Recycled solidfree micro-foam drilling fluid or completion fluid

The invention is a recycled solidfree micro-foam drilling fluid or a completion fluid, which comprises the following components in parts by weight: 1. 2-3 parts of recycled solidfree micro-foam composite treatment agent SD-LNA; 2. 0.5-1 part of low-density solidfree tackifier SD-LNV; 3 0.5-1 part of low-density modifier SD-LFD; 4. 0.5-1 part of low-density foam stabilizer SD-LFS; 5. 0.5-1 of low-density flow type modifier SD-LFR; and 6. 100 parts of water. According to a normal preparation method, the above substances are added into water successively, mixed and stirred evenly under normal temperature and normal pressure. The invention has the advantages of low density, high viscosity, small low fluid loss, good lubricating property, strong landwaste suspension property, easy maintenance, fine cleaning capability of wells, fine inhibitory capability on clay and shale, no micro-foam convergence, recycled use and the like, can be widely applied in engineering such as petroleum, geologic drilling and the like, i