阅读说明：本技术 使瓜尔胶/硼酸盐体系在高压下的粘度降低最小化的添加剂 (Additives to minimize viscosity reduction of guar/borate systems under high pressure ) 是由 梁枫 加伊桑·阿勒-蒙塔什里 阿卜杜勒拉曼·F·阿尔哈比 于 2018-03-01 设计创作，主要内容包括：一种用作压裂液中的耐压双交联剂凝胶的组合物,该组合物包含：聚合物,该聚合物能够提高流体的粘度；含硼交联剂,该含硼交联剂能够交联聚合物；以及过渡金属氧化物添加剂,该过渡金属氧化物添加剂能够交联聚合物。(A composition for use as a pressure resistant dual crosslinker gel in a fracturing fluid, the composition comprising: a polymer capable of increasing the viscosity of the fluid; a boron-containing crosslinking agent capable of crosslinking the polymer; and a transition metal oxide additive capable of crosslinking the polymer.)

1. A composition for forming a pressure resistant dual crosslinker gel in a fracturing fluid, the composition comprising:

a polymer;

a boron-containing crosslinking agent; and

an additive of a transition metal oxide, wherein,

wherein the boron-containing crosslinker and the transition metal oxide additive are capable of crosslinking the polymer to form the pressure resistant dual crosslinker gel.

2. The composition of claim 1, wherein the concentration of the polymer is between 12pptg and 100 pptg.

3. The composition of claim 1 or claim 2, wherein the polymer is selected from the group consisting of: guar gum, guar derivatives, polyvinyl alcohol, mannose containing compounds, and combinations thereof.

4. The composition of any of claims 1-3, wherein the concentration of the boron-containing crosslinker is between 0.002 and 2 wt% of the fracturing fluid.

5. The composition of any one of claims 1 to 4, wherein the boron-containing crosslinker is selected from the group consisting of: borates, boric acid, and combinations thereof.

6. The composition of claim 5, wherein the boron-containing crosslinker comprises a borate selected from the group consisting of: sodium borate, sodium pentaborate, sodium tetraborate, calcium borate, magnesium borate, and combinations thereof.

7. The composition of any one of claims 1 to 6, wherein the concentration of the transition metal oxide additive is between 0.0002 wt% and 2 wt% of the fracturing fluid.

8. The composition of any one of claims 1 to 7, wherein the transition metal oxide additive is selected from the group consisting of: transition metal oxide nanoparticles, transition metal oxide nanoparticle dispersions, polymer material stabilized transition metal oxides, transition metal oxide nanoparticles with other metal nanoparticles, and metal organic polyhedra containing transition metal oxides.

9. The composition of claim 8, wherein the transition metal oxide additive comprises transition metal oxide nanoparticles selected from the group consisting of: zirconia nanoparticles, titania nanoparticles, ceria nanoparticles, and combinations thereof.

10. The composition of any one of claims 1 to 9, wherein the polymer comprises guar gum, the boron-containing crosslinker comprises sodium borate, and the transition metal oxide additive comprises CeO₂And (3) nanoparticles.

11. The composition of any one of claims 1 to 10, wherein the transition metal oxide additive has a diameter in a range between 5nm and 100 nm.

12. A composition for use in a hydraulic fracturing process, the composition comprising:

a pressure-resistant fluid, the pressure-resistant fluid comprising:

a pressure resistant dual crosslinker gel comprising:

a polymer,

a boron-containing crosslinking agent, and

an additive of a transition metal oxide, wherein,

wherein the boron-containing crosslinker and the transition metal oxide additive are capable of crosslinking the polymer; and

a fracturing fluid, wherein the pressure resistant dual crosslinker gel is capable of viscosifying the fracturing fluid to produce the pressure resistant fluid,

wherein the viscosity of the pressure resistant fluid is greater than 150cP at a pressure of 8000psi at 150 degrees Fahrenheit.

13. The composition of claim 12, wherein the concentration of polymer is between 15pptg and 100 pptg.

14. The composition of claim 12 or claim 13, wherein the polymer is selected from the group consisting of: guar gum, guar derivatives, polyvinyl alcohol, mannose containing compounds, and combinations thereof.

15. The composition of any of claims 12-14, wherein the concentration of the boron-containing crosslinker is from 0.002 wt.% to 2 wt.% of the pressure-resistant fluid.

16. The composition of any one of claims 12 to 15, wherein the boron-containing crosslinker is selected from the group consisting of: sodium borate, sodium pentaborate, sodium tetraborate, and combinations thereof.

17. The composition of any one of claims 12 to 16, wherein the concentration of the transition metal oxide additive is between 0.0002 wt% of the fracturing fluid and 2 wt% of the fracturing fluid.

18. The composition of any one of claims 12 to 17, wherein the transition metal oxide additive is selected from the group consisting of: transition metal oxide nanoparticles, transition metal oxide nanoparticle dispersions, polymer material stabilized transition metal oxides, transition metal oxide nanoparticles with other metal nanoparticles, and metal organic polyhedra containing transition metal oxides.

19. The composition of claim 18, wherein the transition metal oxide additive comprises transition metal oxide nanoparticles selected from the group consisting of: zirconia nanoparticles, titania nanoparticles, ceria nanoparticles, and combinations thereof.

20. The composition of any one of claims 12 to 17, wherein the transition metal oxide additive comprises cerium oxide nanoparticles at a concentration of 0.02 wt% of the fracturing fluid.

21. The composition of any one of claims 12 to 20, further comprising a proppant.

22. The composition of any one of claims 12 to 21, wherein the fracturing fluid is an aqueous-based fracturing fluid.

23. The composition of any one of claims 12 to 22, wherein the transition metal oxide additive has a diameter in a range between 5nm and 100 nm.

Technical Field

Compositions and methods related to hydraulic fracturing are disclosed. In particular, compositions and methods for stabilizing guar/borate crosslinked gels are disclosed.

Background

Guar gum is a high molecular weight, water-soluble galactomannan polysaccharide used in hydraulic fracturing processes. As with all hydraulic fracturing fluids, guar-based fluids need to maintain sufficient viscosity to prevent proppant settling and to ensure proppant transport into the fracture. To achieve the desired viscosification of the fracturing fluid while minimizing the amount of guar, cross-linking agents such as borax may be used to cross-link the guar molecules. These guar/borate crosslinking fluids may be pumped at a pressure sufficient to fracture the rock of the formation, thereby enabling the proppant and gel mixture to penetrate into the fracture. Conventional guar/borate crosslinked fluids may be used in hydraulic fracturing processes at temperatures in the range of 100 degrees fahrenheit (37.8 degrees celsius (° c)) to 300 degrees fahrenheit (148.9 ℃). However, the viscosity of guar/borate crosslinked fluids can exhibit a reversible response to a variety of effects including mechanical shear, pH, and temperature. In addition, these fluids lose viscosity during pressure increases. At pressures greater than 2500psi, the viscosity of the guar/borate crosslinked fluid will decrease due to some or all of the viscosity loss caused by the crosslinking agent. It will be appreciated that as the pressure is increased, the crosslinking between the cis-hydroxy group and the borate will proceed in reverse, resulting in a decrease in viscosity. The viscosity reduction occurs almost immediately after the pressure increase.

One way to minimize the pressure response of guar/borate crosslinked fluids is to use high polymer loading guar-based polymers. Another option to minimize the pressure response of guar/borate crosslinked fluids is to use high doses of crosslinking agents. However, these options can result in an initial viscosity that causes excessive friction during pumping of the fracturing fluid and can result in gels that are difficult to break after the hydraulic fracturing is complete. Both of these options result in increased costs of the fracturing fluid.

Disclosure of Invention

Compositions and methods related to hydraulic fracturing are disclosed. In particular, compositions and methods for stabilizing guar/borate crosslinked gels are disclosed.

In a first aspect, a composition for forming a pressure resistant dual crosslinker gel in a fracturing fluid is provided. The composition includes a polymer capable of increasing the viscosity of the fracturing fluid, a boron-containing crosslinking agent, and a transition metal oxide additive, wherein both the boron-containing crosslinking agent and the transition metal oxide additive are capable of crosslinking the polymer.

In certain aspects, the concentration of polymer is between 15 pounds per thousand gallons (pptg) and 100 pptg. In certain aspects, the polymer is selected from the group consisting of: guar gum, guar derivatives, polyvinyl alcohol, mannose containing compounds, and combinations thereof. In certain aspects, the concentration of boron-containing crosslinker is between 0.002 and 2 wt.% of the fracturing fluid. In certain aspects, the boron-containing crosslinker is selected from the group consisting of: boron salts, boric acid, and combinations thereof. In certain aspects, the boron-containing crosslinker is a boron salt selected from the group consisting of: sodium borate, sodium pentaborate, sodium tetraborate, calcium borate, magnesium borate, and combinations thereof. In certain aspects, the concentration of the transition metal oxide additive is between 0.0002 weight percent (wt%) and 2 wt% of the fracturing fluid. In certain aspects, the transition metal oxide is selected from the group consisting of: transition metal oxide nanoparticles, transition metal oxide nanoparticle dispersions, polymer material stabilized transition metal oxides, transition metal oxide nanoparticles with other metal nanoparticles, and metal organic polyhedra containing transition metal oxides. In certain aspects, the transition metal oxide additive comprises transition metal oxide nanoparticles selected from the group consisting of: zirconia nanoparticles, titania nanoparticles, ceria nanoparticles, and combinations thereof. In some aspectsIn one aspect, the transition metal oxide additive comprises a dispersion of zirconia nanoparticles at a concentration of 0.04 wt% of the fracturing fluid. In certain aspects, the transition metal oxide additive comprises a titanium oxide nanoparticle dispersion at a concentration of 0.12 wt% of the fracturing fluid. In certain aspects, the transition metal oxide additive comprises a cerium oxide nanoparticle dispersion at a concentration of 0.02 wt% of the fracturing fluid. In certain aspects, the polymer comprises guar gum, the boron-containing crosslinker comprises sodium borate, and the transition metal oxide comprises CeO₂And (3) nanoparticles. In certain aspects, the transition metal oxide additive has a diameter in a range between 5nm and 100 nm.

In a second aspect, a composition for a pressure resistant fluid for use in a hydraulic fracturing process is provided. The composition comprises a pressure resistant fluid. The pressure resistant fluid comprises a pressure resistant dual crosslinker gel and a fracturing fluid. The pressure resistant dual crosslinker gel comprises a polymer, a boron-containing crosslinker capable of crosslinking the polymer, and a transition metal oxide additive capable of crosslinking the polymer. The pressure resistant dual crosslinker gel is capable of viscosifying the fracturing fluid to produce a pressure resistant fluid.

In certain aspects, the pressure-resistant fluid comprises a proppant. In certain aspects, the fracturing fluid is a water-based fracturing fluid.

Drawings

These and other features, aspects, and advantages of the scope of the present invention will become better understood with regard to the following description, appended claims, and accompanying drawings. It is to be noted, however, that the appended drawings illustrate only a few embodiments and are therefore not to be considered limiting of its scope, for the scope of the invention may admit to other equally effective embodiments.

Fig. 1 provides a flow chart of a modified Anton Parr rheometer for introducing viscous fluid into a pressure chamber.

FIG. 2 shows the viscosity (at 10/sec(s) of a crosslinked 30pptg guar/borate crosslinking fluid at 150 degrees Fahrenheit with pressure change^-1) In cP) response.

FIG. 3 shows cerium oxide (CeO)₂) The pressure-resistant double-crosslinking agent gel of the nano particles is 150 bloomViscosity in degrees of Vickers under pressure change (at 10 s)^-1In cP) response.

FIG. 4 shows fluid 1A (without nanoparticles) and fluid 1B (with 0.02 wt% CeO) of example 1₂Dispersion) viscosity response.

FIG. 5 shows fluids 1A (without nanoparticles), 1B (with 0.02 wt.% CeO) of example 1₂Dispersion), fluid 1C (with 0.04 wt% CeO)₂Dispersion) and fluid 1D (with 0.08 wt% CeO)₂Dispersion) viscosity response.

FIG. 6 shows a composition having 30pptg guar and CeO in the absence of a boron-containing crosslinker₂Comparison of viscosity curves of fluids of dispersions.

FIG. 7 shows fluids 2A (without nanoparticles), 2B (with 0.02 wt.% zirconium dioxide (ZrO) of example 2₂) Dispersion) and fluid 2C (with 4 wt% ZrO)₂Dispersion) viscosity response.

FIG. 8 shows a composition having 30pptg guar and ZrO in the absence of boron-containing crosslinkers₂Comparison of viscosity curves of fluids of dispersions.

FIG. 9 shows fluid 3A (without nanoparticles), fluid 3B (with 0.02 wt% titanium oxide (TiO) of example 3₂) Dispersion) and fluid 3C (with 0.12 wt% TiO)₂Dispersion) viscosity response.

FIG. 10 shows guar gum and TiO at 30pptg in the absence of boron-containing crosslinker₂Comparison of viscosity curves of fluids of dispersions.

Detailed Description

While the scope of the present invention will be described in conjunction with several embodiments, it is to be understood that one of ordinary skill in the relevant art will appreciate that many examples, variations and modifications of the apparatus and methods described herein are within the scope of the present invention. Accordingly, the described embodiments are set forth without a loss of generality to, and without imposing limitations upon, the embodiments. It will be appreciated by a person skilled in the art that the scope of the present invention includes all possible combinations and uses of the specific features described in the specification.

Described herein are compositions and methods of pressure resistant dual crosslinker gels that can be used in hydraulic fracturing processes. Advantageously, the pressure resistant dual crosslinker gel exhibits reduced viscosity reversibility over the entire pressure range of the downhole environment. Advantageously, because the viscosity of the pressure resistant bis-crosslinker gel is in a similar range as conventional polymer/borate systems, the frictional pressure does not increase and the same pumping system supplying conventional guar/borate crosslinking fluids can be used to deliver the pressure resistant bis-crosslinker gel.

As used throughout, "pressure resistant dual crosslinker gel" refers to a gel produced by: crosslinking the borate crosslinkable polymer containing the boron-containing crosslinking agent and the transition metal oxide nanoparticle additive allows the gel to experience viscosity fluctuations due to pressure changes, but the gel is less sensitive to pressure changes than conventional polymer/borate systems in the absence of the transition metal oxide nanoparticle additive.

As used throughout, "cis-hydroxy group" refers to a compound having a 1, 2-diol in which the hydroxy group (-OH) is in cis geometry (e.g., mannose) in, for example, a cyclic sugar molecule, or which may form cis geometry when bonded to boron or a transition metal (e.g., polyvinyl alcohol).

As used throughout, "metal-organic polyhedra" refers to a hybrid type of solid crystalline material that is constructed from highly modular, pre-designed Molecular Building Blocks (MBBs) assembled in situ into discrete structures (0-D) containing clusters of polyvalent metal nodes.

As used throughout, "absent" means that the composition or method is excluded, or absent.

As used throughout, "ligand" refers to an ion or molecule that binds to a central metal atom to form a coordination complex.

The pressure resistant dual crosslinker gel may comprise a polymer, a boron-containing crosslinker, and a transition metal oxide additive. The pressure resistant dual crosslinker gel may be mixed with a fracturing fluid to produce a pressure resistant fluid.

The polymer may be any water-soluble polymer containing cis-hydroxyl groups. Examples of polymers containing cis hydroxyl groups may include guar, guar derivatives, polyvinyl alcohol, mannose containing compounds, and combinations thereof. The polymer content of the pressure resistant dual crosslinker gel may be between 12 pounds per thousand gallons (pptg) and 100 pptg. In at least one embodiment, the concentration of polymer is 30 pptg. In at least one embodiment, the polymer is guar gum. The polymer may be provided in the form of a powder, a liquid mixture or a liquid slurry.

The boron-containing crosslinking agent may be any compound containing boron capable of crosslinking with a cis-hydroxyl group. Examples of boron-containing crosslinkers can include borates, boric acid, and combinations thereof. Examples of boron salts include sodium borate, sodium pentaborate, sodium tetraborate (borax), calcium borate, magnesium borate, and combinations thereof. In at least one embodiment, the boron-containing crosslinking agent is sodium borate. The content of boron-containing crosslinker of the pressure resistant dual crosslinker gel may be between 0.002 and 2 wt.% of the pressure resistant fluid. The boron-containing crosslinking agent can crosslink the polymer to form a gel.

The transition metal oxide additive is a water-insoluble particulate compound. The transition metal oxide additive can be a metal oxide additive capable of crosslinking a polymer at a pressure between 2,500psi (17.24MPa) and 15,000psi (103.42 MPa). The transition metal oxide additive itself acts as a crosslinker and thus there is no separate crosslinker attached to its surface. Examples of transition metal oxide additives may include transition metal oxide nanoparticles, suspensions of transition metal oxide nanoparticles, polymeric material stabilized transition metal oxides, transition metal oxide nanoparticles with other metal nanoparticles, and metal organic polyhedra containing transition metal oxides.

Examples of the transition metal oxide nanoparticles may include zirconium dioxide (ZrO)₂) Nanoparticles, titanium dioxide (TiO)₂) Cerium oxide (CeO)₂) Nanoparticles and their useCombinations of (a) and (b).

The transition metal oxide nanoparticle dispersion can include transition metal oxide nanoparticles dispersed in an aqueous fluid. Examples of aqueous fluids may include water, glycols, ethers, and combinations thereof. Examples of the transition metal oxide nanoparticle dispersion may include ZrO₂Nanoparticle dispersion, TiO₂Nanoparticle dispersion, CeO₂Nanoparticle dispersions and combinations thereof. In at least one embodiment, the transition metal oxide may be added in the form of a transition metal oxide nanoparticle dispersion.

The polymeric material stabilized transition metal oxide may include a polyvinylpyrrolidone (PVP) stabilized transition metal oxide. Examples of PVP stabilized transition metal oxides include PVP stabilized ZrO₂Granular, PVP stabilized TiO₂Granular, PVP stabilized CeO₂And (3) granules.

The transition metal oxide nanoparticles "with other metal nanoparticles" may include a mixture of transition metal oxide nanoparticles and metal nanoparticles.

Examples of the metal-organic polyhedra include those containing ZrO₂Of a metal organic polyhedron containing TiO₂And a metal organic polyhedron containing CeO₂The metal organic polyhedra of (1).

The transition metal oxide additive may be nanoparticles having a diameter in a range between 5 nanometers (nm) and 100 nm. The smaller the particle size, the greater the surface area of the particular material. In at least one embodiment, the transition metal oxide additive has a diameter in a range between 5nm and 15 nm. In at least one embodiment, the transition metal oxide additive has a diameter in a range between 30nm and 50 nm. In at least one embodiment, the transition metal oxide additive has a diameter in a range between 45nm and 55 nm. In at least one embodiment, the transition metal oxide additive may include ZrO₂Nanoparticles, TiO₂Nanoparticles, CeO₂Nanoparticles, and combinations thereof. In at least one embodiment, the additive may be dried (e.g., an aggregate of particles)) A transition metal oxide additive is added.

In at least one embodiment, a transition metal oxide additive may be added to the well fracturing fluid. The concentration of the transition metal oxide additive may be between 0.0002 wt% and 2 wt% of the fracturing fluid. In at least one embodiment, the transition metal oxide additive is present at a concentration of 0.02 wt% of the fracturing fluid. In at least one embodiment, the transition metal oxide additive is present at a concentration of 0.04 wt% of the fracturing fluid. In at least one embodiment, the transition metal oxide additive is present at a concentration of 0.06 wt% of the fracturing fluid. In at least one embodiment, the transition metal oxide additive is present at a concentration of 0.08 wt% of the fracturing fluid. In at least one embodiment, the transition metal oxide additive is present at a concentration of 0.1 wt% of the fracturing fluid. In at least one embodiment, the transition metal oxide additive is present at a concentration of 0.12 wt% of the fracturing fluid.

The boron-containing crosslinking agent can crosslink cis hydroxyl groups of the polymer. In at least one embodiment, the cis hydroxyl groups of the polymer begin to crosslink upon addition of the boron-containing crosslinking agent. In at least one embodiment, the cis hydroxyl groups of the polymer begin to crosslink upon reaching the triggering pressure of the pressure-resistant fluid. Boric acid salts of boron-containing crosslinking agents boric acid (B (OH) may be used₃) Boric acid can be dissociated in water to produce borate anion (B (OH)4^-) And hydrogen ion (H)⁺). The crosslinking reaction occurs between the borate anion and the cis hydroxyl groups on the polymer. The reaction between the borate anion and the cis hydroxyl group occurs in 1 millisecond or less. It is understood that such short reaction times explain the rapid viscosity recovery of borate-crosslinked gels when subjected to shear rates. It is understood that a near-linear decrease in borate signal from borates with four attached organic groups indicates that subjecting the borate/cis hydroxyl to pressures greater than 2500psi can cause destruction of the B-O-C bond. This indicates that the process reverses somewhat when the pressure is reduced to less than 2500 psi. Without being bound by a particular theory, it is believed that under high pressure, the boron-containing crosslinking agent is released from the cis hydroxyl groups of the polymer,while the transition metal oxide additive may gradually crosslink with free hydroxyl groups to maintain crosslinking of the polymer. In at least one embodiment, the transition metal oxide additive is not a 1:1 ratio in place of the crosslinking of the boron-containing crosslinker, because the degree of reaction of boron with the cis hydroxyl groups is different from the degree of reaction of boron with the polymer. In at least one embodiment, the pressure resistant dual crosslinker gel is pH sensitive, as pH affects the crosslink density in the pressure resistant dual crosslinker gel, with higher pH resulting in greater crosslink density.

The fracturing fluid of the pressure fluid may be any water-based fracturing fluid that can be used for hydraulic fracturing. The pressure resistant fluid may comprise proppant. In at least one embodiment, the pressure resistant dual crosslinker gel may be mixed with a fracturing fluid at the wellsite such that a pressure resistant fluid is produced at the wellsite.

In at least one embodiment, the viscosity of the pressure resistant fluid (containing 0.1 wt% transition metal oxide additive in the fracturing fluid) is five times the fluid viscosity of a conventional polymer/borate system without transition metal oxide additive at 8000 psi.

The pressure resistant fluid may contain other additives such as surfactants, biocides, clay stabilizers, breakers, and gel stabilizers. The pressure resistant dual crosslinker gel does not contain boric acid. The pressure resistant dual crosslinker gel is free of silica nanoparticles, including functionalized silica nanoparticles. In at least one embodiment, the pressure resistant dual crosslinker gel is free of additional additives.

In at least one embodiment, the pressure resistant dual crosslinker gel comprises guar gum, sodium borate, and ZrO₂And (3) nanoparticles.

In at least one embodiment, the pressure resistant dual crosslinker gel comprises guar gum, sodium borate, and TiO₂And (3) nanoparticles.

In at least one embodiment, the pressure resistant dual crosslinker gel comprises guar gum, sodium borate, and CeO₂And (3) nanoparticles.

In at least one embodiment, the pressure resistant dual crosslinker gel is free of chelating agents or chelating ligands. In at least one embodiment, the pressure resistant dual crosslinker gel is free of transition metal complexes, which are water soluble complexes in which the transition metal is coordinated to a ligand that is different from the counterion.