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 LESA (Log Evaluation System Analysis)

Open and Cased Hole Log Analysis

LESA is Windows® based software that will provide complete log analysis and interpretation. The software is fully 32-bit compliant for Windows Vista/7/8/10 (or any associated server versions, including 64-bit editions). The following file formats are supported:

  • LAS
  • LBS
  • LIS (many flavors, through a conversion step)
  • ASCII (many flavors, some through a conversion step)

Most open-hole logs may be incorporated into the interpretations, from a minimum of a single porosity log, to any combination of modern log suites. Interpretations incorporate specific tool response of the major service companies.

The software provides the user a series of templates for graphical output and gives the ability to modify these or create totally new templates as needed. Net pay calculations can be determined for any designated interval, using cutoff parameters defined by the interpreter. Sub-zones are summed for a complete reservoir appraisal.

Key Benefits

  • Complete complex lithology, shaley sand formation log analysis
  • Extendible through user-defined routines, to implement other analyses
  • Runs under all modern versions of Microsoft® Windows™

Display Samples

LESA Cross Plot Example ~ LESA Histogram Example ~ LESA Log or Depth Plot Example

Click on each of these images to see a full-color/full-resolution screen-shot!

Data Editing Samples

LESA Numerical Curve Editing Example ~ LESA Visual Curve Editing Example

Click on each of these images to see a full-color/full-resolution screen-shot!

What are its Analysis Capabilities?

Quick-Look Analysis (Preliminary)

This requires minimal choices from the interpreter. The program’s expert system gives estimates of shale and fluid properties necessary for a full shaley-formation analysis. These program-determined properties can be edited as required. All standard Quick-Look interpretational procedures are interpreted, and source documents are recognized on each appropriate graphical output.

Quick-Look Analysis (Advanced)

This option allows the interpreter to zone the reservoir and input specific parameters to perform a complete shaley formation analysis.

In-Depth Analysis

Environmental corrections, porosity and matrix cross plots are available for major service company tools. A preliminary choice of clean and shale intervals is available from program-determined analyses and initial operator input. Detailed zonation can then be performed with complete editing capability.

Full shaley-formation analysis involves simultaneous calculations of 10 different saturation models. A large number of cross plots can be used to help in detailed reservoir interpretation. On all cross plots, analog traces of the logs may be included, and an independent depth zonation, recognized by color differentiation, can be recognized. Any other data can be recorded as a Z plot (routinely Vsh is presented).

Core-log comparisons are available for all standard core measurements. Log-calculated permeability and relative permeability involves recognition of rock-typing through porosity/irreducible water saturation relationships. User-defined equations and programs can be incorporated into the overall reservoir analysis.

Mechanical Properties

Mechanical properties can be estimated using density and sonic log input. Shear travel times are estimated (if not available) from compressional travel times.

Coal Bed Methane Analysis

The software recognizes coal from analyses of density, neutron, sonic, and resistivity curves. The interpreter can choose cutoff values to distinguish coal from other rock types.

Standard analyses involve recognition of:

  • Coal rank
  • Ash content
  • Carbon content
  • Volatile matter content
  • Moisture content
  • Gas content
  • Gas in Place
  • Cumulative gas in place

Six different methods of determining gas content and gas in place are automatically calculated. Estimates of gas deliverability are included. Graphical output includes presentations similar to Schlumberger and Halliburton. Included on the output are bulk volumes of water and hydrocarbons for he non-coal intervals. Gross and net reservoir parameters for the non-coal intervals are available.

Total Organic Carbon

Total organic carbon (TOC) and pyrolisis S2 values are calculated using the technique of Passey AAPG December 1990.

Visual Curve Editing

The visual curve editing feature of LESA allows the user to modify any well curve in a visual interface. When the interpreter selects this option, the entire display screen becomes the visual curve editing window. The software provides several choices, including Drag Mouse Editing, Horizontal Curve Shifting, Vertical Curve Shifting, Rubberized Curve Shifting and the ability to reset the editing. The interpreter also has the option of selecting Tagged Shifting Mode, which allows all selected curves to be in a single track and modified in unison.

Multi-Mineral Analysis

LESA has the capability of using any number of open-hole logs to determine rock and reservoir components. Tables are included which define log responses to commonly-occurring sedimentary minerals, reservoir liquids and gases. These tables can be edited and expanded at user discretion.

The interpreter selects the components that are expected to be present, and the program determines percentages of each component. Up to seven different components may be examined at any one time. The method requires availability of the appropriate logs (mostly porosity logs and gamma ray).

Program Capabilities

  • User defined equations and routines.
  • Detailed core/log comparisons available.
  • Scatter plots of any raw or calculated data.
  • Extensive on-line help and tutorial
  • Depth plots allowing user defined panels with any raw or calculated data.
  • User defined toolbar for most often used commands.
  • Color filling of any data stream or between data streams on a log plot.
  • Large number of cross plots to define zone parameters.
  • Metric, English or mixed units capability
  • Program determined zonation, fully editable.
  • Variety of analog plots to illustrate log and core comparisons, rock and fluid properties, and final computed reservoir values.

Calculation Procedures

Porosity Logs

  • Hierarchy of porosity automatically chosen, may be overridden by user.
  • GRN, SNP, and CNL (NPHI and TNPH) may be analyzed.
  • Logic for interpretation of density and gamma-gamma logs incorporated.
  • Total and shale-corrected (effective) porosities are automatically determined.
  • Density and neutron porosity as pressure-dependent functions.
  • Sonic porosity from time-series or empirical formulas.
  • Environmental calculations available for gamma ray and density logs.
  • Tool specific cross plot porosity charts for Schlumberger, Halliburton and Western Atlas tools.
  • Porosity calculated from density / neutron, neutron/sonic, sonic / density, or individual porosity logs.

Resistivity Logs

  • Rt and Rxo may be calculated from most commonly encountered logs, involving solution to tornado charts (Schlumberger, Halliburton and Western Atlas).
  • Rxo calculated from micro logs, and combined with induction and 16-inch normal to provide a pseudo dual induction – Rxo combination.
  • Rt and Rxo available when log suites are limited.

Fluid Saturation

  • Sw from Archie, Simandoux, Total Shale, Dual Water, Waxman Smits, Indonesian, Fertl, Fertl-hammack, Laminated Shale or Rocky Mountain.
  • Different saturation profiles may be assumed to determine fluid saturation variations away from the wellbore.
  • Oil and Gas distinguished by detailed analysis of density/neutron / resistivity logs.

Matrix/Shale Identification

  • MID plot for both time-series and empirical sonic log interpretation.
  • Program-determined matrix/shale recognition, which may be user-modified.
  • Radioactive and non-radioactive shales may be distinguished.
  • Matrix Identification plot.
  • Vsh from four different sources.


  • Cased hole neutron time-lapse analysis for gas storage or reservoir depletion studies.
  • Gross and net reservoir parameters by subzone and for the total reservoir.
  • Total organic carbon using delta resistivity method.
  • Extensive visual and tabular curve editing capability.
  • Coal bed methane analytic capability.

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