Abstract A typical oil and gas surface production scheme consists of gathering systems where individual wells are connected en route to a common separator. These wells are invariably at differing distances and may also be connected with different size pipelines and other pressure-reducing devices. However, they do have some overriding commonalities: they are all expected to be culminating into a common pressure at the separator and, often, at the other end they also start at a common pressure, that of the reservoir. The latter is time dependent, reflecting reservoir depletion. The production rate greatly depends on the well "plumbing", the surface network and, of course, the fluid properties. The pressure drop depends on the flow rate and the inlet pressure and the system temperature. In such a situation, production engineers have a number of tools at their disposal to maximize the production rate: a more drastic approach is to change the production tubing and/or the surface pipelines, add pumps etc. A more benign approach is to optimize the choke sizes and, especially, anticipate, the time of such choke changes or work in the system a schedule for variable choke adjustments. We have developed a multi-well network optimization scheme that uses a mathematical solver, which employs a large number of equations, which, when solved simultaneously, allow the finding of the system optimum rate, points towards the appropriate choke sizes (as the reservoir pressure declines) and re-sizes the diameter of the surface network tubulars. We present here both the methodology and example applications for natural gas gathering systems.