综合物探技术在承德某小区地热资源勘查中的应用

Application of Integrated Geophysical Prospecting on Geothermal Resource Exploration in a Chengde Residential Area

承德市北双桥区地热受东西向断裂构造控制,其深部太古界单塔子群白庙组为本区的主要热储目的层。现有地质资料表明热储层深度大于1500m,为此采用可控源音频大地电磁测深法(CSAMT)圈定,小线框瞬变电磁法验证的综合勘探技术。某测线的CSAMT探测结果表明,在桩号200~400m、深度1 500m,视电阻率等值线横向出现波动,推断为赋水断层所致,瞬变电磁多测道曲线在此处的双峰异常佐证了CSAMT探测成果。依据综合勘探解释成果,在该测线300m处设计孔位,孔深2 200m。钻探显示在深度1 772~1 895m处揭露断层带,抽水最大流量490m3/h,井底温度65℃,井口水温47℃,与本次综合勘探结果吻合。

The geothermal field in the Beishuangqiao District,Chengde City is controlled by EW faulted structure,its deep part Archeozoic Dantazi Group Baimiao Formation is the main geothermal reservoir prospecting target. Available geological data have shown that the depth of the reservoir is below 1500 m. Thus an integrated prospecting of CSAMT sounding( controlled source audio-magnetotelluric sounding) to delineate and small loop TEM( transient electromagnetic method) to verify the reservoir has been used. The prospecting result of a line has shown that between the 200 m and 400 m locators at depth 1500 m,the isoline of apparent resistivity appeared lateral fluctuation,it is inferred the result of water-bearing fault; the double-crest anomaly of TEM multiple channel curves has supported the result from CSAMT sounding. Based on integrated prospecting interpreted results,a borehole has been designed at 300 m locator of the line with depth 2200 m. The drilling has shown that a fault zone revealed between depth 1772 ~ 1895 m. Pumping test maximum flow is 490 m3/h,bottom temperature 65℃,and wellhead water temperature 47℃,accord with integrated prospecting results.