阅读说明：本技术 低温井固井用前置隔离液及其制备方法 (Pre-spacer fluid for low-temperature well cementation and preparation method thereof ) 是由 陆长青 彭金龙 闫联国 王冲 陈滨 姚文强 刘军康 徐杨 李全双 韩双艳 于 2021-07-08 设计创作，主要内容包括：本发明涉及一种低温井固井用前置隔离液及其制备方法,原料组分如下,水400份、悬浮剂2份、表面活性剂4份、防塌隔离剂：12-20份和重晶石粉180-490份；防塌隔离剂的制备步骤：将100份水升温后加入4份辛基酚聚氧乙烯醚,加入18-22份乙烯基三乙氧基硅烷,搅拌得到有机硅预聚合乳液；将2份十二烷基苯磺酸钠溶于100份水中,滴加丙烯酸醋单体得到预乳化液A,单体为预混合的9-11份甲基丙烯酸甲酯、18-22份丙烯酸丁酯和4份甲基丙烯酸羟乙酯；向100份水中加入0.3-0.5份过硫酸钾配置成溶液B；将有机硅预聚合乳液缓慢滴加预乳化液A和溶液B,用三乙醇胺将pH值调节至7-8,得到防塌隔离剂JS-1。本发明的隔离液具有很好的防塌性能,能够保护井眼的安全,冲洗效果好,携带泥饼的能力强。(The invention relates to a preposed spacer fluid for low-temperature well cementation and a preparation method thereof, wherein the raw materials comprise 400 parts of water, 2 parts of suspending agent, 4 parts of surfactant and anti-collapse spacer agent: 12-20 parts of barite powder and 180-490 parts of barite powder; the preparation method of the anti-collapse release agent comprises the following steps: heating 100 parts of water, adding 4 parts of octylphenol polyoxyethylene ether, adding 18-22 parts of vinyl triethoxysilane, and stirring to obtain an organic silicon prepolymerization emulsion; dissolving 2 parts of sodium dodecyl benzene sulfonate in 100 parts of water, and dropwise adding an acrylic acid-acetic monomer to obtain a pre-emulsion A, wherein the monomer is premixed 9-11 parts of methyl methacrylate, 18-22 parts of butyl acrylate and 4 parts of hydroxyethyl methacrylate; adding 0.3-0.5 part of potassium persulfate into 100 parts of water to prepare solution B; slowly and dropwise adding the pre-emulsion A and the solution B into the organic silicon pre-polymerization emulsion, and adjusting the pH value to 7-8 by using triethanolamine to obtain the anti-collapse separant JS-1. The isolation liquid has good anti-collapse performance, can protect the safety of a well hole, has good flushing effect and strong mud cake carrying capacity.)

1. The preposed isolating fluid for well cementation of the low-temperature well is characterized by comprising the following raw material components in parts by weight: 400 parts of suspending agent TAS 155: 2 parts of surfactant XP-1: 4 parts of an anti-collapse release agent JS-1: 12-20 parts of barite powder: 180-490 parts; the anti-collapse release agent JS-1 comprises the following raw material components in percentage by weight, and deionized water: 300 parts of octyl phenol polyoxyethylene ether: 4 parts of vinyltriethoxysilane: 18-22 parts of sodium dodecyl benzene sulfonate: 2 parts of methyl methacrylate: 9-11 parts of butyl acrylate: 18-22 parts of hydroxyethyl methacrylate: 4 parts and potassium persulfate: 0.3-0.5 part.

2. The pad spacer fluid for well cementation according to claim 1, wherein the pad spacer fluid comprises the following raw materials in percentage by weight: 400 parts of suspending agent TAS 155: 2 parts of surfactant XP-1: 4 parts of an anti-collapse release agent JS-1: 12 parts of barite powder: 180 parts of (A); the anti-collapse release agent JS-1 comprises the following raw material components in percentage by weight, and deionized water: 300 parts of octyl phenol polyoxyethylene ether: 4 parts of vinyltriethoxysilane: 18 parts of sodium dodecyl benzene sulfonate: 2 parts of methyl methacrylate: 9 parts of butyl acrylate: 18 parts of hydroxyethyl methacrylate: 4 parts and potassium persulfate: 0.3 part.

3. The pad spacer fluid for well cementation according to claim 1, wherein the pad spacer fluid comprises the following raw materials in percentage by weight: 400 parts of suspending agent TAS 155: 2 parts of surfactant XP-1: 4 parts of an anti-collapse release agent JS-1: 16 parts of barite powder: 300 parts of (A); the anti-collapse release agent JS-1 comprises the following raw material components in percentage by weight, and deionized water: 300 parts of octyl phenol polyoxyethylene ether: 4 parts of vinyltriethoxysilane: 20 parts of sodium dodecyl benzene sulfonate: 2 parts of methyl methacrylate: 10 parts of butyl acrylate: 20 parts of hydroxyethyl methacrylate: 4 parts and potassium persulfate: 0.4 part.

4. The pad spacer fluid for well cementation according to claim 1, wherein the pad spacer fluid comprises the following raw materials in percentage by weight: 400 parts of suspending agent TAS 155: 2 parts of surfactant XP-1: 4 parts of an anti-collapse release agent JS-1: 20 parts of barite powder: 490 parts; the anti-collapse release agent JS-1 comprises the following raw material components in percentage by weight, and deionized water: 300 parts of octyl phenol polyoxyethylene ether: 4 parts of vinyltriethoxysilane: 22 parts of sodium dodecyl benzene sulfonate: 2 parts of methyl methacrylate: 11 parts and butyl acrylate: 22 parts of hydroxyethyl methacrylate: 4 parts and potassium persulfate: 0.5 part.

5. The preparation method of the preposed isolating fluid for low-temperature well cementation is characterized in that the preposed isolating fluid comprises the following raw material components in parts by weight: 400 parts of suspending agent TAS 155: 2 parts of surfactant XP-1: 4 parts of an anti-collapse release agent JS-1: 12-20 parts of barite powder: 180-490 parts; the preparation method of the anti-collapse release agent JS-1 sequentially comprises the following steps: firstly, heating 100 parts of deionized water to 70 ℃, adding 4 parts of octylphenol polyoxyethylene ether, cooling to 60 ℃, adding 18-22 parts of vinyl triethoxysilane, preserving heat, stirring for 2 hours, stirring for 20 minutes at the rotation speed of 300-500rpm, stirring for 30 minutes at the rotation speed of 300rpm, and stirring for 200rpm at the stirring rotation speed of 150-200rpm at the rest of time to obtain an organic silicon prepolymerization emulsion; dissolving 2 parts of sodium dodecyl benzene sulfonate in 100 parts of deionized water, then dropwise adding an acrylic acid-acetic monomer, wherein the acrylic acid-acetic monomer is premixed with 9-11 parts of methyl methacrylate, 18-22 parts of butyl acrylate and 4 parts of hydroxyethyl methacrylate, and stirring for 0.5 hour at a rotating speed of more than 300rpm to obtain a pre-emulsion A; thirdly, adding 0.3-0.5 part of potassium persulfate into 100 parts of deionized water to prepare a solution B; stirring the organic silicon pre-polymerization emulsion at the rotating speed of 300rpm, heating to 70 ℃, slowly dropwise adding the pre-emulsion A and the solution B, finishing dropwise adding within 1 hour, heating to 80 ℃, stirring at the rotating speed of 150rpm and 200rpm, keeping the temperature for 2 hours, and cooling to below 40 ℃; and fifthly, regulating the pH value to 7-8 by using triethanolamine to obtain the collapse preventing separant JS-1.

6. The preparation method of the pre-spacer fluid for the low-temperature well cementation as claimed in claim 5, wherein the pre-spacer fluid comprises the following raw material components in percentage by weight: 400 parts of suspending agent TAS 155: 2 parts of surfactant XP-1: 4 parts of an anti-collapse release agent JS-1: 12 parts of barite powder: 180 parts of (A); the anti-collapse release agent JS-1 comprises the following raw material components in percentage by weight, and deionized water: 300 parts of octyl phenol polyoxyethylene ether: 4 parts of vinyltriethoxysilane: 18 parts of sodium dodecyl benzene sulfonate: 2 parts of methyl methacrylate: 9 parts of butyl acrylate: 18 parts of hydroxyethyl methacrylate: 4 parts and potassium persulfate: 0.3 part.

7. The preparation method of the pre-spacer fluid for the low-temperature well cementation as claimed in claim 5, wherein the pre-spacer fluid comprises the following raw materials in percentage by weight: 400 parts of suspending agent TAS 155: 2 parts of surfactant XP-1: 4 parts of an anti-collapse release agent JS-1: 16 parts of barite powder: 300 parts of (A); the anti-collapse release agent JS-1 comprises the following raw material components in percentage by weight, and deionized water: 300 parts of octyl phenol polyoxyethylene ether: 4 parts of vinyltriethoxysilane: 20 parts of sodium dodecyl benzene sulfonate: 2 parts of methyl methacrylate: 10 parts of butyl acrylate: 20 parts of hydroxyethyl methacrylate: 4 parts and potassium persulfate: 0.4 part.

8. The preparation method of the pre-spacer fluid for the low-temperature well cementation as claimed in claim 5, wherein the pre-spacer fluid comprises the following raw materials in percentage by weight: 400 parts of suspending agent TAS 155: 2 parts of surfactant XP-1: 4 parts of an anti-collapse release agent JS-1: 20 parts of barite powder: 490 parts; the anti-collapse release agent JS-1 comprises the following raw material components in percentage by weight, and deionized water: 300 parts of octyl phenol polyoxyethylene ether: 4 parts of vinyltriethoxysilane: 22 parts of sodium dodecyl benzene sulfonate: 2 parts of methyl methacrylate: 11 parts and butyl acrylate: 22 parts of hydroxyethyl methacrylate: 4 parts and potassium persulfate: 0.5 part.

Technical Field

The invention relates to oil and gas well cementation, in particular to a preposed spacer fluid for low-temperature well cementation; the invention also relates to a preparation method of the preposed spacer fluid for low-temperature well cementation, belonging to the technical field of oil and gas well cementation.

Background

The oil well cement used in the existing well cementation is silicate oil well cement, and has the outstanding problems that the setting time of cement paste is long, the strength development is slow, and especially under the condition of a shallow well, because the well is shallow and the ground temperature is low, the cement paste is difficult to form high enough strength in the normal required waiting setting time, and the production and exploitation requirements cannot be met.

When well cementation is carried out, after a well hole and an annular space are cleaned through circulation of drilling fluid, the preposed spacer fluid needs to be injected into a casing string firstly, then well cementation cement slurry is injected to reach the designed well cementation amount, and the preposed spacer fluid isolates the drilling fluid from the well cementation cement slurry. For years, researchers in various countries deeply research the preposed isolating liquid aiming at the problem of well cementation under the low-temperature condition, and develop a plurality of novel isolating liquids, thereby obtaining abundant research results and greatly developing the low-temperature well cementation technology.

The low-temperature isolating liquid system commonly used at present is mainly a flushing type isolating liquid, the main component is water, and a high-efficiency flushing agent and a tackifier are added into the water, so that the isolating liquid has poor isolating effect, large water loss, low rock debris carrying efficiency and low suspension capacity, and is easy to cause formation damage or failure of well cementation operation.

Disclosure of Invention

The invention aims to overcome the defects in the prior art, and provides the preposed isolating fluid for low-temperature well cementation, which can well isolate drilling fluid and well cementation cement slurry, has good anti-collapse performance, can protect the safety of a well bore, has good flushing effect on a casing and the well bore, strong mud cake carrying capacity and good displacement effect on the drilling fluid.

In order to solve the technical problems, the invention provides a preposed isolating fluid for low-temperature well cementation, which comprises the following raw material components in parts by weight: 400 parts of suspending agent TAS 155: 2 parts of surfactant XP-1: 4 parts of an anti-collapse release agent JS-1: 12-20 parts of barite powder: 180-490 parts; the anti-collapse release agent JS-1 comprises the following raw material components in percentage by weight, and deionized water: 300 parts of octyl phenol polyoxyethylene ether: 4 parts of vinyltriethoxysilane: 18-22 parts of sodium dodecyl benzene sulfonate: 2 parts of methyl methacrylate: 9-11 parts of butyl acrylate: 18-22 parts of hydroxyethyl methacrylate: 4 parts and potassium persulfate: 0.3-0.5 part.

As a preferable scheme of the invention, the preposed isolating liquid comprises the following raw material components in percentage by weight: 400 parts of suspending agent TAS 155: 2 parts of surfactant XP-1: 4 parts of an anti-collapse release agent JS-1: 12 parts of barite powder: 180 parts of (A); the anti-collapse release agent JS-1 comprises the following raw material components in percentage by weight, and deionized water: 300 parts of octyl phenol polyoxyethylene ether: 4 parts of vinyltriethoxysilane: 18 parts of sodium dodecyl benzene sulfonate: 2 parts of methyl methacrylate: 9 parts of butyl acrylate: 18 parts of hydroxyethyl methacrylate: 4 parts and potassium persulfate: 0.3 part.

As a preferable scheme of the invention, the preposed isolating liquid comprises the following raw material components in percentage by weight: 400 parts of suspending agent TAS 155: 2 parts of surfactant XP-1: 4 parts of an anti-collapse release agent JS-1: 16 parts of barite powder: 300 parts of (A); the anti-collapse release agent JS-1 comprises the following raw material components in percentage by weight, and deionized water: 300 parts of octyl phenol polyoxyethylene ether: 4 parts of vinyltriethoxysilane: 20 parts of sodium dodecyl benzene sulfonate: 2 parts of methyl methacrylate: 10 parts of butyl acrylate: 20 parts of hydroxyethyl methacrylate: 4 parts and potassium persulfate: 0.4 part.

As a preferable scheme of the invention, the preposed isolating liquid comprises the following raw material components in percentage by weight: 400 parts of suspending agent TAS 155: 2 parts of surfactant XP-1: 4 parts of an anti-collapse release agent JS-1: 20 parts of barite powder: 490 parts; the anti-collapse release agent JS-1 comprises the following raw material components in percentage by weight, and deionized water: 300 parts of octyl phenol polyoxyethylene ether: 4 parts of vinyltriethoxysilane: 22 parts of sodium dodecyl benzene sulfonate: 2 parts of methyl methacrylate: 11 parts and butyl acrylate: 22 parts of hydroxyethyl methacrylate: 4 parts and potassium persulfate: 0.5 part.

Compared with the prior art, the invention has the following beneficial effects: 1. the suspending agent TAS155 can increase the viscosity and the suspension performance of the spacer fluid, form a certain viscosity difference with the drilling fluid, and is beneficial to the later-stage displacement efficiency; the surfactant XP-1 can eliminate bubbles generated in the preparation process of the spacer fluid; the anti-collapse release agent JS-1 can increase the compatibility among the drilling fluid, the release fluid and the cement paste, and avoid the occurrence of accelerated setting after the mixing of the drilling fluid, the release fluid and the cement paste, which leads to the construction failure; the barite powder is used to pre-adjust the density of the spacer fluid. 2. The prevalence index of the preposed isolation liquid is less than 0.7, the preposed isolation liquid has good advantages in rheology and mud cake carrying, has good anti-collapse performance, and can protect the safety of well construction; 3. the flushing efficiency of the preposed spacer fluid on the oil-based drilling fluid is up to more than 97 percent, loose mud cakes on a well wall and a sleeve can be more effectively flushed, the well can be further cleaned, and the cementing strength of a cement sheath and a first cementing surface of the sleeve and a second cementing surface of the well can be improved; 4. the rheological property under the low temperature condition is good, and the rheological property is good, thereby being beneficial to displacing drilling fluid.

The invention also aims to overcome the defects in the prior art and provide a preparation method of the preposed isolating fluid for low-temperature well cementation, the prepared preposed isolating fluid can well isolate drilling fluid and well cementation cement slurry, has good anti-collapse performance, can protect the safety of a well hole, has good flushing effect on a casing and the well hole, strong mud cake carrying capacity and good displacement effect on the drilling fluid.

In order to solve the technical problems, the invention provides a preparation method of a preposed isolating fluid for low-temperature well cementation, which comprises the following raw material components in parts by weight: 400 parts of suspending agent TAS 155: 2 parts of surfactant XP-1: 4 parts of an anti-collapse release agent JS-1: 12-20 parts of barite powder: 180-490 parts; the preparation method of the anti-collapse release agent JS-1 sequentially comprises the following steps: firstly, heating 100 parts of deionized water to 70 ℃, adding 4 parts of octylphenol polyoxyethylene ether, cooling to 60 ℃, adding 18-22 parts of vinyl triethoxysilane, preserving heat, stirring for 2 hours, stirring for 20 minutes at the rotation speed of 300-500rpm, stirring for 30 minutes at the rotation speed of 300rpm, and stirring for 200rpm at the stirring rotation speed of 150-200rpm at the rest of time to obtain an organic silicon prepolymerization emulsion; dissolving 2 parts of sodium dodecyl benzene sulfonate in 100 parts of deionized water, then dropwise adding an acrylic acid-acetic monomer, wherein the acrylic acid-acetic monomer is premixed with 9-11 parts of methyl methacrylate, 18-22 parts of butyl acrylate and 4 parts of hydroxyethyl methacrylate, and stirring for 0.5 hour at a rotating speed of more than 300rpm to obtain a pre-emulsion A; thirdly, adding 0.3-0.5 part of potassium persulfate into 100 parts of deionized water to prepare a solution B; stirring the organic silicon pre-polymerization emulsion at the rotating speed of 300rpm, heating to 70 ℃, slowly dropwise adding the pre-emulsion A and the solution B, finishing dropwise adding within 1 hour, heating to 80 ℃, stirring at the rotating speed of 150rpm and 200rpm, keeping the temperature for 2 hours, and cooling to below 40 ℃; and fifthly, regulating the pH value to 7-8 by using triethanolamine to obtain the collapse preventing separant JS-1.

As a preferable scheme of the invention, the preposed isolating liquid comprises the following raw material components in percentage by weight: 400 parts of suspending agent TAS 155: 2 parts of surfactant XP-1: 4 parts of an anti-collapse release agent JS-1: 12 parts of barite powder: 180 parts of (A); the anti-collapse release agent JS-1 comprises the following raw material components in percentage by weight, and deionized water: 300 parts of octyl phenol polyoxyethylene ether: 4 parts of vinyltriethoxysilane: 18 parts of sodium dodecyl benzene sulfonate: 2 parts of methyl methacrylate: 9 parts of butyl acrylate: 18 parts of hydroxyethyl methacrylate: 4 parts and potassium persulfate: 0.3 part.

As a preferable scheme of the invention, the preposed isolating liquid comprises the following raw material components in percentage by weight: 400 parts of suspending agent TAS 155: 2 parts of surfactant XP-1: 4 parts of an anti-collapse release agent JS-1: 16 parts of barite powder: 300 parts of (A); the anti-collapse release agent JS-1 comprises the following raw material components in percentage by weight, and deionized water: 300 parts of octyl phenol polyoxyethylene ether: 4 parts of vinyltriethoxysilane: 20 parts of sodium dodecyl benzene sulfonate: 2 parts of methyl methacrylate: 10 parts of butyl acrylate: 20 parts of hydroxyethyl methacrylate: 4 parts and potassium persulfate: 0.4 part.

As a preferable scheme of the invention, the preposed isolating liquid comprises the following raw material components in percentage by weight: 400 parts of suspending agent TAS 155: 2 parts of surfactant XP-1: 4 parts of an anti-collapse release agent JS-1: 20 parts of barite powder: 490 parts; the anti-collapse release agent JS-1 comprises the following raw material components in percentage by weight, and deionized water: 300 parts of octyl phenol polyoxyethylene ether: 4 parts of vinyltriethoxysilane: 22 parts of sodium dodecyl benzene sulfonate: 2 parts of methyl methacrylate: 11 parts and butyl acrylate: 22 parts of hydroxyethyl methacrylate: 4 parts and potassium persulfate: 0.5 part.

Compared with the prior art, the invention has the following beneficial effects: 1. the suspending agent TAS155 can increase the viscosity and the suspension performance of the spacer fluid, form a certain viscosity difference with the drilling fluid, and is beneficial to the later-stage displacement efficiency; the surfactant XP-1 can eliminate bubbles generated in the preparation process of the spacer fluid; the anti-collapse release agent JS-1 can increase the compatibility among the drilling fluid, the release fluid and the cement paste, and avoid the occurrence of accelerated setting after the mixing of the drilling fluid, the release fluid and the cement paste, which leads to the construction failure; the barite powder is used to pre-adjust the density of the spacer fluid. 2. The prevalence index of the preposed isolation liquid is less than 0.7, the preposed isolation liquid has good advantages in rheology and mud cake carrying, has good anti-collapse performance, and can protect the safety of well construction; 3. the flushing efficiency of the preposed spacer fluid on the oil-based drilling fluid is up to more than 97 percent, loose mud cakes on a well wall and a sleeve can be more effectively flushed, the well can be further cleaned, and the cementing strength of a cement sheath and a first cementing surface of the sleeve and a second cementing surface of the well can be improved; 4. the rheological property under the low temperature condition is good, and the rheological property is good, thereby being beneficial to displacing drilling fluid.

Drawings

FIG. 1 is a scanning electron micrograph of the surface and cross section of a filter cake according to an embodiment of the present invention.

FIG. 2 is a scanning electron micrograph of the surface and cross section of a filter cake according to example two of the present invention.

FIG. 3 is a scanning electron micrograph of the surface and cross section of a filter cake according to example three of the present invention.

FIG. 4 is a graph of water loss for API water loss measurements for examples one through three of the present invention and comparative examples.

Detailed Description

Example one

The preposed spacer fluid for low-temperature well cementation comprises the following raw material components in percentage by weight: 400 parts of suspending agent TAS 155: 2 parts of surfactant XP-1: 4 parts of an anti-collapse release agent JS-1: 12 parts of barite powder: 180 parts.

The preparation method of the anti-collapse release agent JS-1 sequentially comprises the following steps: the method comprises the steps of heating 100 parts of deionized water to 70 ℃, adding 4 parts of octylphenol polyoxyethylene ether, cooling to 60 ℃, adding 18 parts of vinyl triethoxysilane, preserving heat, stirring for 2 hours, stirring at 300rpm for 20 minutes, stirring at 300rpm for 30 minutes, and stirring at 150rpm for the rest of time to obtain silicone pre-polymerization emulsion;

dissolving 2 parts of sodium dodecyl benzene sulfonate in 100 parts of deionized water, and then dropwise adding an acrylic acid-acetic monomer, wherein the acrylic acid-acetic monomer is premixed with 9 parts of methyl methacrylate, 18 parts of butyl acrylate and 4 parts of hydroxyethyl methacrylate, and stirring for 0.5 hour at a rotating speed of more than 300rpm to obtain a pre-emulsion A;

thirdly, adding 0.3 part of potassium persulfate into 100 parts of deionized water to prepare a solution B;

stirring the organic silicon pre-polymerization emulsion at the rotating speed of 300rpm, heating to 70 ℃, slowly dropwise adding the pre-emulsion A and the solution B at the same time, after dropwise adding for 45 minutes, heating to 80 ℃, stirring at the rotating speed of 150rpm, keeping the temperature for 2 hours, and then cooling to 35 ℃;

and fifthly, regulating the pH value to 7 by using triethanolamine to obtain the collapse preventing separant JS-1.

Example two

The preposed spacer fluid for low-temperature well cementation comprises the following raw material components in percentage by weight: 400 parts of suspending agent TAS 155: 2 parts of surfactant XP-1: 4 parts of an anti-collapse release agent JS-1: 16 parts of barite powder: 300 parts.

The preparation method of the anti-collapse release agent JS-1 sequentially comprises the following steps: the preparation method comprises the steps of heating 100 parts of deionized water to 70 ℃, adding 4 parts of octylphenol polyoxyethylene ether, cooling to 60 ℃, adding 20 parts of vinyl triethoxysilane, preserving heat, stirring for 2 hours, stirring for 20 minutes at a rotating speed of 400rpm, stirring for 30 minutes at a rotating speed of 300rpm, and stirring for 180rpm in the rest of time to obtain silicone pre-polymerization emulsion;

dissolving 2 parts of sodium dodecyl benzene sulfonate in 100 parts of deionized water, and then dropwise adding an acrylic acid-acetic monomer, wherein the acrylic acid-acetic monomer is premixed with 10 parts of methyl methacrylate, 20 parts of butyl acrylate and 4 parts of hydroxyethyl methacrylate, and stirring at the rotating speed of 320rpm for 0.5 hour to obtain a pre-emulsion A;

thirdly, adding 0.4 part of potassium persulfate into 100 parts of deionized water to prepare a solution B;

stirring the organic silicon pre-polymerization emulsion at the rotating speed of 300rpm, heating to 70 ℃, slowly dropwise adding the pre-emulsion A and the solution B at the same time, after dropwise adding is completed within 50 minutes, heating to 80 ℃, stirring at the rotating speed of 180rpm, keeping the temperature for 2 hours, and then cooling to 40 ℃;

and fifthly, regulating the pH value to 7.5 by using triethanolamine to obtain the collapse preventing separant JS-1.

EXAMPLE III

The preposed spacer fluid for low-temperature well cementation comprises the following raw material components in percentage by weight: 400 parts of suspending agent TAS 155: 2 parts of surfactant XP-1: 4 parts of an anti-collapse release agent JS-1: 20 parts of barite powder: 490 parts.

The preparation method of the anti-collapse release agent JS-1 sequentially comprises the following steps: firstly, heating 100 parts of deionized water to 70 ℃, adding 4 parts of octylphenol polyoxyethylene ether, cooling to 60 ℃, adding 22 parts of vinyl triethoxysilane, preserving heat, stirring for 2 hours, stirring at a rotating speed of 500rpm for 20 minutes, then at a rotating speed of 300rpm for 30 minutes, and stirring at a rotating speed of 200rpm for the rest of time to obtain silicone pre-polymerization emulsion;

dissolving 2 parts of sodium dodecyl benzene sulfonate in 100 parts of deionized water, and then dropwise adding an acrylic acid-acetic monomer, wherein the acrylic acid-acetic monomer is premixed with 11 parts of methyl methacrylate, 22 parts of butyl acrylate and 4 parts of hydroxyethyl methacrylate, and stirring at the rotating speed of 350rpm for 0.5 hour to obtain a pre-emulsion A;

thirdly, adding 0.5 part of potassium persulfate into 100 parts of deionized water to prepare a solution B;

stirring the organic silicon pre-polymerization emulsion at the rotating speed of 300rpm, heating to 70 ℃, slowly dropwise adding the pre-emulsion A and the solution B at the same time, after dropwise adding for 1 hour, heating to 80 ℃, stirring at the rotating speed of 200rpm, keeping the temperature for 2 hours, and then cooling to 40 ℃;

and fifthly, regulating the pH value to 8 by using triethanolamine to obtain the collapse preventing separant JS-1.

Firstly, filtering the preposed spacer fluid in the first to third embodiments under medium pressure to obtain a filter cake, standing the filter cake at 30 ℃ for one day, and then carrying out scanning electron microscope analysis, wherein the scanning electron microscope pictures of the surface and the section of the filter cake are shown in figures 1 to 3.

As is clear from fig. 1 to 3, the filter cake surface has a clear milky film. As can be seen from the comparison of FIGS. 1 to 3, the coverage area of the membrane varies with the addition of the anti-collapse release agent JS-1, regardless of the surface or cross section of the filter cake. When 16 parts of the anti-collapse release agent JS-1 is added, the surface of the filter cake is basically and uniformly covered with a layer of film. When the addition of the anti-collapse release agent JS-1 is increased to 20 parts, the film covering the surface and the cross section of the filter cake is not obviously changed, so the formula of the second embodiment is most economical, and the anti-collapse performance is also good.

Secondly, the rheological properties of the pre-spacer fluids with different densities of the first to the third examples are tested at normal temperature and 60 ℃, and the test result data are shown in table 1:

。

wherein, n: prevalence index, K: consistency factor, η p: plastic viscosity,. tau.o: dynamic shear stress. It can be seen that the viscosity and shear force of the pre-spacer fluid increase with increasing density; the plastic viscosity and dynamic shear stress of the same composition pre-spacer fluid increase with increasing temperature. The rheological curve of the preposed isolating liquid is more regular under the condition of 60 ℃, the change of the n value is always in the range of 0.6-0.7, and the preposed isolating liquid has good rheological and mud cake carrying performances in the range. Compared with the common spacer fluid, the popularity index is less than that of the common formula, and the spacer fluid has good advantages in rheology and mud cake carrying.

Thirdly, investigating the suspension stability of the preposed isolating liquid with different densities: the pre-spacers of examples one to three were placed in a water bath at 60 ℃ for 8 hours at room temperature, and then the density of the pre-spacers was measured by taking the solutions from the upper, middle and lower three different sites, and the results are shown in table 2:

。

from the above table, it can be seen that the density difference of the upper, middle and lower parts of each group of the preposed isolating liquid is smaller after standing for 8 hours at normal temperature or 60 ℃, but the construction requirements can be met; compared with the common spacer fluid in the current market, the high-efficiency high-.

And fourthly, inspecting the API water loss amount of the preposed isolating liquid with different densities: the requirement for the water loss of the front spacer fluid is that the water loss is generally less than 150mL/(30min, 7 MPa). The low water loss has certain significance for controlling the collapse of the well wall and reducing the damage of the stratum, and the performance of the preposed spacer fluid can be kept unchanged, thereby better playing a role in well cementation construction.

When the pre-spacer fluids of the first to third examples were subjected to the API water loss test, the test results are shown in table 3, and it can be seen that the water loss is much lower than 150mL/(30min, 7 MPa):

。

the water loss profile was plotted for the test procedure at room temperature, as shown in fig. 4, and it can be seen that: along with the increase of the density of the preposed isolating liquid, the API water loss amount of the preposed isolating liquid is gradually reduced, the rapid increase of the water loss amount is concentrated in 5 minutes, and the increase of the water loss amount is obviously slowed after 5 minutes.

Fifthly, carrying out a washing efficiency evaluation experiment on the preposed isolating liquid in the second embodiment; firstly weighing an outer cylinder of a rheometer, wherein the weight of the outer cylinder is 153.83g, then soaking the outer cylinder of the rheometer in oil-based drilling fluid for 2min, taking out the outer cylinder and weighing when mud does not drip to obtain 161.66g, then flushing the outer cylinder on the rheometer for 10 min at the rotating speed of 300rpm by using the preposed isolating liquid of the second embodiment, taking out the outer cylinder, weighing when no liquid drips, wherein the weight of the outer cylinder is 154.06g, and the flushing efficiency is calculated as follows: (161.66-154.06)/(161.66-153.83) ≈ 100% 97.1%. The flushing efficiency of the spacer fluid on the oil-based drilling fluid reaches more than 80 percent, namely the spacer fluid is qualified, and the flushing efficiency of the spacer fluid is far higher than that of a conventional product.

Sixthly, investigating the compatibility of the preposed spacer fluid and the polysulfonate drilling fluid: the pre-spacer fluid and the polysulfonate drilling fluid of the second embodiment are sequentially mixed according to the proportion and the sequence in the following table, and are fully stirred and mixed on a high-speed stirrer, and then the pre-spacer fluid and the polysulfonate drilling fluid are transferred to a rotational viscometer for measuring the rheological property, and the data of the test results are shown in table 4:

。

it can be seen from table 4 that the dynamic shear stress τ o of the drilling fluid is reduced by adding the pre-spacer fluid, and the dynamic shear stress τ o is smaller than that of the drilling fluid raw stock after mixing in any proportion, which shows that the pre-spacer fluid of the invention not only can not increase the dynamic shear stress value of the drilling fluid, but also has the function of reducing the dynamic shear force of the drilling fluid, and the pre-spacer fluid is directly contacted with the drilling fluid before the well cementation cement slurry in the displacement process, so that the shear force of the displaced drilling fluid can be reduced, the flow resistance is reduced, and the displacement of the drilling fluid is facilitated.

In the invention, the suspending agent TAS155 adopts the product of Tianjin BaoEn petroleum engineering technology Limited company, and the execution standard is as follows: Q/SH 1025-0861. The surfactant XP-1 adopts a product of Weihui chemical company Limited and implements the standard: Q/SHCG-32. The barite powder is prepared from the product of Xinzheng Meijiu industry Co., Ltd, Zhengzhou city, and meets GB/T5005-1994 standard.

The products of Shanghai national medicine group chemical reagent company Limited can be adopted as the octyl phenol polyoxyethylene ether OP-10, the vinyl triethoxysilane VETS, the sodium dodecyl benzene sulfonate SDBS, the potassium persulfate KPS, the triethanolamine TEA, the methyl methacrylate MMA, the butyl acrylate BA and the hydroxyethyl methacrylate HEMA.