Polymer anti-caving drilling fluid was used to deal with hole wall instability in constriction of directional geothermal well in Tianjin.

• 针对天津市地热定向井施工中存在的孔壁不稳的问题,经过摸索,采用聚合物防塌钻井液进行护壁堵漏,取得了良好的效果。