 200-300 C

For water vapor: HTTO, CH2TTOH

For water cond. phase: Naphtalene-sulphonic acids

For steam/gas phases: Various PFCs

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Toe-to-Heel Air Injection (THAI)

Cold heavy oilCold heavy oilCold heavy oilCold heavy oil

Combustion zoneCombustion zoneCombustion zoneCombustion zone

Coke zoneCoke zoneCoke zoneCoke zone

Mobil oilMobil oilMobil oilMobil oil

InjectedInjectedair andair andwaterwater

InjectedInjectedair andair andwaterwater

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Tracers for THAI

Requirement: Tracers stable at oil com-bustion temperatures

For air: 127127XeXe, 133133XeXe, 8585KrKr, 4He For water vapor: HTTO For water cond. phase: 2222NaNa++, Cl-

For CO2: 1414CCO2

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SAGD principleSAGD = Steam-Assisted Gravity Drainage

Steam injection

Oil productionVapor heats up a compartment around the well and mobilizes the oil

The mobilized oil is drained into the lower production well

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Statement

“During the startup and early operation of horizontal SAGD wells, it is important to understand the flow distribution of bitumen and water along the horizontal reservoir interval.

If this distribution is understood, the distribution of steam, injected either at the heel or toe of the steam injector, can be adjusted to optimize the startup and early operation of the SAGD pair”.

JPT

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Tracers for SAGD

Requirement: Tracers stable at temperatures of 200-300 C

For water vapor: HTTO, CH2TTOH

For water cond. phase: Naphtalene-sulphonic acids

For steam/gas phases: Various PFCs

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Low Temp. Solvent (VAPEX)

Production wellProduction wellProduction wellProduction well

Injection wellInjection wellInjection wellInjection wellDraining diluted and deasphalted oilDraining diluted and deasphalted oil

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Tracers for VAPEXpresently in pilot tests

Requirement: Temperature is not a stability issue for the tracers but they

must be stable against biodegradation

For light injected HC: T- or 14C-labelled propane, isopropane, butane,

isobutane, pentane etc.

For cond. aq-phase: FBA, Naphtalene-sulphonic acids, HTO and several

more

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SAGD and VAPEX combined-high-temperature recovery – in pilot stage

Production wellProduction wellProduction wellProduction well

Injection wellInjection wellInjection wellInjection well

Mobilized oilMobilized oil

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Tracers for combined SAGD and VAPEX

Requirement: Tracers for water vapor, water condensed phase and gas phase stable at temperatures of 200-300 C as for SAGD

Additional: Radiolabelled light HC tracers as for VAPEX

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OutlookOutlook

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Tracer development line

1945 1955 1975 1985 2008 2015

He-gas

131I-, HTO

•SCN- (?)•Co(CN)6

3- (?)•Radiolabellednatural gases

•Alcohols

Lab studies:•Radioactive

inorg. & org. w & g•Non-radioactive

w & g

•New high-temperature gas and water tracers

•Tracers for heavy oil EOR•Oil-partitioning tracers.•Functional nano-tracers

•PFC gas tracers•FBA water tracers•New gas tracers

•New water tracers

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Tracer molecules

become constantly

more complex

Are these among the future candi-dates??

Borrowed from Nick D. Kim

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Fluorescent and radioactive nano-particles

Particle coreemission

Particle core and functional layer

emission

Particle core and multifunctional layer emission

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Surfactant: Alpha-olefine sulphonatelabelled with radioactive nuclides

OHCH3(CH2)8CHCH2CH2SO3

- Na+

OH14CH3(CH2)8CHCH2CH2SO3

- Na+

OHCH3(CH2)8CTCH2CH2SO3

- Na+

CH3(CH2)8CH = CHCH235SO3- Na+

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Tracer injection pumpTracer injection pumpIFE personnelIFE personnel

Tracer operations in the North Sea 1Tracer operations in the North Sea 1

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Learning to operate the gas tracer sampling kit

Learning to operate the gas tracer sampling kit

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HybridHybrid

EndEnd