High-viscosity CMC has higher viscosity and better suspension and rock-carrying ability, which can provide better proppant carrying and longer effective period. Therefore, in highly permeable, porous and complex formations, it may be more appropriate to choose high-viscosity CMC, which can improve the suspension and rock-carrying capabilities of the drilling fluid, reduce the precipitation of cuttings, reduce the pressure loss between wells, and improve drilling efficiency.

Low-viscosity CMC has lower viscosity and better rheological properties, which can be mixed and pumped more easily, reducing wear and load on drilling equipment. In scenarios where low viscosity drilling fluid is required, such as horizontal drilling, small hole drilling, etc., it may be more appropriate to choose low viscosity CMC. In addition, low-viscosity CMC also has better lubrication properties, which can reduce friction and wear during drilling and increase the service life of the drill bit.

In summary, when choosing CMC-sodium carboxymethylcellulose as a petroleum drilling fluid additive, you need to make a selection based on specific drilling scenarios and needs. High-viscosity CMC is suitable for scenarios that require better suspension and rock-carrying capabilities, while low-viscosity CMC is suitable for scenarios that require better rheological properties and lubrication properties.