Experimental Evaluation of Carbonated Water Injection to Increase Oil Recovery Using Spontaneous Imbibition

Abstract

Carbon dioxide flooding is known for increasing the production of oil as enhanced oil recovery (EOR). Conventional carbon dioxide flooding aims to reach minimum miscibility pressure (MMP) before altering oil properties in the reservoir. However, current conditions are that most fields have reached the mature state, so the reservoir pressure is depleted, thus it is hard to reach MMP. Carbonated water is water into which carbon dioxide has been dissolved, under certain conditions. The carbonated water injection (CWI) technique might be a solution for injecting carbon dioxide bellow MMP. The performance of this technique is examined using a physical model designed to show the wettability alteration mechanism of carbonated water. The physical model was made from a glass chamber filled with unaltered water. A saturated core was then placed inside the chamber below a funnel shaped narrow tube that read the oil recovery for each milliliter scale. The chamber was sealed and carbon dioxide injected into the water body. The water inside the chamber was therefore altered to become carbonated water after a period of soaking time. The oil expelled from the core was spontaneously measured by reading the scale on the top of the graduation tube, which showed how the milliliters oil was gathered, a process that known as imbibition. The process repeated for several concentrations of carbon dioxide in water. The change of injection pressure, power of hydrogen (pH), and oil recovery were measured respected to soaking time. The value of every case, including the unaltered-water-saturation case, were compared. This injection technique could result in 0–37% oil recovery.

Attachment

$$ {\text{CO}}_{2} + {\text{H}}_{2} {\text{O }} \rightleftharpoons {\text{H}}_{2} {\text{CO}}_{3} $$

(1)

or,

$$ {\text{H}}_{2} {\text{CO}}_{3} + {\text{H}}_{2} {\text{O}} \rightleftharpoons {\text{HCO}}_{3}^{ - } + {\text{H}}_{3} {\text{O}}^{ + } . $$

(2)