Abstract: A slug of solution, comprising a linear polymer such as polysulfone, polyethylene terephthalate or polyimide dissolved in a "good" solvent, such as morpholine, dimethylformamide m-cresol or dimethylsulfoxide, respectively, is emplaced in the near-wellbore region of an unconsolidated sand reservoir. A second slug comprising a poor solvent for the polymer, such as water or water+2-methanol is pumped into the region to contact the first slug. The linear polymer is precipitated and forms a three-dimensional network of interconnected strands extending through the fluid flow channels between the sand grains. The network functions to consolidate the sand without significantly damaging permeability. Petroleum and other fluids can then be produced without loose sand being entrained in the fluids. If necessary, this permeable network of plastic threads can be removed by re-injecting a slug of the good solvent to re-dissolve the plastic and reform the original linear polymer solution.