Marine and Petroleum Geology ( IF 4.2 ) Pub Date : 2021-03-27 , DOI: 10.1016/j.marpetgeo.2021.105048 Ammar Abdlmutalib , Osman Abdullatif , Abdullah Alqubalee , Luis Gonzalez , John Humphrey
Storm-wave sediments are considered a potential unconventional resource in the Middle East region, i.e., the early Silurian Qusaiba Member of the Qaliba Formation in Saudi Arabia. Extremely few studies have examined the controls of lithofacies heterogeneity on pore types, sizes, distribution, and connectivity. Therefore, this study intended to illustrate lithofacies controls on pore systems using various integrated approaches. Based on lithofacies analysis, seven lithofacies were identified and interpreted as storm-wave-dominated distal, medial, and proximal shelf deposits. The results of this study reveal two main types of pore systems: interparticle and intraparticle pores, which have been thoroughly recongized across all recognized lithofacies. Nuclear magnetic resonance (NMR) data showed positively and negatively skewed bimodal porosity distribution curves in the proximal and distal shelf lithofacies, respectively; however, the NMR data of medial shelf lithofacies were found to be normally distributed with unimodal distribution curves. Phyllosilicate minerals associated with interparticle pores (≤1 μm) were observed in the distal lithofacies; however, larger-scale interparticle pores were observed in both medial and proximal lithofacies. Such variation was also reflected in the NMR curves, resulting in negatively and positively skewed distribution curves of T2. Diagenetic facies (i.e., calcite, phosphate, pyrite, iron oxides, and clay minerals cementations) occurred during syndepositional, early, and intermediate burial stages before oil generation window. This study facilitates the understanding of the impacts of lithofacies and diagenetic facies on the pore system, and, the petrophysical characteristics of mudrocks in similar depostional settings.
中文翻译:
岩相对暴雨含泥沙细粒沉积物孔隙系统演化的影响。西北沙特阿拉伯志留纪早期Qusaiba成员(Qaliba组)
风暴波沉积物被认为是中东地区潜在的非常规资源,即沙特阿拉伯Qaliba组的志留纪Qusaiba早期成员。很少有研究检查岩相非均质性对孔隙类型,大小,分布和连通性的控制。因此,本研究旨在说明采用各种综合方法对孔隙系统的岩相控制。根据岩相分析,确定了七个岩相,并将其解释为风暴波为主的远端,中层和近端陆架沉积物。这项研究的结果揭示了孔隙系统的两种主要类型:颗粒间和颗粒内孔隙,这些孔隙在所有公认的岩相中都已被彻底确认。核磁共振(NMR)数据分别显示了近端和远端陆架岩相的正态和负态偏斜双峰孔隙度分布曲线;然而,内侧架子岩相的NMR数据发现具有单峰分布曲线的正态分布。在远端岩相中观察到了与颗粒间孔隙(≤1μm)相关的硅硅酸盐矿物。然而,在内侧和近侧岩相均观察到较大的颗粒间孔隙。这种变化也反映在NMR曲线中,从而导致T2的分布呈负偏斜和正偏斜。成岩相(即方解石,磷酸盐,黄铁矿,氧化铁和黏土矿物胶结)发生在成油期之前的沉积,早期和中期埋藏阶段。