Classification of sedimentary rocks from Southeast Asia using Si-Ca-Al triangle developed based on PXRF data.
As I indicated in my last article, field portable x-ray fluorescence (XRF) is a very reliable and effective tool to analyze any type of sample not only in metal exploration and mining but also in oil and gas exploration and production. A case study was carried out on 221 samples collected from an oil and gas drill site in Southeast Asia. The prepared samples were analyzed using a portable XRF analyzer using 120 seconds total analysis time (30 seconds on each filter). Field studies and observations indicated that all these samples are sedimentary (with local bedding planes). Mud logging showed that there are three major intervals:
from 137 to 603m consists of thick siltstone layer with interbedded sandstone and minor claystone,
from 603 to 723m consists of thick sandstone layer interbedded with siltstone and local claystone, and
from 723 to 2232m dominated by claystone and siltstone interbedded with minor sandstone and rare limestone.
The portable XRF data were evaluated and a Si-Ca-Al discrimination triangle was developed. This triangle not only discriminates between various major interval lithologies, but also the thin interbeds along with subtle geochemical changes in beds and transition from one lithology to another can be monitored easily. Read the entire Application of XRF in Mud Logging case study.