It is the most important control index of specific gravity mud, and its size is mainly determined by the solid content and the specific gravity of the solid. The solid content refers to the weight or volume percentage of solid particles in the mud. We know that the pressure and pressure formed by different specific gravity are different.

The specific gravity will play a corresponding role in mud wall protection and support. The greater the specific gravity, the greater the pressure, and the greater the supporting force of mud to the surrounding wall. Only from this perspective, for areas with poor formation stability, the specific gravity of mud will be relatively controlled to achieve stability. However, if the specific gravity is too large, it means that the content of useless solid in the mud is too high, which will not only easily lead to the thickening of mud skin, but also lead to the loss of rheological properties, resulting in the increase of the pressure of injection, which will make injection more difficult.

Therefore, in different application scenarios, it is necessary to design the specific gravity of the mud and increase the weight of the mud when necessary. The commonly used weighting materials are made of inert substances insoluble in water by grinding. The conditions for weighting materials are high density, low abrasion, easy crushing and no interaction with other components in mud. Commonly used weighting materials in the industry include barite powder, perlite, etc.

However, it should be noted that in the traditional bentonite slurry making process, the viscosity and specific gravity are basically positively correlated, and the influence on the construction is generally consistent. However, some special chemical slurries are different from it. They often use a very small amount of chemical additives to improve the viscosity of the slurry. Because of the small amount of additives, the specific gravity hardly changes, but the increase of viscosity also plays the role of wall protection and support, which is their characteristic.

The new thixotropic mud is closer to chemical mud, and the molding state of bentonite mud can be adjusted by a small amount of additives, so as to play a supporting or lubricating role. In order to meet different demands and adapt to different working conditions, we also began to study the adjustment method of its specific gravity. Only in this way can it be widely used in various shield, pipe jacking, vertical shaft and other construction methods. We also look forward to the application and communication with people in the industry.