pnc and pns logs

8/3/2019 Pnc and Pns Logs

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1

Society of Petroleum Engineers

How to maximize the value of mature HC fields?

Workshop

Budapest, 18. November 2010.


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2

Getting the Most out of PNC & PNS LogsTo Increase Production in Mature Fields

Jason Gendur and Frank Thompson

Schlumberger


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Diagnose Existing Problems inProducing Wells

Find Bypassed Hydrocarbons

Remedial Actions

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Getting the Most out of PNC & PNS LogsTo Increase Production in Mature Fields


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Petrophysical Evaluation

Problems

Completions Restrictions (Tool OD)

Behind-Casing Measurements

Flowing or Shut in

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Tubing Scale or Corrosion Casing Condition Completions Design


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PNS Vs PNC

Pulsed Neutron Capture

GR Count Vs time

Measuring macroscopic neutron

cross section (S)

Pulsed Neutron Spectroscopy

GR Count Vs Energy For C/O Ratio

Spectroscopy

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PNC

PNS


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Applications in Mature Fields

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Problem Conditions Solutionwater saturation in depletedoil reservoir

Salty connate water PNC logging

water saturation in depletedoil reservoir

Fresh water PNS logging

Bypassed gas zone detection Thin layers PNC logging with WINR gasdetection

Petrophysical evaluation inold field

Only resistivity-SP open holelogs available

PNS & PNCSpectrolith for lithology

Oil saturation Gas cap PNS and PNC

Current oil saturation Water injection, variable

water salinity

PNS and PNC

Water production Flow behind casing Water flow logging


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PNC and PNS Diagnostics

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RST Pro


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PNC Measurement

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Sigma (S)

Porosity

BoreholeSalinity


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Sigma Log

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Sigma Log

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GRCorrelation Shale

Volume

Neutron Porosity

Sigma

Gas IndicationCount Rates

IRAT

WINR


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GRCorrelation Shale

Volume

Neutron Porosity

Sigma

Gas IndicationCount Rates

IRAT

WINR

log = (water * fSw) Water+ (hydrocarb* f(1-Sw)) Hydrocarbon+ (matrix * (1-f-Vshale)) Matrix+ (shale * Vshale) Shale

Problem Conditions SolutionBypassed gas zonedetection

Thin layers PNC logging with WINRgas detection


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Sigma Log

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hywamaclmahyma Vcl

Sw

SS

SSSSSS

f

flog


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WINR Curve for Gas

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PNC Measurement

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PNS Measurement C/O

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PNS Measurement C/O

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PNS Measurement Spectrolith

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PNS Spectrolith

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SONIC

TRAVEL TIMESDEEP

MEDIUM

SHALLOW

GAMMA RAY

Are highresistivityintervals pay?

Problem Conditions SolutionPetrophysical evaluation inold field

Only resistivity-SP openhole logs available

Spectrolith for lithologydetermination

SONIC

TRAVEL TIMESDEEP

MEDIUM

SHALLOW


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SONIC

TRAVEL TIMESDEEP

MEDIUM

SHALLOW

GAMMA RAY


PayZone?




SONIC

TRAVEL TIMESDEEP

MEDIUM

SHALLOW


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SONIC

TRAVEL TIMESDEEP

MEDIUM

SHALLOW

GAMMA RAY


NO

Payzone in sand?YES





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Lithology

Gas Sigma

Oil Sigma & C/O

Problem Conditions SolutionOil saturation Gas cap PNS and PNC


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Problem Conditions Solution

Petrophysical evaluation inold field



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Old Logs

Unswept Oil

DepletedLayer


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Water injection: Fingering of injectedwater drops initialproduction (300b/d) Variable watersalinity C/O mode

OHRST

Problem Conditions SolutionCurrent oil saturation Water injection, variable

water salinityPNC logging


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Conclusion

PNS and PNC measurements from RSTPro (Sigma, C/O,Spectrolith) are used to maximize the value of mature fields

Diagnose existing problems

Water saturation in depleted oil reservoirs

Identify fluid contacts (water-oil-gas)

Find bypassed hydrocarbons

Gas detection in thin zones

Remaining oil saturation

Remedial actions

Water production behind casing

Quantitative petrophysical evaluation in old wells

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Questions

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pnc and pns logs

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