Pore Scale Study for CO2 Storage and Enhanced Oil Recovery

Xingxun Li, Xianfeng Fan

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Abstract

CO2 storage, oil and gas recovery are geological scale engineering, but controlled by the displacement and migration of fluids and gas at pore scale, which are ultimately controlled by pore wettability, pore surface chemistry and roughness, pore structure and the interactions between gas, oil, water and pore surfaces. Experimental rigs built in our laboratory can quantitatively analyse the effect of pore wettability, pore structure and CO2 phases on the displacement of oil by water and CO2, or saline water by CO2 in single pores and core sample under a high pressure. Our results indicate that pore wetting is significantly different from the wettability measured from a flat surface, and CO2 phase significantly affect their pore wetting. The static pore contact angle increases dramatically from about 200 to 40o when pore size varying from 300μm to 1000μm. The dynamic pore contact angle varies not only with pore size, but also significantly with the fluids applied. The contact angles of CO2-water and CO2-brine systems increase from 120° up to 155°, and CO2-decane contact angles increase from 28° to 38°, when CO2 phase changes from gas to liquid or supercritical under a pressure range from 0 to 100 bar. The contact angle does not change significantly when temperature increases from 20 to 40 °C if there is no CO2 phase change. CO2-fluid contact angles in a FEP pore are in the order of θgasCO2<θsupercritical CO2<θliquid CO2. The contact angles of CO2-water, CO2-brine and CO2-decane systems stay approximately around 30°, 40° and 26°, respectively, under a pressure range from 0 to 100 bar and at a temperature of 20°C and 40°C. The CO2 contact angles in a glass pore do not change with CO2 phases: θgasCO2≈θsupercritical CO2≈θliquidCO2. Figure 3 indicates that the water production behaviour for the supercritical CO2-water system is very different from that for gas CO2-water and liquid CO2-water systems. The normalized water production rate of liquid CO2-water system remains at a constant value of approximately 0.95, which is close to 1.0. Due to the significant gas CO2 dissolution effect, the normalized water production rate of gas CO2 injection is smaller than those from liquid CO2 injection by approximately 0.3, and does not vary significantly with water saturation although some minor deviations can be observed. On the other hand, the normalized water production rate of supercritical CO2 injection gives a very different trend, which is larger than 1.0. It gives a non-linear correlation with water saturation. The significant non-linear behaviour ranges from values of water saturation from 1.0 to 0.6. (a) (b) Fig.1 Pore contact angles for DI water, 1-propanol, n-decane and crude oil in glass capillaries (a) Static pore contact angle with a size of 50μm-1000μm, (b) Dynamic pore contact angle in pore with a size of 200 microns Figure 2. Effect of CO2 phase on pore their wettability in oil wetting pores (a) (b) Figure 3, Effect of CO2 phase on its displacement in a sand stone core sample (a) Water production behaviour of gas CO2-water, liquid CO2-water and supercritical CO2-water systems; (b) Normalized water production rates of gas CO2-water, liquid CO2-water and supercritical CO2-water systems against water saturation
Original languageEnglish
Title of host publication SCCS Conference 2015
Publication statusPublished - 2015
Event SCCS Conference 2015 - , United Kingdom
Duration: 28 Oct 2015 → …

Conference

Conference SCCS Conference 2015
CountryUnited Kingdom
Period28/10/15 → …

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