Welan gum

Wellan gum: a new type of biopolysaccharide Wellan gum is a kind of water-soluble extracellular high molecular polysaccharide polymer produced by microbial fermentation. Its molecular skeleton is composed of D-glucose, D-glucuronic acid and L-rhamnose units, and its relative molecular weight is about 8 × 106. Compared with xanthan gum, the aqueous solution of the new biopolysaccharide Wellan gum has the similar properties with xanthan gum, i.e. remarkable shear thinning and good rheological properties. The comparison shows that compared with xanthan gum, the new biopolysaccharide Wellan gum has higher solution viscoelasticity and viscosity stability. Therefore, it is mainly used as thickener, suspending agent, emulsifier, stabilizer, lubricant, film-forming agent and adhesive The agent has good application effect in petroleum industry.

I. characteristics of new biological polysaccharide Velan gum

1. Excellent water solubility and rheological properties

At 25 ℃, the viscosity of 1.0% solution can reach 3300mpa. S, which is twice that of xanthan gum and 100 times that of gelatin.

2. Strong pseudoplasticity

The new bio polysaccharide Velan glue solution has good shear thinning property, and the higher the concentration is, the stronger the thinning strength is.

3. Good thermal stability

The viscoelasticity of the aqueous solution of the new polysaccharide Velan gum has good thermal stability, and the change of the apparent viscosity in the range of 25-100 ℃ is very small, which is basically not affected by the temperature. Even at very low concentration, its aqueous solution has good thermal stability.

4. Acid and alkali (PH) tolerance

In the range of pH 2-12, the apparent viscosity of the aqueous solution does not change with the change of pH.

5. Good salt resistance

The new bio polysaccharide Velan gum has good salt resistance, compatibility with most salts, good compatibility and stability in the presence of many salts. In the presence of high concentration of sugars, it can also maintain a stable thickening system.

6. Good description and compatibility

The new bio polysaccharide Velan gum has a good compatibility with other colloids, and can be compatible with most synthetic or natural thickeners. After mixing, the viscosity increases significantly. For example, when it is mixed with xanthan gum, it shows a strong synergistic thickening effect, and the salt resistance and temperature resistance are not affected.

7. Good suspension and emulsification

The new bio polysaccharide Velan glue solution has the characteristics of pseudoplastic fluid (agitation effect), good suspension function in static state and stable property. It can be used as an excellent suspension stabilizer in industrial production. In addition, the thickening of Wellan gum can reduce the incompatibility between oil phase and water phase, so it can play the role of emulsification.

8. Good biological and environmental safety

The new biopolysaccharide Velan gum is a biopolymer produced from natural raw materials by microbial fermentation, which is non-toxic, biodegradable and environmentally friendly.

II. Application of new bio polysaccharide Velan gum in petroleum industry

1. As oilfield control and flooding auxiliary

With its good thickening, emulsification, suspension, stability and environmental protection, Wellan gum products are very suitable for the current profile control and displacement agents in tertiary oil recovery. The thickening and emulsifying properties of Wellan gum, especially its combination with surfactant, can significantly improve the flow of displacement fluid and crude oil, improve the displacement efficiency, reduce the flow resistance of crude oil, and improve the oil recovery; in addition, as a macromolecular charged material, it can block certain large channels through the agglomeration effect, improve the homogeneity of oil-bearing layers, and make the displacement fluid flow to the residual oil area or immobile area To achieve the goal of increasing and stabilizing production in oil-bearing areas. Velan gum is a kind of degradable environmental protection biopolymer, which can be rapidly degraded into small molecule bioavailable monosaccharide when it returns to the surface with the produced liquid, without any adverse effect on the formation and environment of the oil field.

2. As drilling and production aids - oilfield drilling fluid, completion fluid and workover fluid

The good and stable rheological properties of Velan gum products are that the solid suspension and the pumping fluid adjust the viscosity together;

The strong pseudoplasticity of Velan gum product can reduce the viscosity of the bit at high speed, protect the bit and save the power consumption greatly, but keep the high viscosity at the relatively static drilling position, so as to effectively prevent the borehole wall from collapsing;

In addition, Velan gum products have excellent characteristics in salt resistance, acid and alkali resistance, high salinity resistance, high temperature resistance, etc., and high tolerance in harsh environment, so that it can also meet the requirements of extreme environment such as marine oil reservoir, high salt layer area for drilling fluid.

3. Oilfield fracturing fluid as oilfield fracturing assistant

As a thickener in the fracturing fluid system, Wellan gum has the characteristics of less addition, high stability and strong sand carrying capacity. Compared with the existing fracturing fluid system mainly composed of guar gum, Wellan gum has the outstanding advantages of stable product source, stable price and stable performance.

III. executive standard: Q / 371523qls 002-2016

Technical index

Item

Index

Appearance

Yellow viscous liquid

Solid content /% ≥

One point five

PH value

4-7

Content of crude polysaccharide Velan gum /% ≥

One point three

Apparent viscosity / MPa. S ≥

Five thousand

Viscosity of 10% diluent / MPa. S ≥

One hundred

Viscosity of 10% mineralized water (70000ppm) diluent / MPa · s ≥

Ninety

Maintain the viscosity of 10% diluent at 90 ℃ for 30min / MPa. S ≥

Seventy-five

At present, Velan gum produced by the company has been applied in the oil field.