Stress cycling of proppant packs often occurs during well production operations and is known to be a major contributing factor to proppant pack failure. Proppant crushing occurs due to increasing closure stress as a well is drawn down. The fines generated by such crushing can cause significant damage to proppant pack porosity and fracture conductivity. Additionally, the incidence of proppant flowback (fines and whole proppant) has been reported to be exacerbated by stress cycling.
The addition of deformable beads to the proppant pack has been observed to alleviate both problems and may significantly improve well performance. Testing of various mixtures of the deformable beads and proppant has demonstrated significant reductions in the amount of fines generated and accompanying improvements in proppant pack permeability. Furthermore, the initiation of proppant flowback was observed to require much higher flow rates than in the absence of the beads.
It is thought the process of bead deformation serves to "cushion" the proppant particles from the full brunt of the stress. New laboratory facilities and procedures have been established to study and quantify, proppant flowback, and conductivity as a function of proppant, temperature, flow rate. fracture width, closure stress, and cycle frequency.