| Huizhou Sag is an important place for crude oil production in the Zhuyi Depression. For a long time, research
has been mainly focused on southwestern Huizhou Sag, whereas the study on northern Huizhou Sag is relatively weak and
lacks data support, so the northern Huizhou Sag is still in the early stage of exploration. To promote the oil and gas
exploration process in northern Huizhou Sag, the characteristics and development controlling factors of reservoirs in
Zhuhai Formation and Zhujiang Formation in northern Huizhou Sag were systematically studied by using thin section,
grain size analysis, scanning electron microscopy, zircon dating, reservoir properties and other data. The results show that
the reservoir sandstone of Zhujiang Formation and Zhuhai Formation in the northern Huizhou Sag is mainly composed of
medium to coarse grained quartz sandstone from delta front channels, with high compositional and structural maturity and
low argillaceous content. Pores in the sandstone are dominated by primary intergranular pores, locally enriched with
dissolution pores and kaolinite micropores. This sandstone has high porosity, and the maximum profitable depth is about
3 800 m. The reservoir quality of Zhujiang Formation and Zhuhai Formation in northern Huizhou Sag is mainly controlled
by three factors: high-quality parent rocks, favorable sedimentary facies and constructive diagenetic process. The highquality
metamorphic and intrusive parent rocks in the South China block lead to high quartz content in the sandstone,
laying the foundation for the development of high-quality reservoirs. The fluvial energy of delta front channels is high,
resulting in the deposition of coarse grained sandstone, with low clay content and the best reservoir properties.
Dissolution, as constructive diagenesis, can increase porosity, therefore increase reserves. |
