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Descaling and blockage-removing fluid for clearing blockage in drilling and completion process and preparation method of descaling and blockage-removing fluid

A technology for drilling, completion and plugging removal, which is applied in the direction of drilling compositions, chemical instruments and methods, cleaning tools, etc. It can solve problems such as easy to block reservoirs, difficult flowback, and corroded production casings, etc., to achieve plugging removal good effect

Inactive Publication Date: 2017-12-01
CNPC BOHAI DRILLING ENG
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0002] Most domestic oil fields need to use barite to increase the density during drilling and well completion, and the main components of barite are barium sulfate, strontium sulfate, and calcium sulfate. These are inorganic scales that cannot be removed by conventional pickling. Some oil reservoirs contain barium sulfate, strontium sulfate and calcium sulfate, which undoubtedly increases the difficulty of descaling
In the process of drilling, completion and stimulation, many of the selected well-entry fluid systems are of polymer type, such as polyacrylamide, hydroxypropyl guar gum, etc. These polymers are difficult to degrade and flow back after the operation is completed. It is easy to block the reservoir, and the mud cake formed by these polymers will damage the conductivity of the screen and the original permeability of the formation, resulting in a decrease in the productivity of the treated well
The residual solids and polymers in the mud cake can be dissolved or oxidized by pickling or strong oxidizing agents, but downhole plugging is very complicated, usually a composite scale formed by the accumulation of inorganic scale and organic polymer scale, so pickling and erosion methods are used to deal with it. not effectively
Although the use of invisible acid completion fluid can remove some blockages, there may be various side reactions between acids (hydrochloric acid, acid spit, etc.) and clay and ore skeletons to form sediments to block pores
In addition, pickling will also corrode the production casing after completing the deblocking work of the treated polymer

Method used

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  • Descaling and blockage-removing fluid for clearing blockage in drilling and completion process and preparation method of descaling and blockage-removing fluid
  • Descaling and blockage-removing fluid for clearing blockage in drilling and completion process and preparation method of descaling and blockage-removing fluid
  • Descaling and blockage-removing fluid for clearing blockage in drilling and completion process and preparation method of descaling and blockage-removing fluid

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Effect test

preparation example Construction

[0031] The preparation method of the high temperature resistant anti-swelling agent used is: dissolving 20g of trimethylamine in 100mL of ethanol, adding 60g of 37.5% hydrochloric acid, stirring at normal temperature for 1h to obtain the mixed solution I of trimethylamine hydrochloride; Add 10g of fatty acid ester (16C-18C) to the mixture, continue to stir until the solution is uniform, and obtain mixed solution II; then add 40g of epichlorohydrin dropwise to the mixed solution II, after the addition is completed, add 0.09g, (NH 4 ) 2 S 2 o 8 -NaHSO 3 Stir continuously and heat up to 60°C, stop the reaction after reflux for 5h, and obtain a mixed solution III containing a quaternary ammonium organic cationic polymer; finally add potassium chloride of 60% of the total mass of the mixed solution III to the mixed solution III and mix well , evaporate the solvent to get the anti-high temperature anti-expansion agent for fracturing

[0032] The alkylglucamide used specifically ...

Embodiment 1

[0035] Weigh 55.5 parts of water, 20 parts of DTPA-5Na and 2 parts of KOH into the reactor and mix and stir to form a uniform mixed solution; then add 2 parts of high temperature resistant anti-swelling agent, 3 parts of sodium thiosulfate, 4 parts of Sodium gluconate, 4.5 parts of alkyl glucamide and 4 parts of phosphate surfactant, stir for 1 to 2 hours until each component is completely dissolved; finally add 5 parts of proteolytic enzyme, stir for 30 minutes until evenly mixed, and then get the descaling Blockage solution A.

[0036] After testing, the density of the descaling and plugging solution A is 1.06g / cm 3 , the pH is 10, the surface tension is less than 30mN / m, and the anti-swelling rate of clay is more than 90%.

[0037] The scale removal effect test and the blockage removal effect test were carried out on the descaling and plugging removal solution A prepared in Example 1. specifically,

[0038]The method of descaling effect test is: take by weighing 10g oil ...

Embodiment 2

[0042] Weigh 41 parts of water, 38 parts of DTPA-5Na and 3.5 parts of KOH into the reactor and mix and stir to form a uniform mixed solution; then add 1 part of high temperature resistant anti-swelling agent, 3.5 parts of sodium thiosulfate, 2 parts of Lactic acid, 3 parts of alkylglucamide and 4 parts of phosphoric acid ester surfactant, stir for 1 to 2 hours until all components are completely dissolved; finally add 4 parts of glutamic acid transferase, stir for 30 minutes until the mixture is uniform, and the descaling Blockage solution B.

[0043] After testing, the density of the descaling and plugging solution B is 1.08g / cm 3 , pH 12, surface tension <30mN / m, clay anti-swelling rate ≥ 85%.

[0044] The scale removal effect test and the blockage removal effect test were carried out on the descaling and plugging removal solution B prepared in Example 2. Concrete test method is identical with the method that embodiment 1 adopts.

[0045] Descaling effect test: the test t...

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Abstract

The invention discloses descaling and blockage-removing fluid for clearing blockage in a drilling and completion process and a preparation method of the descaling and blockage-removing fluid. The descaling and blockage-removing fluid comprises the following components in parts by weight: 20-40 parts of a metal chelating agent, 1-5 parts of biological enzymes, 1-2 parts of a high-temperature anti-swelling agent, 2-5 parts of a stabilizer, 1-5 parts of a ligand, 2-5 parts of alkyl glucosamide, 1-5 parts of a phosphate anionic surfactant, 1-5 parts of alkali and 30-60 parts of water. The corresponding preparation method is simple, and the descaling and blockage-removing fluid is applicable to shaft cleaning and blockage removing of immediate vicinity of wellbore in an environment of 80-150 DEG C; the descaling and blockage-removing fluid is capable of clearing scales which cannot be eliminated during acid pickling and in the conventional injected fluid, such as barium sulfate, strontium sulfate, calcium sulfate, the pollution problem on the immediate vicinity of wellbore caused by barite is solved, the permeability is restored and improved, the reservoir skeleton is not damaged, the stability of the reservoir is still maintained after use, and sand production is avoided; in addition, the phenomenon of swelling of the interface and water sensitivity clay can be avoided.

Description

technical field [0001] The invention relates to the technical field of downhole operations in oil and gas fields, in particular to a descaling and plugging removal fluid used for removing plugging in the drilling and completion process and a preparation method thereof. Background technique [0002] Most domestic oil fields need to use barite to increase the density during drilling and well completion, and the main components of barite are barium sulfate, strontium sulfate, and calcium sulfate. These are inorganic scales that cannot be removed by conventional pickling. Some oil reservoirs themselves contain barium sulfate, strontium sulfate, and calcium sulfate, which undoubtedly increases the difficulty of descaling. In the process of drilling, completion and stimulation, many of the selected well-entry fluid systems are of polymer type, such as polyacrylamide, hydroxypropyl guar gum, etc. These polymers are difficult to degrade and flow back after the operation is completed...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C09K8/52E21B37/06
CPCC09K8/52E21B37/06
Inventor 刘音张世林常青王晓磊张建华马田力徐庆祥黄其
Owner CNPC BOHAI DRILLING ENG
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