Simulation of multi-method CO2 capture and purification process

Abstract

Recycling reinjection of CO2 captured and purified from the produced gas of CO2 flooding can not only enhance oil recovery, but also realize the geological storage of CO2, so as to provide good social and economic benefit. With the operation and advancement of CO2 flooding development mode, one single CO2 capture and purification process can hardly deal with the yearly increase and large-scale variation of CO2 content in the produced gas. In order to provide support for the promotion of CO2-EOR technology oil and gas fields, to this end, this paper puts forward four schemes of multi-method CO2 capture and purification process. It includes two-stage hydramine method, one-stage membrane separation + one-stage hydramine method, two-stage membrane separation + one-stage hydramine method, one-stage membrane separation + two-stage hydramine method. And based on the working condition data of CO2 flooding in one certain oilfield, simulation was carried out by using HYSYS software. In addition, the enrichment degree of the CO2 captured and purified by means of different schemes and its energy consumption and economy were analyzed mainly. And the following research results were obtained. First, when the CO2 concentration of the produced gas is low, it is necessary to put the two-stage alcohol amine circulation process into production firstly to realize the deacidification of natural gas while purchasing some pure CO2 to mix at a certain proportion, so as to reach the required CO2 purity of reinjected gas. Second, as the CO2 concentration of the produced gas increases, it is better to use the membrane separation technology before the two-stage alcohol amine circulation process, so that the enriched and purified gas can reach the required CO2 purity of direction reinjection. In conclusion, the research results can provide engineering practical guidance for the formulation of the scheme to enrich and purify CO2 from the produced gas of CO2 flooding.