Mature oil fields face falling reservoir pressure, rising gas-oil ratios and compression systems sized for earlier conditions. As a result, usable gas is often flared. This study develops a multi-objective framework that jointly optimizes booster compression capacity, compressor driver type, separator suction pressure, flare gas recovery capacity and lift gas rate. The objectives are incremental net present value, cumulative oil production and cumulative greenhouse gas emissions over a ten-year horizon. The framework couples well and gas-lift performance, multistage compression, compressor availability, flare header flow variability, emissions and discounted cash flow. It is applied to a representative 24-well gas-lifted field using literature-based inputs, not field data. NSGA-II recovered 99.8 percent of the hypervolume of an exhaustive search of 29,250 designs. Maximizing value alone raised oil output by 39 percent but nearly doubled emissions, because added lift gas and lower suction pressure increased both flaring and engine fuel use. A compromise design with four electric-driven units, a 75 psia suction pressure and 3 MMscfd of flare gas recovery kept 79 percent of the maximum value gain and raised oil output by 34 percent, while cutting emissions by 58 percent and flaring by 91 percent. Flare gas recovery was the cheapest abatement lever, at about USD 7 per tonne, and a carbon price of USD 50 per tonne made it part of the value-maximizing design.