US 5,211,233 AGranted

Consolidation agent and method

AssigneeMobil Oil Corporation

InventorPaul Shu

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Abstract

A sand consolidating method is provided for use in a borehole within an unconsolidated or loosely consolidated oil or gas reservoir which is likely to introduce substantial amounts of sand into the borehole and cause caving. After perforating the borehole's casing at an interval of the formation where sand will be produced, an aqueous silicate solution is injected into said interval. Next, a spacer volume of a water-immiscible hydrocarbonaceous liquid is introduced into the interval. Thereafter, a water-miscible organic solvent containing an alkylpolysilicate and inorganic salt or chelated calcium is injected into the interval. A permeability retentive silicate cement is formed in the interval. Injection of the aqueous silicate and organic solvent is continued until the interval has been consolidated by the silicate cement to an extent sufficient to prevent sand migration and thereby prevent caving.

Claims29

Dependent claims

A sand consolidating method for an unconsolidated or loosely consolidated formation comprising:

a) perforating a cased borehole at an interval expected to produce fines or sand when producing hydrocarbonaceous fluids from said interval;
b) injecting an aqueous solution of a silicate into said interval through perforations contained in the borehole which solution is of a strength sufficient to react with a water-miscible organic solvent containing an alkylpolysilicate and a member of the group consisting of an inorganic salt or chelated calcium thereby forming a permeability retentive cement where said silicate is selected from a member of the group consisting of alkali metal silicate, organoammonium silicate, or ammonium silicate;
c) injecting thereafter a spacer volume of a water-immiscible hydrocarbonaceous liquid into said zone;
and
d) injecting thereafter a water-miscible organic solvent containing an alkylpolysilicate and said group member into said interval in an amount sufficient to react with the aqueous silicate so as to form a silicate cement with permeability retentive characteristics whereupon the interval is consolidated in a manner sufficient to prevent formation sand from being produced from the formation during the production of hydrocarbonaceous fluids.

2 more elements

A sand consolidating method for an unconsolidated or loosely consolidated formation comprising:

(a) perforating a cased borehole at an interval expected to produce fines or sand when producing hydrocarbonaceous fluids from said interval;
(b) injecting an aqueous solution of a silicate into said interval through perforations contained in the borehole which solution is of a strength sufficient to react with a water-miscible organic solvent containing an alkylpolysilicate and a member of the group consisting of an inorganic salt or chelated calcium thereby forming a permeability retentive cement where said silicate is selected from a member of the group consisting of alkali metal silicate, organoammonium silicate, or ammonium silicate;
c) injecting thereafter a spacer volume of a water-immiscible hydrocarbonaceous liquid into said zone in an amount sufficient to remove excess silicate therefrom;
and
d) injecting next a water-miscible organic solvent containing an alkylpolysilicate and said group member into said interval via the perforations in an amount sufficient to react with the aqueous silicate so as to form a silicate cement with permeability retentive characteristics whereupon the interval is consolidated in a manner sufficient to prevent formation sand from being produced from the formation during the production of hydrocarbonaceous fluids, which solvent is selected from a member of the group consisting of methanol, ethanol, higher alcohols, glycols, ketones, tetrahydrofuran, and dimethyl sulfoxide.

2 more elements

Dependencies are inferred from the claim text.