WO2022007390A1

WO2022007390A1 - Solid-free and high-density completion fluid and preparation method therefor

Info

Publication number: WO2022007390A1
Application number: PCT/CN2021/074111
Authority: WO
Inventors: 王冲敏; 苗海龙; 孙强; 李自立; 耿铁; 罗鸣; 张红生; 胡永堂; 陈波; 张万栋
Original assignee: 中海油田服务股份有限公司; 天津中海油服化学有限公司
Priority date: 2020-07-07
Filing date: 2021-01-28
Publication date: 2022-01-13
Also published as: CN111778002A; CN111778002B

Abstract

A solid-free and high-density completion fluid, comprising water, calcium bromide, zinc chloride and an imidazoline additive, wherein the mass ratio of the water, the calcium bromide, the zinc chloride and the imidazoline additive is 10:(22 to 24):(21 to 22):(0.1325 to 0.14). By compounding the calcium bromide and zinc chloride and adding an imidazoline additive, a high-temperature resistant, high-density and solid-free completion fluid which has a density greater than that of calcium bromide or zinc chloride when separately dissolved in water to reach saturation is prepared, such that the density of the completion fluid is (2.002-2.037)g/cm 3, the solution fluidity is good, the apparent viscosity is ≤ 19.50 mPa.s, the corrosion rate on 13 Cr steel test piece is ≦ 0.0333 mm/a at 200ºC under normal pressure, the clay anti-swelling rate is ≥ 87.0%, the solution is transparent and colorless, and the turbidity is ≤ 28.5NTU, thus providing strong science and technology support for the completion and workover of ultra-deep high-temperature oil and gas wells.

Description

A kind of solid-free high-density completion fluid and preparation method thereof

technical field

This article relates to, but is not limited to, the field of completion in oil and natural gas exploitation, and specifically relates to, but is not limited to, a solid-free high-density completion fluid and its preparation method.

Background technique

Completion fluid is mainly used in various operations of completion and workover in oil and natural gas exploitation. It is a kind of production fluid with a large amount of fluid and is closely related to the protection of reservoir performance and oil layer pollution. Before the formation is officially put into production, any liquid used in contact with the production formation due to operational needs is called completion fluid, and completion fluid includes workover fluid in a broad sense. Fluids used in operations to maintain or increase productivity from the start of production are collectively referred to as workover fluids. The main function of the completion fluid is to meet the temperature and pressure requirements of the well used, suppress the well, and prevent the downhole oil and gas flow from blowing out. Therefore, the first requirement is the density and temperature resistance of the completion fluid, and at the same time, it requires little damage to the reservoir. .

The solid-free completion fluid is a high-density liquid obtained by adding soluble salts to water to meet the reservoir pressure. Such salts are called weighting agents. The most commonly used completion fluid weighting agents are: NaCl, KCl, CaCl ₂ , CaBr ₂ , ZnCl ₂ , ZnBr ₂ , potassium pyrophosphate, HCOONa, HCOOK and HCOOCs (cesium formate), etc.

At room temperature, with NaCl, KCl, CaCl _2, and weighting agents may be formulated as HCOONa density (1.05 to 1.39) g cm aqueous / ^3; HCOOK may be formulated with ≤1.57g / cm ³ density of the aqueous solution; may be formulated with CaBr ₂ density ≤1.68g / cm ³ of an aqueous solution; potassium pyrophosphate may be formulated with ≤1.72g / cm ³ density of the aqueous solution; ZnBr ₂ may be formulated with an aqueous solution of density 2.00 to 2.45g / cm ^3; and cesium may be formulated with a density ≤2.367 g/cm ³ aqueous solution, these solutions are all transparent solutions, and if the amount of these salts is increased, the solution becomes cloudy and becomes translucent and opaque solutions. Although https://www.chemicalbook.com describes _{the dissolved grams of ZnCl 2} per 100 ml of water: 395g/20°C, 432g/25°C, in fact, using GR grade ZnCl ₂ with a purity of 98% at room temperature only The transparent aqueous solution with density ≤ 1.85g/cm ³ can be prepared, and if the addition of these salts is also increased, the solution becomes turbid and becomes translucent pale white and opaque milky white solution. Present research density ≤1.70g / cm ³ of the completion fluid is ripe, however, few studies on the density of 2.0g / cm ³ of completion fluids, can increase the density of the weighting agent has only ZnBr _2, Cesium formate and its complex salts with organic salts. Although ZnBr ₂ can aggravate the aqueous solution to a density ^{above 2.0 g/cm 3} , it is not widely used due to its serious corrosion to oil pipes. Cesium formate has attracted widespread attention due to its excellent weighting properties and low corrosiveness. Cesium formate can be configured ^{with solutions with a maximum density of 2.367 g/cm 3} (Jian Weiwei, Xu Tongtai, Zhao Zhongju, Wang Chao, cesium formate and other formate brine solutions) The physical and chemical properties of [J]. Oilfield Chemistry, 2010, 27(1): 100-105), the use of ^{cesium formate aqueous solution with a density greater than (1.80 to 2.19) g/cm 3} as a completion fluid has been used in the North Sea area, European continent , South America, Gulf of Mexico and Asia Pacific and other oilfield applications, the effect is good. Cesium formate brine is an organic brine solution, which is less corrosive to drilling tools and oil and gas pipelines, but is expensive, which limits its application.

With the improvement of drilling technology, deep, ultra-deep well developed, these ultra-deep well completion fluid density and higher requirements temperature, but density ≥2.0g / cm ^3, the temperature reached 200 ℃ solids free completion fluid There is very little technical coverage. If the above-mentioned problems of the existing weighting agents can be solved, they will be widely used.

SUMMARY OF THE INVENTION

The application provides a high temperature resistant and high density solid-free completion fluid compounded by calcium bromide, zinc chloride and imidazoline additives, which overcomes the problem of using zinc chloride alone to dissolve in water and increase the density to 1.85 at normal temperature. After g/cm ³ , it will no longer dissolve, and then add zinc chloride solution to become milky white, the density of calcium bromide saturated aqueous solution is only 1.68g/cm ³ , and neither zinc chloride nor calcium bromide can be used to prepare density ≥ 2.0g/cm ^3. The problem of transparent completion fluid.

The application provides a solid-free high-density completion fluid, comprising: water, calcium bromide, zinc chloride and imidazoline additives; the water, the calcium bromide, the zinc chloride and the imidazole The mass ratio of morphine additive is 10:(22 to 24):(21 to 22):(0.1325 to 0.14); Optionally, the solid-free high-density completion fluid is composed of water, calcium bromide, zinc chloride and imidazoline additives.

The mass concentration of imidazoline in the imidazoline additive is 25.0 wt.% to 40.0 wt.%, preferably, the mass concentration of imidazoline is 35.0 wt.%.

In the solid-free high-density completion fluid provided in the examples of this application, the imidazoline in the imidazoline additive is an oleic acid-based imidazoline synthesized from oleic acid and polyvinylpolyamine;

Or, the imidazoline in the imidazoline additive is purchased from Fukang Chemical Technology Development Co., Ltd., Guanghan City, Sichuan Province, and the trade name is WD-72B.

In the solid-free high-density completion fluid provided in the embodiments of the present application, the preparation method of the oleic imidazoline includes:

a) add water-carrying agent, oleic acid and polyethylene polyamine in the reaction vessel, mix and stir to obtain a mixture;

b) heating and adjusting the temperature of the mixture to 140°C to 180°C, and the reaction time is 1.0h to 2.0h; the preferred temperature is 160°C, and the preferred reaction time is 1.5h;

c) adjust the temperature of the mixture by heating to 180°C to 240°C, and react for 4.5h to 7.5h; the preferred temperature is 220°C, and the preferred reaction time is 6.5h;

d) cooling the product in the reaction vessel heated in step c) to room temperature to obtain oleic imidazoline.

The preparation method of the oleic imidazoline can be composed of the above steps.

In the solid-free high-density completion fluid provided in the examples of the present application, the molar ratio of the oleic acid and polyethylene polyamine is 1.0: (1.2 to 1.3), and the consumption of the water-carrying agent is 30wt. %.

In the solid-free high-density completion fluid provided in the embodiments of the present application, the reaction vessel includes a condenser, and the condenser is configured to remove the water and water-carrying agent generated by the reaction.

In the solid-free high-density completion fluid provided in the embodiments of the present application, the polyethylene polyamine may be selected from any one or more of diethylenetriamine, triethylenetetramine and tetraethylenepentamine.

In the solid-free high-density completion fluid provided in the embodiments of the present application, the water-carrying agent may be xylene.

In the solid-free high-density completion fluid provided in the embodiments of the present application, the solvent of the imidazoline additive is selected from any one or more of methanol, isopropanol and ethanol.

In the solid-free high-density completion fluid provided in the embodiment of the present application, the water is fresh water; the salinity of the water may be ≤1000 mg/L.

In the solid-free high-density completion fluid provided in the embodiments of the present application, the density of the completion fluid ranges from 2.002 g/cm ³ to 2.037 g/cm ³ ; the apparent viscosity of the completion fluid may be 7.50 mPa .s to 19.50mPa.s; the anti-swelling rate can be 87.0% to 91.9%; the turbidity of the completion fluid can be 5.7NTU to 28.5NTU; the corrosion rate of 13Cr coupons at 200°C and normal pressure can be 0.0166 mm/a to 0.0333mm/a.

In another aspect, the present application provides the above-mentioned preparation method of solid-free high-density completion fluid, comprising:

1) in reaction vessel, add described water and described calcium bromide, stir until calcium bromide dissolves completely, form solution;

2) mixing the solution obtained in step 1) with the zinc chloride until the zinc chloride is completely dissolved to form a solution;

3) Stir the solution obtained in step 2) and the imidazoline additive evenly to obtain a solid phase-free high-density completion fluid.

The preparation method of the solid-free high-density completion fluid may consist of the above steps.

In the preparation method provided in the examples of this application, after the calcium bromide in step 1) is completely dissolved, the zinc chloride in step 2) is immediately added.

In the preparation method provided in the embodiment of the present application, the stirring rate of the stirring in step 1) is 300 to 2000 rpm, preferably, the stirring rate is 1000 rpm.

In the preparation method provided in the examples of the present application, the solution in step 3) is first cooled to room temperature and then stirred evenly with the imidazoline additive.

In the preparation method provided in the embodiment of the present application, the stirring rate of the stirring in step 3) is 300 rpm to 2000 rpm, preferably, the stirring rate is 1000 rpm.

In the preparation method provided in the embodiment of the present application, the solution formed in step 1) is translucent and light white, and the turbidity of the solution is 70.0 NTU to 130.0 NTU; the solution formed in step 2) can be a colorless and transparent solution; The solution formed in step 3) can be a colorless transparent solution;

In the preparation method provided in the examples of this application, preferably, the turbidity of the solution formed in the step 2) is 3.2 NTU to 21.3 NTU; preferably, the solution formed in the step 3) is a colorless and transparent solution, and the turbidity 5.7NTU to 28.5NTU.

The present application achieves the following technical effects:

1. Overcome the single use of zinc chloride dissolved in water at room temperature and weighted to a density of 1.85g/cm ³ and no longer dissolved to make the solution milky white; the density of saturated calcium bromide aqueous solution is only 1.68g/cm ³ , using a separate chlorine zinc bromide and calcium can not be formulated ≥2.0g / cm clear completion fluid density problem ³ by calcium bromide and zinc chloride complex, and a density greater than calcium bromide, zinc chloride dissolved in water was prepared separately A high temperature resistant high density solids-free completion fluid with a density at saturation such that the density of the completion fluid is (2.002 to 2.037) g/cm ³ . Provide technical support for ultra-deep well completion and workover.

2. Add imidazoline additives to the solution of calcium bromide or zinc chloride, and the obtained solution has a higher corrosion rate on 13Cr steel coupons at 200 ° C, but in this application, calcium bromide and zinc chloride are compounded and then imidazole is added. The addition of linoline can meet the needs of high temperature and ultra-deep wells at 200 °C. The corrosion of 13Cr steel coupons at 200 °C is smaller than that of calcium bromide and zinc chloride solutions alone. The corrosion rate of the completion fluid provided in this application is ≤0.0333mm/a .

3. The high-temperature and high-density solid-free completion fluid provided by this application has good fluidity and an apparent viscosity of ≤19.50mPa.s; at the same time, it has excellent clay anti-swelling performance, with an anti-swelling rate of ≥87.0%.

Other features and advantages of the present application will be set forth in the description which follows, and in part will be apparent from the description, or may be learned by practice of the present application. Other advantages of the present application may be realized and obtained by the inventions described in the specification.

detail

In order to make the objectives, technical solutions and advantages of the present application clearer, the embodiments of the present application are described in detail below. It should be noted that, the embodiments in the present application and the features in the embodiments may be arbitrarily combined with each other if there is no conflict.

The embodiments of the present application provide a solid-free high-density completion fluid, comprising: water, calcium bromide, zinc chloride and imidazoline additives; the water, the calcium bromide, the zinc chloride and the The mass ratio of the imidazoline additive is 10:(22 to 24):(21 to 22):(0.1325 to 0.14);

In the embodiments of the present application, the preparation method of the oleic imidazoline comprises:

In the examples of the present application, the molar ratio of the oleic acid and the polyethylene polyamine is 1.0:(1.2 to 1.3), and the amount of the water-carrying agent is 30 wt.% of the mass of the oleic acid.

In the embodiments of the present application, the reaction vessel includes a condenser, and the condenser is configured to remove the water and water-carrying agent produced by the reaction.

In the embodiments of the present application, the polyethylene polyamine may be selected from any one or more of diethylenetriamine, triethylenetetramine and tetraethylenepentamine.

In the embodiments of the present application, the water-carrying agent may be xylene.

In the embodiments of the present application, the solvent of the imidazoline additive is selected from any one or more of methanol, isopropanol and ethanol.

In the embodiments of the present application, the water is fresh water; the salinity of the water may be ≤1000 mg/L.

In the embodiment of the present application, the density range of the completion fluid is 2.002g/cm ³ to 2.037g/cm ³ ; the apparent viscosity of the completion fluid may be 7.50mPa.s to 19.50mPa.s; The corrosion rate can be 87.0% to 91.9%; the turbidity of the completion fluid can be 5.7NTU to 28.5NTU; the corrosion rate of 13Cr coupons at 200°C and normal pressure can be 0.0166mm/a to 0.0333mm/a.

In the examples of this application, the oleic acid-based imidazoline additive A is prepared by the following method:

1) Place a 250mL three-necked flask equipped with a condenser, a thermometer and a stirrer in a temperature-adjusting electric heating mantle, add 16.95g of xylene, 56.49g of oleic acid and 24.76g of diethylenetriamine to the three-necked flask, at 300 rpm Stir at a constant speed at a constant speed, and the outlet of the condenser uses a conical flask to receive the water and xylene that come out of the reaction;

2) turn on the thermostat electric heating mantle, make the solution temperature in the there-necked flask reach 160 ℃, and react for 1.5 hours;

3) adjusting the temperature-adjusting electric heating mantle to make the solution temperature in the there-necked flask reach 220°C, and react for 6.5 hours;

4) cooling the brown solution in the three-necked flask synthesized in step 3) to room temperature to obtain oleic imidazoline;

5) Take 50.00 g of the prepared oleic acid-based imidazoline, dissolve it in 92.86 g of methanol, and prepare an imidazoline additive with a mass concentration of 35.0 wt.%.

The imidazoline additive selected in the examples and comparative examples of the present application was purchased from Fukang Chemical Technology Development Co., Ltd., Guanghan City, Sichuan Province, and the brand name is WD-72B. The imidazoline additive was prepared according to the above method, and the mass concentration of the imidazoline additive was 35 wt.%.

In this application, normal temperature generally refers to a temperature between 15°C and 25°C, and is 25°C in the following examples and comparative examples.

Example 1:

In this embodiment, calcium bromide is AR grade, with a purity of 98%, and zinc chloride: GR grade, with a purity of 98%, purchased from Chengdu Huaxia Chemical Reagent Co., Ltd.

The preparation method of the completion fluid of the present embodiment is as follows:

Add 200.0g of tap water to a 1000mL beaker at room temperature, then add 440.0g of raw calcium bromide, stir with a stirrer at 1000 rpm, and after the calcium bromide solid dissolves, the solution becomes translucent and pale white. The turbidity of this solution For 70.0NTU, immediately add 420.0g of raw material zinc chloride, stir the zinc chloride to dissolve, and then cool to normal temperature. At this time, the solution is colorless and transparent, and the turbidity is 7.6NTU. Then add 2.65g of imidazoline additive to the solution. At 1000 rpm, stirring, dissolving and dispersing are uniformly prepared to obtain a high temperature resistant high density solid-free completion fluid A; at this time, the components of the completion fluid A in parts by mass are: water: 10.0 parts, calcium bromide: 22.0 parts, chlorine Zinc compound: 21.0 parts and imidazoline additives: 0.1325 parts; perform performance evaluation according to the following methods and steps:

(1) Density: use a pycnometer to measure the density of the completion fluid obtained in this example at normal temperature;

(2) Apparent viscosity: The apparent viscosity is carried out in accordance with the Chinese national standard "GB/T16783.1-2014 Oil and Gas Industry Drilling Fluid Field Test Part 1 Water-based Drilling Fluid", and the apparent viscosity at room temperature is measured;

(3) Corrosion rate: Add 500 mLD to a high temperature and high pressure coupon corrosion apparatus with a capacity of 500 mL, and evaluate the 13Cr coupons at 200°C and normal pressure according to the China Petroleum and Natural Gas Industry Standard "SY/T0026-1999 Water Corrosion Determination Method" corrosion rate;

(4) Anti-swelling rate: According to the China Petroleum and Natural Gas Industry Standard "SY/T5971-2016 Performance Evaluation Method of Clay Stabilizers for Fracturing, Acidizing and Water Injection in Oil and Gas Fields" - Centrifugal Method, measure the anti-swelling rate of D to clay ;

(5) Turbidity: measure the turbidity of D at room temperature with a turbidity meter, which is a 2100P turbidity meter produced by HACH Company in the United States.

According to the above methods and steps, the measured performance of completion fluid A is:

Density: 2.002g/cm ³ ; Good fluidity of solution, apparent viscosity: 7.50mPa.s; Corrosion rate of 13Cr coupons at 200℃ and normal pressure: 0.0333mm/a; Anti-swelling rate: 91.9%; Solution Transparent and colorless, turbidity: 8.5NTU. Under this raw material composition, the apparent viscosity is the smallest; the anti-swelling rate is the highest.

Example 2:

Add 200.0g of tap water to a 1000mL beaker at room temperature, then add 440.0g of raw calcium bromide, stir with a stirrer at 1000 rpm, and after the calcium bromide solid dissolves, the solution becomes translucent and pale white. The turbidity of this solution For 70.0NTU, immediately add 440.0g of raw material zinc chloride, stir the zinc chloride to dissolve, and then cool to normal temperature. At this time, the solution is colorless and transparent, and the turbidity is 21.3NTU. At 1000 rpm, stirring, dissolving, dispersing, and uniformly preparing a high-temperature-resistant, high-density solid-free completion fluid B; at this time, the components of the completion fluid B in parts by mass are: water: 10.0 parts, calcium bromide: 22.0 parts, chlorine Zinc chloride: 22.0 parts and imidazoline additives: 0.135 parts.

According to the same evaluation method and procedure as in Example 1, the measured properties of completion fluid B are: density: 2.004g/cm ³ ; solution fluidity is good, apparent viscosity: 8.25mPa.s; 200°C, normal pressure The corrosion rate of 13Cr coupons is: 0.0291mm/a; the anti-swelling rate: 91.3%; the solution is transparent and colorless, turbidity: 28.5NTU.

Example 3:

Add 200.0g of tap water to a 1000mL beaker at room temperature, then add 460.0g of raw calcium bromide, stir with a stirrer at 1000 rpm, and after the calcium bromide solid dissolves, the solution becomes translucent and pale white. The turbidity of this solution For 100.6NTU, immediately add 420.0g of raw material zinc chloride, stir the zinc chloride to dissolve, and then cool to room temperature. At this time, the solution is colorless and transparent, and the turbidity is 6.1NTU. Then add 2.70g of imidazoline additive to the solution. At 1000 rpm, stirring, dissolving and dispersing are uniformly prepared to obtain a high temperature resistant and high density solid-free completion fluid C; at this time, the components of the completion fluid C in parts by mass are: water: 10.0 parts, calcium bromide: 23.0 parts, chlorine Zinc chloride: 21.0 parts and imidazoline additives: 0.135 parts.

According to the same evaluation method and procedure as in Example 1, the measured properties of completion fluid C are: density: 2.016g/cm ³ ; solution fluidity is good, apparent viscosity: 8.75mPa.s; 200°C, normal pressure The corrosion rate of 13Cr coupons is: 0.0249mm/a; the anti-swelling rate: 90.7%; the solution is transparent and colorless, turbidity: 6.8NTU.

Example 4:

Add 200.0g of tap water to a 1000mL beaker at room temperature, then add 460.0g of raw calcium bromide, stir with a stirrer at 1000 rpm, and after the calcium bromide solid dissolves, the solution becomes translucent and pale white. The turbidity of this solution For 100.6NTU, immediately add 430.0g of raw material zinc chloride, stir the zinc chloride to dissolve, and then cool to room temperature. At this time, the solution is colorless and transparent, and the turbidity is 13.5NTU. Then add 2.725g of imidazoline additives to the solution. At 1000 rpm, stirring, dissolving and dispersing are uniformly prepared to obtain high temperature resistant and high density solid-free completion fluid D; at this time, the components of completion fluid D in parts by mass are: water: 10.0 parts, calcium bromide: 23.0 parts, chlorine Zinc chloride: 21.5 parts and imidazoline additives: 0.13625 parts.

According to the same evaluation method and procedure as in Example 1, the measured properties of completion fluid D are: density: 2.018g/cm ³ ; solution fluidity is good, apparent viscosity: 9.50mPa.s; 200°C, normal pressure The corrosion rate of 13Cr coupons is: 0.0166mm/a; the anti-swelling rate: 90.1%; the solution is transparent and colorless, turbidity: 14.7NTU.

Example 5:

Add 200.0g of tap water to a 1000mL beaker at room temperature, then add 460.0g of raw calcium bromide, stir with a stirrer at 1000 rpm, and after the calcium bromide solid dissolves, the solution becomes translucent and pale white. The turbidity of this solution For 100.6NTU, immediately add 440.0g of raw material zinc chloride, stir the zinc chloride to dissolve, and then cool to room temperature. At this time, the solution is colorless and transparent, and the turbidity is 17.9NTU. Then add 2.750g of imidazoline additive to the solution. At 1000 rpm, stirring, dissolving and dispersing are uniformly prepared to obtain a high temperature resistant and high density solid-free completion fluid E; at this time, the components of E are grouped as: water: 10.0 parts, calcium bromide: 23.0 parts, zinc chloride: 22.0 parts and imidazoline additives: 0.1375 parts.

According to the same evaluation methods and steps as in Example 1, the measured properties of the completion fluid E are: density: 2.020g/cm ³ ; solution fluidity is good, apparent viscosity: 11.50mPa.s; 200°C, normal pressure The corrosion rate of 13Cr coupons is: 0.0249mm/a; the anti-swelling rate: 89.4%; the solution is transparent and colorless, turbidity: 19.3NTU.

Example 6:

Add 200.0g of tap water to a 1000mL beaker at room temperature, then add 470.0g of raw calcium bromide, stir with a stirrer at 1000 rpm, and after the calcium bromide solid dissolves, the solution becomes translucent and pale white. The turbidity of this solution For 118.7NTU, immediately add 430.0g of raw material zinc chloride, stir the zinc chloride to dissolve, and then cool to normal temperature. At this time, the solution is colorless and transparent, and the turbidity is 9.8NTU. Under stirring at 1000 r/min, stirring, dissolving, dispersing, and uniformly preparing a high-temperature-resistant high-density solid-free completion fluid F; at this time, the components of the completion fluid F in parts by mass are: water: 10.0 parts, calcium bromide: 23.5 parts, Zinc chloride: 21.5 parts and imidazoline additives: 0.1375 parts.

According to the same evaluation methods and steps as in Example 1, the measured properties of the completion fluid F are: density: 2.021g/cm ³ ; solution fluidity is good, apparent viscosity: 10.25mPa.s; 200°C, normal pressure The corrosion rate of 13Cr coupons is: 0.0166mm/a; the anti-swelling rate: 89.4%; the solution is transparent and colorless, turbidity: 10.9NTU.

Example 7:

Add 200.0g of tap water to a 1000mL beaker at room temperature, then add 480.0g of raw calcium bromide, stir with a stirrer at 1000 rpm, and after the calcium bromide solid dissolves, the solution becomes translucent and pale white. The turbidity of this solution For 130.0NTU, immediately add 420.0g of raw material zinc chloride, stir the zinc chloride to dissolve and then cool to normal temperature, at this time the solution is colorless and transparent, the turbidity is 3.2NTU, and then add 2.750g of imidazoline additive to the solution, in At 1000 r/min, stirring, dissolving and dispersing are uniformly prepared to obtain high temperature resistant and high density solid phase-free completion fluid G; at this time, the components of completion fluid G are in parts by mass: water: 10.0 parts, calcium bromide: 24.0 parts, chlorine Zinc chloride: 21.0 parts and imidazoline additives: 0.1375 parts.

According to the same evaluation method and procedure as in Example 1, the measured properties of completion fluid G are: density: 2.019g/cm ³ ; solution fluidity is good, apparent viscosity: 16.00mPa.s; 200°C, normal pressure The corrosion rate of 13Cr coupons is: 0.0208mm/a; the anti-swelling rate: 88.2%; the solution is transparent and colorless, turbidity: 5.7NTU. At this feedstock composition, the turbidity is minimal.

Example 8:

Add 200.0g of tap water to a 1000mL beaker at room temperature, then add 480.0g of raw calcium bromide, stir with a stirrer at 1000 rpm, and after the calcium bromide solid dissolves, the solution becomes translucent and pale white. The turbidity of this solution For 130.0NTU, immediately add 440.0g of raw material zinc chloride, stir the zinc chloride to dissolve and then cool to normal temperature, at this time the solution is colorless and transparent, the turbidity is 16.8NTU, and then add 2.800g of imidazoline additive to the solution, in At 1000 rpm, stirring, dissolving and dispersing are uniformly prepared to obtain a high temperature resistant high density solid-free completion fluid H; at this time, the components of the completion fluid H in parts by mass are: water: 10.0 parts, calcium bromide: 24.0 parts, chlorine Zinc chloride: 22.0 parts and imidazoline additives: 0.14 parts.

According to the same evaluation methods and steps as in Example 1, the measured properties of the completion fluid H are: density: 2.037g/cm ³ ; solution fluidity is good, apparent viscosity: 19.50mPa.s; 200°C, normal pressure The corrosion rate of the 13Cr coupon is: 0.0166mm/a; the anti-swelling rate: 87.0%; the solution is transparent and colorless, and the turbidity is 18.3NTU.

Comparative Example 1:

In this comparative example, calcium bromide is AR grade with a purity of 98%, and zinc chloride: GR grade with a purity of 98%, purchased from Chengdu Huaxia Chemical Reagent Co., Ltd.

The preparation method of the completion fluid of this comparative example is as follows:

Add 200.0g of tap water to a 1000mL beaker at room temperature, then add 450.0g of raw calcium bromide, stir with a stirrer at 1000 rpm, and after the calcium bromide solid dissolves, the solution becomes translucent and pale white with a turbidity of 89.5NTU , Immediately add 450.0g of raw material zinc chloride, stir the zinc chloride to dissolve and cool to normal temperature, the solution is translucent light white at this time, turbidity 257.2NTU, then add 2.750g of imidazoline additive to the solution, at 1000 rpm/ Mixture A is prepared by stirring, dissolving and dispersing uniformly under separate parts; at this moment, the components of mixture A in parts by mass are: water: 10.0 parts, calcium bromide: 22.5 parts, zinc chloride: 22.5 parts and imidazoline additive: 0.1375 parts.

According to the same evaluation methods and steps as in Example 1, the properties of solution A were measured as follows: density: 2.020g/cm ³ ; solution fluidity was good, apparent viscosity: 15.50mPa.s; The corrosion rate of the coupon is: 0.0573mm/a; the anti-swelling rate: 90.1%; the solution is translucent and pale white, and the turbidity is 263.0NTU. With this raw material composition, the solution is translucent to pale white with high turbidity, and cannot be used as a solid-free completion fluid.

Comparative Example 2:

In this comparative example, calcium bromide is AR grade with a purity of 98%, zinc chloride: GR grade with a purity of 98%, purchased from Chengdu Huaxia Chemical Reagent Co., Ltd.; the imidazoline additive is an imidazoline additive.

Add 200.0g of tap water to a 1000mL beaker at room temperature, then add 520.0g of raw calcium bromide, stir with a stirrer at 1000 rpm, and after the calcium bromide solid dissolves, the solution becomes translucent and pale white with a turbidity of 143.6NTU , Immediately add 400.0g of raw material zinc chloride, stir the zinc chloride to dissolve, after dissolution, the solution is colorless and transparent, and the solution becomes viscous, then immediately add 2.800g of imidazoline additive to the solution, at 1000 rpm Stir, dissolve and disperse uniformly to prepare a viscous and difficult-to-flow mixture B; now the mixture B components are in parts by mass: water: 10.0 parts, calcium bromide: 26.0 parts, zinc chloride: 20.0 parts and imidazoline additives: 0.14 parts; according to the same evaluation method and steps as in Example 1, the performance of solution D was measured as:

After the preparation is completed and cooled to room temperature, the solution is more viscous, cannot flow, and cannot be poured out of the prepared container. The density, apparent viscosity, corrosion rate, anti-swelling rate, and turbidity cannot be measured.

With this raw material composition, the solution is difficult to flow at room temperature and cannot be used as a solid-free completion fluid.

Comparative Example 3:

Add 300.0g of tap water to a 1000mL beaker at room temperature, then add 720.0g of raw calcium bromide, stir with a stirrer at 1000 rpm, and after the calcium bromide solid dissolves, the solution becomes translucent and pale white, cool to room temperature, this When the solution is translucent and light white, the turbidity is 279.3NTU, then 4.200g of imidazoline additives are added to the solution, and mixture C is prepared by stirring, dissolving and dispersing at 1000 rpm; The array becomes: water: 10.0 parts, calcium bromide: 24.0 parts, zinc chloride: 0 parts, and imidazoline additive: 0.14 parts.

According to the same evaluation method and procedure as in Example 1, the properties of mixture C were measured as follows: density: 1.785g/cm ³ ; good fluidity of the solution, apparent viscosity: 3.00mPa.s; The corrosion rate of the coupon is: 0.0831mm/a; the anti-swelling rate: 93.8%; the solution is translucent and light white, and the turbidity is 289.3NTU. With this raw material composition, the density is less than 2.0g/cm ³ , the corrosion rate is more than 0.076mm/a, the solution is translucent and pale white, and the turbidity is high, so it cannot be used as a solid-free completion fluid.

Comparative Example 4:

Add 300.0g of tap water to a 1000mL beaker at room temperature, then add 660.0g of raw material zinc chloride, stir with a stirrer at 1000 rpm, after the zinc chloride solid dissolves, the solution becomes colorless and transparent, cool to room temperature, at this time The solution is colorless and transparent, the turbidity is 18.9NTU, then 4.200g of imidazoline additives are added to the solution, and the mixture D is uniformly prepared by stirring, dissolving and dispersing at 1000 rpm; at this time, the components of the mixture D are divided into parts by mass. : Water: 10.0 parts, calcium bromide: 0 parts, zinc chloride: 22.0 parts and imidazoline additives: 0.14 parts.

According to the same evaluation methods and steps as in Example 1, the properties of mixture D were measured as follows: density: 1.807 g/cm ³ ; good fluidity of the solution, apparent viscosity: 6.50 mPa.s; The corrosion rate of the coupon is: 0.7549mm/a; the anti-swelling rate: 93.2%; the solution is transparent and colorless, and the turbidity is 20.3NTU. With this raw material composition, the density is less than 2.0g/cm ³ , the corrosion is severe, the corrosion rate is >0.076mm/a, and it cannot be used as a solid-free completion fluid.

It can be seen from the examples and comparative examples that the calcium bromide and zinc chloride provided by the application are compounded, and the imidazoline additive added to prepare the high-temperature high-density solid-free completion fluid density range is (2.002 to 2.037) g/cm ^{3. The} apparent viscosity is (7.50 to 19.50) mPa.s, the anti-swelling rate is (87.0 to 91.9)%, and the turbidity of the completion fluid is (5.7 to 28.5) NTU; The corrosion rate is 0.0166 to 0.0333 mm/a. Overcome the single use of zinc chloride at room temperature to dissolve in water and increase to a density of 1.85g/cm ³ and no longer dissolve, and then add the solution to become milky white, the density of calcium bromide saturated aqueous solution is only 1.68g/cm ³ , with a separate chloride zinc and calcium bromide density problem can not be formulated ≥2.0g / cm ³ clear completion fluid.

Although the embodiments disclosed in the present application are as above, the described contents are only the embodiments adopted to facilitate the understanding of the present application, and are not intended to limit the present application. Any person skilled in the art to which this application belongs, without departing from the spirit and scope disclosed in this application, can make any modifications and changes in the form and details of the implementation, but the scope of the patent protection of this application still needs to be The scope defined by the appended claims shall prevail.

Claims

A solid phase-free high-density completion fluid, comprising: water, calcium bromide, zinc chloride and imidazoline additives; the mass of the water, the calcium bromide, the zinc chloride and the imidazoline additives The ratio is 10:(22 to 24):(21 to 22):(0.1325 to 0.14);

The mass concentration of imidazoline in the imidazoline additive is 25.0 wt.% to 40.0 wt.%, preferably, the mass concentration of imidazoline is 35.0 wt.%.
The solid-free high-density completion fluid according to claim 1, wherein the imidazoline in the imidazoline additive is an oleic acid-based imidazoline synthesized from oleic acid and polyvinylpolyamine;

Or, the brand name of the imidazoline additive is WD-72B.
The solid-free high-density completion fluid according to claim 2, wherein the preparation method of the oleic imidazoline comprises:

a) adding water-carrying agent, oleic acid and polyethylene polyamine in the reaction vessel, mixing and stirring to obtain a mixture;

b) heating and adjusting the temperature of the mixture to 140°C to 180°C, and the reaction time is 1h to 2h; the preferred temperature is 160°C, and the preferred reaction time is 1.5h;

c) adjust the temperature of the mixture by heating to 180°C to 240°C, and react for 4.5h to 7.5h; the preferred temperature is 220°C, and the preferred reaction time is 6.5h;

d) cooling the product in the reaction vessel heated in step c) to room temperature to obtain oleic imidazoline;

Optionally, the molar ratio of the oleic acid and the polyethylene polyamine is 1.0:(1.2 to 1.3), and the amount of the water-carrying agent is 30 wt.% of the mass of the oleic acid.
The solid-free high-density completion fluid according to claim 3, wherein the polyethylene polyamine is selected from any one or more of diethylenetriamine, triethylenetetramine and tetraethylenepentamine;

Optionally, the water-carrying agent is xylene.
The solid-free high-density completion fluid according to claim 1, wherein the solvent of the imidazoline additive is selected from any one or more of methanol, isopropanol and ethanol.
The solid-free high-density completion fluid according to claim 1, wherein the water is fresh water; optionally, the salinity of the water is ≤1000 mg/L.
The solid-free high-density completion fluid according to any one of claims 1 to 6, wherein the density of the completion fluid ranges from 2.002 g/cm 3 to 2.037 g/cm 3 ; optionally, the The apparent viscosity of the completion fluid is 7.50mPa.s to 19.50mPa.s; optionally, the anti-swelling rate is 87.0% to 91.9%; optionally, the turbidity of the completion fluid is 5.7NTU to 28.5NTU; Optionally, the corrosion rate of the 13Cr coupon at 200° C. and normal pressure is 0.0166 mm/a to 0.0333 mm/a.
The method for preparing a solid-free high-density completion fluid according to any one of claims 1 to 7, comprising:

1) in reaction vessel, add described water and described calcium bromide, stir until calcium bromide dissolves completely, form solution;

2) mixing the solution obtained in step 1) with the zinc chloride until the zinc chloride is completely dissolved to form a solution;

3) Stir the solution obtained in step 2) and the imidazoline additive evenly to obtain a solid phase-free high-density completion fluid.
The method for preparing a solid-free high-density completion fluid according to claim 8, wherein, after the calcium bromide in step 1) is completely dissolved, the zinc chloride in step 2) is immediately added;

The stirring rate of stirring described in step 1) is 300 to 2000 rev/min, preferably, the stirring rate is 1000 rev/min;

Optionally, the solution described in step 3) is first cooled to room temperature and then stirred with imidazoline additive;

Optionally, the stirring rate of the stirring in step 3) is 300 rpm to 2000 rpm, preferably, the stirring rate is 1000 rpm.
The method for preparing a solid-free high-density completion fluid according to claim 8, wherein the solution formed in step 1) is translucent and pale white, and the turbidity of the solution is 70.0 NTU to 130.0 NTU; optionally , the solution formed in step 2) is a colorless and transparent solution; optionally, the solution formed in step 3) is a colorless and transparent solution;

Preferably, the turbidity of the solution formed in the step 2) is 3.2 NTU to 21.3 NTU; preferably, the solution formed in the step 3) is a colorless and transparent solution, and the turbidity is 5.7 NTU to 28.5 NTU.