Analysis On The Basic Characteristics And Causes Of Luoneng Geothermal Area In Wuding County, Yunnan Province

Luoneng Village is located in the South Bank of Jinsha River in the east of Jiyi Town,Wuding County,Yunnan Province.It is located in the ridge of Hongshanwan anticline.The faults are well developed and have good geological background.Geothermal data are widely distributed in the area,especially in hot water ponds where the water temperature is as high as 56 C.However,due to the weak geothermal research in this area,the understanding of geothermal distribution characteristics and thermal structure has not yet started,which seriously restricts the development and utilization of geothermal resources.In this paper,the geothermal zones of hot water ponds and near-dry geothermal zones are taken as the main research objects.The geothermal water in this area is.Combined with geothermal geological background,hydrogeological conditions and data of hot water wells,a systematic analysis is made from the aspects of heat source,geothermal fluid supply source,heat channel,thermal reservoir and caprock characteristics.Based on the conceptual model of geothermal system,the volume method and the geothermal water storage method are used to calculate the geothermal resources and the geothermal water reserves in the geothermal area of the hot water pond,which can provide a scientific basis for the development and utilization of geothermal resources in Luoneng geothermal area.The hydrochemical analysis shows that the geothermal fluid in the study area is weak alkaline water,and the hydrochemical type is relatively simple,mainly Ca-HCO3 type,with low salinity.The content of Si02 in hot water is higher and positively correlated with Cl-content.The thermal storage temperature in the study area was calculated by using silica temperature scale and geothermal gradient.Geothermal water was determined as immature water and mixed with cold water by Na-K-Mg triangulation method.The mixing ratio of cold water was 40-80% based on the thermal fluid mixing model.The temperature before mixing of cold water was 59-91 C,and the thermal cycle depth was about 2.2 km.Hydrogen and oxygen isotope analysis shows.According to the calculation,the recharge source of geothermal area in Hot Water Tang Village is between Yangquan Village and Yangfang Village,and the recharge elevation is between 2251 and 2279 M.The recharge source in dry geothermal area is from Tuzhuang to Dapingzi Village,and the geothermal fluid runoff from southwest to northeast,and the recharge elevation is between 1247 and 1545 M.In the study area,the drift of delta 18 O in the medium-low temperature geothermal system is small,and the exchange of oxygen isotopes between water and rock is not obvious.The geothermal system in the study area is a mixed type of stratiform and zonal dolomite of the Upper Cambrian Ershui Formation and Sinian Dengying Formation.Its heat source comes from the upper mantle heat flow and the decay of radioactive elements,and continuously conducts heat flow to the thermal reservoir through the fold fracture zone and faults in the core of Hongshanwan anticline.The calculated geothermal resources in the geothermal area of De Luoneng hot water pond are 1.57*l014KJ and the annual heat release is 2.762*1011KJ,which indicates that the geothermal resources in De Luoneng hot water pond are relatively rich and the exploitation potential is great.