Routines
CycloLog® Toolbox
The toolbox consists of basic and advanced tools. The basic tools incorporate elements of basic mathematics and statistics. The advanced tools consist of more complex mathematics and a number of time-series analytical algorithms.
The routines can be used in practically unlimited combinations as all the transform operations are always displayed in depth. All the results of the calculations are displayed on screen and are available for immediate geological interpretation. All transformed logs can be exported in ASCII format.
Examples of conventional log analysis
Examples of spectral and spectral attribute analysis
A number of routines are available for conventional or standard wireline log analysis:
- Log Filters
- Log Calculations
- Log Seismic Calculations
- Petrophysical Attributes
Log Filters
Log filters may be used for the enhancement of the original log pattern. Log pattern enhancement may support the visual interpretation as well as correlation of wells. The smoothing log filters (e.g. Median and Average Filters) tend to "block" the log patterns, while enhancement log filters (e.g. Edge Enhancement and Derivative Filters) will display the higher frequency pattern of the log.
Log filters are also used in combination with other log transform operations.
Log Calculations
A number of basic and advanced mathematical functions have been incorporated in the program. Mathematical operations can be performed with each log in a fast and easy way. The following mathematical operations can be performed:
Basic mathematics:
Multiply logs
Divide logs
Add logs
Subtract logs
Advanced mathematics:
Integral calculation of logs
Logarithmic calculation of logs
Exponential calculation of logs
Using "Divide Logs" for spectral logs for example, produces a ratio curve which may give information on the lithological development.
Log Seismic Calculations
One-dimensional seismic synthetics can be generated from the acoustic impedance (divide density with sonic logs), sonic or density together with the reflectivity calculation.
Petrophysical Attributes
Petrophysical attributes are used to support the geological interpretation of logs, and to evaluate the relationship between petrophysical parameters and geological features.
Attribute generation:
GR/Thorium index
Sonic / density derived porosity
Attribute analysis:
Log statistics
Net/Gross calculations
Single log histograms
The program contains several different time series analysis methods for the spectral analysis of logs. In addition, spectral attribute can be generated from the logs through Maximum Entropy Spectral Analysis (MESA) and the prediction error function. Both methods together with understanding of the principles behind climatic-forcing of stratigraphic cyclicity can lead to a near-synchronous correlation based only on standard log data.
Spectral Analysis of Wireline Logs
Time series analysis methods in the program are:
- Fast Fourier Transform (FFT)
- Maximum Entropy Spectral Analysis (MESA)
- Gabor Wavelet Transform (GABOR)
- Native Wavelet Transform (CLGWT)
- Walsh Transform
Spectral Attribute Analysis
This analysis method is based on Maximum Entropy Spectral Analysis (MESA) and the Prediction Error Function.
The Spectral Change Analysis (PEFA) is based on the comparison of measured log values and predicted log values. The output values displayed in PEFA can often be found to correspond to sudden changes in log characteristics and may be related to geologic events, such as changes in climate and/or basin dynamics.
The Spectral Trend Analysis (INPEFA) is the integration of all PEFA values and shows the cumulative difference between the predicted log values and actual log values.
INPEFA is very useful in well correlations and the down hole recognition of major as wells as minor geological events and depositional trends.
One of the unique features of CycloLog® is that all computations are displayed as log transforms in depth. Log transforms are logs whose pattern has been modified by processing, such as mathematical calculations or spectral analysis. Log transforms operate in the depth domain, while the spectral log transforms are displayed in the depth-wave number domain.
Version 3.1 is able to convert all logs in the depth domain into the different time domains, such as relative geologic time or seismic time.
