During the construction of the system, hole opener drilling buried crossing point and allow the excavation site exploration holes, in order to ensure that no damage to other pipelines.
     2, the selection and preparation of drilling mud
     Drilling mud is an important part of the selection and preparation of horizontal directional crossing, is to drill pilot holes pre-reaming and pullback pipe when the "blood."
     The main effect of 2.1 for cooling drilling mud hole, carry the drill cuttings and discharge the ground,
     Stabilizing the cell walls and reduce torque Hydraulic Drilling jars and pull back when drilling.
     2.2 The performance parameters of density, viscosity and bond strength, control the density prevents hole wall collapse, and the size of the drilling mud viscosity decided takeaway chip capacity, bond strength is a measure of drilling mud solid particles in suspension Ability. Only when these three parameters adjusted to an appropriate range, drilling mud to play the biggest role.