Compositions and methods for reducing the permeability of underground strata

摘要

Compositions and methods are used for reducing the permeability of high fluid permeability segments of underground strata, the compositions being injected into the high permeability segments in liquid form and there gelled to reduce the permeability of the segments. A first group of compositions has a pH of at least 4 and comprises a sulfited derivative of a tannin extract together with furfural, formaldehyde or a formaldehyde derivative. The second group of compositions comprises furfural and a gellable vegetable material which can be a tannin extract, a sulfited derivative of a tannin extract, a catechin, an alkaline extract of a coniferous bark or a lignin or sulfonated lignin derivative.