Hydroxy ethyl cellulose is a nonionic polymer in the appearance of white or slightly yellowish plush-like powder. It is prepared from the alkali cellulose and ethylene oxide (or chloroethanol) by the etherification reaction, and belongs to the non-ionic soluble cellulose ethers, non-toxic and tasteless. HEC has good thickening, suspending, dispersing, emulsifying, adhesion, film-forming, water-protecting and providing protective colloid properties, and has been widely used in oil exploration, coatings, construction, medicine and food, textile, paper, high polymer reactions and other fields. It can form a viscous colloidal solution after it has dissolved in water. The product has a tackifying effect in the drilling fluid, and the biggest feature is tackifying but not increasing shear force, with resistance to temperature as high as 110-120℃.
HEC is mainly used for non-solid phase completion fluids and workover fluids of hydrocarbon reservoir aggravated by salt powder or limestone powder. The advantage of using HEC for the preparation of this system is that it has good acid solubility. By acidification treatment, it can effectively remove HEC residues, salt particles and limestone powder particles intruded into formations. The suitable dosage of hydroxy ethyl cellulose in drilling fluid is 0.3-0.6%. when used in completion fluids and workover fluids the amount is determined by laboratory experiments.