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Polysaccharide modified salt-resistant resistance-reducing agent for shale gas fracturing fluid and preparation method thereof

A technology of drag reducing agent and polysaccharide, which is applied in the field of polysaccharide-modified anti-salt drag reducing agent for shale gas fracturing fluid and its preparation, which can solve the problem of solution viscosity drop, inability to meet salt resistance, polymer main chain breakage and degradation, etc. problems, to achieve the effect of increasing the solution viscosity, improving the comprehensive performance of temperature resistance and salt resistance, and obvious solution viscosity

Active Publication Date: 2021-06-04
SHENYANG RES INST OF CHEM IND
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, high-temperature and high-salt oil reservoirs make the application of conventional linear polymers such as partially hydrolyzed polyacrylamides face many problems: with the increase of inorganic salts in high-salinity water, the charge shielding effect between polymer molecular chains is enhanced, and the molecular chains are easily Curl, the apparent viscosity of the solution is greatly reduced; this type of polymer will be hydrolyzed under high temperature and high salt conditions, and the compounding effect of dissolved oxygen in the solution will also cause the main chain of the polymer to break and degrade, which will greatly reduce the solution viscosity. result in reduced performance or even complete failure
[0013] Documents 3, 4, and 5 are just simple mixtures of polymers and polysaccharides. They only conduct feasibility studies from the aspects of association mechanism and rheology, but do not fundamentally improve the salt resistance of polymer chain segments. It proves that the use of polysaccharides alone Or modified polysaccharides are unable to meet the salt resistance 1×10 6 The requirements of salinity above mg / L, shear resistance, temperature resistance and other technological requirements are difficult to apply in industry

Method used

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  • Polysaccharide modified salt-resistant resistance-reducing agent for shale gas fracturing fluid and preparation method thereof
  • Polysaccharide modified salt-resistant resistance-reducing agent for shale gas fracturing fluid and preparation method thereof

Examples

Experimental program
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Effect test

Embodiment 1

[0034] 1) Synthesis method of typical polymerizable modified polysaccharides:

[0035] Synthesis of chemical modification of xanthan gum: a large number of active hydroxyl groups on the outside of xanthan gum molecules react with maleic anhydride, and use the high activity of anhydride to undergo esterification reaction with hydroxyl groups, thereby introducing polymerizable double bonds and synthesizing modified xanthan gum. Raw gum MX (ie xanthan gum maleate (MA)).

[0036] Specific synthesis conditions: Dissolve 10.5g (0.11mol) of maleic anhydride in 100mL of tetrahydrofuran, add 20g (0.0214mol) of xanthan gum to swell for 1 hour; wherein, the molar ratio of xanthan gum to maleic acid is 1:5. Add 0.35g p-toluenesulfonic acid catalyst and 0.002g hydroquinone polymerization inhibitor, heat the system to 60°C, react at constant temperature for 24h, cool the reaction liquid to room temperature, and filter. The filter cake was washed successively with tetrahydrofuran (20mL×1), ...

Embodiment 2

[0040] 1) Synthesis of butyl glucoside maleate: add 102.85g n-butanol in a there-necked flask equipped with a thermometer, a stirrer and a nitrogen pipe, add 0.092g concentrated sulfuric acid dropwise under stirring, divide 5 Add 27.825g of glucose at a time, react at 105°C for 4.5h, use Fehling's reagent to detect the end point of the reaction, after the reaction, add 1mL of 2mol / L NaOH solution to neutralize the excess concentrated sulfuric acid, and distill off n-butanol under reduced pressure. Butyl glucoside is obtained. The obtained 0.15 mol of butyl glucoside was mixed with 29.4 g (0.3 mol) of maleic anhydride, 0.11 g of concentrated sulfuric acid was added, and the reaction was stirred at 60° C. for 3 h to obtain butyl glucoside maleate (BGMAH).

[0041] 2) Preparation of anti-salt drag reducing agent:

[0042] Add 60g solvent naphtha, 10.4g SPAN-80, 1.6g OP-10 to another three-necked flask, stir quickly to disperse into a uniform oil phase; accurately weigh 49g AM, 2...

Embodiment 3

[0044] 1) Synthesis of modified cyclodextrin (β-CD-A A): Weigh a certain amount of β-CD and 1,3-dicyclohexylcarbodiimide (DCC) condensing agent, dissolve in DMF, and heat at room temperature Add acrylic acid with the same molar ratio as DCC dropwise, and after adding dropwise for 30 minutes, continue to react at 80°C for 3 hours. After the reaction, remove the precipitated solid by vacuum filtration, and precipitate the crude product from the filtrate with acetone. Treatment, dissolving in distilled water and methanol, acetone precipitation and purification, vacuum drying to obtain acrylic acid β-cyclodextrin ester.

[0045] 2) Preparation of salt-resistant drag-reducing agent: synthesized according to the mass ratio of AM:AMPS:AA:modified cyclodextrin=10:1:2:0.6, the total mass fraction of the monomer is 30%, and the emulsifier adopts SPAN-80 and SMO-5 composite, the dosage is 4.5% of the total mass, kerosene is the reverse phase solvent, the addition is 20% of the total mass...

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Abstract

The invention relates to preparation of a resistance-reducing agent, in particular to a polysaccharide modified salt-resistant resistance-reducing agent for shale gas fracturing fluid and a preparation method thereof. The salt-resistant resistance-reducing agent is a copolymer with a viscosity-average molecular weight of 7000000-18000000, wherein the monomer in the copolymer structure comprises the following components in parts by weight: 45-89 parts of acrylamide, 5-20 parts of hydrolyzed acrylamide or acrylic acid, 1-5 parts of modified polysaccharide and 5-30 parts of unit B. According to the invention, a novel polymerizable salt-resistant monomer is formed by carrying out structural modification on several biological polysaccharides and introducing double-bond groups, and is copolymerized with acrylamide and other monomers according to a certain proportion to form a polymer, wherein the polymer is high in molecular weight and more stable, and has the excellent performance of the biological polysaccharides and the acrylamide, so that a novel salt-resistant and high-temperature-resistant polyacrylamide copolymer is formed, and is particularly suitable for a high-salinity water fracturing process.

Description

technical field [0001] The invention relates to the preparation of a drag reducing agent, in particular to a polysaccharide-modified salt-resistant drag reducing agent for shale gas fracturing fluid and a preparation method thereof. Background technique [0002] At present, with the stable production of conventional oil and gas in the world and the growth of demand, the exploration and development of unconventional oil and gas represented by tight oil and shale oil and gas have sprung up. Entering a turning point where both conventional and unconventional oil and gas development are equally emphasized. Fracturing is an important means to stimulate production of shale gas wells, and drag reducer, as an important additive of fracturing fluid, plays a vital role. [0003] At present, with the depletion of shallow oil and gas resources, the exploration and development of oil and gas reservoirs are gradually shifting to deep formations, the Ca in the fracturing flowback fluid of...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C08F251/00C08F220/56C09K8/68C09K8/90
CPCC08F251/00C09K8/68C09K8/90C08F220/56
Inventor 王洪庆龙惊惊王远周悦孙慧李欣王加友
Owner SHENYANG RES INST OF CHEM IND
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