CN109439309B

CN109439309B - CO (carbon monoxide)2Fracturing fluid thickening agent and preparation method thereof

Info

Publication number: CN109439309B
Application number: CN201811435466.9A
Authority: CN
Inventors: 张健; 王金意; 荆铁亚; 赵文韬; ***
Original assignee: Huaneng Clean Energy Research Institute; China Huaneng Group Co Ltd
Current assignee: Huaneng Clean Energy Research Institute; China Huaneng Group Co Ltd
Priority date: 2018-11-28
Filing date: 2018-11-28
Publication date: 2021-04-20
Anticipated expiration: 2038-11-28
Also published as: CN109439309A

Abstract

The invention discloses a CO₂The fracturing fluid thickening agent comprises the following components in percentage by weight: 50-70% of low molecular weight polyether polymer; 6-15% of modified PDMS; 9-15% of vegetable oil; 11-18% of low-carbon alcohol; 2-4% of tocopherol. The CO is₂The thickener has low price, does not pollute the stratum of an oil-gas reservoir, can reduce the interfacial tension of crude oil rocks, improves the surface wettability of the stratum rocks, is green and environment-friendly, is suitable for fracturing and the like of a water-sensitive oil-gas reservoir, does not need to be flowback, greatly saves water resources and does not discharge three wastes; can also be used for improving CO₂Oil displacement effect.

Description

CO (carbon monoxide)2Fracturing fluid thickening agent and preparation method thereof

Technical Field

The invention belongs to CO₂The technical field of thickening agents, in particular to CO₂A fracturing fluid thickening agent and a preparation method thereof.

Background

Practical experience proves that CO₂The fracturing technology is one of the most potential fracturing yield-increasing methods for low-permeability oil and gas reservoirs, water-sensitive oil and gas reservoirs and especially unconventional oil and gas reservoirs. But due to CO₂Low viscosity, difficult sand carrying, low sand ratio and limited CO₂Application to fracturing.

To overcome the above problems, it is necessary to increase CO₂Viscosity of the fluid. Thus, CO₂The thickener is designed and developed to be supercritical CO₂The most important research direction in the technical field of fracturing. To date, fluoropolymers and polysiloxanes with high levels of CO-solvents are the most effective two types of CO₂Thickener ofGreatly increase CO₂But unfortunately both classes of polymers have limited their practical application due to environmental and cost issues.

Due to CO₂Non-fluoropolymers with poor solvent properties, generally commercially available in CO₂Poor medium solubility, which prevents CO containing carbon, hydrogen and oxygen₂Research and development of thickeners has led to few reports of research into the synthesis of non-fluorine thickener materials with desired structures based on theoretical design.

Destarac summarizes parent CO₂Polymer molecule design principle: the dominant ones, first, are cohesive energy density or polymer-polymer interaction, the weaker the polymer-polymer interaction the more favorable the polymer is for dissolution; secondly, polymer-CO₂Interaction of Lewis bases such as specific polar groups like carbonyl, ether and acetate groups can increase the polymer-CO₂(ii) interaction; and finally, chain flexibility or free volume, wherein the high chain flexibility or the high free volume is beneficial to improving the mixing entropy.

Vinyl acetate polymers, the most CO-philic polymer so far₂With a hydrocarbon-containing polymer, but with a high molecular weight of polyvinyl acetate in CO₂Medium solubility is poor, and only polyvinyl acetate with molecular weight below 1000 can dissolve in CO₂The thickening effect has not been reported in detail.

Chinese patent application 201510745652.2 describes a phenyl glycidyl ether polymer as CO₂Thickener, polyphenyl glycidyl ether, in liquid CO under the condition of 5-30MPa and same temperature and pressure₂Medium or supercritical CO₂Has good solubility in water, and can convert CO into CO₂The viscosity is improved by 1.5 to 2.5 times, and the fluorine-free environment-friendly coating is free from fluorine. But to CO₂The viscosity increase is limited and not suitable for industrial applications.

Disclosure of Invention

The invention aims to provide CO₂A fracturing fluid thickening agent and a preparation method thereof, which aim to solve the technical problems; CO prepared by the invention₂The fracturing fluid thickener is low in price, environment-friendly, green and environment-friendly, and canEffective increase of supercritical CO₂Or liquid CO₂Viscosity of (2), CO after thickening₂Can be used as an anhydrous fracturing fluid and solves the problem of low sand carrying capacity in the prior art.

In order to achieve the purpose, the invention adopts the following technical scheme:

CO (carbon monoxide)₂The fracturing fluid thickener comprises the following components in percentage by weight:

50-70% of low molecular weight polyether polymer;

6-15% of modified PDMS;

9-15% of vegetable oil;

11-18% of low-carbon alcohol;

2-4% of tocopherol.

Further, the low molecular weight polyether polymer is a mixture of polyethylene vinyl ether and polypropylene glycol monobutyl ether.

Further, the mass ratio of the polyethylene vinyl ether to the polypropylene glycol monobutyl ether in the low molecular weight polyether polymer is (40-55): (11-20).

Further, the vegetable oil is one or more of linseed oil, sesame oil, sunflower oil, soybean oil, rapeseed oil, olive oil, rice bran oil, tung oil, castor oil and illegal cooking oil.

Further, the lower alcohol is one or more of methanol, ethanol, propanol, isopropanol and butanol.

Further, tocopherol is used as a stabilizer, and particularly dihydrobenzopyran-6-ol or derivatives thereof.

Further, the modified PDMS is hydroxyl terminated PDMS, amino terminated PDMS or polyether modified PDMS.

CO (carbon monoxide)₂The preparation method of the fracturing fluid thickening agent comprises the following steps:

mixing low molecular weight polyether polymer and vegetable oil, adding low carbon alcohol, heating in water bath to 40-50 deg.C, stirring to mix thoroughly, adding modified PDMS, adding tocopherol, stirring, keeping the temperature for reaction, and cooling to room temperature to obtain CO₂A fracturing fluid thickener.

Further, said CO₂Fracturing fluid thickener and supercritical CO₂Or liquid CO₂After mixing, the viscosity is 5.0 to 9.3 mPas when tested at 40 ℃ and 22 MPa.

Compared with the prior art, the invention has the following beneficial effects:

CO prepared by the invention₂The components of the fracturing fluid thickening agent can act synergistically in CO₂Has good solubility and can effectively thicken supercritical CO₂Or liquid CO₂To make supercritical CO₂Or liquid CO₂The viscosity is increased by over 62.5 times; the invention does not contain high-price organic fluorine polymer or fluorine-containing compound, is green and environment-friendly and is suitable for industrial application.

CO of the invention₂In the preparation process of the fracturing fluid thickening agent, the reaction condition is mild, no special equipment is needed, no three-waste discharge is caused, and the preparation method is green and environment-friendly.

Detailed Description

The invention will now be further described by way of the following examples, but the invention is not limited to the examples illustrated. The following detailed description of the present invention is provided in connection with the examples to facilitate the understanding and appreciation of the technical aspects of the present invention.

Example 1

Mixing 50 g of polyethylene vinyl ether polymer and 20 g of polypropylene glycol monobutyl ether, sequentially adding the mixture into a reactor under the protection of nitrogen and stirring, adding 9 g of linseed oil, uniformly mixing, adding 11 g of methanol, heating in a water bath to 45 ℃, keeping the temperature stable for 1.5 hours to ensure that the mixture is fully mixed and reacted uniformly, then slowly adding 6 g of hydroxyl-terminated PDMS, finally adding 4 g of tocopherol, uniformly stirring, keeping the temperature for 0.5 hour, and cooling to room temperature to obtain the CO-terminated polyethylene glycol (CO) of the invention₂Thickener product JH 1.

Example 2

Mixing 40 g of polyethylene vinyl ether polymer and 10 g of polypropylene glycol monobutyl ether, sequentially adding the mixture into a reactor under the protection of nitrogen and stirring, adding 15 g of sunflower oil, uniformly mixing, adding 17 g of ethanol, heating to 50 ℃ in a water bath, and keeping the temperatureThe temperature is stabilized for 2 hours to ensure that the mixture is fully mixed and reacted uniformly, then 15 g of amino PDMS is slowly added, finally 3 g of tocopherol is added, the mixture is stirred uniformly, the temperature is kept for 1 hour, and the mixture is cooled to the room temperature to obtain the supercritical CO of the invention₂Thickener product JH 2.

Example 3

Mixing 55 g of polyethylene vinyl ether polymer and 11 g of polypropylene glycol monobutyl ether, sequentially adding the mixture into a reactor under the protection of nitrogen and stirring, adding 5 g of vegetable oil and 5 g of olive oil, uniformly mixing, then adding 6 g of methanol and 6 g of ethanol, heating in a water bath to 40 ℃, keeping the temperature for 2 hours stably so as to enable the mixture to be fully mixed and react uniformly, then slowly adding 10 g of hydroxyl PDMS, finally adding 2 g of tocopherol, uniformly stirring, keeping the temperature for 0.5 hour, and cooling to room temperature to obtain the supercritical CO-based catalyst₂Thickener product JH 3.

Example 4

Mixing 45 g of polyethylene vinyl ether polymer and 13 g of polypropylene glycol monobutyl ether, sequentially adding the mixture into a reactor under the protection of nitrogen and stirring, adding 12 g of castor oil, uniformly mixing, adding 18 g of isopropanol, heating in a water bath to 50 ℃, keeping the temperature stable for 2 hours to ensure that the mixture is fully mixed and reacted uniformly, then slowly adding 10 g of amino-terminated PDMS, finally adding 2 g of tocopherol, uniformly stirring, keeping the temperature for 1 hour, and cooling to room temperature to obtain the supercritical CO-based catalyst₂Thickener product JH 4.

The JH thickener system prepared in examples 1-4 of the present invention was tested with supercritical CO using a Haake Mars3 series common high temperature high pressure rheometer in a double-phase rotor test₂Or liquid CO₂Thickening effect after mixing. The test viscosities are shown in the table below.

Although the present invention has been described in detail with reference to the preferred embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted without departing from the spirit and scope of the invention.

Claims

1. CO (carbon monoxide)₂The fracturing fluid thickener is characterized by comprising the following components in percentage by weight:

50-70% of low molecular weight polyether polymer;

6-15% of modified PDMS;

9-15% of vegetable oil;

11-18% of low-carbon alcohol;

2-4% of tocopherol;

the low molecular weight polyether polymer is a mixture of polyethylene vinyl ether and polypropylene glycol monobutyl ether; the mass ratio of the polyethylene vinyl ether to the polypropylene glycol monobutyl ether in the low molecular weight polyether polymer is (40-55): (11-20);

the vegetable oil is one or more of oleum Lini, oleum Sesami, oleum Helianthi, soybean oil, oleum Rapae, oleum Olivarum, rice bran oil, oleum Verniciae fordii, oleum ricini, and illegal cooking oil;

the lower alcohol is one or more of methanol, ethanol, propanol, isopropanol, and butanol;

the tocopherol is dihydrobenzopyran-6-alcohol or a derivative thereof;

the modified PDMS is hydroxyl terminated PDMS, amino terminated PDMS or polyether modified PDMS.

2. A CO as claimed in claim 1₂The preparation method of the fracturing fluid thickening agent is characterized by comprising the following steps:

3. The method of claim 2, wherein the CO is present in a gas phase₂Fracturing fluidThickener and supercritical CO₂Or liquid CO₂After mixing, the viscosity is 5.0 to 9.3 mPas when tested at 40 ℃ and 22 MPa.