  IGR J18027-2016 is an obscured high-mass X-ray binary formed by a neutron
star accreting from the wind of a supergiant companion with a $\sim$4.57 day
orbital period. The source shows an asymmetric eclipse profile that remained
stable across several years. We aim at investigating the geometrical and
physical properties of stellar wind structures formed by the interaction
between the compact object and the supergiant star. In this work we analyse the
temporal and spectral evolution of this source along its orbit using six
archival XMM-Newton observations and the accumulated Swift/BAT hard X-ray light
curve. XMM-Newton light curves show that the source hardens during the ingress
and egress of the eclipse, in accordance with the asymmetric profile seen in
Swift/BAT data. A reduced pulse modulation is observed on the ingress to the
eclipse. We model XMM-Newton spectra by means of a thermally-comptonized
continuum (nthcomp) adding two gaussian emission lines corresponding to Fe
K$\alpha$ and Fe K$\beta$. We included two absorption components to account for
the interstellar and intrinsic media. We found that the local absorption column
outside the eclipse fluctuates uniformly around $\sim$
6$\times$10$^{22}$~cm$^{-2}$, whereas, when the source enters and leaves the
eclipse, the column increases by a factor of $\gtrsim$3, reaching values up to
$\sim$35 and $\sim$15$\times 10^{22}$~cm$^{-2}$, respectively. Combining the
physical properties derived from the spectral analysis, we propose a scenario
where a photo-ionisation wake (mainly) and an accretion wake (secondarily) are
responsible for the orbital evolution of the absorption column, the continuum
emission and the variability seen at the Fe-line complex.
