Polyalcohol drilling fluid has excellent performance, which can solve the stability problem of strong water-sensitive well and strong stress mud shale, and there is no pollution and interference geological logging problems, so the application of polyalcohol drilling fluid is more and more.
At present, nonionic polymer with certain surface activity are widely used.
Cloud point is an important index of nonionic surfactants.When nonionic surfactant aqueous solution is heated, the solution changes from transparent to turbidified or even stratified,the corresponding temperature of this phenomenon is called the cloud point.
The formation of cloud point originates from the interaction between the hydrophilic functional groups of surface living molecules and water molecules.
When the temperature is lower than the cloud point, the hydrophilic functional group and the H＋ in the water molecule are connected by hydrogen bond, and the hydrophilic effect is strong, so the compatibility is good, the appearance is transparent.
When the temperature reaches or is higher than the cloud point, the molecular movement of the hydrophilic functional group is intensified, the hydration is weakened, and it will precipitate out and become muddy.
The cloud point of polyalcohol has a great influence on the lubrication and anti-collapse performance of drilling fluid, which is mainly manifested in:
1. The cloud point of polyalcohol is closely related to lubricity, and the adhesion coefficient decreases continuously with the increase of temperature, and the effect is more obvious at high temperature
2. The cloud point of polyalcohol is closely related to the inhibition, and the inhibition continues to increase with the temperature, and the effect is more obvious at high temperature
In conclusion, polymeralcohol is recommended in conditions above 100 ° C.
