Influence and adjustment of mud specific gravity

Specific gravity is the most important control index of mud, and its size mainly depends on the solid content and the specific gravity of solid in mud. The solid content refers to the weight or volume percentage of solid particles in 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 is, the greater the pressure will be, and the greater the mud's support force to the surrounding wall will be. From this perspective, for areas with poor formation stability, the mud specific gravity will also be relatively controlled to achieve stability. However, a large specific gravity means that the content of useless solid in the mud is too high, which will not only easily cause the mud skin to thicken, but also cause the loss of rheological properties, leading to an increase in the pressure of the injection, which will make the injection more difficult.

Therefore, in different application scenarios, the specific gravity of mud needs to be designed, and mud weight needs to be increased when necessary. The commonly used weighting materials are made of water-insoluble inert substances by grinding. Weighting materials should have the following conditions: high density, low abrasion, easy crushing, and no interaction with other components in the mud. The commonly used weighting materials in the industry include barite powder, perlite, etc.

Barite powder

However, it should be noted that in the traditional bentonite slurry making process, the viscosity and specific gravity are basically positive correlation, and the impact on the construction is roughly the same. Some special chemical muds are different from them. They usually improve the viscosity of the slurry through a very small amount of chemical additives. Due to the small amount of additives, the specific gravity has almost no change, but the increase of viscosity also plays a role of wall protection and support, which is its characteristic.

New thixotropic mud

The new thixotropic mud developed by us is more similar to chemical mud, and the molding state of bentonite mud is adjusted by a small amount of additives to support or lubricate it. In order to meet different needs and adapt to different working conditions, we also began to study the adjustment method of its proportion. In this way, it can be widely used in various shield tunneling, pipe jacking, vertical shaft and other construction methods. We are also looking forward to the application and communication with the industry.