| Title | Pore and Permeability Characteristics and Development Patterns of Karst-Fractured Geothermal Reservoirs |
|---|---|
| Authors | 芳瑜 董 |
| Year | 2026 |
| Conference | World Geothermal Congress |
| Keywords | Karst-fractured geothermal reservoirs, Huanghua Depression, paleokarst landform, Pore and Permeability Characteristics, Development Patterns |
| Abstract | Karst-fractured geothermal reservoirs, characterized by high water yield and easy reinjection, are high-quality geothermal reservoir layers in the sedimentary basins of eastern China. Understanding their development characteristics and formation mechanisms are crucial for the efficient exploration and development of this type of geothermal resources. Focusing on the Ordovician karst-fractured reservoir in the Huanghua Depression, Bohai Bay Basin, China, this study integrates core/thin-section observations, paleokarst landform restoration, and drilling/logging data to analyze spatial development patterns. Ordovician carbonate reservoirs exhibit strong heterogeneity due to multi-stage karst alteration and dissolution-induced fracture expansion, with dissolution pores and small-scale karst caves being key to forming high-quality reservoir zones. Vertically, within 20–150 m from the weathering crust, drilling fluid loss and high porosity/permeability logging responses identify a horizontal phreatic flow zone with intense dissolution and good horizontal connectivity—the most favorable interval for reservoir development. Horizontally, favorable reservoirs are controlled by the paleo-groundwater flow field. During the Indosinian-Yanshanian Stage, exposed Ordovician limestones in the Qianmiqiao buried hill experienced long-term weathering and leaching. In the paleokarst slope areas, with shallow water tables, rapid circulation, low TDS, and strong dissolution, the development of multi-stage bedding karst was promoted, forming ideal zones for karst-fractured reservoir development. In conclusion, high-quality karst-fractured carbonate geothermal reservoirs form within 150m of karst weathering crusts on paleokarst slopes, governed by paleokarst processes. This study provides a theoretical basis for geothermal development in the Huanghua Depression and analogous regions, facilitating cost-effective exploration and enhanced development efficiency. |