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A kind of modified brine workover fluid and preparation method thereof

A workover fluid and brine technology, applied in the direction of chemical instruments and methods, drilling compositions, etc., can solve the problems of easy leakage and other problems, and achieve the effect of easy flowback and good plugging effect

Active Publication Date: 2021-03-30
PETROCHINA CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Due to the higher density of brine, leakage is more likely to occur

Method used

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  • A kind of modified brine workover fluid and preparation method thereof
  • A kind of modified brine workover fluid and preparation method thereof
  • A kind of modified brine workover fluid and preparation method thereof

Examples

Experimental program
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preparation example Construction

[0099] In a second aspect, embodiments of the present invention provide a method for preparing the above-mentioned modified brine workover fluid, which specifically includes the following steps:

[0100] According to the proportion, add a modifier to prevent brine scaling into the brine and stir evenly, then add a viscosifying suspending agent, stir the viscosifying suspending agent until it is evenly dispersed, then add salt-resistant plugging agent, oil-soluble resin and drilling The unidirectional pressure sealing agent is used for the liquid and stirred to disperse evenly to obtain the modified brine workover fluid.

[0101] It can be understood that, according to different brines, different modifiers for preventing brine scaling can be added. For the preparation method of the modifier for preventing brine scaling, refer to the above-mentioned Chinese patent application with the application number 201510907377.X and the title of the invention "a modifier for preventing bri...

Embodiment 1

[0112] This example provides the formulation and preparation method of the salt-tolerant plugging agent, and evaluates the performance of the salt-tolerant plugging agent.

[0113] The raw material formula of the salt-resistant leakage plugging agent of this embodiment is shown in Table 1.

[0114] Table 1

[0115]

[0116] The preparation method of the salt-resistant leakage plugging agent of the present embodiment is as follows:

[0117] Step 1, add 75kg of tap water into the iron bucket A, and then heat it to boiling.

[0118] Step 2, add 25kg of tap water to the iron bucket B, then add sodium tetraborate according to the formula in Table 1, stir to dissolve the sodium tetraborate, then add pregelatinized starch and cornstarch, stir to make the pregelatinized starch and cornstarch After dissolving, sodium chloride was added, and stirring was continued to obtain an emulsion-like mixed solution.

[0119] Step 3: Add the mixed solution obtained in iron bucket B into iron...

Embodiment 2

[0129] This example provides the formulation and preparation method of the viscosifying suspension, and evaluates the performance of the viscosifying suspension.

[0130] The formula of the viscosity-increasing suspending agent of the present embodiment is shown in Table 3.

[0131] In this example, the hydroxymethyl starch used is the product of Renqiu Gaoke Chemical Materials Co., Ltd.

[0132] table 3

[0133]

[0134]

[0135] After mixing hydroxymethyl starch, N,N'-methylenebisacrylamide and sodium thiosulfate according to the formula in Table 3, the viscosity-increasing suspension modifier of this example is obtained. The viscosity-increasing suspension modifier It is a white powdery solid.

[0136] The viscosity-increasing effect of the viscosity-increasing suspension agent 4 in this example on the brine workover fluid is evaluated below, and compared with partially hydrolyzed polyacrylamide (HPAM).

[0137] Viscosifying suspending agent 4 is added in salt bitt...

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Abstract

The invention discloses a modified brine workover fluid and a preparation method thereof, belonging to the technical field of workover fluids for workover during oil-gas field development. The modified brine workover fluid comprises brine, a modifier for preventing brine from fouling, a salt-resistant plugging agent, a tackfying-suspending agent, a unidirectional pressure sealing agent for a drilling fluid and oil-soluble resin. The salt-resistant plugging agent is prepared from the raw materials by mass: 100 parts of water, 8 to 12 parts of natural starch, 0.8 to 2 parts of pregelatinized starch, 1 to 3 parts of sodium tetraborate and 0.7 to 1 part of sodium chloride. The tackifying-suspending agent comprises the following components by mass: 99.0% to 99.5% of hydroxymethyl starch, 0.3% to 0.8% of N,N'-methylenebisacrylamide and 0.1% to 0.2% of thiosulfate. The modified brine workover fluid has the advantages of good plugging effect, a wide plugging range, high salt resistance, easy degradability, etc.

Description

technical field [0001] The invention relates to the technical field of workover fluid used in oil and gas field development, in particular to a modified brine workover fluid and a preparation method thereof. Background technique [0002] Workover operation is an important process in the production and development of oil and gas fields, and it is an important means to maintain the productivity of production wells and slow down the natural decline. During the workover operation, it is usually necessary to inject workover fluid into the wellbore to balance the formation pressure and ensure the safety of the workover operation. As the development of oil and gas fields enters the middle and later stages, the pressure of oil and gas wells gradually decreases, and the workover fluid will leak into the formation, which not only causes pollution of the formation, but also affects the normal operation of the workover. [0003] The application of brine as a workover fluid has certain ...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C09K8/512C09K8/514C09K8/52
CPCC09K8/5083C09K8/5086C09K8/512C09K8/514C09K8/52
Inventor 陈建光胡成亮何丕祥宋玉文李倩饶富培韩项勇王兴伟何川
Owner PETROCHINA CO LTD
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