CO2 capture from flue gases: a possibility to reduce the CO2 footprint in offshore oil installations

Abstract

The production of oil and gas in offshore units (FPSO) requires that all utilities (electricity, mechanical drive, hot fluids for heating and cooling water) must be available in the amount necessary at each operating condition. Lack or surplus of utilities are not allowed. Every production equipment is always sized for the highest demand condition, and then it operates at partial loads most of the time. The entire production of electricity, mechanical power and heating fluids depends on the fuel available in the FPSO - the natural gas produced with oil. Therefore, a typical FPSO has a strong carbon footprint associated with burning fuel. Carbon sequestration in an FPSO is facilitated by the possibility of re-injecting CO2 into the reservoir, contributing to oil recovery. This work analyzes two possibilities for reducing the carbon footprint in a typical Brazilian FPSO: a) the use of a combined cycle for electrical generation, reducing fuel consumption and consequently the carbon footprint and b) the association of an amine absorption system to capture CO2 from gas turbine exhaust gases. The analysis is performed for different oil and gas production conditions, and all systems are analyzed operating at partial loads. The combined cycle alone is capable of reducing CO2 emissions by up to 20%. The CO2 capture system, together with the combined cycle, achieves impressive results, with a reduction in CO2 emissions of around 50% during the entire life of the platform. Problems of space and weight of the equipment are also discussed in the work.