PetrisWINDS Recall PETROS 3 Log Evaluation

PetrisWINDS Recall PETROS 3 is the most recent release of Petris’ petrophysical analysis package. Major improvements have been made in all areas of data handling and processing, particularly in the data correction, log modeling and interpretation areas. New analysis modules include a comprehensive, yet flexible and easy to use, deterministic log analysis module in which water saturation, net pay and log-derived permeability may be readily set up and run quickly. Full multi-zone, multi-well capabilities, with sophisticated zone and zonal parameter 'spreadsheet-like' editing, have been built in to allow the user to run anything from 'quick-look' single well analyses to large multi-well field studies using the same program.

Analysis Modules currently available as part of the PetrisWINDS Recall PETROS 3 system are:

Pre-Calculation

• Environmental and invasion correction
• Multi variate least squares regression
• Curve normalization
• Temperature vs. depth curve construction
• Bad Hole detection, differential caliper, rugosity and stand-off (derived from caliper, density and
• neutron)
• Lithology indicators M (sonic and density), N (neutron and density) and P (neutron and sonic)
• Apparent matrix density
• Apparent sonic matrix transit time
• Apparent neutron-density or neutron-sonic crossplot porosity
• Rw apparent from neutron-density or neutron-sonic
• Apparent mud filtrate resistivity
• Formation water resistivity from SP
• Mineral analysis

The "SANDS" Integrated Analysis Model
The "SANDS" model enables a full petrophysics analysis, including calculation of shale volume, porosity, water saturation, net pay identification and zonal averages of results to be performed within a single module. A comprehensive set of industry-standard algorithms has been incorporated to allow the user to either run a complete analysis or run individual components (such as shale volume calculation) separately.

Full multi-zone, multi-well capability is supported, as are the new "compound parameter" structures, whereby many of the program input parameters may be specified as either constants, or zonal parameters, or curves. The values of all input parameters may be written to the output logs so that the methods used are stored in the database as well as the computed results.

The program may be conveniently divided into four components - SHALE, PORLITH, SATURATION, and NETPAY.

In addition, there are options for recognition of single minerals, such as coal, or anhydrite, and the use of user-developed equations for each component.

SHALE component
Minimum, average or Hodges-Lehmann average of multiple shale indicators. Shale indicators currently available (all with linear/non-linear options):

• Gamma-ray ( also Larionov and 3-part options )
• Spontaneous potential
• EPT attenuation
• Resistivity
• Any other single curve method
• Density-neutron crossplot
• Neutron-sonic crossplot
• Sonic-neutron crossplot
• Any other crossplot method

PORLITH component
Calculates porosity (effective and total). The default model assumes a single mineral plus shale, but calculation of up to four mineral volumes (plus shale) may be performed by a matrix inversion technique. Correlation methods may be switched by depth range, zone, or by curve value (for example, to take account of bad hole effects). Options supported:

• 1 mineral plus shale model. Porosity calculation methods
  • Density
  • Neutron
  • Sonic (Wyllie, Field Equation, Raymer-Hunt-Gardner)
  • Density-neutron (Konen-Batemen or weighted average)
  • Density-sonic
  • Sonic-neutron (Konen-Batemen or weighted average)
  • Density-neutron for porosity and shale volume Density-neutron for porosity and apparent Sx0
  • Density-sonic for porosity and shale volume
  • Sonic-neutron for porosity and shale volume
• 2 minerals plus shale model. Porosity calculation methods:
  • Density-neutron
  • Sonic-neutron
  • Other crossplot (2 input curves)
  • Reconstructed curves may be calculated
    
• Multiple minerals plus shale model. Porosity calculation methods:
  • Matrix inversion (up to 5x5 system) using linear equations corresponding to up to 4 user-defined curves, plus sum to unity constraint for the determination of up to 4 mineral values.

Full iterative hydrocarbon corrections
Rwa calculation from computed porosity

SATURATION component
Sw and Sxo calculations using one of the following saturation equations:

• Archie
• Simandoux (modified, or un-modified form)
• Laminated sand-shale
• Poupon-Leveaux ("Indonesia")
• "Nigeria"
• Dual Water
• Dual porosity
• Generalised dual salinity
• Waxman-Smits (several options for B and Qv calculations provided)
• Normalised Waxman-Smits (Juhasz)

NETPAY component
Post processing of computed results. Options provided:

• Net sand and net pay curve calculation using user-defined cut-off values for shale volume, porosity and water saturation
• Cut-off value sensitivity analysis
  Standard computed results (porosity, water saturation, hydrocarbon pore volume etc.) computed by zone and total interval
• Log derived permeability calculation
• Cased Hole Analysis Model
  
• Cased hole porosities from Schlumberger GST
• Cased hole porosities from Schlumberger TDT
• Cased hole prosities (Atlas)
• Cased hole prosities (Welex)
• Cased hole water saturation from Schlumberger GST
• Cased hole water saturation (Welex)
• Sigma saturation (Schlumberger)
• Sigma saturation (Atlas)

Analysis Summaries
The "SUMMS" summaries module provides curve averages to be computed and reported. Net and net pay intervals may be defined using cut-off criteria for shale volume, porosity and water saturation. Other discriminated intervals may be defined by the use of other curves and cut-off values. Curves may be averaged over net, net pay or other discriminated intervals. Options for averaging include arithmetic, geometric and harmonic, porosity-weighting, curve cumulatives (all with or without thickness weighting), minimum, maximum, standard deviation. The module may be used to create an output file, which may be transferred to spreadsheet programs for inclusion in reports. Full user control over the average table format (field widths, decimal places, titles, and column delimiters) is provided. Cut-off sensitivity analysis in multi-well mode allows rapid determination of the effects of cut-off values on field-wide overall averages.