Carboxymethyl cellulose oil drilling grade is used in fracturing, drilling, and well-cementing fluid as a fluid loss controller and tackifier. CMC can protect the shaft wall and prevent mud loss, thus enhancing recovery efficiency. Carboxymethyl cellulose has the following characteristics.

1. The mud containing CMC can make the good wall form a thin, firm filter cake with low permeability, reducing water loss.

2. After adding CMC into the mud, the drilling rig can obtain low initial shear force so that the mud can easily release the gas wrapped in it, and the debris is quickly discarded in the mud pit.

3. Drilling mud, like other suspension dispersions, has a certain period of existence, and adding CMC can stabilize it and prolong its existence.

4. Mud containing CMC is rarely affected by mold, so it is not necessary to maintain a high pH value and use preservatives.

5. CMC is the treating agent of drilling mud and well-flushing fluid, which can resist the pollution of various soluble salts.

6. The mud containing CMC is stable and can reduce water loss even if the temperature exceeds 150 ℃.

CMC with high viscosity and a high degree of substitution is suitable for low-density mud. In contrast, CMC with low viscosity and a high degree of substitution is ideal for high-density mud. The selection of CMC shall be determined according to the mud type, area, well depth, and other conditions.