天津市沧县隆起内的明化镇组砂岩储层具有泥质含量高、成岩性差、胶结疏松、易出砂的特点，回灌困难的情况普遍存在，制约了地热资源的可持续开发。现有滤水管填砾成井工艺利于保持地层的稳定性和过水效果，但其回灌效果有待提升。从钻井口径、钻井液、钻具组合和洗井等方面对现有滤水管填砾成井工艺进行了优化，优化后的大口径填砾成井工艺，在保证原有的挡砂和支撑效果的同时，扩大了成井口径，增加了地热井取水段的过流面积，通过优化钻井液配方和钻具组合，减少了钻井液对储层的污染，钻井施工后的联合洗井将部分堵塞成分带出地层，起到了疏通地层的作用，减小了对渗流通道的堵塞。应用该工艺施工的2眼明化镇组热储回灌井分别进行了3组回灌试验，试验中最大回灌量分别为32.0 m³/h和58.0 m³/h。与周边同层明化镇组回灌井相比，回灌量分别增加了3.48倍和2.00倍以上，证明优化后的大口径滤水管填砾成井工艺有效提升了明化镇组储层的回灌效果。

The Minghuazhen Formation in the Cangxian Uplift of Tianjin presents a unique challenge for geothermal resource development due to its sandstone reservoirs. These reservoirs are characterized by high shale content, suboptimal lithology, loosely cemented structures, and a tendency for sand flow, all of which complicate the process of reinjecting water back into the reservoir. This difficulty in reinjection poses a significant obstacle to the sustainable development of geothermal resources in the area. The existing well completion technology, which involves filter pipe gravel filling, is beneficial in maintaining the stability of the formation and facilitating water flow. However, improvements are needed in several aspects, including drilling diameter, drilling fluid composition, drilling assembly, and well washing processes, to enhance the effectiveness of reinjection. An optimized large-diameter gravel filling well completion technology has been developed to address these issues. This technology not only preserves the original sand retention and support functions but also increases the well completion diameter, thereby enlarging the flow area of the geothermal wells. Further, by optimizing the drilling fluid formula and drilling assembly, the contamination of the reservoir is minimized. Additionally, a combined well washing technique implemented after drilling operations helps remove plugging components from the formation, aiding in unclogging the permeation channels. Three groups of reinjection tests were carried out on two reinjection wells in Minghuazhen Formation, which were constructed by the new well completion technology. The maximum reinjection rates in the tests were 32.0 m³/h and 58.0 m³/h. Compared with the reinjection wells in the same layer, the reinjection volume increased by 3.48 times and more than 2.00 times respectively, which proved that the optimized gravel filling well completion technology of large-diameter filter pipe improved the reinjection effect effectively.