Understand Where Porosity, Saturation and Net Pay Actually Come From
Petrophysics & Formation Evaluation for Reservoir Engineers
Formation evaluation for engineers who use its output, covering log measurement principles, environmental corrections, porosity and saturation determination, shaly sand analysis, permeability estimation, capillary pressure and saturation height modelling, net pay definition, core-log integration and the uncertainty carried into reservoir volumes.
Petrophysics & Formation Evaluation for Reservoir Engineers
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Petrophysics & Formation Evaluation for Reservoir Engineers - RE-PFE-PEA27
| Code | Date | Time | Duration | Location | Currency | Early Bird Fee Per Person |
|---|---|---|---|---|---|---|
| RE-PFE-PEA27 | 17 - 21 May 2027 | 10 AM CST | 4 Hours Per Day |
Online |
USD |
4000 |
Boost your team's skills and your budget! Enjoy group discounts for collaborative learning. Send an inquiry to info@peassociations.com.
Petrophysics & Formation Evaluation for Reservoir Engineers
Description
Reservoir engineers consume petrophysical output constantly. Porosity, water saturation, net to gross and permeability enter every volumetric calculation, every simulation model and every reserves estimate, usually as single values in a table with no indication of how they were derived or how uncertain they are. Understanding where those numbers come from, which are well constrained and which are interpretive, changes how they are used and what confidence is placed in the results built on them.
This training covers formation evaluation from the engineer's perspective. Log measurement principles are developed for the resistivity, porosity, gamma ray, nuclear magnetic resonance and acoustic measurements, with emphasis on what each actually responds to and the depth of investigation over which it responds. Environmental corrections, borehole effects and invasion are then covered. Porosity determination from single and combined tools follows, then water saturation through the Archie equation and its parameters, with the shaly sand models that apply where Archie does not. Permeability estimation from logs is covered with an honest treatment of its reliability. Capillary pressure, saturation height modelling and free water level determination follow, then net pay and cut-off definition and the effect of cut-off choice on volumes. Core-log integration, uncertainty propagation and the use of petrophysical output in dynamic work close the training.
Water saturation is the most uncertain parameter in the volumetric equation and the one most often presented as certain. The Archie equation requires cementation exponent, saturation exponent and tortuosity factor, all of which are measured on core if measured at all and assumed otherwise. It also requires formation water resistivity, which varies across a field and with depth. In shaly formations Archie does not apply at all, and the shaly sand model chosen changes the answer substantially. A saturation curve on a log plot carries none of this on its face.
Cut-offs deserve more scrutiny than they receive. Net pay is defined by cut-offs on porosity, saturation and shale volume, and those cut-offs are choices. Moving a porosity cut-off by one porosity unit can change net to gross by several percent and in-place volume with it. Cut-offs derived from a producibility argument, tied to permeability and capillary behaviour, are defensible; cut-offs inherited from a previous study or from regional convention are not, and they propagate through every downstream calculation.
Permeability is estimated from logs and measured on core, and the two rarely agree well. Log-derived permeability comes from empirical relationships calibrated on core, and those relationships are rock-type specific and often poorly constrained. Nuclear magnetic resonance improves matters where it is run but still relies on calibration. For reservoir engineering purposes the useful question is usually not the absolute value but the ratio between intervals, and understanding the derivation prevents log permeability from being treated as measurement.
Finally, saturation height modelling is where petrophysics meets reservoir engineering directly. Capillary pressure data from core, converted to reservoir conditions and expressed as a saturation height function, provides the saturation distribution above the free water level that a static model requires. It also provides an independent check on log-derived saturations, and disagreement between the two is a signal worth investigating rather than averaging away.
By the end of this training, participants will be able to:
- Explain what each principal log measurement responds to and over what volume of investigation
- Apply environmental corrections and assess borehole and invasion effects on log response
- Determine porosity from single and combined log measurements and reconcile with core
- Calculate water saturation using the Archie equation and assess the uncertainty in its parameters
- Select and apply shaly sand saturation models appropriate to the formation
- Estimate permeability from logs and state the reliability of the estimate
- Interpret capillary pressure data and build saturation height functions
- Determine free water level and reconcile it with log and pressure evidence
- Define net pay cut-offs with a producibility basis and assess their effect on volumes
- Propagate petrophysical uncertainty into volumetric and dynamic reservoir work
Organisations sending participants to this training will:
- Improve the quality of reservoir engineering work built on petrophysical inputs
- Reduce volumetric errors arising from poorly justified cut-offs and saturation parameters
- Improve integration between petrophysics and reservoir engineering teams
- Strengthen technical review of petrophysical interpretations supplied by contractors
- Improve static model quality through better saturation height modelling
- Improve the design of logging and coring programmes by clarifying what engineering work requires
Participants will:
- Read and interpret a log suite with technical confidence
- Understand which petrophysical outputs are well constrained and which are interpretive
- Challenge cut-offs, saturation parameters and shale models with informed questions
- Build and use saturation height functions
- Propagate petrophysical uncertainty into volumetric results properly
- Work far more effectively with petrophysicists
- Reservoir engineers using petrophysical inputs
- Production and petroleum engineers working on well and reservoir performance
- Simulation engineers building models from petrophysical data
- Reserves and evaluation engineers
- Geologists working alongside petrophysical interpretation
- Technical staff conducting field reviews and due diligence
- Graduate engineers entering subsurface roles
Module 1 - Formation Evaluation Framework
- Objectives of formation evaluation and its deliverables
- Data sources: logs, core, cuttings, formation tests, mud logs
- Logging while drilling and wireline logging comparison
- Log suite selection for different objectives
- Depth reference, depth matching and log quality control
- Borehole environment: mud type, invasion, rugosity, temperature
- Reservoir engineering deliverables from petrophysics
- How petrophysical outputs are used downstream and where errors matter most
Module 2 - Log Measurement Principles
- Gamma ray and spectral gamma ray: shale and mineral identification
- Resistivity: laterolog, induction, array tools and their applications
- Depth of investigation and invasion profiling
- Density: measurement principle, photoelectric factor, corrections
- Neutron: measurement principle, lithology and gas effects
- Acoustic: compressional and shear, and their applications
- Nuclear magnetic resonance: principle, T2 distribution, fluid typing
- Dielectric and other specialised measurements
- Image logs and their applications
- Environmental corrections and their significance
Module 3 - Lithology and Shale Volume
- Lithology identification from log combinations
- Crossplot techniques and their interpretation
- Shale volume estimation from gamma ray
- Shale volume from neutron density and other methods
- Shale distribution: laminated, dispersed, structural
- Effect of shale distribution on log response and reservoir properties
- Mineralogy determination and elemental analysis
- Complex lithology and carbonate evaluation
- Multi-mineral solving and its assumptions
Module 4 - Porosity Determination
- Total, effective and isolated porosity definitions
- Density porosity and matrix density selection
- Neutron porosity and lithology corrections
- Neutron density combination and gas effect
- Sonic porosity and compaction correction
- Nuclear magnetic resonance porosity and its advantages
- Shale corrections to porosity
- Core porosity measurement and overburden correction
- Core-log porosity reconciliation and depth matching
- Porosity uncertainty and its magnitude
Module 5 - Water Saturation in Clean Formations
- Archie equation derivation and its assumptions
- Formation factor, cementation exponent and their measurement
- Resistivity index and saturation exponent
- Tortuosity factor and its variability
- Formation water resistivity determination
- Water salinity variation and its effect
- Temperature effects on resistivity
- Invasion effects and deep resistivity selection
- Sensitivity of saturation to each Archie parameter
- Uncertainty in water saturation and its consequence for volumes
Module 6 - Shaly Sand Analysis
- Why Archie fails in shaly formations
- Conductive clay effects on resistivity
- Cation exchange capacity and its measurement
- Laminated shale models
- Dispersed shale models
- Waxman-Smits model and its parameters
- Dual water model
- Indonesia, Simandoux and other empirical models
- Model selection and its effect on calculated saturation
- Validating shaly sand results against core and production evidence
Module 7 - Permeability Estimation
- Permeability from core: routine measurement and overburden correction
- Klinkenberg correction and its application
- Porosity-permeability relationships and rock typing
- Empirical log permeability estimators and their calibration
- Nuclear magnetic resonance permeability models
- Permeability from formation testers
- Permeability from well tests and its scale difference
- Reconciling permeability across scales
- Vertical permeability and anisotropy estimation
- Reliability of log-derived permeability and its appropriate use
Module 8 - Capillary Pressure and Saturation Height
- Capillary pressure fundamentals and measurement methods
- Mercury injection, porous plate and centrifuge methods
- Converting laboratory capillary pressure to reservoir conditions
- Interfacial tension and contact angle conversion
- Free water level, oil water contact and transition zone
- Saturation height function construction
- Leverett J function and other normalisation approaches
- Rock type dependent saturation height functions
- Reconciling saturation height results with log saturations
- Applying saturation height functions in static models
- Irreducible saturation and its determination
Module 9 - Net Pay, Cut-offs and Rock Typing
- Net rock, net reservoir and net pay definitions
- Cut-off parameters: shale volume, porosity, saturation, permeability
- Deriving cut-offs from producibility rather than convention
- Permeability and capillary pressure basis for cut-offs
- Effect of cut-off choice on net to gross and in-place volume
- Consistency of cut-offs across a field and between studies
- Rock typing methods and their basis
- Flow zone indicator and hydraulic unit approaches
- Linking rock types to relative permeability and capillary pressure
- Rock typing for static and dynamic modelling
Module 10 - Integration, Uncertainty and Application
- Core-log integration workflow and depth matching
- Special core analysis and its use in petrophysical calibration
- Multi-well consistency and field-wide petrophysical models
- Deterministic and probabilistic petrophysical interpretation
- Uncertainty in each petrophysical output
- Propagating petrophysical uncertainty into volumetric estimates
- Petrophysical inputs to static and dynamic models
- Validating petrophysics against production and pressure evidence
- Specifying logging and coring programmes to meet engineering needs
- Reviewing and challenging a petrophysical interpretation constructively
Upon successful completion of this training course, delegates will be awarded an official Certificate of Completion issued by the Petroleum Engineers Association (PEA), an ISO 9001:2015 certified training organization. The certificate carries 10 Credits and formally records the total learning hours completed.
Each certificate is signed by the Course Facilitator and the CEO of the Petroleum Engineers Association, and serves as verifiable proof of professional training that delegates can present to employers and professional bodies worldwide.
Frequently Asked Questions
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