Fracturing fluids for delayed flow back operations
View Patent ↗It has been discovered that certain fracturing fluid compositions can be used to fracture a subterranean formation and be permitted to stay within the formation for a relatively extended period of time, for example 28 days or more, before being flowed back or produced. At least two embodiments are envisioned, a bacteria-containing formulation and an anti-bacterial formulation. Both systems would be expected to prevent the potential of the fluid to oil wet the formulation (water block condition) by keeping the formation water wet through the use of water wetting surfactants or solvents. Additionally, both formulations would control reservoir crude souring (H 2 S generation by in situ sulfate-reducing bacteria), reservoir plugging (via slime biopolymers generated by in situ microbes, inorganic scale deposition like calcium carbonate or barium sulfate, and clay fines migration).
1. A method for fracturing a subterranean formation comprising:
a. pumping an anti-bacterial fracturing fluid composition down a wellbore to a subterranean formation;
b. permitting the fracturing fluid composition to gel;
c. pumping the fracturing fluid composition against the subterranean formation at sufficient rate and pressure to fracture the formation;
d. breaking the fracturing fluid composition gel;
e. leaving the fracturing fluid composition in the formation for at least 28 days; and
f. subsequently flowing the fracturing fluid composition out of the formation;
where the anti-bacterial fracturing fluid composition comprises:
i) at least one hydratable polymer;
ii) at least one water wetting control agent;
iii) at least one clay control agent;
iv) at least one microbe growth control agent;
v) at least one scale inhibitor;
vi) at least one breaking agent; and
vii) at least one biocide different from iv) the microbe growth control agent;
where the anti-bacterial fracturing fluid composition controls both sulfate-reducing bacteria and bio-polysaccharide (slime) production.
2. The method of claim 1 where in the fracturing fluid composition there is an absence of components that contain sulfur, except for sulphonates.
3. The method of claim 1 where the fracturing fluid composition further comprises a crosslinking agent.
4. The method of claim 3 where in the fracturing fluid composition the hydratable polymer is guar and where the crosslinking agent is borate ion.
5. A method for fracturing a subterranean formation comprising:
a. pumping an anti-bacterial fracturing fluid composition down a wellbore to a subterranean formation;
b. permitting the fracturing fluid composition to gel;
c. pumping the fracturing fluid composition against the subterranean formation at sufficient rate and pressure to fracture the formation;
d. breaking the fracturing fluid composition gel;
e. leaving the fracturing fluid composition in the formation for at least 28 days; and
f. subsequently flowing the fracturing fluid composition out of the formation;
where the anti-bacterial fracturing fluid composition comprises:
i) from about 0.12 to about 0.75% bw of at least one hydratable polymer;
ii) from about 0.05 to about 3.0% bv of at least one water wetting control agent;
iii) from about 0.5 to about 12.0% bw of at least one clay control agent;
iv) from about 0.001 to about 2.0% bw of at least one microbe growth control agent;
v) from about 0.05 to about 1.0% bv of at least one scale inhibitor;
vi) from about 0.0001 to about 0.72% bw of at least one breaking agent;
vii) at least one crosslinking agent; and
vii) from about 0.001 to about 1.0% bv of at least one biocide different from iv) the microbe growth control agent;
where the anti-bacterial fracturing fluid composition controls both sulfate-reducing bacteria and bio-polysaccharide (slime) production, and where all proportions are based on the total fracturing fluid composition.
6. The method of claim 5 where in the fracturing fluid composition there is an absence of components that contain sulfur, except for sulphonates.
7. The method of claim 5 where in the fracturing fluid composition the hydratable polymer is guar and where the crosslinking agent is borate ion.
8. A method for fracturing a subterranean formation comprising:
a. pumping a bacterial fracturing fluid composition down a wellbore to a subterranean formation;
b. permitting the fracturing fluid composition to gel;
c. pumping the fracturing fluid composition against the subterranean formation at sufficient rate and pressure to fracture the formation;
d. breaking the fracturing fluid composition gel;
e. leaving the fracturing fluid composition in the formation for at least 28 days; and
f. subsequently flowing the fracturing fluid composition out of the formation;
where the bacterial fracturing fluid composition comprises:
i) at least one polysaccharide hydratable polymer;
ii) at least one water wetting control agent;
iii) at least one clay control agent;
iv) at least one microbe growth control agent;
v) at least one scale inhibitor;
vi) at least one breaking agent; and
vi) at least one polysaccharide-decomposing bacteria.
9. A method for fracturing a subterranean formation comprising:
a. pumping a bacterial fracturing fluid composition down a wellbore to a subterranean formation;
b. permitting the fracturing fluid composition to gel;
c. pumping the fracturing fluid composition against the subterranean formation at sufficient rate and pressure to fracture the formation;
d. breaking the fracturing fluid composition gel;
e. leaving the fracturing fluid composition in the formation for at least 28 days; and
f. subsequently flowing the fracturing fluid composition out of the formation;
where the bacterial fracturing fluid composition comprises:
i) from about 0.12 to about 0.75% bw of at least one polysaccharide hydratable polymer;
ii) from about 0.05 to about 3.0% bv of at least one water wetting control agent;
iii) from about 0.5 to about 12.0% bw of at least one clay control agent;
iv) from about 0.001 to about 2.0% bw of at least one microbe growth control agent;
v) from about 0.05 to about 1.0% bv of at least one scale inhibitor;
vi) from about 0.0001 to about 0.72% bw of at least one breaking agent;
vii) at least one crosslinking agent; and
viii) at least one polysaccharide-decomposing bacteria;
where all proportions are based on the total fracturing fluid composition.