Abstract: The low permeability oil and gas resources in the residual resources are more and more important. Because of
the characteristics of low permeability and low porosity in low permeability reservoir，the formation damage will happen in
drilling and completion，production，production stimulation and EOR. This paper discusses the experimental method of damage
evaluation of the drilling/completion fluid，kill fluid and fracturing fluid when successively contact reservoir in the Chang-
8 formation. The experimental results show that drilling/completion fluids is the most serious damage to the reservoir than
fracturing fluid，and kill fluid is the lightest. Analysis shows that the fluid damage and loss are the main factors of damage to
drilling and completing. Emulsification，residues，liquid trap，soaking time；natural fractures and hydraulic fracture blockage；
the cooling effect of fracturing fluid are the main factors of fracturing fluid damage. The paper puts forward the suggestion to
improve drilling fluid with sealing agent，improves the fracturing techniques and fracturing fluid to provide basic parameters
for the systems formation damage control engineering.

Key words: low permeability reservoirs, working fluids, formation damage, fracturing fluid