广域电磁法在苏北盆地厚覆盖区地热勘查中的应用

APPLICATION OF WIDE FIELD ELECTROMAGNETIC METHOD IN GEOTHERMAL EXPLORATION OF THICK COVERED AREA IN NORTHERN JIANGSU BASIN

为了解决强干扰地区电磁数据采集质量差和厚覆盖区目标热储层埋深大的难题,丰富沉积盆地型地热资源勘探的技术手段,在江苏苏北盆地厚覆盖区开展了广域电磁法地热勘查工作.经过野外资料采集和数据处理,获得了地下3.5 km以浅的电性结构,划分出7套电性层,结合地层物性特征识别出7套地层,查明了主要热储层的埋深及厚度,部署了DR1地热井,完井井深2535 m,并于1634~2535 m钻遇三垛组一段和戴南组二段热储层,涌水量432 m3/d,出水水温63.0℃.钻探结果表明广域电磁法在地热勘探中取得了良好的应用效果,可为类似地区开展地热勘查工作提供参考.

To solve the problems of poor quality of electromagnetic data acquisition in strong interference area and large buried depth of target thermal reservoir in thick covered area,and to enrich the technical means of sedimentary basintype geothermal resource exploration,the geothermal exploration by means of wide field electromagnetic method(WFEM)is carried out in the thick covered area of Northern Jiangsu Basin.Through field data gathering and data processing,the study obtains the electrical structure at the depth of 3.5 km below surface,delineates 7 sets of electrical layers,identifies 7 sets of strata based on the physical characteristics,and ascertains the burial depth and thickness of major thermal reservoirs.The DR1 geothermal well is deployed with a completion depth of 2535 m.The thermal reservoirs from the first member of Sanduo Formation and the second member of Dainan Formation are drilled at 1634-2535 m,with the water inflow of 432 m3/d and water temperature of 63.0℃.The drilling results show that WFEM has achieved good results in geothermal exploration and can provide reference for geothermal exploration in similar areas.