During the site construction, the followings had been used: (1) Finely dispersed drilling fluid: NV-1 + SM +
CMC ; (2) Low solids drilling fluid: NV-1 + cmc + cellulose + fluid loss agent + +NH4-PAN + SM, etc.; (3) Nonsolids
salty mud: salt + k-PAN + SM + KHm; (4) Polymer non-solid drilling fluid: SM +k-PAM+ NH4-PAN ; (5)
PAB special mud (good flushing ability, hard configuration and maintenance); (6) Potassium polymer drilling fluid.
Field application test that polymer drilling fluid has a long-term property of maintaining the stability of hole wall.