Appeal No. 2005-2446 Page 4
Application No. 09/951,099
Claims 1-3 and 7 are representative of the subject matter on appeal:
1. A method of fracturing a subterranean formation which surrounds a well bore,
comprising the steps of:
(a) providing a fracturing fluid comprising (i) an aqueous liquid; (ii) a
polysaccharide soluble or dispersible in said aqueous liquid in an amount sufficient to
increase the viscosity of said aqueous liquid; (iii) an enzyme breaker which degrades
said polysaccharide; and (iv) a compound according to Formula I in an amount sufficient
to reduce the polysaccharide-degrading activity of said enzyme breaker;
wherein:
R1 is selected from the group consisting of: -F, -NR3R4 wherein R3 and R4 are
each independently selected from the group consisting of H, loweralkyl,
R2 is selected from the group consisting of –H and –OH; and
n is 0 to 3;
then;
(b) injecting said fracturing fluid into said well bore at a pressure sufficient to form
fractures in the subterranean formation which surrounds said well bore; then
(c) reducing the pH of said fracturing fluid by an amount sufficient to increase the
polysaccharide-degrading activity of said enzyme; and then
(d) releasing the pressure from said fracturing fluid.
2. A method according to claim 1, wherein said enzyme is a ß-mannanase.
3. A method according to claim 1, wherein said enzyme is a ß-glucosidase.
7. A method according to claim 1, wherein said compound of Formula I is
2-amino-2-hydroxymethyl-1,3-propanediol.
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