Modified welan gum, preparation method thereof, water-based fracturing fluid composition and water-based fracturing fluid

A technology of water-based fracturing and Welan gum, which is applied in the direction of drilling compositions, chemical instruments and methods, etc., can solve the problem of no cross-linking-viscosification system, slow dissolution of Welan gum, and gel-forming properties Poor problems, to achieve the effect of low cost, increased viscosity, enhanced viscosity

Active Publication Date: 2019-11-26
CHINA PETROLEUM & CHEM CORP +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0004] However, the viscosity of Welan gum itself is not high, and the molecular structure of Welan gum is composed of mannose, glucose and rhamnose, and the molar ratio of mannose, glucose and rhamnose is 1:2:2, which makes its cis The proportion of hydroxyl groups is only one-third of that of guar gum, and there is a high proportion of hydrophobic groups, which leads to slow dissolution and poor gelation performance of Welan gum. It can only be considered to be theoretically capable of crosslinking , because its cross-linking is very difficult, in the field of fracturing, Welan gum is usually regarded as a non-cross-linkable polymer, and there is no cross-linking-adhesive system combined with it

Method used

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  • Modified welan gum, preparation method thereof, water-based fracturing fluid composition and water-based fracturing fluid
  • Modified welan gum, preparation method thereof, water-based fracturing fluid composition and water-based fracturing fluid
  • Modified welan gum, preparation method thereof, water-based fracturing fluid composition and water-based fracturing fluid

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preparation example Construction

[0016] According to the first aspect of the present invention, there is provided a preparation method of modified Welan gum, the method comprising: in the presence of an organic solvent and a phase transfer catalyst, contacting Welan gum with citric acid to obtain citric acid modified Sexual Welan gum.

[0017] According to the present invention, the phase transfer catalyst can be various conventional phase transfer catalysts in the art, preferably a quaternary ammonium salt phase transfer catalyst, such as but not limited to benzyltriethylammonium chloride, tetraethylammonium chloride , Tetrabutylammonium Bromide, Tetrabutylammonium Chloride, Tetrabutylammonium Bisulfate, Trioctylmethylammonium Chloride, Dodecyltrimethylammonium Chloride, Tetradecyltrimethylammonium Chloride at least one of ammonium chloride and trimethyloctadecylammonium chloride. Preferably, the phase transfer catalyst is trimethyloctadecylammonium chloride.

[0018] Wherein, the amount ratio of the Welan...

preparation example 1

[0055] This preparation example is used to illustrate the preparation of citric acid modified Welan gum

[0056] In a three-necked flask, take 5g of Welan gum and 5g of trimethyloctadecylammonium chloride and mix them in 80ml of toluene under stirring conditions to prepare a suspension of 62.5g / L. Add 1.39g of citric acid Add the crystals into the above suspension at a substantially constant speed within 30 minutes, stir at a speed of 450rpm to fully dissolve it; react at normal pressure, 90°C, and 500rpm for 10 hours, take out the reaction solution, and pour it into The product was precipitated in a large amount of absolute ethanol, washed, filtered with suction, and dried at 60°C for 24 hours to obtain the modified Velan gum product A1. The water solubility and viscosity are shown in Table 1.

preparation example 2

[0058] This preparation example is used to illustrate the preparation of citric acid modified Welan gum

[0059] In a three-necked flask, mix 5g of Welan gum and 7.5g of trimethyloctadecylammonium chloride in 83ml of toluene under stirring conditions, and prepare a suspension of about 60g / L. Mix 2.5g of lemon The acid crystals were added to the above-mentioned suspension at a substantially constant speed within 20 minutes, stirred at a speed of 500 rpm to allow it to fully dissolve; reacted at normal pressure, 110°C, and 550 rpm for 9 hours, took out the reaction solution, and poured Add a large amount of absolute ethanol to precipitate the product, wash, filter with suction, and dry at 70°C for 12 hours to obtain the modified Velan gum product A2. See Table 1 for water solubility and viscosity.

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Abstract

The invention relates to the field of petroleum extraction, and in particular relates to a water-based fracturing fluid composition and a water-based fracturing fluid. The water-based fracturing fluidcomposition contains a thickening agent, a cross-linking agent, a fracturing auxiliary agent and water, and the water-based fracturing fluid composition is characterized in that the thickening agentis citric acid-modified welan gum. The water-based fracturing fluid is prepared from the above fracturing fluid composition through the following steps: mixing the thickening agent, the fracturing auxiliary agent and the water to obtain a base fluid; and mixing the base fluid and the crosslinking agent to form the water-based fracturing fluid. When the water-based fracturing fluid composition provided by the invention is used to prepare the water-based fracturing fluid, the citric acid-modified welan gum and the cross-linking agent can be subjected to a crosslinking reaction to form a freeze gel system with shear viscosity (80 DEG C@170 s<-1>, 90 min) maintained at 80 mPa.s or more, the shear viscosity is better than an industry standard of Q/SH 0351-2010 ''Technical Requirements of Water-Based Crosslinking chemicals'' and the water-based fracturing fluid meets the requirements of fracturing site construction.

Description

technical field [0001] The invention relates to the field of petroleum exploitation, in particular to a modified welan gum and a preparation method thereof, a water-based fracturing fluid composition and a water-based fracturing fluid. Background technique [0002] Since the middle of last century, hydraulic fracturing technology has been the main stimulation technology in oil and gas development at home and abroad. After entering the new century, hydraulic fracturing technology, as a key technology for the development of unconventional resources such as tight sandstone oil and gas, coalbed methane and shale oil and gas, has been highly valued. Among them, vegetable gums represented by guar gum and their derivatives are the most important thickeners in water-based fracturing fluid systems, accounting for more than 90% of the total usage. However, planting products such as guar gum are significantly affected by regions and climates, are highly speculative, and have large pri...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C08B37/00C09K8/68
CPCC08B37/006C09K8/685C09K8/90
Inventor 祝纶宇刘希胡晓娜杨金彪方昭伊卓
Owner CHINA PETROLEUM & CHEM CORP
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