1. FC-FR220S has strong salt resistance. Through indoor experiments, adjust the salt content of the drilling fluid system used for evaluation to investigate the salt resistance of FC-FR220S product after aging at 200 ℃ in the base mud with different salt content. The experimental results are shown in Figure 1:

Remark: Composition of base slurry for evaluation: 6% w/v sodium soil+4% w/v evaluation soil+1.5% v/v alkali solution (40% concentration);

HTHP fluid loss shall be tested at 150℃ at 3.5MPa.

It can be seen from the experimental results in Figure 1 that FC-FR220S has excellent performance in controlling HTHP fluid loss under different salt contents, and has stable performance and excellent salt resistance.

2. FC-FR220S has excellent thermal stability. The indoor experiment is conducted to investigate the temperature resistance limit of FC-FR220S product in 30% brine slurry by gradually increasing the aging temperature of FC-FR220S. The experimental results are shown in Figure 2:

Remark: HTHP fluid loss is tested at 150 ℃ and 3.5MPa.

It can be seen from the experimental results in Figure 2 that FC-FR220S still has a good role in controlling HTHP fluid loss at 220℃ with the increase of temperature, and has excellent temperature resistance and can be used for deep well and ultra deep well drilling. The experimental data also shows that FC-FR220S has the risk of high temperature desorption at 240℃, so it is not recommended to use it at this temperature or higher.

3. FC-FR220S has good compatibility. The performance of FC-FR220S after aging at 200℃ in sea water, compound brine and saturated brine drilling fluid systems is investigated through laboratory experiments. The experimental results are shown in Table 2:

Table 2 Performance Evaluation Results of FC-FR220S in Different Drilling Fluid Systems

It can be seen from the experimental results in Table 2 that FC-FR220S has good compatibility and is an excellent fluid loss control for controlling HTHP fluid loss of drilling fluid systems such as sea water, compound brine and saturated brine, etc.