The mud fluid formulated by petroleum drilling polyanionic cellulose (PAC－HV, PAC－LV) has good water loss reduction, inhibition, high temperature resistance and salt resistance.Pulping in fresh water, 4% brine and saturated brine; when the dosage is 35-40% of traditional CMC, its viscosity enhancement and filtration loss reduction capabilities are similar in freshwater drilling fluids, and it is better in 4% brine and saturated brine drilling fluids, that is, it has stronger salt paste resistance and is used in oil drilling, especially suitable for deep wells, high-temperature wells, brine wells and offshore oil drilling.

Suitable for any mud from fresh water to saturated brine；

For pulping, the pulping capacity of PAC can reach 2-3 times that of ordinary CMC；

Low-viscosity PAC can effectively reduce the amount of filtration loss, high-viscosity PAC has a high amount of pulping, and the effect of reducing filtration and water loss is obvious.；

The mud fluid can inhibit the dispersion and expansion of clay and shale in a high-salt medium, so that the well wall pollution can be controlled and the time of clay hydration, expansion and dispersion can be delayed.；

Has good ability to protect colloids；

PAC can be used in many complex formations such as salt, paste, high temperature, and difficult drilling conditions such as oceans and deserts.；

It is ideal for PAC to be used as an inhibitor and water loss reducing agent in drilling fluids. The mud fluid formulated by PAC can inhibit the dispersion and expansion of clay and shale in high-salt media, so that well wall pollution can be controlled.In the workover fluid, the workover fluid formulated is low-solid phase, which will not block the permeability of the production layer due to solids, and will not damage the production layer; and it has a low water loss, which reduces the amount of water entering the production layer, and the incoming water will form a water ballast phenomenon due to the blocking of the emulsion.

The workover fluid formulated with PAC provides advantages that other workover fluids do not have.：

Protect the production layer from sexual damage；

It has the carrying capacity to clean the borehole, and the workload of maintaining the borehole is reduced；

It has the ability to resist the infiltration of water and sediment, and it rarely blisters.；

It can be stored or transferred from well to well, which is lower than ordinary mud workover fluid.The fracturing fluid formulated with PAC in the fracturing fluid can withstand 2% KCI solution (it must be added when preparing the fracturing fluid) and has good solubility, easy to use, can be formulated on site, and has a fast glue-forming speed and strong sand-carrying ability.Used in formations with low osmotic pressure, its fracturing effect is better.