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Modified brine workover fluid and preparation method thereof

A technology for workover fluid and brine, applied in chemical instruments and methods, drilling compositions, etc., can solve problems such as easy leakage, and achieve the effect of easy flowback and good leakage blocking effect.

Active Publication Date: 2019-02-26
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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  • Modified brine workover fluid and preparation method thereof
  • Modified brine workover fluid and preparation method thereof
  • Modified brine workover fluid and preparation method thereof

Examples

Experimental program
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Effect test

preparation example Construction

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

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

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

Embodiment 1

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

[0113] Table 1 shows the raw material formulation of the salt-resistant leak-stopping agent in this example.

[0114] Table 1

[0115]

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

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

[0118] Step 2, add 25kg of tap water in 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, and stir to make the pregelatinized starch and cornstarch. Dissolve, then add sodium chloride and continue stirring to obtain an emulsion-like mixed solution.

[0119] Step 3, add the mixed solution obtained in the iron bucket B into the iron bucket ...

Embodiment 2

[0129] This example provides the formulation and preparation method of the thickening suspending agent, and evaluates the performance of the thickening and suspending agent.

[0130] The formula of the thickening suspending agent of this example is shown in Table 3.

[0131] In this embodiment, the hydroxymethyl starch used is the product of Renqiu High-tech Chemical Materials Co., Ltd.

[0132] table 3

[0133]

[0134]

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

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

[0137] The viscosity-increasing suspending agent 4 was added to the brine and calcium brin...

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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 for well workover in the process of 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 an important means to maintain the productivity of production wells and slow down the natural decline. In the process of workover operation, workover fluid is usually injected into the wellbore to balance the formation pressure and ensure the safety of the workover operation. As the oil and gas field development enters the middle and late stages, the pressure of oil and gas wells gradually decreases, and the workover fluid will leak into the formation, which not only causes the pollution of the formation, but also affects the normal operation of the workover operation. [0003] Brine as a workover fluid has the...

Claims

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Application Information

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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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