碳酸盐岩有机质丰度测试新方法

常规有机碳测试中仅对残余固相进行测试而忽略了酸解液,而前人研究证实酸解液中含有一定量的有机质。为了准确定量碳酸盐岩样品的总有机碳(TOC),提出蒙脱石增稠元素分析的新方法。本次研究以配比标样(CaCO₃+SiO₂+有机质标样)作为研究对象,对配比标样进行传统有机碳测试以及酸解后利用蒙脱石增稠进行元素分析的新方法测试。结果显示加入有机质标样为小分子有机酸(盐)的配比标样的传统有机碳测试的相对误差为98.5%~99.6%,加入大分子有机质的配比标样传统有机碳测试的相对误差较小,为11.9%~48.1%。而酸解后蒙脱石增稠进行元素分析测试的方法中,总有机碳(TOC)的相对误差为0.76%~19.46%。不同有机碳浓度的配比标样的元素分析法测试结果的相对误差随着有机碳浓度的增大而减小。新有机碳测试方法中,由于除去无机碳后将残渣与酸解液混合均匀并增稠,避免了有机碳的流失,更能客观反映样品总有机碳(TOC)。

A New Method to Measure the Value of Organic Abundance in Carbonate Rocks

Considering the organic carbon in the acid solution, a new method is presented for measuring organic carbon in carbonate. It utilizes turface to thicken the residue& acid solution, then the carbon content of sample is analyzed by Elements Analyzer. We prepared standard samples (CaCO₃+SiO₂+ organic materials) to have common TOC test and new method test. Results showed: The common TOC test of standard samples which added acetic acid, calcium acetate, phenylformic acid and calcium benzoate showed a high relative error in TOC value from 98.50% to 99.66%; The common TOC test of standard samples which added stearic acid, calcium stearate, I-II type kerogen and II-III type kerogen showed a lower relative error in TOC value from 11.90% to 48.12%;The new TOC method test showed a lowest relative error in TOC value from 0.76% to 19.46%. The new TOC method test of standard samples with different TOC Theoretical values showed that the relative error decreased with TOC concentration increasing. Because of mixing and thickening the residue and acid solution after removing the inorganic carbon in initial step, it avoided the organic carbon from loss and could accurately quantify TOC value.