The use of nanomaterials for alteration of wettability is a method that has grown in prominence after the development of techniques for synthesizing nanosized particles in the late 1980s. In this paper, after a review of the fundamentals of wettability alteration, a discussion of nanomaterials used for wettability alteration is provided. Among these nanomaterials, nanoparticles of silica and polysilicone indicate better results in terms of efficiency on incremental oil recovery in waterflooding.
Wettability is the tendency of a fluid to spread over a specific surface and is relative to other existent fluids in that system and is defined by the contact angle of a droplet of the fluid and the surface. It is a result of adhesion forces between the fluid and the minerals of the rock. The wettability of a rock ranges from strongly water-wet to strongly oil-wet and is a result of brine/oil/rock interactions in a reservoir. There are different types of rocks on the basis of these interactions and wettabilities:
1. If no, or equal, tendency is shown from oil or brine to spread over the surface of the rock, the system is said to have neutral wettability or intermediate wettability.
2. Because different mineralogies coexist in an oil reservoir, different wettabilities are also expected. If this variety in the reservoir is not negligible, then, in different parts of the reservoir, different chemical interactions between fluids and rocks are observed and, consequently, some areas of the reservoir indicate strongly water-wet behavior whereas some other areas indicate strongly oil-wet behavior. This heterogeneous wettability behavior is known as fractional wettability.
3. In some cases, the smaller pores are occupied by water and can be considered water-wet, while larger pores are captured by oil. This type of wettability distribution is known as mixed wettability, in which the residual oil saturation is low because the oil is displaced more easily from larger pores....
A Study of Wettability-Alteration Methods With Nanomaterials Application
01 December 2015