Choosing CMC-carboxymethylcellulose sodium as oil drilling mud water retaining agent has the following advantages:

Good suspension and rock-carrying ability: High viscosity CMC can provide better proppant carrying and longer validity period, which can improve the suspension and rock-carrying ability of drilling fluid, reduce cuttings precipitation, and improve drilling efficiency.

Improve mud performance: CMC can form a thin and hard filter cake on the well wall with low permeability, thereby reducing water loss, reducing mud clogging and adhesion, and improving mud performance.

Salt resistance and stability: CMC has good salt resistance and stability, can maintain good performance in high salinity environments, and reduce mud performance fluctuations caused by changes in salinity.

Environmental protection: CMC is a high-polymer fiber ether made from chemical modification of natural cellulose. Compared with other chemical mud additives, it has better environmental protection and can reduce environmental and ecological pollution.

Easy to use: CMC has low viscosity, is easy to mix and pump, and can reduce wear and load on drilling equipment.

In summary, choosing CMC-sodium carboxymethylcellulose as a water-retaining agent for oil drilling mud can provide good suspension and rock-carrying capabilities, improve mud performance, have salt resistance and stability, and is environmentally friendly, and is easy to use.