Preparation of low molecular plant gum

Abstract

The invention relates to a method for preparing low-molecular vegetable gum through chain scission of macromolecular vegetable gum by a physical or chemical method. At present, a fracturing fluid used in fracturing reconstruction of an oil gas field is the fracturing fluid mainly taking macromolecules as a thickening agent, influences reliability in construction and is easy to cause pollution to environment. Through a chemical degradation method, the macromolecular vegetable gum in an ethanol and water solution has chemical reaction with inorganic alkali, inorganic acid or organic acid, so that part of a macromolecular chain of the macromolecular vegetable gum is fractured, and the low-molecular vegetable gum having molecular weight of between 10,000 and 400,000 is obtained. When the low-molecular vegetable gum is used as the fracturing fluid, return liquid can be recycled after the construction so as to save a large quantity of water resource and chemical agents; and the method effectively reduces and avoids environmental pollution caused by the emission of waste liquid.

Description

Technical field:

[0001] The invention relates to a method for preparing low-molecular-weight plant-based gums by breaking chains of high-molecular-weight plant-based gums by using physical or chemical methods. Background technique:

[0002] At present, the fracturing fluid used in oil and gas field fracturing reconstruction is mainly fracturing fluid with polymer as thickener, which generally has the following disadvantages:

[0003] 1. Gel breakers such as peroxides and biological enzymes must be used in the fracturing fluid so that the polymers in the fracturing fluid can degrade in the formation, reduce the viscosity of the fracturing fluid, and facilitate its flow back from the formation to the ground.

[0004] 2. Because the gel breaker must be used in the fracturing fluid, the gel breaker always reduces the viscosity of the fracturing fluid during the fracturing process, which affects the reliability of the construction.

[0005] 3. The filter cake formed by the fract...