Factors Affecting the Stability of Proppant in Propped Fractures: Results of a Laboratory Study

Abstract

ABSTRACT Factors controlling the stability of proppant in propped fractures were identified and investigated experimentally. The results indicate that the absolute size, distribution and type of proppant may affect stability, and hence the likelihood of proppant flowback. The extent of aTbedment of the proppant into the rock (determined by closure stress and rock hardness) was found to play a key role in stabilising the pack. In addition, channels, which may form due to proppant settling before fracture closure, were found to significantly reduce stability. These are, therefore, favourable sites for proppant flowback. A numerical study has been used to determine lengths of unpropped fractures which may be maintained open due to the rock stiffness. The implications of these results for well productivity and the understood mechanisms of proppant flowback, in the field, are discussed.