Sand consolidation methods

Abstract

Methods are provided for selectively consolidating naturally occurring mineral grains such as sand grains within a subterranean formation to form a fluid permeable barrier, which restrains the movement of said particles when oil passes through the barrier. When applied to formations in which at least a portion of the sand grains are coated with a viscous oily residue of crude oil, or where the pore spaces between the sand grains contain excessive quantities of water, either of which interfere with the polymerization of the polymerizable monomer employed for said consolidation, a preflush is utilized which functions both to remove the oily residue from the said grains and to remove water from the pore spaces of the formation adjacent to the wellbore. the preflush is preferably an ester such as ethyl acetate or butyl acetate in an amount sufficient to occupy substantially all of the pore space of the formation into which the polymerizable component employed for sand consolidation are subsequently injected. In one preferred embodiment and acid catalyst such as sulfuric acid is added to the preflush. After injection of the preflush, the sand consolidation fluid usually containing a monomer or oligomer of furfuryl alcohol is injected, either mixed with steam to form a mulitphase treating fluid or injected as a liquid phase into the formation.