the use of msfl log to identify new production opportunities in mature tight … · 2014-10-21 ·...

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The use of MSFL log to identify new production opportunities in mature tight

and fractured carbonate reservoirs

Author: Riccardo Martin

San Donato Milanese 13-14-15 October 2014

2013-2014 Master in Petroleum Engineering and Operations

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The use of MSFL log to identify new production opportunities in mature tight and

fractured carbonate reservoirs

2San Donato Milanese 15-16-17 October 2014

Author

Riccardo Martin

Division eni S.p.A.

Upstream & Technical Services

Dept. GICA/LAIP

Company Tutors

Marco Andrea Salvadeo (GICA)

Antonella Bersani (LAIP)

Maria Teresa Galli (GICA)

University Tutor

Prof. Francesca Verga

Master in Petroleum Engineering 2013-2014

Stage Subject


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List of Content

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� Project Scope

� Geological Setting

� Used Data

� Data Analysis

� Conclusions and Suggestions



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Project Scope

• In order to exploit mature carbonaticreservoirs, new ways to find smallfractured intervals are needed.

• The Micro Spherical Focused Log (MSFL)has been considered a suitablecandidate for such purpose.

• The goal of this study is to verify theability of the MSFL to detect thoselevels.

• The stage activity mainly relied on logsand fracture analysis of Eni oil-fieldsfrom 3 Italians macro-areas,characterized similar structural settings.

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Mesozoic of North Italy

Apula Platform

Hyblean Plateau


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List of Content

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� Project Scope


� Used Data

� Data Analysis




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Hyblean Plateau

• The area is part of theforeland basin of theAppenninic-Magrebeidchain, where the GelaNappe is imposed on anautochthonous bodycalled Hyblean Plateau.

• The Hyblean Plateau isconstituted by a LateTriassic/early Jurassiccarbonate platform.

• Sciacca Formation is themain reservoir and theNoto and RabbitoFormations aresecondary targets.

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Mesozoic of North Italy

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• The petroleum system is located into in the Po Plain, inthe foreland of the Southern Alps and the Appennines.

• The reservoir targets are located in the Middle-UpperTriassic part of the Mesozoic succession, a hugefragmented carbonate platform.

• The petroleum system has two reservoirs, the Dolomia diM. S. Giorgio (lower reservoir) and the couple DolomiaPrincipale /Dolomia a Conchodon (upper reservoir).

Mineralizedlevels


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Apula Platform

• The area is part of the Mesozoic ApulaPlatform that was buried by the tectonicunits of the Allochtonous Complex of theMetaponto Nappe.

• A carbonate platform was established on theApula Platform during the Mesozoic andpersisted until the end of the Cretaceous.

• The stratigraphy shows a continuousdeposition of carbonates during all theMesozoic, so the Apula Platform isconsidered a single layer reservoir.

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List of Content

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� Project Scope


� Used Data

� Data Analysis




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Work Flow

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• Review of technical literature (internal and/or published reports, papers, etc.)regarding main carbonate reservoirs in Italy.

• Selection of wells suitable for the analysis.

• Data import from eni databases to Geolog, a formation evaluation product suitefor petrophysical, geological analysis and well data management.

• Petrophysical analysis based on RCA porosity and permeability data.

• Log data analysis through comparison between MSFL track, P21 values and

RCA data. Comparison with other resistivity logs with higher investigationdepth.

• Final presentation and summary report preparation.


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Used Data

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The amount of data used for this work includes:

• 12 wells coming from 3 Italian macro-areas.

• Total of 47 cores for an overall interval of 978 meters.

• For each well a dataset composed by: Logs, Core Fracture Data, Routine Core Analysis,

Core Photos.

WELL MSFL LLS LLD CALI GR CGR SGR RCA P21

TIN 02 B X X X X X X X X NO

ALE 03 D X X X X X NO NO X NO

ALE 01 X X X X X X X X X

ALE 01 D X X X X NO X X X X

DIBE 01 X X X X NO X X X X

TIN 03 D X X X X NO X X X X

TIN 04 D X X X X NO X X X X

TIN 02 D X X X X X X X X X

TIN 05 D X X X NO X X X X X

TIN 09 X X X X X X X X X




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Micro Spherical Focused Log

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• The MSFL is a miniaturized version of theSpherically Focused Log, belonging to the familyof the Laterologs.

• The tool is placed on a pad pushed against thewall of the hole.

• The arrangement of the electrodes forces thecurrent flow to take a spherical shape.

• Shallow investigation depth (about 4”) and highvertical resolution (1”- 6”).

• Main purpose is to investigate the resistivity ofthe flushed zone.

• The difference of resistivity between flushed zoneand massive intervals can help detecting fracturedlevels.


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Fracture Analysis

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• Qualitative and quantitative analysis performed oncores.

• Qualitative description using spreadsheets.

• Quantitative analysis provides fracture orientationand numeric indexes.

• P21 index is the density of fracture expressed ascumulative length for unit of area.

• The P21 used is the cumulative of the open fractures.

RU

BB

LE


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List of Content

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� Project Scope


� Used Data

� Data Analysis




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Petrophysical analysis: Hyblean Plateau

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• The orange field corresponds to the matrixcontribution.

• The blue zone is typical of a fracture system.

• In the porosity versus permeability plot twodifferent trends can be seen.

TIN 03 D


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Petrophysical analysis: Mesozoic of North Italy

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• The poro/perm plot shows a scattereddistribution of the values.

• The dots arrangement in the Xplot Kvvs. Kh is indicative of a isotropicbehaviour.

• The contribution of the fracturing to thepermeability is indicated in the bluecircle.

TIN 10

TIN 10


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• The matrix trend represents the whole porosity/permeability system.

Petrophysical analysis: Apula Platform

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• Presence of fracture and matrix contribution.

ALE 03 DDIBE 01


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Petrophysical analysis: Apula Platform

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DIBE 01 ALE 03 Dir

DIBE 01 ALE 03 D


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Log Analysis: layout

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TIN 03 D


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Log Analysis

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TIN 03 D

• The other resistivity logs donot register the peaks seenby the MSFL.

• P21 follows the trend ofthe MSFL.


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Log Analysis

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• The Caliper confirms thepresence of more brittleintervals.

• The MSFL trend is confirmedby the permeability values.

• P21 follows the trend ofthe MSFL.

TIN 09


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Log Analysis: Clay Effect

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• There is a mismatchbetween P21 and MSFL inthis well.

• This situation is coincidentwith an increase of theclay content (CGR log).

• The MSFL response isstrongly influenced by theclay water.

TIN 10


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Log Analysis: Use of Core Photos

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• The conditions of the core cause an underestimation of the real density of fracture.

• It is still possible to evaluate the trend of the MSFL using the core photos.

TIN 04 D

• High values of MSFL corresponding to a low fractured core section.

• Dropping values of MSFL corresponding to a rubble interval.


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Log Analysis: Image Log calibration

• Analysis performed usingcore photos and Image log(FMS) in substitution of theP21.

• In this case the recording ofthe FMS is not optimal.

• It is still possible to identifythe presence of porouszones on the MSFL usingthe core photos and theRCA data.

• This method could be a wayto calibrate the FMS andextend the analysis in non-cored intervals

ALE 03 D


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Log Analysis: Use of Microlosses

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TIN 02 D

• The micro losses data help to extend theinterpretation.

• This particular analysis has to be performed at abigger scale.

• A decreasing trend in the MSFL is coincidentwith the higher losses.

• In correspondence with the presence of thelower losses, the MSFL assumes an increasingtrend.


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Log Analysis: Cutoff

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• Proposal of a cutoff on thewells with good matchbetween MSFL and P21.

TIN 03 D


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• Cutoff defined at 200ohmm.

• The cutoff permits tohighlight the intervals withthe best porosity andpermeability values.

• The cutoff permits to cutthe intervals with the worstporosity and permeabilityvalues.

TIN 03 D


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TIN 12



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• Cutoff defined at 100 ohmm.

• Best result is reached with alower value of cutoff.

• Necessity to calibrate thecutoff on the characteristicsof every field.

TIN 12


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List of Content

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� Project Scope


� Data Used

� Analysis




Stage Subject


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Conclusions and Suggestions

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• The MSFL calibrated with well data, is a useful tool to measure the Rxo and soto identify fractured levels into tight carbonate reservoirs.

• This method is a qualitative characterization that needs to be integrated withother data.

• The efficiency of the method is maximum when used with P21 and RCA.

• The presence of clays makes difficult to use this method because the clay watergives lower resistivity.

• The analysis can be extended in non-cored intervals using other data like microlosses.

� It is possible to propose a cut-off that could be a reliable parameter to highlight the intervals with the best petrophysical properties.


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Conclusions and Suggestions

Future applications include:

• Definition of a cutoff also for clay bearing layers.

• Calibration of the method using also “gas while drilling” data.

• Application of the method for non-Italian carbonate fields.


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Acknowledgements

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I would thank Eni Upstream & Technical Services

Division Management for permission to present this

work and related results and GICA/LAIP colleagues

for the technical support and needed assistance.

San Donato Milanese 13-14-15 October 2014

the use of msfl log to identify new production opportunities in mature tight … · 2014-10-21 ·...

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