In-situ gelation of silicates in drilling, well completion and oil production

Abstract

Silicate polymerization and gelation have been performed within subterranean formations to plug large cavities and reduce fluid flow capacity. Often during drilling a rock zone is encountered which produces a large amount of water or brine. This fluid dilutes the drilling fluid, greatly reducing its effectiveness. Conversely, large volumes of expensive drilling fluid can flow into a high permeability “thief zone”. A solution to these problems is to inject a carefully designed silicate solution which gels in a controlled fashion. This forms an impermeable plug, greatly reducing fluid flow into or from the problem zone. Similar processes are used to reduce the undesirable flow of water into producing oil wells. Silicate systems with longer gelation times are also used to plug high-permeability zones in injection wells so water or other injection fluids flow into other zones still containing appreciable oil saturations.