Geothermal gradient is one of the most important parameters for geothermal exploration and exploitation. Mud is generally used as a drilling fluid in geothermal wells. According to energy conservation law, when the drilling penetrates through an aquifuge or aquitard, its temperature can be used to establish the mathematical analysis model for estimating the geothermal gradient. The recorded mud temperatures in some practical drilling cases in southwest China have been applied to study the influence radius of geotherm that is conducted by surrounding rock into the derived formula. The fitting calculation results show that the absolute error is generally very low, being less than 10%, which indicates that the proposed formula can be used to effectively predict the geothermal gradient. The calculation indicates that it is only when the rock conductive influencing radius is very small (around 0.25m) that it is possible to have a reasonable solution.
The shuttling effect of soluble polysulfides and the inadequate conductivity of sulfur and lithium sulfide impede the practical utilization of lithium–sulfur batteries. To address this issue, the polar δ-MnO2 nanosheets with a 2D morphology can provide abundant anchor and catalytic sites for polysulfides. However, the poor intrinsic conductivity restricts the transformation ability. Herein, we introduce mixed Mn4+/Mn3+ valence states in δ-MnO2 nanosheets by a facile annealing method to promote the redox kinetics of polysulfides. This treated MnO2 maintains its 2D morphology, providing abundant absorption sites for polysulfides, while the introduction of mixed valence states enhances charge transfer and facilitates reaction kinetics. As a result, the lithium–sulfur battery achieves high areal capacities of 7.0 mAh cm–2 at 0.56 mA cm–2 and 4.0 mAh cm–2 at 1 mA cm–2 after 100 cycles with a sulfur loading of 10.91 mg cm–2 and an E/S ratio of 6.46 μL mg–1.
Yizhang, located in south of Hunan province of China is rich in geothermal resources. This paper aimed to study the concentrations of cations, e.g., K + , Ca 2+ , Na + , Mg 2+ and conducted the analysis of the environmental isotope characteristics of δD, δ 18 O and 13 C. Further there are explained the rules of the generation and evolution of geothermal groundwater in Yizhang. The temperature of geothermal groundwater in Yizhang was between 34.2 and 45.4 °C, with a neutral pH and a high electrical conductivity. The hydrogeochemical characteristics changed in the order HCO3-Ca, HCO3-Ca, HCO3-SO4-Ca, SO4-Ca-Mg corresponding to surface water-underground cold water-Yongkou hot springs-Yiliu hot springs in Yizhang area. Compared with that in Yongkou area, the water-rock interaction of groundwater lasted for a longer time in a more enclosed environment in Yiliu area. The δD-δ 18 O isotope analysis showed that the geothermal groundwater was generated from atmospheric rainfall and the recharge height of geothermal field was between 695~1040m. The 13 C isotope analysis demonstrated that the CO2 generated during water-rock interactions was induced by factors of biogenetic, atmosphere, mantle and carbonate rocks degeneration. The result of this study was that the geothermal groundwater in Yongkou and Yiliu was formed from the same thermal resource in the same environment. Our research contributed to the determination of the border of geothermal groundwater fields, the modelling of the geological thermal reservoir structure, and the environmental evaluation of the groundwater in Yizhang, Hunan province, China.
As an important parameter, the temperature of the thermal reservoir is essential to the classification of the geothermal system and the potential of geothermal resources. The inversion coupling study of the geothermal field is an important basis for establishing the genetic model for the geothermal field of Ruidian, Western Yunnan Province, China. With a geothermal flow of up to 120.5mW/m 2 , and an average geothermal gradient of 4.61°C/100m, the Tengchong-Ruidian area is a high temperature geothermal area, where the highest hot spring water temperature can reach 91.5°C. The geothermal reservoirs there can be divided into shallow and deep thermal reservoirs. By using the Log (Q/K) curve method and the Na-K-Mg triangle diagram method, this paper finds that the underground hot water in the study area is in an unsaturated state and mixed with cold water. Then it calculates the thermal reservoir temperature and analyzes the deep temperature characteristics of the subsurface thermal fluid and the mixing process of the hot and cold water using the SiO2 solubility geothermometer, the dissolved chloride-enthalpy plot, the dissolved silica-enthalpy graph, and the linear regression equations iteration solution methods. The conclusion obtained from this study is that the temperature of the shallow thermal reservoir is about 145°C, that the temperature of the deep thermal reservoir about 220°C, and that the proportion of cold water mixed generally between 60% and 70%. The comprehensive research results of the temperature field in the study area provide theoretical and data support for the establishment of the genetic mechanism for the Ruidian geothermal field.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.