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Solutions for Ultra-Long-Distance Horizontal Directional Drilling through Pipelines

Solutions to common questions in the construction of ultra-long-distance horizontal directional drilling through pipelines:

(1) Oriented construction: When faced with ultra-long-distance horizontal directional drilling, the internationally advanced directional hole dual-drilling rig synchronization construction technology is adopted; the dual-drilling rigs are synchronized and coordinated at both ends of the excavation point and the soil entry point to solve the long-distance crossing In the pilot hole construction, the drill pipe is unstable and the strength is insufficient.

(2) Reaming construction: Each entry point is equipped with a drilling rig, one provides torque and the other provides tension, which avoids the problem of out of control of the reamer caused by the excessively long drill rod, reduces the risk of reaming construction, and improves Reaming speed.

Hole washing: After each reaming construction, the hole should be washed with a twisting cage. If satisfactory results cannot be obtained from one washing of the holes, the holes should be washed 2 to 3 times to thoroughly clean the gravel and the holes in the holes. Impurities.

(3) Drag-back construction: The “two-by-one” construction method is adopted to reduce the friction during the drag-back process, and solve the construction problems of excessive drilling rig thrust and easy damage to the pipeline in the long-distance pipeline drag-back.

(4) Mud process:

  1. Mud ratio in the guiding phase:

(1) Guide hole oblique hole section: In order to ensure the carrying of drill cuttings and clean the holes, control the loss of mud and prevent hole collapse, it is necessary to increase the content of solid wall agent and tackifier.

(2) Horizontal hole section of the pilot hole: increase the content of chip cleaning agent and lubricant, appropriately reduce viscosity and shear force, ensure good rheological properties of the mud, make the cuttings return to the ground smoothly, enhance the lubricity of the mud, and reduce the drilling rig Rotation and propulsion resistance.

  1. Mud ratio at the reaming stage: The reaming section is to enhance the wall-building performance of the mud and prevent the hole wall from collapsing and shrinking. It is necessary to increase the content of wall-fixing agent and viscosity increasing agent.
  2. Mud ratio in the drag-back stage: improve the lubricity of the mud, reduce friction resistance, enhance the effect of carrying debris, and increase the content of debris removal agent and lubricant.

The viscosity control of the mud should be based on the stratum conditions of the crossing section. During the construction, a special mud with high quality and high performance must be formulated according to the actual stratum conditions.

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