雄安新区容城地热田热储空间结构及资源潜力

Structure of geothermal reservoirs and resource potential in the Rongcheng geothermal field in Xiong’an New Area

雄安新区地热条件优越,尤其是牛驼镇凸起和容城凸起具有多年的地热开发历史。容城地热田绝大部分地区适合地热的规模化开发,同时容城地区也是新区建设初期主要的规划开发区,地热资源在服务新区生态文明建设和清洁供暖方面具有重要的意义。容城地热田主要热储层包括新近系明化镇组孔隙型砂岩热储,寒武系、蓟县系以及长城系基岩热储。蓟县系为区域主要的热储层,埋深700~3000 m,厚度500~2000 m,热储温度50~98℃,具有水量大、水质好、储层易于回灌的特点;长城系热储在凸起中心部位仍具有较大的开采潜力,D14钻孔显示长城系热储单位涌水量达到2.6 m^3/h·m,井口水温63.7℃,可作为新区的后备资源。容城地热田按照主要热储层上部覆盖地层构造差异由西向东分别为西部斜坡区、中央隆起区、东部断陷区,由西向东热储开发潜力逐渐变大。本文通过热储法计算了容城地热田年地热可采资源量折合标准煤76.3万t;数值法模拟了水位下降不低于150 m,开采井温度下降小于2℃条件下,年地热可采资源量折合标准煤81.09万t,两者结果相近,评价结果可为容城地热资源规划开发提供参考。

Xiong’an New Area provides superior geothermal conditions.Especially,the Niutuozhen and the Rongcheng uplifts have witnessed many years of geothermal development.The majority of geothermal fields in the Rongcheng are suitable for large-scale geothermal development.Also,the Rongcheng is the main planning and development area in the early development stage of Xiong’an New Area.Geothermal resources are of great significance in developing the ecology and clean heating the Xiong’an New Area.The main thermal reservoirs in the Rongcheng geothermal field include porosity-type geothermal reservoir of the Neogene Minghuazhen Formation,and the bedrock thermal reservoir of the Cambrian,Jixian System and the Changcheng System.The bedrock thermal reservoir of the Jixian System is the main thermal reservoir in the region,with a buried depth of 700~3000 m,a thickness of 500~2000 m,and a temperature of 50~98℃.It is characterized by large water volume,high water quality,and the inclination to reinjection.There is great potential for exploitation at the center of uplift in the Changcheng System.The D14 borehole shows that under the Changcheng System,the water yield for the stratigraphic unit reaches 2.6 m^3/h·m and the wellhead water temperature is 63.7℃,which is suitable for the backup geothermal resources in Xiong’an New Area.Based on the stratigraphic structure of the upper thermal reservoirs,the Rongcheng geothermal field is divided into the slope zone in the west,uplift in the center and fault depression in the east.From the west to the east,the development potential for thermal reservoirs gradually increases.The annual recoverable geothermal resources in the Rongcheng geothermal field were 763000 tons of standard coal.According to numerical methods,under the condition that the water level dropped to no less than 150 m and the temperature of the exploitation well went down by less than 2℃,the annual recoverable resources of geothermal energy was equivalent to 810900 tons of standard coal.The results from both methods are similar.The evaluation results can provide reference for the planning and development of geothermal resources in Rongcheng.