Brittleness Index
This Loglan calculates a BI (Brittleness Index) of rocks either by their elastic properties, or by their mineralogical composition.
Software Platform: Geolog
Developer: Jeff Taylor
Submission Date: 09/11/2015
This Loglan calculates a BI (Brittleness Index) of rocks either by their elastic properties, or by their mineralogical composition.
Software Platform: Geolog
Developer: Jeff Taylor
Submission Date: 09/11/2015
There are three predominant groups of definitions for brittleness index (BI) in the recent literature of unconventional resource exploration and production. The three groups characterize the BI of rocks from their elastic properties, their petrophysical properties and their strength properties, respectively. The fact that there is not a single definition of a brittleness index, but a confusing amount of different brittleness indices is easily verified by simple internet search, and has been highlighted in discussions, e.g. Hall (2013).
Along with a Brittleness Index, dynamic properties from Sonic and Density are also computed.
The following is calculated:
Brittleness is calculated a number of different ways. The most common is by using mineralogy, however accurate mineralogy is most often obtained using XRD lab measurements on rock samples (expensive) or from the calculated petrophysics mineralogy. SPE 168589 discusses this in more detail.
Another approach is to look at the geomechanical properties of the rocks using the sonic and density logs, computing various mechanical moduli and calibrating them to static measurements. See SPE 115258.
A simple variation on this technique is to use dynamic sonic (log) measurements directly. However, this means the results are not calibrated, but are good at comparing nearby/regional well data or for looking at relative differences. Set the ratios to 1.0 for an uncalibrated brittleness.