CN110903817B

CN110903817B - Viscosity reducer for reducing viscosity of base liquid of vegetable gum temporary plugging rubber plug and preparation method thereof

Info

Publication number: CN110903817B
Application number: CN201811081578.9A
Authority: CN
Inventors: 管保山; 刘玉婷; 梁利; 才博; 杨文轩
Original assignee: Petrochina Co Ltd
Current assignee: Petrochina Co Ltd
Priority date: 2018-09-17
Filing date: 2018-09-17
Publication date: 2022-08-05
Anticipated expiration: 2038-09-17
Also published as: CN110903817A

Abstract

The present invention provides a viscosity reducer for reducing the viscosity of vegetable glue temporary plugging base liquid and a preparation method thereof. The method includes the following steps: (1) adding a boron compound to a mixed solvent, and making the boron compound completely Dissolving to obtain solution A; (2) adding alkali to the solution A to adjust the system to be alkaline; then heating the system, and adding polyhydroxy acid salts under stirring conditions to react to obtain an organic boron solution; ( 3) after the described organic boron solution is cooled, add borax to it again to obtain a semi-solid substance; (4) dry the semi-solid substance, and then grind the obtained solid substance into powder and spheronize after the drying to obtain the viscosity reducing agent for reducing the viscosity of the base fluid for temporary plugging of vegetable glue. The viscosity reducer is a boron ion-rich viscosity reducer, which can improve the construction difficulties caused by the rapid swelling and high viscosity of the vegetable glue temporary plugging plug base liquid.

Description

Viscosity reducer for reducing viscosity of base liquid of vegetable gum temporary plugging rubber plug and preparation method thereof

Technical Field

The invention relates to a viscosity reducer for reducing viscosity of a base liquid of a vegetable gum temporary plugging rubber plug and a preparation method thereof, belonging to the technical field of oil exploitation.

Background

Due to the seepage capability among cracks or the heterogeneity of reservoirs, a chemical temporary plugging rubber plug is adopted to plug old cracks in the old well repeated fracturing, unconventional reservoir volume fracturing, vertical well layered fracturing, horizontal well staged fracturing and complex well reconstruction, the trend of the fractured cracks is changed in a mode of not strongly plugging stratum rock pores, new cracks are made, oil flow channels are improved, and the purpose of increasing the yield is achieved. The plant gum temporary plugging rubber plug is an important class of temporary plugging rubber plugs, and is a high-strength jelly type rubber plug formed by using high-concentration plant gum base liquid and a cross-linking agent matched with the high-concentration plant gum base liquid. In the field use process, a delayed crosslinking agent is generally adopted, and the swelling of the vegetable gum in water is delayed or prevented by changing a crosslinking environment and the like, so that the low viscosity of the base liquid at the initial construction stage is realized. However, the above-mentioned methods have limited ability to retard or prevent the swelling of the vegetable gum, and the viscosity rapidly increases after the addition of the cross-linking agent, which also increases the construction friction. Because the increase of the viscosity of the vegetable gum base liquid to the construction risk at the initial stage is difficult to solve, the application of the vegetable gum temporary plugging rubber plug is not as wide as the application of the polymer temporary plugging rubber plug.

Chinese patent CN106350043A mentions that soluble polymers can be used in carboxymethyl starch with self-swelling function to form temporary plugging agent; chinese patent CN107129560A mentions a method for synthesizing temporary plugging particles by using vegetable gums such as corn starch as raw materials; chinese patent CN103725275A mentions a method for synthesizing a plugging rubber plug by using a mixture of a polymer and a vegetable gum as raw materials; however, the methods described above all use vegetable gum as the raw material of the rubber plug, but do not describe how the prepared high-viscosity base solution is constructed without affecting the effect.

Therefore, the technical problems to be solved in the art are solved by providing a viscosity reducer for reducing the viscosity of the base liquid of the vegetable gum temporary plugging rubber plug and a preparation method thereof.

Disclosure of Invention

In order to solve the above disadvantages and shortcomings, an object of the present invention is to provide a method for preparing a viscosity reducer for reducing the viscosity of a base fluid of a vegetable gum temporary plugging rubber plug.

The invention also aims to provide the viscosity reducer for reducing the viscosity of the base liquid of the vegetable gum temporary plugging rubber plug prepared by the preparation method.

The invention also aims to provide a vegetable gum temporary plugging rubber plug precursor mixture which comprises the viscosity reducer for reducing the viscosity of the base liquid of the vegetable gum temporary plugging rubber plug.

Still another object of the present invention is to provide a vegetable gum temporary plugging rubber plug base fluid comprising the vegetable gum temporary plugging rubber plug precursor mixture.

The invention also aims to provide application of the vegetable gum temporary plugging rubber plug base fluid in repeated fracturing of old wells, unconventional reservoir volume fracturing, vertical well separate-layer fracturing, horizontal well staged fracturing and complex-condition well reconstruction.

In order to achieve the above objects, in one aspect, the present invention provides a preparation method of a viscosity reducer for reducing viscosity of a base liquid of a vegetable gum temporary plugging rubber plug, wherein the preparation method comprises the following steps:

(1) adding a boron compound into the mixed solvent, and completely dissolving the boron compound to obtain a solution A;

(2) adding an alkali to the solution A to adjust the system to be alkaline; heating the system, and adding the polyhydroxy acid salt to react under the stirring condition to obtain an organic boron solution;

(3) after the organoboron solution is cooled, adding borax into the organoboron solution to obtain a semisolid substance;

(4) and drying the semisolid substance, grinding the dried solid substance into powder, and rolling to obtain the viscosity reducer for reducing the viscosity of the base liquid of the temporary vegetable gum plugging rubber plug.

According to a specific embodiment of the present invention, in the preparation method, the step (1) specifically comprises: adding boron compound into the mixed solvent, heating to 70-75 ℃, and stirring for 10-20min at the temperature to completely dissolve the boron compound to obtain solution A.

According to a specific embodiment of the invention, in the step (1) of the preparation method, the mixed solvent is a mixture of water and glycerol, and the volume ratio of the water to the glycerol is 1:1-1: 3.

According to a specific embodiment of the present invention, in the preparation method, the boron compound is used in an amount of 10 to 15% by volume of the mixed solvent.

According to a specific embodiment of the present invention, in the preparation method, the boron compound comprises one or a combination of borax, boric acid, sodium diborate and sodium pentaborate.

According to a specific embodiment of the present invention, in the step (2) of the preparation method, the amount of the base is 1 to 5% by volume of the mixed solvent.

According to a specific embodiment of the present invention, in the preparation method, the alkali comprises one or more of sodium carbonate, sodium bicarbonate and sodium hydroxide.

According to a specific embodiment of the present invention, in the step (2) of the preparation method, the polyhydroxy acid salt is used in an amount of 10 to 25% by volume of the mixed solvent.

According to a specific embodiment of the present invention, in the preparation method, the polyhydroxy acid salt includes one or a combination of several of sodium gluconate, sodium alginate, sodium hydroxysulfonate and glycerol sodium salt.

According to a specific embodiment of the present invention, in the step (2) of the preparation method, the temperature is raised to raise the temperature of the system to 80-95 ℃.

According to a specific embodiment of the present invention, in the step (2) of the preparation method, the reaction temperature is 80 to 95 ℃ and the reaction time is 4 to 5 hours.

According to the specific embodiment of the present invention, in a preferred embodiment of the present invention, the stirring in step (2) is performed at a low speed, but the present invention does not specifically require the specific stirring speed of the stirring, and a person skilled in the art can reasonably set the stirring speed according to the operation requirement as long as the object of the present invention can be achieved.

According to a specific embodiment of the invention, in the step (3) of the preparation method, the volume ratio of the organoboron solution to the borax is 1:1-1: 2.

According to a specific embodiment of the present invention, in the step (4) of the preparation method, a mixed solvent is added during the spheronization process as a solvent for the spheronization process.

According to a specific embodiment of the invention, in the step (4) of the preparation method, the volume ratio of the mixed solvent used in the spheronization process to the semi-solid substance is 1: 0.3-0.5.

According to a specific embodiment of the present invention, in the step (4) of the preparation method, the mixed solvent used in the spheronization process is a mixture of water and glycerol, and the volume ratio of the two is 1:1-1: 3.

According to a specific embodiment of the invention, in the preparation method, the viscosity reducer for reducing the viscosity of the base liquid of the vegetable gum temporary plugging rubber plug is in a granular shape, and the particle size (diameter) of the viscosity reducer is 2-4 mm.

On the other hand, the invention also provides the viscosity reducer for reducing the viscosity of the base liquid of the vegetable gum temporary plugging rubber plug, which is prepared by the preparation method of the viscosity reducer for reducing the viscosity of the base liquid of the vegetable gum temporary plugging rubber plug.

According to a particular embodiment of the invention, said viscosity reducing agent is in the form of particles having a size (diameter) of 2-4 mm.

On the other hand, the invention also provides a vegetable gum temporary plugging rubber plug precursor mixture which comprises vegetable gum and the viscosity reducer for reducing the viscosity of the base liquid of the vegetable gum temporary plugging rubber plug.

According to a specific embodiment of the invention, in the mixture of the vegetable gum temporary plugging rubber plug precursor, the volume ratio of the viscosity reducer to the vegetable gum is 0.8-1.5: 5.

According to a specific embodiment of the present invention, in the mixture of the plant gum temporary plugging rubber plug precursor, the plant gum comprises one or more of guar gum and derivatives thereof, fenugreek gum and derivatives thereof, and sesbania gum.

Wherein, the derivatives of guar gum (such as hydroxypropyl guar gum) and fenugreek gum are conventional substances used in the field, and can be obtained by commercial or self-preparation.

In another aspect, the invention further provides a vegetable gum temporary plugging rubber plug base solution, which comprises the vegetable gum temporary plugging rubber plug precursor mixture and water.

According to the specific embodiment of the invention, in the vegetable gum temporary plugging rubber plug base solution, the amount of the vegetable gum temporary plugging rubber plug precursor mixture is 5-10% of the volume of water.

On the other hand, the invention also provides application of the vegetable gum temporary plugging rubber plug base fluid in repeated fracturing of old wells, unconventional reservoir volume fracturing, vertical well separate layer fracturing, horizontal well staged fracturing and complex well reconstruction.

According to the specific embodiment of the invention, the vegetable gum temporary plugging rubber plug base fluid can be applied to old well repeated fracturing, unconventional reservoir volume fracturing, vertical well separate layer fracturing, horizontal well staged fracturing, complex well and other reservoir reconstruction needing temporary packing.

The viscosity reducer for reducing the viscosity of the base liquid of the vegetable gum temporary plugging rubber plug is a boron ion-rich viscosity reducer, and can solve the problem of construction difficulty caused by high viscosity of the base liquid of the vegetable gum temporary plugging rubber plug due to fast swelling. The viscosity reducer can be directly placed into the vegetable gum, and when the vegetable gum base liquid is prepared subsequently, the high-concentration boron ions can enable the vegetable gum to be easy to curl water and branched chains and not beneficial to permeation and combination of water molecules, so that swelling of the vegetable gum in water is limited, and the purpose of reducing the viscosity of the vegetable gum base liquid is achieved. In subsequent construction, a cross-linking agent and a regulator are added to provide a cross-linking group, and the cross-linking environment is changed to open the plant rubber branched chain and combine with the cross-linking agent to form a high-strength gel rubber plug, so that reservoir cracks are blocked.

Drawings

FIG. 1 is a graph showing the relationship between viscosity and the amount of viscosity reducer used in test example 2 of the present invention.

Detailed Description

In order to clearly understand the technical features, objects and advantages of the present invention, the following detailed description of the technical solutions of the present invention will be made with reference to the following specific examples, which should not be construed as limiting the implementable scope of the present invention.

Example 1

The embodiment provides a viscosity reducer for reducing the viscosity of a base liquid of a vegetable gum temporary plugging rubber plug, which is prepared by a preparation method comprising the following steps:

adding 10V/V% (25mL) boric acid into 250mL mixed solvent of water and glycerol (the mixing ratio is 1:1), heating to 75 ℃, stirring for 20min at the temperature until the boron compound is completely dissolved, adding 2V/V% (2.5mL) sodium hydroxide to adjust the pH value of the reaction to be alkaline, heating the mixture to 90 ℃, keeping the temperature basically constant during the heating, adding 10V/V% (25mL) sodium gluconate under the condition of low-speed stirring, and reacting for 4 hours to obtain the organic boron solution. After cooling the organic boron solution, adding borax, and mixing the two according to the volume ratio of 1:1 to form a semisolid substance; putting the semisolid substance into a dryer to be dried into a solid state, grinding the dried solid substance into powder, putting the powder into a rounding machine to be rounded, adding a mixed solvent of water and glycerol (the mixing ratio is 1:1) serving as a solvent in the rounding process, and rounding the powder into 2mm particles to obtain the viscosity reducer for reducing the viscosity of the base liquid of the vegetable gum temporary plugging rubber plug, wherein the viscosity reducer is marked as viscosity reducer A.

Example 2

adding 12V/V% (60mL) borax into 500mL of mixed solvent of water and glycerol (the mixing ratio is 1:3), heating to 70 ℃, stirring for 20min at the temperature until the boron compound is completely dissolved, adding 1V/V% (5mL) sodium hydroxide and 3V/V% (15mL) sodium bicarbonate to adjust the pH value of the reaction to be alkaline, heating the mixture to 90 ℃, keeping the temperature basically constant during the reaction, adding 25V/V% (125mL) sodium alginate under the condition of low-speed stirring, and reacting for 4.5 hours to obtain the organic boron solution. After cooling the organic boron solution, adding borax, and mixing the two according to the volume ratio of 1:1 to form a semisolid substance; and (2) putting the semisolid substance into a dryer to be dried to be in a solid state, grinding the dried solid substance into powder, putting the powder into a rounding machine to be rounded, adding a mixed solvent (the mixing ratio is 1:1) of water and glycerol into the rounding process to serve as a solvent in the rounding process, and rounding the powder to form 4mm particles to obtain the viscosity reducer for reducing the viscosity of the base liquid of the vegetable gum temporary plugging rubber plug, wherein the viscosity reducer is marked as viscosity reducer B.

Example 3

The embodiment provides a vegetable gum temporary plugging rubber plug base fluid which is prepared by a method comprising the following steps:

adding the viscosity reducer A obtained in example 1 into guar gum to form a mixture, wherein the volume ratio of the viscosity reducer A to the guar gum is 0.8: 5;

and dissolving the mixture in water at a volume ratio of 6:100 to prepare the base liquid of the vegetable gum temporary plugging rubber plug, which is marked as base liquid A.

Example 4

adding the viscosity reducer B obtained in the example 2 into hydroxypropyl guar gum to form a mixture, wherein the volume ratio of the viscosity reducer B to the hydroxypropyl guar gum is 1: 5;

and dissolving the mixture in water at a volume ratio of 8:100 to prepare the base liquid of the vegetable gum temporary plugging rubber plug, which is marked as base liquid B.

Test example 1

The viscosity of the base fluid A provided in example 3 at different preparation times is measured, and the viscosity data is shown in the following Table 1, wherein the viscosity is measured according to the water-based fracturing fluid performance evaluation method SY/T5107-2016 in the oil and gas industry.

TABLE 1

Test time (min)	Viscosity, mPas
		0	9
1	9
		3	9
5	7.5
		10	6
15	6
		20	6
30	6
		60	6

As can be seen from table 1, the viscosity of the base solution of the vegetable gum temporary plugging rubber plug provided in example 3 of the present invention can be maintained below 10mPa · s.

Test example 2

Adding different amounts of viscosity reducer B prepared in example 2 into hydroxypropyl guar to form a mixture, wherein the volume ratio of the viscosity reducer B to the hydroxypropyl guar is 0.8:5, 1.0:5, 1.2:5, 1.4:5 and 1.5:5 respectively;

and respectively dissolving the mixtures in water, wherein the volume ratio of the mixture to the water is 8:100, and preparing the vegetable gum temporary plugging rubber plug base liquid.

The viscosity of the vegetable gum temporary plugging rubber plug base liquid is respectively tested after 10min of preparation, and the viscosity measurement is carried out according to the water-based fracturing fluid performance evaluation method of the oil and gas industry standard SY/T5107-2016.

The relationship between the viscosity and the dosage of the viscosity reducer is shown in fig. 1, and it can be known from fig. 1 that the viscosity of the base liquid of the vegetable gum temporary plugging rubber plug is in a descending trend along with the continuous increase of the dosage of the viscosity reducer, which indicates that the viscosity reducer provided by the invention has the function of reducing the viscosity. Specifically, when the volume ratio of the viscosity reducer B to the hydroxypropyl guar gum provided in the embodiment of the invention is 0.8:5, 1.0:5, 1.2:5, 1.4:5, and 1.5:5 (namely V/V is 0.16, 0.20, 0.24, 0.28, and 0.30), respectively, the viscosity of the base liquid of the vegetable gum temporary plugging rubber plug can be reduced to less than 10mPa · s, and the use of the viscosity reducer for reducing the viscosity of the base liquid of the vegetable gum temporary plugging rubber plug provided by the invention can avoid the occurrence of construction failure caused by excessively high viscosity of the base liquid in the liquid preparation and construction processes.

Claims

1. a preparation method for reducing the viscosity reducer of vegetable glue temporarily blocking glue plug base fluid viscosity, is characterized in that, described preparation method is made up of the following steps:

(1) adding a boron compound to the mixed solvent and completely dissolving the boron compound to obtain solution A; the amount of the boron compound is 10-15% of the volume of the mixed solvent; the mixed solvent in step (1) is water and the mixture of glycerol, the volume ratio of the two is 1:1-1:3;

(2) adding alkali to the solution A to adjust the system to be alkaline; then heating the system, and adding a polyhydroxy acid salt under stirring conditions to react to obtain an organoboron solution; described in step (2) The temperature of reaction is 80-95 ℃, and the reaction time is 4-5 hours;

The consumption of the alkali described in the step (2) is 1-5% of the mixed solvent volume;

The consumption of the polyhydroxy acid salt described in the step (2) is 10-25% of the mixed solvent volume;

(3) after the described organoboron solution is cooled, add borax to it again to obtain a semi-solid substance; in step (3), the volume ratio of the organoboron solution and the borax is 1:1-1:2 ;

(4) drying the semi-solid matter, then grinding the obtained solid matter after drying into powder and spheronizing, to obtain the described viscosity reducer for reducing the viscosity of the plant glue temporary plugging base fluid, the described The viscosity reducer used to reduce the viscosity of the plant glue temporary plugging plug base fluid is granular, and its particle size is 2-4mm;

In step (4) spheronization process, add mixed solvent as the solvent of spheronization process, the volume ratio of described mixed solvent and semi-solid substance is 1:0.3-0.5, and described mixed solvent is the mixture of water and glycerol, The volume ratio of the two is 1:1-1:3.

2. preparation method according to claim 1 is characterized in that, step (1) specifically comprises: adding boron compound to mixed solvent, be warming up to 70-75 ℃, and stirring 10-20min at this temperature makes boron compound completely Dissolve to obtain solution A.

3. The preparation method according to claim 1, wherein the boron compound comprises one or a combination of borax, boric acid, sodium diborate, and sodium pentaborate.

4. preparation method according to claim 1 is characterized in that, described alkali comprises one or the combination in sodium carbonate, sodium bicarbonate and sodium hydroxide.

5. preparation method according to claim 1 is characterized in that, described polyhydroxy acid salt comprises the combination of one or more in sodium gluconate, sodium alginate, sodium hydroxysulfonate and glycerol sodium salt .

6 . The preparation method according to claim 1 or 2 , wherein the temperature increase in step (2) is to increase the temperature of the system to 80-95° C. 7 .

7. the viscosity reducer for reducing the viscosity of vegetable glue temporary plugging base liquid viscosity prepared by the preparation method of the viscosity reducer for reducing the viscosity of plant glue temporary plugging base liquid according to any one of claims 1-6 , the viscosity reducer is granular, and its particle size is 2-4mm.

8 . A vegetable glue temporary plugging plug precursor mixture, comprising vegetable glue and the viscosity reducing agent of claim 7 for reducing the viscosity of a vegetable glue temporary plugging glue plug base fluid. 9 .

9 . The vegetable glue temporary plugging plug precursor mixture according to claim 8 , wherein the volume ratio of the viscosity reducing agent to the vegetable glue is 0.8-1.5:5. 10 .

10. The vegetable gum temporary plugging plug precursor mixture according to claim 8 or 9, wherein the vegetable gum comprises guar gum and its derivatives, coumarin and its derivatives, and succulent gum. one or a combination of several.

11. A vegetable glue temporary plugging base liquid, comprising the vegetable glue temporary plugging precursor mixture according to any one of claims 8-10 and water.

12 . The vegetable glue temporary plugging base liquid according to claim 11 , wherein the amount of the vegetable glue temporary plugging precursor mixture is 5-10% of the water volume. 13 .

13. The plant glue temporary plugging base fluid of claim 11 or 12 is used for re-fracturing in old wells, unconventional reservoir volume fracturing, vertical well split-layer fracturing, horizontal well staged fracturing and complex situation wells. Retrofit applications.