Ignoring the presence of pyrite can lead to errors in the estimation of Total Organic Carbon (TOC) since pyrite has significantly higher density and conductivity compared to other minerals in shale formations. This study aims to improve the accuracy of estimating TOC from well log data by accounting for the pyrite effect in Eagle Ford shale. To this end, more than 50 feet of preserved cores samples from the Eagle Ford were analyzed using laboratory pyrolysis, X-ray fluorescence (XRF), X-Ray Diffraction (XRD), and spectral core gamma system. Since there is significant vertical heterogeneity in the Eagle Ford shale, parameters such as TOC, pyrite content, Gamma ray intensity, content of Fe and S, and concentrations of U, Th, and K were analyzed on a fine scale in the Upper and Lower Eagle Ford respectively. Analysis of laboratory TOC data were applied to calibrate TOC data using geophysical well logs methodologies. Pyrite data from XRD analysis were used to find the relationship between pyrite and organic matter and to determine the effect of pyrite on well logs. Well-log-based TOC calculation methods were improved by considering pyrite as an adjustable parameter in equations. Schmoker's (1983) four-component system rock model and Alfred and Vernik's (2013) twopore system model are two representatives of density-log-based TOC calculation methods. Based on these two models, a new petrophysical model considering pyrite and organic porosity was developed. In this research, empirical correlation between TOC and pyrite was explored. Changes of Fe and S concentrations with depth and Gamma ray intensity was determined. The trends of Fe sand S contents matched Gamma ray intensity very well in the depth range from 13790 ft to 13825 ft. Empirical relationships were found between TOC and Gamma ray intensity, TOC and Uranium, respectively. Furthermore, a new petrophysical model considering pyrite and organic porosity was validated with TOC and density data from shale formations. The proposed model improves the estimation of TOC calculation in Eagle Ford formation by the incorporation of pyrite effect.
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机译：忽略黄铁矿的存在可能导致估计总有机碳（TOC）的误差，因为与页岩形成的其他矿物相比，硫铁矿具有明显较高的密度和导电性。本研究旨在通过占Eagle Ford页岩中的黄铁矿效应来提高估算TOC的准确性。为此，使用实验室热解，X射线荧光（XRF），X射线衍射（XRD）和光谱核心γ系统，分析来自Eagle Ford的超过50英尺的保存核样品。由于Eagle Ford页岩中存在显着的垂直异质性，因此在上下尺度和下部的尺度上分析了诸如TOC，黄铁矿含量，γ射线强度，Fe和S含量的参数，以及U，Th和K的浓度鹰福特分别。应用实验室TOC数据的分析使用地球物理井测井方法来校准TOC数据。来自XRD分析的黄铁矿数据用于找到黄铁矿和有机物之间的关系，并确定黄铁矿对井原木的影响。基于良好的基于良好的TOC计算方法通过考虑黄铁矿作为方程中的可调参数而得到改善。 Schmoker's（1983）四组件系统摇滚模型和Alfred和Vernik（2013）突引系统模型是基于密度对数的TOC计算方法的两个代表。基于这两种模型，开发了一种考虑黄铁矿和有机孔隙的新的岩石物理模型。在这项研究中，探索了TOC和黄铁矿之间的经验相关性。确定了具有深度和伽马射线强度的Fe和S浓度的变化。 Fe Sand S含量的趋势与伽马射线强度相匹配，在深度范围内，从13790英尺到13825英尺处的深度范围内。TOC和伽马射线强度，TOC和铀之间发现了经验关系。此外，考虑黄铁矿和有机孔隙率的新的岩石物理模型用来自页岩形成的TOC和密度数据验证。所提出的模型通过掺入黄铁矿效应来改善Eagle Ford形成的TOC计算的估计。
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