Abstract
An understanding of the mechanisms by which oil is displaced from porous media requires the knowledge of the role of wettability and capillary forces in the displacement process. The determination of representative capillary pressure (Pc) data and wettability index of a reservoir rock is needed for the prediction of the fluids distribution in the reservoir: the initial water saturation and the volume of reserves. This study shows how wettability alteration of an initially water-wet reservoir rock to oil-wet affects the properties that govern multiphase flow in porous media, that is, capillary pressure, relative permeability, and irreducible saturation. Initial water-wet reservoir core samples with porosities ranging from 23 to 33%, absolute air permeability of 50 to 233 md, and initial brine saturation of 63 to 87% were first tested as water-wet samples under air-brine system. This yielded irreducible wetting phase saturation of 19 to 21%. The samples were later tested after modifying their wettability to oil-wet using a surfactant obtained from glycerophtalic paint; and the results yielded irreducible wetting phase saturation of 25 to 34%. From the results of these experiments, changing the wettability of the samples to oil-wet improved the recovery of the wetting phase.
Highlights
Wettability refers to the tendency of one fluid to spread on or adhere to a solid surface in the presence of immiscible fluids as shown in Figure 1 [1]
The results of relative permeability of the core samples were estimated assuming that the Brooks and Corey formula prescribe their relationships (7); the results are presented in the tables
This study has shown how wettability alteration of an initially water-wet reservoir rock to oil-wet reservoir rock affects the properties that govern multiphase flow in porous media, that is, capillary pressure, relative permeability, and irreducible saturation
Summary
Wettability refers to the tendency of one fluid to spread on or adhere to a solid surface in the presence of immiscible fluids as shown in Figure 1 [1]. The wettability varies from point to point depending upon the surface roughness [2], immobile adsorbed liquid layers [3], and the adsorptive properties of the mineral constituents. Most common aquifer materials such as quartz, carbonates, and sulfates are strongly water wet. It is the wettability of the reservoir rock that controls the distribution of oil and water and affects their movement through pore spaces. Understanding wettability in porous media is, by itself, a difficult problem. Controlling it to modify the behavior of reservoir rock presents a more complex problem. No satisfactory method exists for in situ measurement of wettability, and it is necessary to estimate the wettability of reservoir rocks from laboratory measurements
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
