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Modified calcium brine workover fluid and preparation method thereof

The technology of calcium brine and workover fluid is applied in the field of modified calcium brine workover fluid and its preparation, which can solve the problems of water lock damage and decrease of reservoir production, and achieve the effect of reducing interfacial tension, simple construction and good oil layer protection. Effect

Inactive Publication Date: 2019-10-29
PETROCHINA CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, when the above-mentioned modified calcium brine workover fluid is used in low-permeability reservoirs, it will cause water lock damage, resulting in a decline in reservoir production

Method used

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Examples

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Effect test

preparation example Construction

[0043] On the other hand, the embodiment of the present invention also provides a preparation method of modified brine workover fluid, the preparation method comprising the following steps:

[0044] Step S1, according to the weight percentage of each component, adding a scale inhibitor modifier to the calcium brine, and stirring evenly to form a first mixed solution;

[0045] Step S2, adding a waterproof locking agent to the first mixed solution, and stirring evenly to form a second mixed solution;

[0046] Step S3, adding a fluid loss control agent into the second mixed solution and stirring evenly to obtain a modified calcium brine workover fluid.

[0047] Among them, the fluid loss control agent includes the following components in parts 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, 0.7 parts of sodium chloride Part ~ 1 part.

[0048] The fluid loss control agent based on the abov...

Embodiment 1

[0059] This embodiment provides a modified calcium brine workover fluid, the preparation method of which is as follows: firstly add a density of 1.26g / cm2 into a beaker 3 and 94 parts by mass of calcium brine, and then add 4 parts by mass of antiscaling modifier, and stir evenly. Continue to add 1 part by mass of waterproof locking agent into the beaker, and stir evenly. Continue to add fluid loss reducer with a mass fraction of 1 part into the beaker, and stir evenly to obtain a modified calcium brine workover fluid

[0060] Among them, the waterproof locking agent includes the following components in parts by mass: 25 parts of cationic fluorocarbon surfactants, 25 parts of nonionic fluorocarbon surfactants, 15 parts of foaming agents, octadecyltrimethyl 35 parts of ammonium chloride.

[0061] Scale inhibitor modifier has the following components in weight percent: 18% of aminotrimethylene phosphonic acid, 4% of sodium dioctyl sulfosuccinate, 2% of cetyltrimethylammonium ch...

Embodiment 2

[0065] This embodiment provides a modified calcium brine workover fluid, the preparation method of which is as follows: firstly add a density of 1.30g / cm2 into a beaker 3 And 93 parts by mass of calcium brine, and then add 4 parts by mass of antiscaling modifier, and stir evenly. Continue to add 1 part by mass of waterproof locking agent into the beaker, and stir evenly. Continue to add 2 parts by mass of fluid loss reducer to the beaker, and stir evenly to obtain the modified calcium brine workover fluid

[0066] Among them, the waterproof locking agent includes the following components in parts by mass: 35 parts of cationic fluorocarbon surfactants, 25 parts of nonionic fluorocarbon surfactants, 5 parts of foaming agents, octadecyltrimethyl 35 parts of ammonium chloride.

[0067] Scale inhibitor modifier has the following components in weight percent: 20% aminotrimethylene phosphonic acid, 5% sodium dioctylsulfosuccinate, 2% cetyltrimethylammonium chloride, and 0.2% tribut...

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Abstract

The invention discloses a modified calcium brine workover fluid and a preparation method thereof, belonging to the technical field of oil and gas exploitation. The modified calcium brine workover fluid comprises the following components by weight: 2% to 4% of a scale-inhibiting modifier, 0.5% to 1% of an anti-water-blocking agent and 1% to 2% of a fluid loss agent, with the balance being calcium brine. The anti-water-blocking agent comprises the following components by mass: 25-35 parts of a cationic fluorocarbon surfactant, 15-25 parts of a non-ionic fluorocarbon surfactant, 5-15 parts of a foaming agent and 25-35 parts of octadecyltrimethylammonium chloride. The workover fluid provided by the invention has good oil layer protection effect, an API filter loss of less than 5 ml / 30min, saltresistance of up to 600,000 ppm, interfacial tension of less than 1 mN / m, a core permeability recovery rate of more than 95%, and temperature resistance of no less than 120 DEG C.

Description

technical field [0001] The invention relates to the technical field of oil and gas exploitation, in particular to a modified calcium brine workover fluid and a preparation method thereof. Background technique [0002] During the development of oil and gas fields, calcium brine workover fluid is usually injected into oil and gas wells to balance the formation pressure and maintain the productivity of oil and gas wells. Among them, the main components of calcium brine are calcium chloride and a small amount of calcium sulfate, magnesium chloride, sodium chloride and so on. [0003] During use, in order to prevent formation scaling caused by calcium brine workover fluid, scale inhibitor modifier is generally added to calcium brine workover fluid to modify it. However, when the above-mentioned modified calcium brine workover fluid is used in low-permeability reservoirs, water lock damage will occur, resulting in a decrease in reservoir production. Contents of the invention ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C09K8/08C09K8/12
CPCC09K8/08C09K8/12
Inventor 何丕祥王兴伟朱红云韩项勇熊英郭志强滕国权张杰梁晓亮
Owner PETROCHINA CO LTD
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