Magnetic Resonance Imaging Logging, development and evolution as a fundamental

evaluation tool in the reservoir management

Ron Cherry, Maged Fam and Emiliano López

Geological & Reservoir Overview

Formation Evaluation Problems

High uncertainty in reservoir evaluation using conventional Log

Analysis, due to:

• Multilayer reservoirs made up of an average of 20 stacked layers, about 5 mt. each.

• Low formation water salinity

• Several water/oil and gas/light oil contacts randomly distributed throughout a rock column of 1000 mts. (average 1500 to 2500 mts.)

• Complex lithology (shaly and tuffaceous sand reservoirs)

• Different hydrocarbon types

Core Porosity vs Permeability Core Porosity vs Permeability

Core measurements on samples from

about 60 wells, 800 samples from San

Jorge Basin

Porosity (%)

Perm

eab

ilit

y (

md

)

0.001

0.01

0.1

1

10

100

1000

0 5 10 15 20 25 30 35 40

Porosity (%)

Perm

eab

ilit

y (

md

)

Grain Density Vs Core Porosity

Core Porosity (%)

Gra

in D

en

sit

y (

G/c

3)

Matrix Density Distribution in so called “Sandstone” from San Jorge Basin

Matrix Density Distribution in so called “Sandstone” from San Jorge Basin

MRI Core Porosity (%)

Core

Poro

sit

y (

%)

Core Porosity Vs MRI Core Porosity

MRI Core Porosity vs. Core PorositySan Jorge Basin

MRI Core Porosity vs. Core PorositySan Jorge Basin

Geometric Mean T2 Cutoff vs. DepthGeometric Mean T2 Cutoff vs. Depth

The high degree of variation in the T2 cutoff range may cause some inconsistencies in the final Interpretation.

Thus the SBVI method is a better technique for determining BVI.

Geometric Mean T2 Cutoff (ms)

Dep

th (

m)

Geometric Mean T2 Cutoff Vs. Depth

SBVI Coef.

0.0XXX

Spectral Bulk

Volume Irreductible

SBVI

Spectral Bulk

Volume Irreductible

SBVI

Core Permeability and MRI Permeability Models (md)

Dep

th (

m)

Core Permeability and MRI Permeability Models Vs Depth

N.B.: MRI Permeability data is based on SVBI model

Core Permeability and MRI Permeability ModelsVs Depth

Core Permeability and MRI Permeability ModelsVs Depth

N.B.: MRI Permeability data is based on SVBI model

Core Permeability Vs MRI Permeability ModelsCore Permeability Vs MRI Permeability Models

MRI Permeability Models (md)

Core

Perm

eab

ilit

y (

md

)

MRI Permeability Models Vs Core Permeability

MRIL Pre-job

Planning

ActivationSelection @

Logging speed

MRIL Life CycleMRIL Life Cycle

Specify ObjectivesReservoir Properties &

Problems

Borehole Conditions

Size, mud, temp….etc

Data Processing

&Interpretation

Core Analysisif available

Resistivity log

PrognosisSelection of Zones

to TestSTIMRIL

Compare

Test Results Yes

Met reservoirObjectives

No

Field LogQC

Tool PhysicsTool PhysicsAcquisition Acquisition ParametersParameters

G, TG, TEE, T, TWW

Expected Fm. Fluid Expected Fm. Fluid PropertiesProperties

Temp., Pressure &Temp., Pressure &ViscosityViscosity

Mud PropertiesMud PropertiesBorehole SizeBorehole Size

MRILMRILForwardForward

Modeling Modeling PlannerPlanner

waterwateroiloil

gasgas

waterwateroiloil

gasgas

waterwater

oiloil

MRI Forward ModelMRI Forward Model

Petrophysical Solution!!!

MRI Specific Acquisition and Interpretation Techniques

“one logging pass”

EDMEnhanced Diffusion Method (Hydrocarbons 2-50 cp)

TDATime Domain Analysis (Hydrocarbons < 2 cp)

But….!!!

2400 L/H100 % SW

1800 L/H75 % SW

ShortTE LongTE

MRI Prognosis:Heavy OIL

MRI Prognosis:Water

How can we distinguish Heavy OIL from Water ???

Special Design for Heavy OIL detection…

MRIL Ultra Long TE Activation

ShortTE LongTE UltraLongTE

2400 L/H100 % SW

1800 L/H75 % SW

MRI Prognosis:Heavy OIL

MRI Prognosis:

Water

ShortTE LongTE UltraLongTE

Initial Test Result (8hs Swabbing): 2400 L/H – 100% SW

Final Test Result (24hs Swabbing): 2400 L/H – 88% SW

Heavy OIL Detection Example

Halliburton Question regarding details on test results

Dear Customer:“…If We understand well, the formation was producing water for 8 hours before starting to produce Oil …??You have insisted to keep it producing because there was a very good signal on the MRI Ultra-Long Te activation,….. Is that correct …??...”

Customer’s response

“It's correct...It has been a very good news today, because up to yesterday, we couldn't believe that from that signal it would be only water... We insisted and it was 2400 l/h x 88% of water (may be the amount of water would have declined if we would wait more time... but for us it was enough seeing some oil)…”

Composite Log MRI Interpretation EDM + TDA

Flow920 L/H40 % SW

MRI PrognosisLight Oil w/ HGOR

Shot-Te/Long-Tw TDALong-Te/Long-TW Dif. S.-Te/L.TW-S.Tw

EDM

Fluid Typing: Light OIL

MRI PrognosisLight OIL

Flow x 12mmWet GAS

P/D 280psiP/E 1560 psi

MRI PrognosisGAS

MRI PrognosisGAS

Fluid Typing: GAS

Halliburton’s Reservoir Fluids Prognosis SheetBased on MRIL Interpretation

Magnetic Resonance Imaging (MRI) Logs as a fundamental evaluation tool in the reservoir Management

• Determination of Porosity, Independent to Matrix

• Determination of Bulk Volume Irreducible Water

• Reliable Permeability Indicator (absolute after Calibration)

• Identify Fluid Type (Gas, Oil & Water) by zone

• Identification of Rock Quality…Permeability, Porosity & Clay

• Determine variations of Hydrocarbon types (Resistivity independent)…

…Heavy, Intermediate, Light Oil or Gas

ConclusionsConclusions