  Applying chemical additives (molecule inhibitors or dispersants) is one of
the common ways to control asphaltene agglomeration and precipitation. However,
it is not clear why at some conditions the synthetic flocculation inhibitors as
well as resins not only do not inhibit the asphaltene agglomeration,, they may
also promote it, and why the increasing of the additive concentration may lead
to the diminishing of their efficacy. To clarify this issue, in the present
work we have performed a set of vapor preassure osmometry experiments
investigating the asphaltene agglomeration inhibition by commercial and new
inhibitor molecules in toluene and o-diclorobenzene. Monte Carlo computer
modeling has been applied to interpret some unexpected trends of molar mass of
the Puerto Ceiba asphaltene clusters at different concentrations of inhibitor,
assuming that inhibitors efficiency is directly related to their adsorption on
the surface of asphaltene or its complexes. It has been found that a
self-assembly of inhibitor molecules, induced by relative lyophilic or
lyophobic interactions, may be a reason of the inhibitor efficacy declining.
