Abstract This paper evaluates the integration of a turboexpander–generator (TXG) system into offshore gas production facilities as an alternative to conventional topside choke valves (CCV). Using process simulations over a 23-year production profile, the study quantifies the system's impact on platform power balance, emissions reduction, condensate recovery, and economic performance. Results indicate that replacing conventional throttling with near-isentropic expansion can generate a significant share of the platforms power requirement while reducing fuel gas consumption, leading to an estimated 222,000-tonne reduction in CO2 emissions over the field life. The substantial cooling effect from expansion also increased condensate recovery by approximately 309,000 Sm3. Beyond the plateau phase, the system demonstrated continued value during production decline by rerouting recycled gas streams from compressors to recover otherwise lost energy. Additionally, the configuration can be adapted to accommodate new tie-in fields, enabling sustained energy recovery and process optimization after the original field transitions off plateau production. An upstream heater was incorporated to control downstream temperatures, enabling the use of waste heat from gas turbines to increase gas enthalpy prior to expansion, effectively converting otherwise wasted heat into electrical energy. The study also proposes avoiding re-bundling of export or re-injection compressors during off-design operation by recycling gas back to the TXG system to produce power and exploit waste energy sources as decline progresses. This paper also assesses the increased range of production and energy-efficiency optimization strategies enabled by the TXG system. Net present value (NPV) analyses indicated robust economic performance, with internal rates of return between 23% and 63%, The P50 and P10 cases were profitable without carbon tax incentives. These findings demonstrate that TXG systems can extend field life, enhance process efficiency, and reduce emissions while maintaining operational flexibility, supporting offshore decarbonization strategies.
Bjerkmo et al. (Mon,) studied this question.