1. Drilling cycle requirements
The requirements for drilling fluid in drilling cycle are low pump pressure (low viscosity), strong sand carrying capacity (high dynamic shear force), low starting pump pressure (low static shear force), good lubricity, low friction and small wear (less solid particles).
2. Keep wellbore stable
The drilling fluid pressure column should be used to balance the formation pressure and the density of drilling fluid is stable. The pressure column of drilling fluid should be used to balance the pressure of oil and gas in drilling oil and gas reservoirs, and the density of drilling fluid should be appropriate. Drilling fluids are required to overcome unstable formation performance, such as mudstone water absorption and expansion resulting in hole shrinkage; conglomerate and volcanic rock water caused collapse, salt rock water and karst cave formation, that is, different quality drilling fluids are required.
3. Require drilling fluid to protect oil and gas reservoirs
After drilling oil and gas reservoirs, drilling fluid contacts with oil and gas reservoirs. In order to prevent drilling fluid from damaging oil and gas reservoirs, drilling fluid is required to have small loss of water, thin mud cake (after drilling fluid loss, solid pressure difference solid particles form mud cake rings on the wellbore), low solid content and low hydration effect of filtrate (filtrate enters formation and occurs with liquid in formation). Chemical action, etc.
4. Protecting the environment and ecology
Drilling fluids often contain crude oil, diesel oil, various oils and a large number of chemical treatment agents. In order to prevent the possible environmental and ecological impact of drilling fluids, harmless and non-toxic drilling fluids are required.