Ultra-dry three-phase flue gas foam for oil-gas fields and preparation method thereof

Abstract

The disclosure discloses an ultra-dry three-phase flue gas foam for oil-gas fields and preparation method thereof. The ultra-dry three-phase flue gas foam is produced by a gas phase, a liquid phase and a solid phase; the gas phase is a flue gas; the foaming solution is an aqueous solution of a surfactant, a pH adjuster, and an inorganic salt; the solid phase is a composite of fly ash and nano silica; the foam quality is 90%-99%. The solid phase foam stabilizer is a compounded system of fly ash particles and nano silica particles, which is not only low in cost but also can form a stable solid particle adsorption layer on the foam film. Thus the instability of the foam such as film rupture, gas diffusion and bubble aggregation can be greatly reduced, and the stability of the foam can be effectively improved.

Claims

1. An ultra-dry three-phase flue gas foam for oil-gas fields, which is produced by a gas phase, a liquid phase and a solid phase, wherein the gas phase is a flue gas produced by a coal-fired power plant; the liquid phase is an aqueous solution of a surfactant, a pH adjuster, and an inorganic salt; the surfactant is a mixture of sodium a-olefin sulfonate and sodium dodecylbenzene sulfonate; a mass ratio of the sodium a-olefin sulfonate to the sodium dodecylbenzene sulfonate is 1:4-5; a carbon atom number of the sodium -olefin sulfonate is 14 to 18; the solid phase is a mixture of fly ash and nano silica; a foam quality of the three-phase flue gas foam is 90%.

2. The ultra-dry three-phase flue gas foam for oil-gas fields according to claim 1, wherein the flue gas is subjected to desulfurization, denitration and deoxidation treatment; a total volume fraction of nitrogen and carbon dioxide in the flue gas is 90%.

3. The ultra-dry three-phase flue gas foam for oil-gas fields according to claim 1, wherein the pH adjuster is sodium bicarbonate, sodium carbonate or potassium carbonate; the inorganic salt is potassium chloride.

4. The ultra-dry three-phase flue gas foam for oil-gas fields according to claim 3, wherein the liquid phase is composed of the surfactant with a concentration of 0.1-0.5% by weight, the pH adjuster with a concentration of 0.025-0.085% by weight, the inorganic salt with a concentration of 0.5-2% by weight, and the balance of water.

5. The ultra-dry three-phase flue gas foam for oil-gas fields according to claim 1, wherein the liquid phase is composed of the surfactant with a concentration of 0.1-0.5% by weight, the pH adjuster with a concentration of 0.025-0.085% by weight, the inorganic salt with a concentration of 0.5-2% by weight, and the balance of water.

6. The ultra-dry three-phase flue gas foam for oil-gas fields according to claim 1, wherein in the three-phase flue gas foam for the oil-gas fields, a mass concentration ratio of the solid phase to the surfactant is 1.5-1.75:1.

7. The ultra-dry three-phase flue gas foam for oil-gas fields according to claim 1, wherein the fly ash is obtained by electrostatic capture of the coal-fired power plant.

8. The ultra-dry three-phase flue gas foam for oil-gas fields according to claim 1, wherein the fly ash is spherical, and an average particle diameter of the fly ash is 15 m; a particle diameter of the nano silica particles is 8-30 nm and a specific surface area is 100-300 m.sup.2/g; a wetting angle of surfaces of the nano silica particles to water is 30-65; a mass ratio of the fly ash to the nano silica particles is 8-9:1.

9. A method of preparing the ultra-dry three-phase flue gas foam for oil-gas fields according to claim 1, comprising the steps of: 1) taking a portion of the surfactant to prepare an aqueous surfactant solution; 2) adding the solid phase to the aqueous surfactant solution to obtain a first mixed liquid; 3) adding the remaining amount of the surfactant to the first mixed liquid to obtain a second mixed liquid; 4) adding the pH adjuster and the inorganic salt to the second mixed liquid to obtain a third mixed liquid; 5) simultaneously injecting the flue gas and the third mixed liquid into a foam generator, and after mixing, the ultra-dry three-phase flue gas foam for oil-gas fields is obtained; an injection speed of the flue gas is not less than 9 times of an injection speed of the third mixed liquid.

Description

DESCRIPTION OF THE EMBODIMENTS

(1) The experimental methods used in the following embodiments are conventional methods unless otherwise specified.

(2) The materials, reagents and the like used in the following embodiments are commercially available unless otherwise specified.

Embodiment 1: Ultra-Dry Three-Phase Flue Gas Foam for Oil-Gas Fields

(3) The raw materials comprise a gas phase, a liquid phase and a solid phase, and their specific components are as follows:

(4) the gas phase is the flue gas produced by the coal-fired power plant, and the flue gas has been subjected to desulfurization, denitrification and deoxidation processes, the total volume fraction of nitrogen and carbon dioxide in the flue gas is 93%.

(5) In the solid phase, the maximum particle size of the fly ash is 46 m, and the average particle diameter is 1.3 m. The mass ratio of SiO.sub.2, Al.sub.6Si.sub.2Oi.sub.3 and Fe.sub.2O.sub.3 in fly ash was 63%, 26% and 6%, respectively. The wetting angle of the fly ash particle to distilled water is 57; the average particle size of nano-silica in the solid phase is about 15 nm, the specific surface area is 160 m.sup.2/g, the wetting angle of the nano-silica particles to distilled water is 63; and the mass ratio of fly ash to nano-silica particles is 8.5:1.

(6) The composition of the liquid phase is as follows: surfactant with the concentration of 0.4% by weight, NaHCO.sub.3 with the concentration of 0.025% by weight, KCl with the concentration of 0.5% by weight, and the balance of water, wherein the surfactant is a mixture of sodium -olefin sulfonate and sodium dodecylbenzene sulfonate with a mass ratio of 1:4, wherein the carbon atom number of the sodium -olefin sulfonate is 14 to 18.

(7) The preparation of the ultra-dry three-phase flue gas foam for oil-gas fields comprises the following steps:

(8) mixing of the surfactant with a preset percentage with water, stirring until the surfactant is completely dissolved, an aqueous surfactant solution is obtained; adding the solid phase with a mass fraction of 0.6 wt % (the concentration ratio of solid phase and surfactant in the formed foam is 1.5:1) to the aqueous surfactant solution, and stirring the mixture sufficiently until the solid particles are uniformly dispersed, the first mixed liquid is prepared; adding of the surfactant with a preset percentage to the first mixed liquid, slowly stirring until the surfactant is completely dissolved, the second mixed liquid is prepared; adding NaHCO.sub.3 and KCl with a preset percentage to the second mixed liquid, slowly stirring until NaHCO.sub.3 and KCl are completely dissolved, the third mixed liquid is prepared; injecting the flue gas and the third mixed liquid into the foam generator simultaneously, wherein the injection speed of the flue gas of the coal-fired power plant is controlled to be 9 times of that of the third mixed liquid, and after being thoroughly mixed by the foam generator under normal temperature and normal pressure, an ultra-dry three-phase flue gas foam is made, and the foam quality is 90%.

(9) Injecting the foam into the visual crack model after its preparation, stopping the flow of the foam, observing and recording the change of the particle size of foam over time. The specific observation method refers to the experimental method in Physical simulation of the flow characteristics of foam in cracks the Journal of Central South University (Natural Science Edition), Vol. 48, No. 9, 2017 or Wall slipping behavior of foam with nanoparticle-armored bubbles and its flow resistance factor in cracks Scientific Reports, Vol. 7, No. 1, 2017. The formed foam is dense and uniform, and the average particle diameter of the foam observed at 5 minutes, 15 minutes, and 60 minutes is 52 m, 61 m, and 96 m, respectively, the water content in the foam is only about 10%, and the foam film is thin and stable, the bubbles aggregation is slow and the foam shows good stability.

(10) Injecting the foam into the coaxial cylinder test unit of the Anton Paar MCR302 rheometer after its preparation. When a rotor shear rate is 170 s.sup.1, and under normal temperature and normal pressure, the initial apparent viscosity of the foam is about 85 mPa.Math.s, the apparent viscosity of the foam at about 60 minutes is about 52 mPa.Math.s. The apparent viscosity of the third mixed liquid (i.e., foaming solution) was stabilized at 2.6 mPa.Math.s under the same conditions, and the viscosity of the foam corresponding to third mixed liquid was greatly increased.

(11) After the foam preparation is completed, injecting the foam into the coaxial cylinder test unit of the Anton Paar MCR302 rheometer under the back pressure of 10 MPa. When a rotor shear rate is 170 s.sup.1 and under a normal temperature, the initial apparent viscosity of the foam is about 96 mPa.Math.s, the apparent viscosity at 60 minutes is about 87 mPa.Math.s. The foam has a higher viscosity, and longer stabilization time under a high pressure than a normal pressure, and the foam exhibits good pressure resistance.

(12) After the foam preparation is completed, injecting the foam into the coaxial cylinder test unit of Anton Paar MCR302 rheometer under the back pressure of 10 MPa. When a rotor shear rate is 170 s.sup.1 and the temperature is 230 C., the initial apparent viscosity of the foam is about 62 mPa.Math.s. The apparent viscosity of the foam is about 30 mPa.Math.s after 60 minutes. The foam with the foam quality of 90% can still exist at 230 C. and exhibit a certain viscosity. The foam shows good thermal stability.

Embodiment 2: Ultra-Dry Three-Phase Flue Gas Foam for Oil-Gas Fields

(13) The raw materials comprise a gas phase, a liquid phase and a solid phase, and the specific components are as follows:

(14) the gas phase is the flue gas produced by the coal-fired power plant, and the flue gas has been subjected to desulfurization, denitrification and deoxidation processes, the total volume fraction of nitrogen and carbon dioxide in the flue gas is 93%.

(15) In the solid phase, the maximum particle size of fly ash is 13 m, and the average particle diameter is 0.5 m. The mass ratio of SiO.sub.2, Al.sub.6Si.sub.2O.sub.13 and Fe.sub.2O.sub.3 in fly ash was 71 wt %, 18 wt %, and 3 wt %, respectively. The wetting angle of the fly ash particle to distilled water is 54; the average particle size of nano-silica in the solid phase is about 15 nm, the specific surface area is 160 m.sup.2/g, the wetting angle of the nano-silica particles to distilled water is 63; and the mass ratio of fly ash to nano-silica particles is 8.5:1.

(16) The composition of the liquid phase is as follows: surfactant with the concentration of 0.4% by weight, NaHCO.sub.3 with the concentration of 0.025% by weight, KCl with the concentration of 0.5% weight, and the balance of water, wherein the surfactant is a mixture of sodium -olefin sulfonate and sodium dodecylbenzene sulfonate with a mass ratio of 1:4, wherein the carbon atom number of the sodium -olefin sulfonate is 14 to 18.

(17) The preparation of the ultra-dry three-phase flue gas foam for oil-gas fields comprises the following steps:

(18) mixing of surfactant with a preset percentage with water, stirring until the surfactant is completely dissolved, an aqueous surfactant solution is obtained; adding the solid phase with a mass fraction of 0.6 wt % (the concentration ratio of solid phase and surfactant in the formed foam is 1.5:1) to the aqueous surfactant solution, and stirring the mixture sufficiently until the solid particles are uniformly dispersed, the first mixed liquid is prepared; adding of the surfactant with a preset percentage to the first mixed liquid, slowly stirring until the surfactant is completely dissolved, a second mixed liquid is prepared; adding NaHCO.sub.3 and KCl with a preset percentage to the second mixed liquid, slowly stirring until NaHCO.sub.3 and KCl are completely dissolved, a third mixed liquid is prepared; injecting the flue gas and the third mixed liquid into the foam generator simultaneously, wherein the injection speed of the flue gas of the coal-fired power plant is controlled to be 12 times of that of the third mixed liquid, and after being thoroughly mixed by the foam generator under 95 C. and normal pressure, an ultra-dry three-phase flue gas foam is made, and the foam quality is 92.3%.

(19) Injecting the foam into the visual crack model after its preparation, stopping the flow of the foam, observing and recording the change of the particle size of foam over time. The specific observation method refers to the experimental method in Physical simulation of the flow characteristics of foam in cracks the Journal of Central South University (Natural Science Edition), Vol. 48, No. 9, 2017 or Wall slipping behavior of foam with nanoparticle-armored bubbles and its flow resistance factor in cracks Scientific Reports, Vol. 7, No. 1, 2017. The formed foam is dense and uniform, and the average particle diameter of the foam observed at 5 minutes, 15 minutes, and 60 minutes is 47 m, 64 m, and 118 m, respectively, the water content in the foam is only about 7.7%, and the foam film is thin and stable, the bubbles aggregation is slow and the foam shows good temperature resisting stability.

(20) Injecting the foam into the coaxial cylinder test unit of the Anton Paar MCR302 rheometer after its preparation. When a rotor shear rate is 170 s.sup.1, and under a normal temperature, and a normal pressure, the initial apparent viscosity of the foam is about 76 mPa.Math.s, the apparent viscosity of the foam at about 60 minutes is about 49 mPa.Math.s. The apparent viscosity of the third mixed liquid (i.e., foaming solution) was stabilized at 2.1 mPa.Math.s under the same conditions, and the viscosity of the foam corresponding to third mixed liquid was greatly increased.

(21) After the foam preparation is completed, injecting the foam into the coaxial cylinder test unit of the Anton Paar MCR302 rheometer under the back pressure of 10 MPa. When a rotor shear rate is 170 s.sup.1 and under a normal temperature, the initial apparent viscosity of the foam is about 85 mPa.Math.s. The apparent viscosity of the foam after 60 minutes is about 71 mPa.Math.s. The foam has a higher viscosity and longer stabilization time under a high pressure than a normal pressure, and the foam exhibits good pressure resistance.

(22) After the foam preparation is completed, injecting the foam into the coaxial cylinder test unit of Anton Paar MCR302 rheometer under the back pressure of 10 MPa. When a rotor shear rate is 170 s.sup.1 and the temperature is 230 C., the initial apparent viscosity of the foam is about 53 mPa.Math.s. The apparent viscosity of the foam is about 29 mPa.Math.s after 60 minutes. The foam with the foam quality of 92.3% can still exist at 230 C. and exhibit a certain viscosity. The foam shows good thermal stability.

Embodiment 3: Ultra-Dry Three-Phase Flue Gas Foam for Oil-Gas Fields

(23) The raw materials comprise a gas phase, a liquid phase and a solid phase, and the specific components are as follows:

(24) the gas phase is the flue gas produced by the coal-fired power plant, and the flue gas has been subjected to desulfurization, denitrification and deoxidation processes, the total volume fraction of nitrogen and carbon dioxide in the flue gas is 93%.

(25) In the solid phase, the maximum particle size of fly ash is 46 m, and the average particle diameter is 1.3 m. The mass ratio of SiO.sub.2, Al.sub.6Si.sub.2O.sub.13 and Fe.sub.2O.sub.3 in fly ash was 63 wt %, 26 wt %, and 6 wt %, respectively. The wetting angle of the fly ash particle to distilled water is 57; the average particle size of nano-silica in the solid phase is about 15 nm, the specific surface area is 160 m.sup.2/g, the wetting angle of the nano-silica particles to distilled water is 63; and the mass ratio of fly ash to nano-silica particles is 8:1.

(26) The composition of the liquid phase is as follows: surfactant with the concentration of 0.47% by weight, NaHCO.sub.3 with the concentration of 0.033% by weight, KCl with the concentration of 0.5% by weight, and the balance of water, wherein the surfactant is a mixture of sodium -olefin sulfonate and sodium dodecylbenzene sulfonate with a mass ratio of 1:4.5, wherein the carbon atom number of the sodium -olefin sulfonate is 14 to 18.

(27) The preparation of the ultra-dry three-phase flue gas foam for oil-gas fields comprises the following steps:

(28) mixing of surfactant with a preset percentage with water, stirring until the surfactant is completely dissolved, an aqueous surfactant solution is obtained; adding the solid phase with a mass fraction of 0.6 wt % (the concentration ratio of solid phase and surfactant in the formed foam is 1.5:1) to the aqueous surfactant solution, and stirring the mixture sufficiently until the solid particles are uniformly dispersed, the first mixed liquid is prepared; adding of the surfactant with a preset percentage to the first mixed liquid, slowly stirring until the surfactant is completely dissolved, a second mixed liquid is prepared; adding NaHCO.sub.3 and KCl with a preset percentage to the second mixed liquid, slowly stirring until NaHCO.sub.3 and KCl are completely dissolved, a third mixed liquid is prepared; injecting the flue gas of the coal-fired power plant and the third mixed liquid into the foam generator simultaneously, wherein the injection speed of the flue gas of the coal-fired power plant is controlled to be 19 times of that of the third mixed liquid, and after being thoroughly mixed by the foam generator under normal temperature and normal pressure, an ultra-dry three-phase flue gas foam is made, and the foam quality is 95%.

(29) Injecting the foam into the visual crack model after its preparation, stopping the flow of the foam, observing and recording the change of the particle size of foam over time. The specific observation method refers to the experimental method in Physical simulation of the flow characteristics of foam in cracks the Journal of Central South University (Natural Science Edition), Vol. 48, No. 9, 2017 or Wall slipping behavior of foam with nanoparticle-armored bubbles and its flow resistance factor in cracks Scientific Reports, Vol. 7, No. 1, 2017. The formed foam is dense and uniform, and the average particle diameter of the foam observed at 5 minutes, 15 minutes, and 60 minutes is 152 m, 186 m, and 207 m, respectively, the water content in the foam is only about 5%, and the foam film is thin and stable, the bubbles aggregation is slow and the foam shows good temperature resisting stability.

(30) Injecting the foam into the coaxial cylinder test unit of the Anton Paar MCR302 rheometer after its preparation. When a rotor shear rate is 170 s.sup.1, and under a normal temperature, and a normal pressure, the initial apparent viscosity of the foam is about 47 mPa.Math.s, the apparent viscosity of the foam at about 60 minutes is about 36 mPa.Math.s. The apparent viscosity of the third mixed liquid (i.e., foaming solution) was stabilized at 3.1 mPa.Math.s under the same conditions, and the viscosity of the foam corresponding to third mixed liquid was greatly increased.

(31) After the foam preparation is completed, injecting the foam into the coaxial cylinder test unit of the Anton Paar MCR302 rheometer under the back pressure of 10 MPa. When a rotor shear rate is 170 s.sup.1 and under a normal temperature, the initial apparent viscosity of the foam is about 59 mPa.Math.s. The apparent viscosity of the foam after 30 minutes is about 52 mPa.Math.s. The foam has a higher viscosity and longer stabilization time under a high pressure than a normal pressure, and the foam exhibits good pressure resistance.

(32) After the foam preparation is completed, injecting the foam into the coaxial cylinder test unit of Anton Paar MCR302 rheometer under the back pressure of 10 MPa. When a rotor shear rate is 170 s.sup.1 and the temperature is 230 C., the initial apparent viscosity of the foam is about 36 mPa.Math.s. The apparent viscosity of the foam is about 19 mPa.Math.s after 30 minutes. The foam with the foam quality of 95% can still exist at 230 C. and exhibit a certain viscosity. The foam shows good thermal stability.