Making Log Calculations in a Flow
This articles provides an overview of how to use a Flow to before basic log calculations. To do this, the following Flow tools are used:
- LogInput >> Bring the log data into the Flow
- LogMath >> Perform some calculation
- LogOutput >> Writes the log data to a new log database.
There can be as many LogMath tools added to a flow as one would like, and they can be added to existing Flows ushc as a Log Clean-up Flow.
The LogMath tool is extremely flexible. It can create new curves or operate on a Mnemonic, Alias, Curve family, or All curves. It can make multiple new curves in one LogMath tool.
An example is shown below for making a basic set of petrophysical calculations (i.e., which you might do if you were a Geoscience user and not a Petrophysics user):
In the screenshot above the curves with the leading underscore such as _gr_clean are not written out, but are only available for the calculations. There are also several built in functions available such as clamp and ifelse that useful for making calculations. In this example GR_FINAL (and similar curves) were already present in the input database. However, for convenience GR_COMP (and similar) are available to the LogMath tool.
Another example, where some basic clipping is performed is shown below:
In this first LogMath we are simply nulling all mnemonics that alias to GR if they are less than zero. This means if we have mnemonics like GRA, GRC or GR1 they will all be acted upon.
In this very similar example we are acting on ResD, but instead of acting on the Alias, we are acting on the "Curve family", which includes the full suite of resistivity curves (resd_induction alias, resd_laterolog alias, etc).
These concepts can be chained together to perform dozens of calculations in a single Flow.
Tips and Tricks
- Remember that you can do many operations in a Flow sequentially, so you can have one master Flow that can be set up once and then be used across all your future projects.
- LogMath greatly simplifies working with aliases and curve families compared to Python. It already has an understanding of this.
- Remember that in a Flow we pass LAS files individually. So LAS1 is passed independent of LAS2, even if for the same well. In some cases, this may necessitate you wanting to use a LogSplicing or CpiLogCalc tool before passing the data onto a LogMath tool.
Related Insights
Quick Start Module
Purpose The Quick Start module is designed to help users quickly set dozens of common parameters by selecting a handful of basic options from dropdown menus. Parameters There are three parameters that are set on a zone-by-zone basis and two parameters that are set on a full-well basis. These are as follows. Discussion The parameters are linked to what are called named_defaults in the software. These are collections of defaults that can be set through assigning a single parameter.
Sample data to get started
Need some sample data to get started? The files below are from data made public by the Wyoming Oil and Gas Commission. These will allow you to get started with petrophysics, mapping, and decline curve analysis. Well header data Formation tops data Deviation survey data Well log data (las files) Production data (csv) or (excel) Wyoming counties shapefile and projection Wyoming townships shapefile and projection Haven’t found the help guide that you are looking for?
NMR Interpretation Module
Purpose The NMR interpretation module allows users to calculate porosity, bound and free fluids from the measure T1 and T2 distributions from NMR tools. Primary Outputs Discussion In oil and gas well logging, the $T_2$ distribution is used as a high-resolution "map" of the formation's pore system. While a standard porosity tool tells you how much fluid is there, NMR tells you where that fluid is trapped and whether it will flow.