Integration of geomechanical, geological, geochemical, and petrophysical characterization is critical to enhance production from organic-rich mudrocks. This paper introduces an integrated rock classification method in the Eagle Ford Formation shales and marls in southern Texas, consisting of organic-rich fossiliferous marine shale deposited during the Late Cretaceous. A joint inversion of triple-combo, spectral gamma-ray, and elemental capture spectroscopy logs was initially conducted to estimate volumetric concentrations of minerals, porosity, and fluid saturation. Effective elastic properties such as Young’s modulus and Poisson’s ratio as well as minimum horizontal stress were then estimated as a function of depth. Rock classification was finally performed based on geologic texture and geochemical properties, as well as well-log–based estimates of petrophysical and geomechanical properties.The introduced method was applied to two wells located in the oil window of the Eagle Ford Formation (average gas–oil ratio of less than 2000 SCF/STB). The results of the integrated rock classification demonstrated similar organic richness and petrophysical properties in both wells. However, the geomechanical rock classification as derived from in situ stress profiles suggests higher proportions of the rock class with better completion quality (55% of net thickness in one well vs. 34% in the other well). A 90-day report on the cumulative oil production of this well shows an additional 11,000 bbl (i.e., 20% more oil production) compared to the second well. This observation was accounted for by geomechanical properties and the distribution of rock classes that differentiate reservoir quality and production.

中文翻译：

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通过整合岩石物理、地质、地球化学和地质力学特征对 Eagle Ford 组的岩石进行分类

地质力学、地质学、地球化学和岩石物理特征的整合对于提高富含有机质泥岩的产量至关重要。本文介绍了德克萨斯州南部 Eagle Ford 组页岩和泥灰岩中的综合岩石分类方法，该页岩由晚白垩世沉积的富含有机质化石的海相页岩组成。最初进行了三重组合、光谱伽马射线和元素捕获光谱测井的联合反演，以估计矿物的体积浓度、孔隙度和流体饱和度。然后将有效弹性特性（例如杨氏模量和泊松比）以及最小水平应力估计为深度的函数。最后根据地质结构和地球化学性质进行岩石分类，以及基于测井的岩石物理和地质力学特性估计。引入的方法应用于位于 Eagle Ford 地层油窗内的两口井（平均气油比小于 2000 SCF/STB）。综合岩石分类结果表明，两口井的有机质丰富度和岩石物理性质相似。然而，根据原位应力剖面得出的地质力学岩石分类表明，岩石类别的比例更高，完井质量更好（一口井净厚度为 55%，另一口井为 34%）。这口井 90 天的累计石油产量报告显示，与第二口井相比，产量增加了 11,000 桶（即，石油产量增加了 20%）。