7 789 139 and 7 784 543 the disclosures of which are incorporated herein by reference or other similar devices adjustment of pressure drop across individual permeability devices is possible in accordance with the teaching hereof such that the desired permeability over the length of the borehole 12 or 14 as described herein is achievable referring to fig2 a chart of the flow of fluid over the length of borehole 12 is shown without permeability control and with permeability control the representation is stark with regard to the profile improvement with permeability control in order to determine the appropriate amount of permeability for particular sections of the borehole 12 or 14 one needs to determine the pressure in the formation over the length of the horizontal borehole formation pressure can be determined measured in a number of known ways pressure at the heel of the borehole and pressure at the toe should also be determined measured this can be determined in known ways once both formation pressure and pressures at locations within the borehole have been ascertained the change in pressure u03b4p across the completion can be determined for each location where pressure within the completion has been or is tested mathematically this is expressed as u03b4p location p formation u2212 p location where the locations may be the heel the toe or any other point of interest a.