湘西北HY1井下寒武统牛蹄塘组页岩储层可压性评价

为系统深入研究湘西北地区下寒武统牛蹄塘组页岩储层可压裂性,以HY1井为依托,通过密集取心采样、实验测试分析、测井综合解释等多种方法手段,系统分析了牛蹄塘组页岩储层有机地球化学特征、储集物性、裂缝发育特征、脆性矿物组成、岩石力学性质,进而探讨了牛蹄塘组富有机质页岩可压裂性.结果表明:HY1井牛蹄塘组有机碳含量高(0.25...

Fracability Evaluation of Shale Reservoir in the Lower Cambrian Niutitang Formation of Well HY1, Northwestern Hunan

In order to evaluate the fracability of the Lower Cambrian Niutitang Formation (Fm.) shale reservoir in northwestern (NW) Hunan, we took the well HY1 as the research target.Through intensive core sampling, experimental analysis, integrated logging interpretation and other methods, the characteristics of organic carbon content, reservoir physical property, fracture characteristics, brittle mineral compositions, and rock mechanic properties were systematically analyzed, and the shale reservoir fracability further discussed. The results show that the Niutitang Formation in well HY1 is featured by high organic carbon content (0.25% to 13.3%, average 2.91%), and the organic-rich shale developed in the lower Niutitang Formation is 65 m thick. Fractures are less developed in organic-rich shale with the low density (0.27 to 1.21pieces/m), but shale-bedding fractures are developed. The Niutitang Fm. shale is also featured by high mineral brittleness index (17.7% to 86.4%), high static Young’s modulus (37 to 62 GPa), low static Poisson’s ratio (0.14 to 0.26), and high two-phase horizontal pressure difference coefficient (0.21 to 0.54). Overall, the Niutitang Fm. shale reservoir is favorable for fracturing with high brittleness and rock strength, yet the existence of a large number of shale bedding fractures increases the fracture complexity, and give certain negative impact on fracture generation. The double wing fracture is easy to form due to the high two-phase horizontal pressure difference. Therefore, the leakage caused by shale bedding fractures and the influence on fracture height and length extension should be considered comprehensively in fracturing design.