雄安牛驼镇凸起区高渗性白云岩对上覆地层温度场的影响

牛驼镇凸起区内岩溶型白云岩广泛发育，其层内地下水对流造成浅表温度异常，沉积盖层段的地温梯度值为50.0℃·km-1，但随着高渗性白云岩埋深的增加，上覆沉积盖层段地温梯度值逐渐减小.本文以6口钻井测温曲线和213块样品热物性资料为基础，对高渗性白云岩层内流体对流对上覆地层温度影响的大小开展水热耦合研究.结果表明：一定厚度高渗透层随着其埋深的增加对浅部地层温度的影响减小，2.0 km厚度高渗层其温度影响范围在3.0 km左右；当高渗透层埋深一定时，其温度影响会随着其厚度的增加而增大.其次，通过安01测温曲线获取牛驼镇凸起底部变质基岩温度场特征，地温梯度值为18.6℃·km-1，结合其热导率值，计算知热流值在58.2 mW·m-2左右.通过该热流值累加上上部碳酸盐和沉积岩层生热率热流值贡献，得知牛驼镇凸起区及周边真实地表热流值为59.6 mW·m-2左右.相比于受到地下水对流或热折射效应影响的沉积盖层段90.0 mW·m-2的"热流值"，通过该变质基岩层段计算出的地表热流值更加能够反映该区域的热流值背景.

Influence of the groundwater convection within the high permeability formation on the overlying temperature field in Niutuozhen uplift

The Karst dolomite is widely developed in Niutuozhen uplift, and the groundwater convection within this formation results in the abnormally high temperature field within the near-surface sedimentary layers, which the geothermal gradient can even reach 50.0℃·km-1. However, with the increase in/of the high permeability formation thickness, the geothermal gradient within the sedimentary layer decreased gradually. Based on the 6 boreholes temperature logging and 213 core samples thermophysical parameters measurement, the temperature distribution influenced by heat convection within the karst formation was studied by using the hydrothermal coupling. The results show that when the high permeability formation thickness is a constant, the temperature disturbance influenced by heat convection will decrease with the increase in the formation buried depth. When the high permeability formation thickness is 2.0 km, the temperature influenced by groundwater convection was 3.0 km around. Moreover, when the high permeability formations buried depth is a constant, the greater influence on the temperature distribution will occur with the increase in the formation thickness. After the measurement of borehole temperature of the An01, the temperature field of the metamorphic formation can be obtained. The geothermal gradient was 18.6℃·km-1, multiplying by the thermal conductivity value, the basal heat flow within the upper metamorphic layer was 58.2 mW·m-2. After accumulating the heat flow value contributed by the radioactive heat production from the overlying formation, the surface heat flow value was 59.6 mW·m-2 for the Niutuozhen area. Compared with the heat flow value 90.0 mW·m-2 within the sedimentary layer, which was greatly influence by the groundwater convection or heat refraction, the surface heat flow value 59.6 mW·m-2 can more accurately reflect the thermal state of this area.