沉积盆地砂岩热储回灌试验研究--以山东禹城市为例

Reinjection experimental research on sedimentary basin sandstone reservior--A case study of Yucheng City, Shandong

禹城市为东营组热储地热资源开采利用集中区,因地热资源集中开采及地热尾水的直接外排,造成了水化学污染、热污染及热储层压力下降等一系列地质环境问题。本次在禹城市地热资源开发利用现状调查的基础上,在禹城市栖庭水岸开展地热回灌试验研究,回灌模式为自然同层对井回灌。根据本次回灌试验取得的数据,对回灌量与回灌压力关系、回灌对热储层水质影响、回灌对热储层温度影响规律进行了分析研究并根据拟合回灌量与水位升幅关系曲线计算了最大回灌量。分析结果表明:回灌量随压力的增大而增大,单位回灌量随回灌压力的增大呈减小趋势;回灌井因灌入了矿化度比其自身地热水矿化度高的水源,所以回灌后采集的回灌井地热水矿化度比回灌试验之前高,但因采灌井开采热储层属于同层热储,故回灌对热储层水质影响小;本次试验采灌井间距较大,故回灌对热储层温度无影响;计算确定该回灌井最大回灌量为70 m^3/h。本次回灌试验研究为禹城市地热资源可持续开发利用提供了依据。

Yucheng City is a concentrated area of Dongying Formation for the exploitation and utilization of thermal reservior geothermal resources. Due to the concentrated exploitation of geothermal resources and the direct discharge of geothermal tailwater, a series of geological environmental problems, such as water chemical pollution, thermal pollution and pressure drop of thermal reservoir have been caused. Based on the investigation of the exploitation and utilization of geothermal resources in Yucheng City, the geothermal reinjection experiment was carried out in the Xitingshuian of Yucheng City. Based on the data obtained from the reinjection experiment, the relationship between the reinjection amount and the reinjection pressure, the influence of the reinjection on the water quality of the thermal reservoir, and the influence pattern of the reinjection on the temperature of the thermal reservoir were analyzed and studied, and the maximum reinjection amount was calculated based on the curve fitting the relationship between the reinjection amount and the water level rise.The results show that the amount of reinjection increases with the increase of pressure, and the unit reinjection decreases with the increase of pressure.Because the reinjection well is filled with water with a higher salinity than its own geothermal water, the salinity of the geothermal water collected after the reinjection is higher than that before the reinjection test. However, since the thermal reservoir mined by the reinjection well belongs to the same layer, the influence of the reinjection on the water quality of the thermal reservoir is small. In this test, the spacing between wells is large, so the reinjection has no influence on the temperature of the thermal reservoir.The calculation determined that the maximum reinjection amount of the reinjection well was 70 m^3/h.This study provides a basis for the sustainable development and utilization of the geothermal resources in Yucheng City.