  This article presents a priori error estimates of the miscible displacement
of one compressible fluid by another in a porous medium. The study utilizes the
$H(\rm div)$ conforming virtual element method (VEM) for the approximation of
the velocity, while a non-conforming virtual element approach is employed for
the concentration. The pressure is discretised using the standard piecewise
discontinuous polynomial functions. These spatial discretization techniques are
combined with a backward Euler difference scheme for time discretization. Error
estimates are established for velocity, pressure and concentration. The article
also includes numerical results that validate the theoretical estimates.
