Application of Analytical Pyrolysis and Cupric Oxide Oxidation to Characterization of Nonextractable Organic Constitutents in Drilling Fluids and Sediments

Abstract

A study was conducted to develop analytical methods suitable for the characterization of the nonextractable organic mud additives (organic polymers) in drilling mud formulations and sediments. Two analytical techniques were evaluated for this purpose: analytical pyrolysis, which involves pyrolysis gas chromatography and pyrolysis gas chromatography/mass spectrometry of organic polymers, and a cupric oxide oxidation technique, which is specific for the analysis of lignin-derived organic matter (lignosulfonates). The pyrolysis technique was suitable for characterizing and distinguishing between individual drilling mud additives. However, upon formulating those additives into drilling muds (bentonite, barite, and caustic) and sediments, their relative abundance and total pyrolysis yields decreased greatly. This decrease in abundance and yields in pyrolysis products is thought to be caused by the catalytic and/or sorptive effects of the clay matrix during pyrolysis. As a result, we conclude that the pyrolysis technique has limited application to the characterization of organic polymers in drilling fluids and sediments. The cupric oxide oxidation technique was a sensitive specific indicator of lignosulfonates and, to a lesser extent, lignites in mud formulations. The major oxidation products of the technique are vanillyl phenols, with concentrations that vary, presumably according to lignosulfonate purity, but make up more than 90% of the total lignin-derived oxidation products. Vanillyl phenol content and total lignin content were identified as the most suitable tracers of drilling mud discharges.