Application of polyanionic cellulose sodium (PAC)

(1) Application of PAC in drilling fluids

PAC is an ideal inhibitor and fluid loss reducer. The mud fluid prepared with PAC can inhibit the dispersion and expansion of clay and shale in high-salt media, thereby controlling the wellbore contamination. Since PAC has better reaction uniformity, higher substitution degree, better transparency, and excellent salt and heat resistance than CMC, it has a higher slurry volume (PAC-HV) and lower filtration water loss (PAC-LV) measured by the OCMA standard.

(2) Application of PAC in well repair fluids

The well repair fluid prepared with PAC is low in solid phase, so it will not block the permeability of the production layer due to solids, and will not damage the production layer; it also has a low water loss, which means that the amount of water entering the production layer is reduced, and the water entering will form a water-stagnation phenomenon due to emulsion blockage.

The workover fluid prepared with PAC provides advantages that other workover fluids do not have;

Protect the production layer from permanent damage;

Has the ability to carry clean wellbore and reduces the workload of wellbore maintenance;

Has the ability to resist water and silt infiltration and rarely foams;

Can be stored or transferred between wells, and is cheaper than general mud workover fluid;

(3) The role of PAC in fracturing fluid

The fracturing fluid prepared with PAC can withstand 2% KCL solution (must be added when preparing fracturing fluid) and has good solubility. It is easy to use, can be prepared on site, has a fast gelling speed, and has a strong sand carrying capacity. When used in low osmotic pressure formations, its fracturing effect is even more outstanding.