Proppant flowback control is one of the main issues in hydraulic fracture modeling
since the propping agent maintains the crack in an open state and therefore
provides oil inflow to the wellbore. The main objective of this paper is to determine
the conditions that can lead to proppant flowback during the direct operation of
the well. The main outcome of this paper is an evolution criterion for
proppant flowback occurrence, which takes the external pressures affecting the
proppant particles, the proppant properties, and the crack opening width into
account. We propose a two-component continuum model consisting of
the proppant and the oil to find the stress-strain state of the proppant
and thereby to obtain the stress components in the evolution criterion.
We solve both a stationary problem for estimating the probability of the
proppant flowback occurrence under regular conditions as well as a transient
problem for taking the possibility of fast changing external conditions into
account.