Abstract
The Xiong'an Area in the Bohai Bay Basin is a typical superimposed basin rich in geothermal resources within deeply buried marine carbonate rocks. The Wumishan Formation in the Xiong'an Area, Bohai Bay Basin, hosts high-quality dolomite reservoirs vital for geothermal resource development within deeply buried marine carbonates. Granular, algal, and micritic dolomites dominate the formation with reservoir spaces comprising primary pores, karst pores, and fractures. Supergenetic karstification drives the formation of extensive karst cavities, enhancing reservoir quality, while cementation significantly reduces the porosity. Geochemical signatures reveal large-scale weathered-crust karst systems at the formation's top, with localized hydrothermal fluid influence postcrystallization. High-quality reservoirs, primarily in algal dolomite of the intertidal zone, are shaped by sedimentation and multistage karstification driven by Qinyu, Indochinese, and Yanshan-Xishan tectonic movements, creating abundant karst pores and caves. These findings elucidate the petrological and diagenetic controls on reservoir development, providing critical insights for optimizing exploration strategies and predicting reservoir quality in the Bohai Bay Basin and analogous paleocarbonate geothermal systems. This study enhances our understanding of the petrological and diagenetic controls on high-quality dolomite reservoirs in the Wumishan Formation, highlighting the critical role of sedimentation and multistage karstification processes. These findings offer valuable guidance for optimizing exploration strategies and predicting reservoir quality in deeply buried paleocarbonate systems within the Bohai Bay Basin and similar geological settings.