The Fengcheng Formation,located in the Mahu sag of the Junggar basin,has significant potential for shale oil resources.Diagenesis plays a critical role in reservoir development;however,its complex evolution,influenced by tectonic movements and deep hydrothermal fluids,has obscured the understanding of diagenetic stages and their impacton reservoir properties.This lack of clarity restricts the exploration and development of oil and gas resources in the area.This study employed a comprehensive suite of techniques,including thin section identification,carbon and oxygen isotope analysis,cathode luminescence,scanning electron microscopy,and mineral composition analysis,to investigate the diagenetic history of the Fengcheng Formation.The results reveal that the dolomitic shale reservoir originated in a closed saline lacustrine environment and underwent a complex diagenetic sequence characterized by mechanical compaction/pressure solution,dissolution,multistage cementation,and multitype metasomatic alternation.Compaction,cementation,and dissolution emerged as the main diagenesis processes influencing porosity development within the reservoir.Compaction and cementation significantly contributed to the deterioration of reservoir properties,while dissolution played a crucial role in enhancing porosity and improving reservoir quality.This study provides insights into the complex relationship between diagenesis and the physical properties of the dolomitic shale reservoir in the Fengcheng Formation.The findings offer a theoretical framework for comprehending the development mechanism of shale reservoirs in this formation and facilitate the enhancement of shale oil exploration accuracy.
维普
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