| Title | Geothermal and other mineral resources joint exploration and development potential in Sanshui Basin |
|---|---|
| Authors | Xuhui Xu, Ying Zhang, Jianyun Feng, Jun Luo, Yan Zeng |
| Year | 2023 |
| Conference | World Geothermal Congress |
| Keywords | Sanshui Basin, Geothermal, Oil and gas, Helium, Rock salt. |
| Abstract | Sanshui Basin is a cretaceous- paleogene fault-depression basin developed on the crystalline basement of upper Paleozoic shallow Marine carbonate rocks and Mesozoic igneous rocks. The formation has a maximum cumulative thickness of more than 7000 meters and an area of about 3300 km2. The basin as a whole has a lozge-shaped NW to SE distribution, which can be divided into Baoyue sag, Hekou-Dalan uplift, Xiaotang sag ，Hefeng uplift ，Yanbu sag and Luzhou sag. Yanshanian granites are exposed on the north and south sides of the basin, and a small amount of Paleogene volcanic rocks are found in the basin. Drilling from top to bottom in Baoyue sag revealed Quaternary sands and clays, Neogene-Paleogene-Cretaceous sand and mudstone intermixed with a small amount of salt rock and volcanic rock, and Permian-Carboniferous limestone. Gravity, aeromagnetic and wide field electromagnetic reveal the presence of granites in the deep. The average geothermal gradient of Cenozoic strata is 2.73℃/100m, and that of Permian qixia formation is 2.88℃/100m. It is estimated that the deep heat storage temperature at 3000 m of Baoyue sag is about 100℃, and the temperature at 5000m is above 150℃. There are middle temperature geothermal resources exist in karst reservoir of Permian Carboniferous limestone and Middle-high temperature geothermal resources exist in weathering crust of deep granite and fault zone type reservoir. These geothermal resources have the prospect of resource utilization mainly for refrigeration industry and also for heating and power generation. Since 1950s, oil and gas exploration has been carried out in Shui Basin. Oil and gas and CO2 have been obtained and exploited from Permian limestone fractures and sandstone reservoirs of the third member of Paleogene Buxin Formation in Baoyue Sag. The helium content of some natural gas reaches industrial grade (0.1%) and is believed to come from deep mantle. Also，there are large areas of red salt-bearing structures in the Buxin Formation of paleogene. In gekeng salt mine, salt rock has a thickness of more than 1000m. Industrial mining of salt mine began in 1988, injecting fresh water into Wells and then extracting brine. A large number of dissolved cavities have been formed, which has the potential to build salt caked gas storage and hydrogen storage. Sanshui Basin is located in the Pearl River Delta region of Guangdong Province and belongs to the Guangdong-Hong Kong-Macao Greater Bay Area, which is the most economically dynamic area in the world. The demand for resources and energy is very strong. At present, shallow-buried oil and rock salt resources are mainly exploited in the area. In the future, oil and gas exploration and development will expand to the deep, and the exploration of oil and gas controlled by deep faults, especially helium-rich gas, will become the main direction. The comprehensive exploration and development of various mineral resources combined with geothermal，petroleum（especially helium-rich natural gas），rock salt and salt cavern gas storage will become the characteristics of Sanshui. |