Reduce CO2-Oil Miscible Pressure By Injection Man-Made Miscible-Slug to Enhance Oil Recovery

Abstract

Objectives/Scope: The purpose of this thesis is to reduce CO2-oil minimum miscible pressure (MMP) in CO2 flooding some heavy oil which is difficult to miscible with CO2 in general cases. 2 Methods, Procedures, Process: In order to reduce CO2-oil minimum miscible pressure (MMP), a brave idea of injection miscible-slug instead of pure CO2 into reservoir was proposed, and then several slim-tube tests with different pressures were deployed to acquire the composition of miscible-slug, and a consecutive series of output samples including oil and gas from slim-tube at different injection pore-volume CO2 were collected, composition of every output samples was tested and analyzed by using equipment of liquid phase chromatograph and gas phase chromatograph. 3 Results, Observations, Conclusions: Composition of consecutive output samples at different injection pore-volume CO2 were obtained through the help of gas & oil phase chromatograph, and the result above shows the quit difference between miscible-slug and immiscible-slug. The components with molecular weight lighter than C18 are mainly extracted by CO2 immiscible-slug, while some additional components with molecular weight between C18 and C25 are also extracted by CO2 miscible-slug. Moreover, low-carbon molecules are initially extracted, with the ongoing flooding, higher-carbon molecules are gradually extracted. Based on the composition of consecutive output samples, man-made miscible-slug for the this oil reservoir was made up and the slug PV was amplified used for injection instead of CO2, another slim-tube test using above man-made miscible-slug was deployed again with pressure lower than MMP obtained from above series of slim-tube tests, the result shows a CO2 –oil miscible flooding and the idea of CO2 –oil MMP reduction comes true. 4 Novel/Additive Information: A method of reduction CO2 –oil MMP by injection man-made miscible-slug made up from slim-tube tests was proved, which would improve a lot of oil reservoir immiscible with CO2 into miscible with CO2 under reservoir temperature.