Abstract: Low pressure and super-low permeability reservoir is of more rock pressure sensitivity than conventional permeability reservoir. In this paper, the formula for calculation of non-dimensional oil or liquid productivity index by considering changes of starting-up pressure and permeability pressure sensitivity is deduced. Taking Niujuanhu reservoir with low pressure and super-low permeability in Tuha oil field as an example, the variation between non-dimensional oil or liquid productivity index and water cut is discussed when oil-water viscosity ratio, starting-up pressure and permeability deformation factor are changed dynamically. The studied result shows that the dynamic change of starting-up pressure of such a reservoir has obvious effect on the non-dimensional oil or liquid productivity index. Moreover, this index is much more affected by the starting-up pressure and permeability deformation factor than that of conventional low permeability reservoir.

Key words: low pressure, starting-up, pressure gradient, non-dimensional oil productivity index, non-dimensional liquid productivity index