1. A method of developing a petroleum reservoir from a computer-based reservoir model including a set of grid cells to which values of parameters obtained from measurements within the petroleum reservoir are assigned, comprising: defining with the computer-based reservoir model, according to the parameters, a global objective function measuring differences between measured historical data values and simulated historical data values; processing the global objective function into a sum of local objective functions with each local objective function measuring the differences over a geographic region of the reservoir and being defined from parameters having an impact on the historical data corresponding to each region with the parameters having an impact being selected from among the parameters obtained from the measurements and each region being determined to minimize a number of parameters having an impact; modifying the values by minimizing the global objective function by a gradient method wherein derivatives of the local objective functions relative to the parameters having an impact are estimated by parameter perturbation based on a perturbation matrix having a rank equal to a number of the parameters having an impact of the local objective function; and developing the reservoir using the reservoir model.