Characteristics of fractures development and its controlling factors within the buried hill reservoirs from the Archaean metamorphic basement in the Bozhong Sag, Bohai Bay Basin, Eastern China

作者：Wei Wang, Jian Yi, Xuanlong Shan, Xintao Zhang, Xiaojian Liu, Pengcheng Liu, Shuyue Ren · 发表于：Frontiers in Earth Science · 年份：2022 · DOI：10.3389/feart.2022.935508 · 被引用次数：14 · 研究领域：Hydrocarbon exploration and reservoir analysis、Hydraulic Fracturing and Reservoir Analysis、Seismic Imaging and Inversion Techniques

Metamorphic rocks have almost no primary pore space, and their formation of large-scale reservoirs depends on fractures and related secondary pore space formed by tectonic and fluid activities. The BZ19-6 block in the Bozhong Sag, Bohai Bay Basin, is the largest and deepest buried basement condensate field of buried-hill in the world, and its reservoirs are characterized by strong heterogeneity. In this paper, we systematically summarize the characteristics of fracture development, explore the main factors controlling fracture development, establish a fracture development model and clarify the influence of fractures on reservoir quality by using core and microscopic thin section observations, physical property data, imaging logging data and 3D seismic data analysis. The results show that the major types of fractures in the study area are tectonic fractures and dissolution fractures. In particular, the tectonic fractures are widely developed, accounting for 71.7% of the total number of fractures. Migmatization controls the lithological distribution of Archean metamorphic rocks. The migmatitic granite, having the highest degree of migmatization, is the dominant lithology for fracture development because it is rich in brittle minerals, such as feldspar and quartz. Strong compressional orogeny occurred during Indosinian period when many fractures initially developed, which become dominant among the tectonic fractures. Compression-tension-compression multistage tectonic movements ...