Characteristics of Neogene thermal reservoir in Weihe basin

Weihe basin is rich in geothermal resources.The development and utilization of geothermal resources is helpful to adjust energy structure, improve environmental protection and reduce haze pollution.Through regional geology, geophysics, petroleum exploration and geothermal well drilling, this paper makes an in-depth study on geothermal geological conditions, physical properties and reservoir evaluation in Weihe basin.The results show that the Moho surface and Curie uplift in Weihe basin have thin lithosphere and good deep thermal background; The pore types of the newly recent Zhangjiapo Formation and the Lantian-Bahe Formation were dominated by primary intergranular pores, and the pores of the Gaoling Group were not developed; The porosity of Zhangjiapo Formation of Neogene Pliocene is 3.35%~31.2%, with an average of 13.3%;permeability is 0.47×10^-3~235×10^-3μm², average 29.2×10^-3μm²; the reservoir type belongs to class Ⅳ reservoir; the porosity of Lantian-Bahe Formation of Miocene is 5.2%~31.2%, with an average of 17%;permeability is 0.05×10^-3~5684×10^-3μm², average 326×10^-3μm²; the reservoir type belongs to class Ⅲ reservoir; the porosity of Gaoling Group of Miocene is 2.5%~13.9%, with an average of 5.8%;permeability 0.01×10^-3~11.04×10^-3μm², average 0.75×10^-3μm²; the reservoir type belongs to class Ⅵ reservoir; the compaction curve of sand and mudstone shows that Zhangjiapo constituent rock has weak strength, shallow to medium burial, normal weak compaction of rock, weak consolidation semi consolidation of sediment, easy sand production, and is in early diagenetic stage B.The acoustic moveout values of the lower section of Lantian-Bahe Formation and Gaoling Group mostly deviate, and the acoustic moveout values do not change significantly with the increase of depth, which is reflected in the characteristics of medium compaction strong compaction.Due to the deep burial of Lantian-Bahe Formation and Gaoling Group, the sediments are semi consolidated sandstone, which is not easy to produce sand.Lantian-Bahe Formation and Gaoling Group are mainly in late diagenetic stage A.Through the study of Neogene thermal reservoirs, it is believed that the thermal reservoirs in the Weihe River Basin are relatively stable.Promoting the geothermal water development in this area has guiding significance for realizing the goals of 2030 carbon peak, 2060 carbon neutral and double carbon.