Application of a water based nanofluid for wettability alteration of sandstone reservoir rocks to preferentially gas wetting condition

Abstract

Condensate and water banking around gas condensate wells result in vital well deliverability issues. Wettability alteration of near wellbore region to gas wetting condition is known to be the most novel and the only permanent method, to improve condensate well productivity. In this work, a water based nanofluid is used to change the wettability of sandstone reservoir rocks from strongly liquid wetting to intermediate gas wetting condition. Static contact angle measurements demonstrated significant increase of liquid phase contact angle as a result of chemical treatment with SurfaPore M nanofluid. The characteristics of SurfaPore M adsorption on sandstone rock are quantified through kinetic and equilibrium adsorption studies, as well as the stability of the used chemical against NaCl brine salinity in ambient condition,. Air/liquid spontaneous imbibition tests along with core flooding experiments were utilized to study the effect of wettability on two phase fluid flow through porous media. It has been concluded that kinetic behavior of SurfaPore M-sandstone system conforms pseudo-second order, while Freundlich isotherm matches the equilibrium adsorption data; these results eventuate multilayer chemisorption of NPs on sandstone surface. The results of spontaneous imbibition tests showed remarkable decrease of the ultimate amount of imbibed liquid by factors of 0.09 and 0.17 for n-decane and water, respectively. Also, the results of water injection experiments demonstrated the increase in liquid phase mobility by a factor of 3.2 as a result of surface modifiers in high permeability sandstone core plug. Furthermore, it is concluded that the utilized nanofluid is better to be used in high permeability sandstone rocks. The results of this research pave the way for possible future field applications of SurfaPore M nanofluid chemical in gas condensate reservoirs to alleviate production difficulties.