Conversion of XRD Data from Weighting (%) to Volume (%) for Validation of Volume of Clay
1. What is XRD Data?
XRD data in petrophysics can represent the percentage of mineral types contained in clay mineral groups and non-clay mineral groups. Several types of clay minerals, such as illite, smectite, and chlorite are often found in XRD data. XRD data can be used for more accurate validation when calculating clay volumes.
 |
| Example of XRD data validation in clay and shale volume calculation (Yadav et al., 2012) |
2. How to Convert XRD Data?
The XRD data in the report is usually in weighted form, therefore it needs to be converted to volume form. The simple basic formula used is:
\( \rho = \frac{m}{V} \)
\( \rho = \) density
\( m =\) mass
\( V =\) volume
Sequentially, the steps required to convert XRD data are:
a. Multiplying the percentage of each mineral in weighted form by the total mass of the sample, to obtain the mass of the mineral per type.
b. Dividing the percentage in weighted form by the density to obtain the volume value
c. Summing up the total volume of clay minerals and the total volume of minerals
d. Dividing the total volume of clay minerals by the total volume of minerals, to obtain the volume of clay in per cent form
e. Convert the percent value to decimal, ready for use in well data processing applications, such as Interactive Petrophysics.
3. Convert XRD Data
Reference: Yadav, L., Dutta, T., & Sinha, N. (2012). Reconciliation of core and log data analysis in very thin reservoirs of Krishna Godavari Basin, India. Society of Petroleum Engineers. https://doi.org/10.2118/149017-MS
