Research progress and prospect of plugging technologies for fractured formation with severe lost circulation

SUN Jinsheng,BAI Yingrui,CHENG Rongchao,LYU Kaihe,LIU Fan,FENG Jie,LEI Shaofei,ZHANG Jie,HAO Huijun

Table 1. Typical lost circulation control materials and their main working mechanisms.

Type of lost circulation material Typical lost circulation materials Main working mechanisms Bridging Granular Walnut shell, rubber, asphalt, diatomaceous earth, shell, etc. Plug fracture channels via bridging and accumulating Flake Mica flake, vermiculite, rice husk, resin flake, etc. Fill gaps between accumulated particles Fibrous Sawdust, cotton fiber, flax fiber, carbon fiber, etc. Stretch fiber to form a network to strengthen the accumulated body High water- loss type Clay, fly ash, asbestos fiber, calcium carbonate, etc. Rapidly lose water in the fractures to form a plugging layer Liquid-absorbing swellable type Hydrophilic/lipophilic resin, pre-crosslinked gel particles, etc. Swell after absorbing liquid then fill the fracture space Flexible gels Polyacrylamide gel, polyacrylonitrile gel, polyvinyl alcohol gel, biogel, etc. React in fractures and form gel, which partitions the wellbore from the formation Curable type Thixotropic cement, slag, polyurethane, phenolic resin, etc. Form high-strength solidified body via underground reactions Smart materials Shape memory polymers, shape memory metals, temperature-sensitive gels, self-healing gels, etc. Undergo spontaneous physical and chemical reactions when stimulated by the environment and then plug fractures