X-ray Fluorescence Analysis of High-Density Brines Using a Compton Scattering Ratio Technique

Abstract

AbstractHigh-density brines are used to control high pressure during oil and gas well operations. These dense brines (15 to 20 lb/gal) are solutions prepared from sale such as calcium chloride, calcium bromide, zinc bromide and/or combinations. During stages of completion, excessive losses of these expensive brines to the production zone can occur. Before the brine is reused in other oil and/or gas well operations, the brine may need to be reweighted. An analysis of the brine composition must be obtained to properly add the correct amount of salts.Standard addition or internal standardization methods are commonly used in X-ray fluorescence (XRF) applications but negate one of the advantages of XRF-elimination of tedious sample preparation. Scattered X-ray intensity has been used successfully to correct matrix effects in XRF applications. A Compton scatter ratio method is very advantageous for samples having a low atomic number, for which the scattered intensity is high. This paper describes an XRF method for determining Ca, CI, and Zn in high-density brines as well as the matrix correction for Br using a scattered X-ray ratio technique.