Altering Wettability of Carbonate Rock by In Situ Coating of Functional Nanoparticles at Harsh Reservoir Conditions for Reducing Condensation

Extraction of hydrocarbons, such as natural gas, may be impeded by a variety of reasons, such as condensate formation in the subsurface formation. Pressure gradients near the well bore of producers often lead to the formation of condensate banks, which subsequently hinder gas production by reducing gas permeability in gas-condensate wells. Research suggests that wettability is a crucial factor in condensate accumulation. Altering the wettability of the rock from liquid-wetting to intermediate gas-wetting can greatly enhance mobility of the liquid phase in a gas–liquid system, thereby significantly improving gas well deliverability in a gas condensate reservoir.<br/>In this research, we report a novel wettability alteration method for reducing condensate utilizing functionalized silica nanoparticles in situ formed and assembled to the surface of subsurface formation in extreme reservoir condition at high temperature and high salinity. The process includes introducing a reactive mixture including an aqueous solution, urea, dopamine, a silica nanoparticle precursor, a silane grafting compound, and an alcohol compound into the subsurface formation. Ammonia is generated in situ through thermal decomposition of the urea, which catalyzes the silica nanoparticle precursor to hydrolyze for forming silica nanoparticles. Polymerization of the dopamine at reservoir temperature could enhance the adhesion of nanoparticles on carbonate rock, and meanwhile silane coupling molecules are grafted onto the silica nanoparticles, thereby forming functionalized silica nanoparticles. The functionalized silica nanoparticles are hydrophobic, oleophobic, or both, and the assembled and aggregated nanoparticles on rock can decrease the surface tension of the subsurface formation, resulting increase of relative permeability and decrease of condensate banking at the wellbore.