In the construction of HDD, mud plays an important role in improving the overall speed of cutting and suspending drill cuttings. Enhancing mud treatment technology and the performance of mud control equipment is the essential measures during horizontal directional drilling operation.

 

Mud solid control and Mud recovery is the technical approach to control the solid particle of the mud.It can clear harmful solids phase and reserve Useful from mud.The techniques follows Louis Stokes theorem,which clarifies mathematical relation of Small spherical particles free sedimentation in liquids.

V=g( ρS- ρ)d2/18η :
V-velocity of deposition of particle cm/s;
d-particle size;
g-acceleration of gravity,981cm/s2
η-Liquid viscosity,cP
ρS-particle density,g/cm3
ρ-Liquid Density

This law is the basic formula of analysis using of gravity to separate.