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  • Petrophysics Across the Petroleum Industry from a Core to a CEO

    Australian Oil and Gas Exhibition and Conference 23 February 2017 Andrew Buffin

  • What is Petrophysics ?

    Wikipedia: Petrophysics from the Greek

    (petra) rock (physis) nature

    The study of physical and chemical rock

    properties and their interactions with fluids

    The description of oil and/or gas distributions and production flow capacity of reservoirs, from interpretations of pore systems and fluid interactions using all available downhole data.

  • A Brief History of Petrophysics

    Shell (Interpreted Log Data Petrophysics) Archie, G.E. (1942) An empirical quantitative relationship between porosity,

    electrical conductivity, and brine saturation of rocks. Laid the foundation for modern well log interpretation Pickett Plot A graphical representation of Archie Equation

    MH Waxman- LJM Smits (1968) An equation that relates the electrical conductivity of a

    water-saturated shaly sand

    Service companies (Acquired Log Data) Schlumberger founded in 1926 by brothers Conrad and

    Marcel Schlumberger and recorded the first-ever electrical resistivity well log in 1927

    Halliburton, Baker Hughes, Weatherford

    Typical logging combo: 1936/1950s: Spontaneous Potential, Resistivity. 1950s/60s: Gamma Ray (GR), Neutron, Microlog 1970s/80s: Sonic, Density, Fluid sampling, Digital data. Data

    transmission started 1990-Today: Logging While Drilling, Down-hole fluid typing,

    Nuclear Magnetic Resonance (NMR), Array and Image Data, Data transmission commonplace

  • 4

    The Petrophysicists Contribution

    More of the parameters used in the calculation of STOIIP are provided by Petrophysics than any other discipline!

    Where, STOIIP = Stock tank oil initially in place GRV = Gross rock volume Net = Net Reservoir Gross = Gross Reservoir = Porosity Sw = Water Saturation B0 = Formation Volume Factor








    Reservoir Engineer


  • The Basic Role of Petrophysics

    Permeability derived empirically using relationships of log data with core permeability.

    Environment of Deposition

    Lithology Volume of Shale (Vsh) Depth and depth of formations Porosity Fluid phase, gas, oil, water Fluid saturations Sw, So, Sg Moveable Hydrocarbons Net Sand / Net Pay Subsurface Pressures Temperature Velocity/Time Seismic responses Correlation with other wells

  • The Thin Bed Problem and Solution

    Heterogeneity is common in the rock column

    In rock beds less than 2 feet thick, log resolution is impacted by being strongly influenced by adjacent beds.

    Thinly laminated sand-shale sequences can have clean sands, which are not resolved

    Over thinbedded and shale intervals, horizontal resistivity is heavily biased toward lowresistivity shale and is less sensitive to the hydrocarbon-bearing sandstone resistivity

    Supressed resistivity data and high shale volume result in missed hydrocarbons

    An accurate evaluation of low-resistivity pay in thinly bedded or laminated reservoirs, requires an additional vertical resistivity measurement

    This provides much better sensitivity to the presence of hydrocarbons.

    The resistivity is measured in three dimensions and calculates both vertical and horizontal resistivity (Rv and Rh, respectively) from direct induction

    This leads to reliable identification and accurate petrophysical evaluation of low-resistivity pay by determining the Rv, Rh sand fraction and porosity

    GR Res

    GR Rh Rv

  • The Complex Lithology Problem and Solution

    Probabilistic petrophysics: Run in complex reservoirs with a variable and mixed mineralogy Used to solve for multiple clay minerals within the reservoir To constrain the result to a specific outcome, this may be determined from

    petrology studies, core analysis, XRD etc. Solves for volumetric fractions and defines bulk mineralogy, grain matrix density,

    porosity and fluid saturations There is not one unique solution

    Pyritic Sand: High PEF High Density High Grain Density Suppressed Resistivity

    Results in: If D-N log used a high Vsh Low porosity High Water Saturation Potentially Missed pay

  • 8

    Where (do) the Petrophysicists sit (?)

    Geologist Static model input Porosity &

    Permeability Saturation Height Net Sand & Pay Shale volume Fluid contacts

    Commercial (Reserves) Porosity Water Saturation Net Pay

    Geophysics Rock Physics Gassmann Substitution

    Reservoir Engineer Dynamic model input Relative Permeability Saturation Height

    Drilling Pore Pressure Bit Selection Lithology

    Geomechanics Core Analysis Sonic / Density Rock Strength

    Production Technologists Porosity &

    Permeability Fluid Analysis Test depths Perforation Depths Petrophysicist

    Service Providers Data, data and More Data

  • Petrophysics from a Core to a CEO

    A Core

    An Ex-CEO

  • Petrophysics State of the Art

    The highest level of general development, as of a device, technique, or scientific field achieved at a particular time

    Petrophysical data is used across all the subsurface disciplines how its used is important.

    Are you answering the right questions? Design your evaluation programme to answer the subsurface

    challenges Data QC & QA with appropriate data editing and corrections Petrophysical data acquired to identify hidden reserves or

    missed pay Petrophysical techniques and tools developed with demand

    from the industry

  • Petrophysics The Future

    Artificial Intelligence?

    AI allows a computer to make all the mistakes that humans make only faster

    Attributed to E. R. (Ross) Crain, a retired Consulting Petrophysicist taken from his web site: Crain's Petrophysical Handbook

    Technology changes in the next few years Down hole reservoir

    engineering laboratory Down hole core laboratory Nano-technology Robotics on fully automated

    oil and gas fields Direct measurement of

    permeability 4 D real time-reservoir

    monitoring Data integration and


  • Thank you [email protected]

    mailto:[email protected]