昆明地热田的成因与外延

摘要

A combined exploration & production well was drilled successfully in Wanxichong valley,in the periphery of Kunming geothermal field.The depth of the well is 2 001.6 m,the water temperature at the well head is 55 ℃,and the pumping rate of the well is 1 230 m3/d.Through the drilling study,the following formation rules of the sedimentary geothermal reservoir in Yunnan province can be summarized.Firstly,for areas where the depth of the carbonate rock strata is large enough,and areas where the temperature of the thermal water is estimated to be higher than 45 ℃according to geothermal gradient in the carbonate rock, these areas can be target areas for constructing geothermal wells,especially in faulted karst basins.Second-ly,the distribution of carbonate rock strata in Upper Sinian Series Dengying Formation and Lower Cambrian Series Yuhucun Formation is very stable and the unconformable surfaces,faults and fracture structures in these carbonate rock strata form the major channels of the deep confined thermal water,resulting in the de-velopment of deep buried karst in the carbonate rock strata.Therefore,these carbonate rock strata have been common thermal water aquifers.Based on the above-mentioned rules and the geological and hydrogeological investigation,it is advised that the southeastern boundary of Kunming geothermal field can be extended from Wujiaying Village of Chenggong County to the southern side of Jincheng Town for around 20 km.%在昆明地热田外围万溪冲成功钻探深度2001.6 m,井口水温55℃,涌水量1230 m3/d 的探采结合井。通过此次钻探研究验证了对云南省层状热储形成规律的认识,一是在碳酸盐岩地层埋深足够大,按地温梯度推算碳酸盐岩热储层温度达到45℃以上的地段,均具有钻凿可利用的地热水井的地热地质条件,尤其是在断陷盆地中；二是震旦系上统灯影组和下寒武统渔户村组碳酸盐岩地层分布稳定,其中的不整合面、断裂构造是深层承压水传输的通道,形成了地热水深远程径流,导致了深岩溶发育,因此是普遍存在的地热水储层。根据以上认识和本次勘探取得的新突破,结合研究区的地质、水文地质资料进行分析推断,将昆明地热田东南边界由呈贡吴家营附近向南推进至晋城镇南边,外延20余 km。