古潜山热储开发对地面沉降的影响机制研究

古潜山是中国水热型地热的主要富集区,具有分布广、潜力大、开发利用条件好等特点,同时也是中国地面沉降相对严重的地区。廓清古潜山区地面沉降的影响机制是区域地下水资源以及地热资源的合理规划与开发利用的基础。本文从地面沉降的机理出发,以雄安新区为例,从第四系厚度、黏性土含量、水位变化、土体固结性、地下水的越流补给以及地下水开采量6个方面分析了对地面沉降的影响,认为雄安新区地面沉降的发生主要受第四纪地层中地下水的超采和砂岩热储的采灌不均衡两个因素的影响,其中地下水超采是地面沉降的主要因素,砂岩热储层的无序开发是诱发地面沉降的次要因素,碳酸盐岩热储的开发尽管会造成热储压力的下降,但受碳酸盐岩压缩性能的影响储层不会产生明显的压缩变形。研究结果可以为新区地面沉降的防治及能源规划提供支撑。

Influence mechanism of ancient buried hill geothermal development on land subsidence

Ancient buried hill is a main rich area of hydro-geothermal in China,which has the characteristics of wide distribution,great potential and good development and utilization conditions,and it is also the area with relatively serious land subsidence.Therefore,clarifying the influence mechanism of ground subsidence in the buried hill area is the basis for the reasonable planning,development and utilization of regional groundwater resources and geothermal resources.Based on the mechanism of land subsidence,with Xiong'an district as an example,combined with analysis on the Quaternary thickness,clayey soil content,water level change,soil consolidation,groundwater recharge and its withdrawal,the influence on land subsidence by development of geothermal was studied,which indicates that the occurrence of land subsidence in Xiong'an new area is mainly affected by two factors:over-extraction of groundwater in Quaternary and unbalance of sandstone thermal reservoir.Among them,the overexploitation of groundwater is the main factor of land subsidence and the disordered development of sandstone thermal reservoir is the secondary one.Although the development of carbonate reservoir will cause the decrease of reservoir pressure,the reservoir will not produce obvious compression deformation under the influence of the compression performance of carbonate.As a result,the research can provide support for land subsidence prevention and energy planning in Xiong'an new area.