High-temperature-resistant cleaning type spacer fluid

Abstract

The invention discloses a high-temperature-resistant cleaning type spacer fluid, and relates to the technical field of oilfield development and drilling, and the spacer fluid comprises the following components in parts by weight: 0.2-3 parts of a mixture of xanthan gum and modified diquat, 2-15 parts of an efficient cleaning agent, 0.5-5 parts of an anti-pollution agent, 0.2-3 parts of a dispersant, 0.1-0.5 part of a defoaming agent, 0.5-5 parts of ultrafine powder, 30-80 parts of a weighting agent and 25-90 parts of water. The spacer fluid has good compatibility with cement paste and drilling fluid, can keep stable performance at a high temperature of 220 DEG C, and has a good flushing effect.

Description

Technical Field

[0001] The invention relates to the technical field of oilfield development and drilling, and in particular to a high-temperature resistant cleaning type isolation fluid. Background Art

[0002] With the continuous exploitation of oil and gas resources, ultra-deep wells emerge in an endless stream, and even 10,000-meter deep wells are drilled. Correspondingly, the temperature at the bottom of the well is getting higher and higher. The static temperature at the bottom of a 10,000-meter deep well is expected to be 240°C, and the circulating temperature is 216°C. As drilling continues to go deeper, the wellbore becomes smaller and smaller, the annular space gap becomes smaller and smaller, and the difficulty of drilling becomes greater and greater. In order to reduce the friction resistance of the drill bit, the later drilling fluid is very likely to be an oil-based drilling fluid. The oil-based drilling fluid in the well brings great challenges to the later cementing. However, the existing flushing fluid can only maintain stable performance and flushing efficiency at 190°C and below. There is an urgent need for a cleaning fluid that can clean the oil-based drilling fluid on the well wall at a high temperature of 220°C. Summary of the invention

[0003] In order to solve the above technical problems, the purpose of the present invention is to provide a high temperature resistant cleaning spacer fluid. The spacer fluid of the present invention has good compatibility with cement slurry and drilling fluid, can maintain stable performance at a high temperature of 220°C, and has a good flushing effect.

[0004] The technical solution of the present invention to solve the above technical problems is as follows: a high temperature resistant cleaning isolation fluid is provided, comprising the following components in parts by weight: 0.2-3 parts of a mixture of xanthan gum and modified diutan gum, 2-15 parts of a high-efficiency cleaning agent, 0.5-5 parts of an anti-pollution agent, 0.2-3 parts of a dispersant, 0.1-0.5 parts of a defoaming agent, 0.5-5 parts of an ultrafine powder, 30-80 parts of a weighting agent and 25-90 parts of water.

[0005] Furthermore, the following components are included in weight: 2 parts of a mixture of xanthan gum and modified diutan gum, 8 parts of a high-efficiency cleaning agent, 3 parts of an anti-pollution agent, 2 parts of a dispersant, 0.3 parts of a defoaming agent, 2 parts of ultrafine powder, 50 parts of a weighting agent and 60 parts of water.

[0006] Furthermore, the modified diutan gum is prepared by the following method: after diutan gum is irradiated with plasma, it is evenly mixed with fluorosilane in a mass ratio of 8-12:1 to obtain the modified diutan gum.

[0007] Furthermore, the plasma irradiation is performed for 30-60 min.

[0008] Furthermore, the mass ratio of xanthan gum to modified diutan gum is 1:2-5.

[0009] Furthermore, the high-efficiency cleaning agent includes the following components in parts by weight: 8-15 parts of alcohol ether phosphate, 3-8 parts of fatty alcohol polyoxyethylene ether, 5-10 parts of alkylphenol polyoxyethylene ether, 10-15 parts of sodium salt of dioctyl sulfonate succinate, 4-10 parts of ethylenediaminetetraacetic acid, 8-12 parts of anhydrous ethanol, 5-10 parts of triethanolamine borate and 20-57 parts of water.

[0010] Furthermore, the anti-pollution agent is at least one of hydroxyethylidene diphosphonic acid, sodium hydroxyethylidene diphosphonate, sodium pyrophosphate, sodium gluconate and molasses.

[0011] Furthermore, the dispersant is a sulfonated aldehyde ketone condensate.

[0012] Furthermore, the defoaming agent is a silicone defoaming agent.

[0013] Furthermore, the ultrafine powder is a mixture of microsilica powder and nano-silica; the mass ratio of microsilica powder to nano-silica is 10:1-2.

[0014] Furthermore, the weighting agent is ultrafine barite powder or iron ore powder.

[0015] The present invention has the following beneficial effects: 1. The low-temperature viscosity of common suspending agents is proportional to the amount of diutan gum added, which limits the amount of diutan gum added. However, the appropriate amount of low-temperature viscosity will reduce its viscosity at high temperatures, resulting in a problem of reduced suspension ability. The present invention performs plasma hydrophobic modification on diutan gum, so that the aqueous solution of the modified polymer has a low viscosity at low temperatures, thereby increasing the amount of diutan gum added in the isolation fluid at low temperatures. At high temperatures, the hydrophobic groups are ionized, restoring the high viscosity of the polymer, so that the isolation fluid still has good suspension ability at high temperatures. The isolation fluid can meet the construction requirements of 220°C high-temperature wells.

[0016] 2. After being exposed to high temperatures, the flushing effect of existing similar products is significantly reduced, and the oil-based mud on the well wall cannot be flushed. The present invention introduces alcohol ether phosphate into the high-efficiency flushing agent to improve its temperature resistance. Under the synergistic effect of ethylenediaminetetraacetic acid, it can ensure a good flushing effect at high temperatures.

[0017] 3. Existing similar products only focus on the use effect, but do not consider its negative effects. The present invention introduces triethanolamine borate into the isolation fluid, which can slow down the corrosion of the isolation fluid on the metal casing, thereby extending the production life of the oil and gas well. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is a maintenance curve diagram of the high temperature resistant cleaning type isolation fluid of Example 1; Figure 2 This is a diagram showing the flushing test results of the high temperature resistant cleaning type isolation fluid of Example 1; Figure 3 It is the cement slurry thickening curve; Figure 4 This is the thickening curve of the cement slurry and drilling fluid with a volume ratio of 7:3; Figure 5 This is the thickening curve of the cement slurry, spacer fluid and drilling fluid mixed slurry with a volume ratio of 7:1:2; Figure 6 This is the thickening curve of the slurry with a volume ratio of 5:5 between the spacer fluid and the drilling fluid; Figure 7 This is the thickening curve of the slurry with a volume ratio of cement slurry to spacer fluid of 7:3. DETAILED DESCRIPTION

[0019] The principles and features of the present invention are described below, and the examples are only used to explain the present invention and are not used to limit the scope of the present invention. If no specific conditions are specified in the embodiments, they are carried out according to normal conditions or conditions recommended by the manufacturer. If the manufacturer of the reagents or instruments is not specified, they are all conventional products that can be purchased commercially.

[0020] Example 1 A high temperature resistant cleaning isolation fluid comprises the following components in parts by weight: 2 parts of a mixture of xanthan gum and modified dimethoate in a mass ratio of 1:3, 8 parts of a high efficiency cleaning agent, 3 parts of hydroxyethylidene diphosphonic acid, 2 parts of a sulfonated aldehyde ketone condensate, 0.3 parts of an organosilicon defoamer, 2 parts of a mixture of microsilica powder and nano silicon dioxide in a mass ratio of 10:1.5, 50 parts of ultrafine barite powder and 60 parts of water; The modified diutan gum is prepared by the following method: after diutan gum is irradiated with plasma, it is uniformly mixed with fluorosilane in a mass ratio of 10:1 to obtain the modified diutan gum; The high-efficiency cleaning agent is composed of the following concentration components: 10 parts of alcohol ether phosphate, 5 parts of fatty alcohol polyoxyethylene ether, 8 parts of alkylphenol polyoxyethylene ether, 12 parts of sodium salt of dioctyl sulfonate succinate, 6 parts of ethylenediaminetetraacetic acid, 10 parts of anhydrous ethanol, 6 parts of triethanolamine borate and 43 parts of water.

[0021] Example 2 A high temperature resistant cleaning isolation fluid comprises the following components in parts by weight: 0.2 parts of a mixture of xanthan gum and modified dimethoate in a mass ratio of 1:2, 2 parts of a high efficiency cleaning agent, 0.5 parts of sodium hydroxyethylidene diphosphonate, 0.2 parts of a sulfonated aldehyde ketone condensate, 0.1 parts of an organosilicon defoamer, 0.5 parts of a mixture of microsilica powder and nano silicon dioxide in a mass ratio of 10:1, 30 parts of ultrafine barite powder and 25 parts of water; The modified diutan gum is prepared by the following method: diutan gum is irradiated with plasma, and then mixed with fluorosilane in a mass ratio of 8:1 to obtain the modified diutan gum; The high-efficiency cleaning agent comprises the following components in parts by weight: 8 parts of alcohol ether phosphate, 3 parts of fatty alcohol polyoxyethylene ether, 5 parts of alkylphenol polyoxyethylene ether, 10 parts of sodium salt of dioctyl sulfonate succinate, 4 parts of ethylenediaminetetraacetic acid, 8 parts of anhydrous ethanol, 5 parts of triethanolamine borate and 57 parts of water.

[0022] Example 3 A high temperature resistant cleaning isolation fluid comprises the following components in parts by weight: 3 parts of a mixture of xanthan gum and modified dimethoate in a mass ratio of 1:5, 15 parts of a high efficiency cleaning agent, 5 parts of sodium pyrophosphate, 3 parts of a sulfonated aldehyde ketone condensate, 0.5 parts of an organosilicon defoamer, 5 parts of a mixture of microsilica powder and nano silicon dioxide in a mass ratio of 10:2, 80 parts of iron ore powder and 90 parts of water; The modified diutan gum is prepared by the following method: after diutan gum is irradiated with plasma, it is uniformly mixed with fluorosilane in a mass ratio of 12:1 to obtain the modified diutan gum; The high-efficiency cleaning agent comprises the following components in parts by weight: 15 parts of alcohol ether phosphate, 8 parts of fatty alcohol polyoxyethylene ether, 10 parts of alkylphenol polyoxyethylene ether, 15 parts of sodium salt of dioctyl sulfonate succinate, 10 parts of ethylenediaminetetraacetic acid, 12 parts of anhydrous ethanol, 10 parts of triethanolamine borate and 20 parts of water.

[0023] Test Example 1 Referring to the formula of the cleaning spacer fluid of the present invention, diutan gum and modified diutan gum were used to prepare cleaning spacer fluids at an addition amount of 0.5%, and their rheological properties were measured at room temperature and high temperature. The results are shown in Table 1.

[0024] Table 1 Rheological properties test results of cleaning isolation fluid

[0025] As shown in Table 1, under the condition of the same amount of dimethoate, the rheological value of the spacer fluid prepared with modified dimethoate is significantly reduced at low temperature, while the performance of the two is similar at high temperature, indicating that the spacer fluid prepared with modified dimethoate has a lower consistency at low temperature and recovers its consistency at high temperature. Therefore, the amount of modified dimethoate that can be added at low temperature is significantly increased, which can increase the suspension capacity of the spacer fluid under high temperature conditions.

[0026] Test Example 2 Referring to Example 1, an isolation liquid (blank sample) without triethanolamine borate was prepared. The blank sample and the isolation liquid of Example 1 were placed together with the polished casing iron sheet under high temperature and high pressure for curing for 1 hour, and then taken out for observation. The results are shown in Table 2.

[0027] Table 2 Casing iron sheet maintenance results

[0028] It can be seen from Table 2 that the triethanolamine borate introduced into the isolation fluid of the present invention can slow down the corrosion of the metal casing.

[0029] Test Example 3 Basic Performance (1) High temperature maintenance The high temperature resistant cleaning isolation fluid of Example 1 was cured at 220°C for 4 h. The curing curve is as follows: Figure 1 shown.

[0030] Depend on Figure 1 It can be seen that the consistency curve of the cleaning spacer fluid is stable, and no adverse phenomena such as thickening and agglomeration occur during the curing process.

[0031] (2) Flushing effect The high temperature resistant cleaning isolation fluid of Example 1 was used to perform flushing tests at room temperature and 220°C high temperature conditions. The results are as follows: Figure 2 And as shown in Table 3.

[0032] Table 3 Flushing test results

[0033] Depend on Figure 2 As shown in Table 3, the flushing rate of the isolation fluid is high under both low and high temperature conditions, which meets its own performance.

[0034] Test Example 4: Slurry compatibility The high temperature resistant cleaning spacer fluid of Example 1 was mixed with drilling fluid and cement slurry in different proportions to evaluate the liquid compatibility. The thickening results are as follows: Figure 3-7 And as shown in Table 4.

[0035] Table 4 Compatibility evaluation results

[0036] Depend on Figure 3-7 As shown in Table 4, the cleaning spacer fluid has good compatibility with the drilling fluid and cement slurry after being mixed, and the thickening time is significantly increased, indicating that the compatibility is greatly improved after the spacer fluid is added.

[0037] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modification, equivalent substitution or improvement made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A high temperature resistant cleaning isolation fluid, characterized in that: The invention comprises the following components in parts by weight: 0.2-3 parts of a mixture of xanthan gum and modified diutan gum, 2-15 parts of a high-efficiency cleaning agent, 0.5-5 parts of an anti-pollution agent, 0.2-3 parts of a dispersant, 0.1-0.5 parts of a defoaming agent, 0.5-5 parts of ultrafine powder, 30-80 parts of a weighting agent and 25-90 parts of water.

2. The high temperature resistant cleaning isolation fluid according to claim 1, characterized in that: The invention comprises the following components in parts by weight: 2 parts of a mixture of xanthan gum and modified diutan gum, 8 parts of a high-efficiency cleaning agent, 3 parts of an anti-pollution agent, 2 parts of a dispersant, 0.3 parts of a defoaming agent, 2 parts of ultrafine powder, 50 parts of a weighting agent and 60 parts of water.

3. The high temperature resistant cleaning isolation fluid according to claim 1, characterized in that: The modified diutan gum is prepared by the following method: after diutan gum is irradiated with plasma, it is evenly mixed with fluorosilane in a mass ratio of 8-12:1 to obtain the modified diutan gum.

4. The high temperature resistant cleaning isolation fluid according to claim 1, characterized in that: The mass ratio of the xanthan gum to the modified diutan gum is 1:2-5.

5. The high temperature resistant cleaning isolation fluid according to claim 1, characterized in that: The high-efficiency cleaning agent comprises the following components in parts by weight: 8-15 parts of alcohol ether phosphate, 3-8 parts of fatty alcohol polyoxyethylene ether, 5-10 parts of alkylphenol polyoxyethylene ether, 10-15 parts of sodium salt of dioctyl sulfonate succinate, 4-10 parts of ethylenediaminetetraacetic acid, 8-12 parts of anhydrous ethanol, 5-10 parts of triethanolamine borate and 20-57 parts of water.

6. The high temperature resistant cleaning isolation fluid according to claim 1, characterized in that: The anti-pollution agent is at least one of hydroxyethylidene diphosphonic acid, sodium hydroxyethylidene diphosphonate, sodium pyrophosphate, sodium gluconate and molasses.

7. The high temperature resistant cleaning isolation fluid according to claim 1, characterized in that: The dispersant is a sulfonated aldehyde ketone condensate.

8. The high temperature resistant cleaning isolation fluid according to claim 1, characterized in that: The defoamer is an organosilicon defoamer.

9. The high temperature resistant cleaning isolation fluid according to claim 1, characterized in that: The ultrafine powder is a mixture of microsilicon powder and nano silicon dioxide; the mass ratio of the microsilicon powder to the nano silicon dioxide is 10:1-2.

10. The high temperature resistant cleaning isolation fluid according to claim 1, characterized in that: The weighting agent is ultrafine barite powder or iron ore powder.

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