Foam fracturing fluid with double interface layers of a phlogisticated air-liquid CO2 for shale gas production and preparation method thereof

Patent metadata

Field	Value
Publication number	US-10934467-B2
Application number	US-202016735553-A
Country	US
Kind code	B2
Filing date	Jan 6, 2020
Priority date	Jan 10, 2019
Publication date	Mar 2, 2021
Grant date	Mar 2, 2021

Abstract

The disclosure discloses a foam fracturing fluid with double interface layers of a phlogisticated air-liquid CO2 for shale gas development, and a preparation method thereof. The foam fracturing fluid is prepared from a liquid CO2 phase, a gas phase and a nano-enhancer; the liquid CO2 phase is formed by dissolving a mixture of gas-soluble foaming agents in liquid CO2; the gas phase is a gas mixture of phlogisticated air and saturated vapor of the liquid CO2; the nano-enhancer is an aqueous solution of a mixture of hydrophobic silica nanoparticles, a cosolvent and a water-soluble surfactant. In the fracturing fluid prepared by the present disclosure, the phlogisticated air was encapsulated by the liquid CO2 to form an interface layer, the liquid CO2 was further encapsulated by the nano-enhancer to form the other interface layer, which enhanced the structural stability of the fracturing fluid while achieving high viscosity and thermal stability.

First claim

What is claimed is:

1. A foam fracturing fluid with double interface layers of a phlogisticated air-liquid CO 2 , wherein, the foam fracturing fluid is prepared from a liquid CO 2 phase, a gas phase and a nano-enhancer; wherein, the phlogisticated air is air with a content of oxygen being ≤5% by volume; the double interface layers of the foam fracturing fluid refers to an interface layer formed by encapsulating the phlogisticated air with the liquid CO 2 and the other interface layer formed by encapsulating the liquid CO 2 with the nano-enhancer;
the liquid CO 2 phase is formed by dissolving a mixture of gas-soluble foaming agents in liquid CO 2 ;
the mixture of gas-soluble foaming agents is a mixture comprising at least two of 2-trifluoromethane-3-methoxydecafluoropentane, 3-ethoxytridecafluorohexane, fluorobutane ethyl ether, fluorobutane methyl ether and 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether;
an initial volume concentration of the mixture of gas-soluble foaming agents in the liquid CO 2 phase is 0.2% to 2.0% by volume;
the gas phase is a gas mixture of phlogisticated air and saturated vapor of the liquid CO 2 ;
the nano-enhancer is an aqueous solution of hydrophobic silica nanoparticles, a cosolvent and a mixture of water-soluble surfactants; wherein, the cosolvent is a solvent that solubilizes the hydrophobic silica nanoparticles;
the hydrophobic silica nanoparticles are modified by silanol groups, and a density of the silanol groups is 0.3 to 0.5/nm 2 , a wetting angle of the hydrophobic silica nanoparticles to distilled water is 107° C.˜125° C., a particle size of the hydrophobic silica nanoparticles is 10˜40 nm;
the cosolvent is ethanol, ethylene glycol or isopropanol;
the mixture of water-soluble surfactants is a mixture of sodium bis(2-ethylhexyl) sulfosuccinate and sodium α-sulfofatty acid methyl ester.

2. The foam fracturing fluid according to claim 1 , wherein foam quality of the foam fracturing fluid is 40% to 90%; wherein, the foam quality refers to a percentage of a volume of the gas phase of the foam fracturing fluid to a total volume of the foam fracturing fluid.

3. The foam fracturing fluid according to claim 1 , wherein
in the gas phase, a gas partial pressure of the phlogisticated air is at least one time as that of the saturated vapor of liquid CO 2 .

4. The foam fracturing fluid according to claim 1 , wherein the nano-enhancer is composed by the hydrophobic silica nanoparticles with a concentration of 0.4%˜2.0% by weight, the cosolvent with a concentration of 0.1%˜0.5% by weight, the mixture of water-soluble surfactants with a concentration of 0.1%˜0.6% by weight, and the balance of water.

5. The foam fracturing fluid according to claim 3 , wherein the nano-enhancer is composed by the hydrophobic silica nanoparticles with a concentration of 0.4%˜2.0% by weight, the cosolvent with a concentration of 0.1%˜0.5% by weight, the mixture of water-soluble surfactants with a concentration of 0.1%˜0.6% by weight, and the balance of water.

6. The foam fracturing fluid according to claim 1 , wherein in the foam fracturing fluid, the content of the nano-enhancer is ≤9% by volume.

7. The foam fracturing fluid according to claim 3 , wherein in the foam fracturing fluid, the content of the nano-enhancer is ≤9% by volume.

8. The foam fracturing fluid according to claim 4 , wherein in the foam fracturing fluid, the content of the nano-enhancer is ≤9% by volume.

9. The foam fracturing fluid according to claim 5 , wherein in the foam fracturing fluid, the content of the nano-enhancer is ≤9% by volume.

10. A preparation method of the foam fracturing fluid according to claim 1 , comprising the following steps:
1) preparing the aqueous solution of the hydrophobic silica nanoparticles, the cosolvent and the mixture of water-soluble surfactants so as to obtain the nano-enhancer;
2) injecting the nano-enhancer into a high-pressure agitated autoclave, and then injecting the phlogisticated air to a predetermined pressure;
3) while CO 2 gas is injected into the high-pressure agitated autoclave by a booster pump, injecting the mixture of gas-soluble foaming agents, after stirring, the foam fracturing fluid is obtained.

11. The preparation method according to claim 10 , wherein the predetermined pressure is 7˜50 MPa;
wherein a Waring Blender method is utilized for stirring, and the stirring is performed for 3 to 8 minutes at a speed of 3000 to 5000 rpm.

Assignees

• China Univ Of Petroleum—Beijing
• Univ China Petroleum Beijing

Inventors

• Lv Qichao
• Zhou Tongke
• Zheng Rong
• Dong Zhaoxia
• Zheng Haimin
• Zhang Juan
• Lin Meiqin
• Yang Zihao
• Wang Jingxue

Classifications

• B01F23/235

  for making foam · CPC title

• B01F23/2319

  Methods of introducing gases into liquid media · CPC title

• C09K8/703 Primary

  Foams · CPC title

• C09K8/38 Primary

  Gaseous or foamed well-drilling compositions · CPC title

• C09K2208/10

  Nanoparticle-containing well treatment fluids · CPC title