摘要
云南腾冲县热海热田是我国西南的一个重要高温水热对流系统。本文根据热田地质、地表显示、热泉水化学和同位素组分等资料,推断热储岩体是块状花岗岩体;对比多种地球化学温标认定热储温度为230℃;推算了热储内部未发生沸腾前的热储流体化学和同位素组分;讨论了热水和冷水的混合与稀释状况;发现地下沸腾带接近地表,肯定热田为一高温热水系统,从而有可能估算热储内部的压力。最后,对水岩平衡作了推测。
The geothermal reservoir of this field is the Late Cretaceous granite, which lacks primany permeability but has secondary permeability owing to the presence of many active faults and fissures. The net fissures in the weathering crust at the top of granite form a subhorizontal shallow geothermal reservoir.
The thermal water discharged from springs is mainly of the Na-Cl-HCO_3, Na-HCO_3-Cl and Na-SO_4 types. Different geothermometers were used to evaluate the reservoir temperature. The temperature of the shallow reservoir represented by T_R averages 170℃; the calculated temperature of the reservoir represented by T Na—K—Ca is about 230℃; the temparature of the bottom of the reservoir represented by T_k is about 275℃.
In a single-stage steam separation process, the initial components before boiling within the reservoir were estimated by the heat and mass balance equation. The mixing and dilution of thermal fluids are discussed by means of the sodium-chloride diagram and the traingle diagram of Na, K and Mg contents. Spring water samples from the region(?) Nos. 3 and 6. have been evaporated and concentrated re-equilibrated on the surface. That from No. 5 is cold groundwater and further heated by steam with a very low Cl content; No. 19, the endmember of cold water in this area; No. 15, spring water close to the hot water which is separated from steam. Samples from other spring regios are of mixed origin formed at different depths. After the study of the nature of the reservoir by use of the boiling point-depth curve equation and fractionation of isotopes, the authors hold that the Rehai (Hot Sea) field is a high-temperature hot water system with the subsurface boiling zone close to the surface. The reservoir is a single-phase one containing saturated water. Thus the reservoir pressure at different depths can be calculated. The water/rock equilibration is inferred finally.
出处
《地质学报》
EI
CAS
CSCD
北大核心
1991年第1期73-85,共13页
Acta Geologica Sinica
基金
国家自然科学基金(D14021)
