US 6,143,699 A · Process for reducing permeability in a subterranean formation

Abstract

A method is provided for blocking high permeability channels in subterranean geological formations, using swelling clay. A slurry is prepared by mixing swelling clay, such as bentonite, into an aqueous solution containing the salt of certain cations, which inhibit clay swelling. The cations K.sup.+, Ca.sup.2+ and Mg.sup.2+, among others, are inhibitive of clay swelling. The clay slurry is introduced into a geological formation, where it preferentially enters channels of high permeability. There the slurry is contacted by NaCl brine solution present in natural or injected drive fluids, and the inhibitive cations bound to the clay particles are replaced by Na.sup.+ ions, which attract water molecules and promote clay swelling. The Na.sup.+ -clay swells to up to 10 times its original volume, causing the slurry to acquire a gel-like consistency. The clay gel so formed is capable of blocking the flow of water, and can resist pressure of up to 500 kPa per meter.

Claims22

Dependent claims

A method for controlling the flow of at least one fluid in a subterranean formation having at least a first region, said first region having (i) at least Na.sup.+, and (ii) a first permeability, K.sub.1, with respect to said fluid, said method comprising:

(a) making an inhibitive electrolyte solution having water and at least one inhibitive compound, said inhibitive compound having at least one cation and anion;
(b) making a clay slurry by mixing at least about 20 weight percent of clay with said inhibitive electrolyte solution so that, to the extent clay gel is produced, if any, the flowability of said clay slurry is not substantially inhibited;
(c) injecting said clay slurry into said formation, so that at least a portion of said clay slurry contacts said first region having at least Na.sup.+ ;
(d) allowing a clay gel to form in said first region so that K.sub.1 is reduced to produce a lower permeability, K.sub.1L, with respect to said fluid;
and
(e) controlling the flow of at least a majority of said at least one fluid into or from said first region.

3 more elements

Dependencies are inferred from the claim text.

Process for reducing permeability in a subterranean formation

Life of this patent

Process for reducing permeability in a subterranean formation

Life of this patent

Abstract

Claims22