The work attempts to address six key questions: (i) do we continue to fix the problems of gravity segregation in the horizontal gas floods or find an effective alternative?, (ii) is there a happy-medium between single-slug and WAG processes that would outperform both?, (iii) what are the controlling multiphase mechanisms and fluid dynamics in gravity drainage processes?, (iv) what are the mechanistic issues relating to gravity drainage?, and (v) how can we model the novel GAGD process using traditional analytical and empirical theories and (vi) what are the roles of the classical...