A computer implemented method of obtaining measures in a data processing system of three dimensional reservoir in a subsurface hydrocarbon producing reservoir partitioned for modeling purposes into reservoir model partitioned as an array of a grid of cells extending over the three dimensions of the reservoir, the reservoir having a plurality of production wells producing hydrocarbons and a plurality of injection wells for injection of fluids into the reservoir to stimulate production, a plurality of observation wells for monitoring reservoir pressure, and with less than all of the production and injection wells having permanent downhole pressure measurement systems installed therein, the method comprising the computer processing steps of: (a) receiving in real time pressure and flow rate data from the production wells, real time pressure and flow rate data from the injection wells and real time pressure data from the observation wells based on measurements from the measurement systems; (b) obtaining a measure of real time reservoir pressure for a partial pressure array composed of wells having permanent downhole pressure measurement systems installed therein based on pressure measurements from the measurement systems; (c) updating a history match model using the received flow rate data and performing simulated pressure calculations in the cells of the full array of cells extending over the three dimensions of the reservoir on a reservoir simulator in the data processing system using the updated history match model; (d) obtaining a measure of pressure difference between real time reservoir pressure and simulated pressure for the wells having downhole pressure gauges; (e) performing a geostatistical interpolation of pressure in the cells of the full array of cells extending over the full array of the three dimensions of the reservoir based on the obtained measure of difference between real time reservoir pressure and simulated pressure for the wells having downhole pressure gauges; (f) forming a measure of real time upscale pressure over the full array of the three dimensions of the reservoir based on the results of the performed geostatistical interpolation; and (g) assembling in memory of the data processing system the measure of real time upscale pressure over the full array of the three dimensions of the reservoir. (a) receiving in real time pressure and flow rate data from the production wells, real time pressure and flow rate data from the injection wells and real time pressure data from the observation wells based on measurements from the measurement systems; (b) obtaining a measure of real time reservoir pressure for a partial pressure array composed of wells having permanent downhole pressure measurement systems installed therein based on pressure measurements from the measurement systems; (c) updating a history match model using the received flow rate data and performing simulated pressure calculations in the cells of the full array of cells extending over the three dimensions of the reservoir on a reservoir simulator in the data processing system using the updated history match model; (d) obtaining a measure of pressure difference between real time reservoir pressure and simulated pressure for the wells having downhole pressure gauges; (e) performing a geostatistical interpolation of pressure in the cells of the full array of cells extending over the full array of the three dimensions of the reservoir based on the obtained measure of difference between real time reservoir pressure and simulated pressure for the wells having downhole pressure gauges; (f) forming a measure of real time upscale pressure over the full array of the three dimensions of the reservoir based on the results of the performed geostatistical interpolation; and (g) assembling in memory of the data processing system the measure of real time upscale pressure over the full array of the three dimensions of the reservoir.