Integrated studies on pore fabric anisotropy have increased the general understanding of fluid flow patterns through reservoir rocks. In this study, pore anisotropy was studied based on measuring permeability and formation resistivity factors in vertical and horizontal directions for 130 plug samples from a total of 65 oriented block samples. These samples were representatively collected for the Nubia sandstones C and D in the western southern onshore of the Gulf of Suez. In addition, the porosity was measured using two techniques, namely water and helium injection. The effective pore radius r₃₅ and the pore radius of the displacement pressure (r_dp) were also measured. Petrographic studies of some representative thin sections and scanning electron microscope studies (SEM) were applied to study the mineral compositions of the studied samples to declare the most important porosity-reducing and porosity-enhancing diagenetic factors. The results show that the studied samples can be categorized into three rock types (RRTs), namely quartz arenite (RRT1), quartz wacke (RRT2) and mudstone (RRT3). The best storage and flow capacity was assigned to the RRT1 samples, whereas the least quality was assigned to the RRT3 samples. This could be attributed to wide pore throat distributions and the anisotropy of pore spaces due to the presence of a vertical subsidiary fracture system that dominated in many samples. This system was enhanced by introducing authigenic kaolinite as pore-filling clay minerals, causing the reduction in vertical permeability but supporting the vertical electric current flow. For the RRT3 samples, this vertical micro-fracture system was reduced by silica cementation which caused the reduction in both fluid and electric current flow. The pore anisotropy of most of the studied samples is in the range of slight anisotropy with some exceptions in the RRT3 samples which are characterized by moderate anisotropy.

中文翻译：

---

埃及苏伊士湾陆上寒武纪-奥陶纪努比亚砂岩的孔隙结构各向异性：地表露头模拟

关于孔隙结构各向异性的综合研究增加了对通过储层岩石的流体流动模式的一般理解。在这项研究中，基于测量总共65个定向块状样品中的130个插塞样品在垂直和水平方向上的渗透率和地层电阻率因子，研究了孔隙各向异性。这些样品是从苏伊士湾南部南部陆上的努比亚砂岩C和D中代表性收集的。另外，使用两种技术测量孔隙率，即水和氦气注入。有效孔隙半径r ₃₅和位移压力的孔隙半径（r _dp）也进行了测量。通过对一些代表性薄片的岩石学研究和扫描电子显微镜研究（SEM）来研究所研究样品的矿物成分，从而阐明最重要的减孔和增孔成岩因素。结果表明，研究样品可分为石英砂（RRT1），石英瓦克（RRT2）和泥岩（RRT3）三种岩石类型（RRTs）。最佳的存储和流量分配给RRT1样本，而最低的质量分配给RRT3样本。这可能归因于在许多样品中占主导地位的垂直副裂缝系统的存在，这是由于孔喉分布较宽以及孔隙空间的各向异性。通过引入自生高岭石作为填孔粘土矿物来增强该系统，导致垂直磁导率降低，但支持垂直电流。对于RRT3样品，这种垂直微裂缝系统由于二氧化硅胶结作用而减少，这导致流体和电流的减少。大多数研究样品的孔隙各向异性都在轻微的各向异性范围内，RRT3样品中有一些例外，其特征是中等各向异性。