1 、Process Flow of Ground Horizontal Directional Drilling
Horizontal directional drilling from ground is a process of obtaining stratigraphic data to meet the engineering design requirements through on-site compilation, recording, testing and analyzing of rock samples by selecting proper construction site and setting up drilling field on the ground in line with the actual engineering features and implementation conditions, adopting a complete package of high-performance combined directional drilling rigs and a supporting measurement while drilling system, continuously and accurately angle building and coring in the form of inclined holes, and then horizontally drilling and coring after reaching the target formation.The specific process flow is shown in the figure below。
(1) It is mainly applicable to the horizontal core drilling, directional drilling and troublesome zone drilling for the ground engineering, municipal works, tunnel etc.
(2) The firmness coefficient f of the formation shall be ≤10.
3 、Technical Parameters of Process
(1) Drilling Depth: ≥1,000m;
(2) Deviation of Drilling Trajectory: ±0.5°;
(3) Ending Offset: ≤2m horizontally, and ≤1m vertically;
(4) Measurement Accuracy of Drilling Angle: ±0.1°;
(5) Measurement Accuracy of Drilling Azimuth: ±0.3°;
(6) Coring Recovery Rate: In conformity with the requirements of the investigation specifications and standards of the industry.
4 、Process Advantages
(1) In light of the drilling trajectory control technology, continuous “linear” survey can be performed along the design axis of the tunnel within certain scope to improve the survey accuracy, which optimizes from the “point” survey of vertical hole to the “line” survey of horizontal hole. The formation survey accuracy is enhanced to satisfy the detailed geological survey requirements;
(2) With the ability of directional angle building and branching, it realizes big drilling coverage and high drilling utilization rate;
(3) When the works to be performed pass underneath important structures, the drilling can be performed by angle building in inclined hole, which overcomes the dilemma of conventional vertical drilling;
(4) It satisfies the requirements of drilling construction for various ground engineering, municipal works, tunnel and troublesome zone without restrictions by the survey environment and place;
(5) The wireline coring and drilling coring processes are adopted for coring with high coring recovery rate.
(6) It is capable of geophysical prospecting while drilling to implement acoustic and electrical in-hole geophysical survey.
(7) The mutual verification of geophysical survey while drilling with drilling realizes accurate and advanced geological forecasting.
The horizontal directional drilling equipment from ground is mainly composed of full hydraulic high-performance combined directional crawler drilling rig, measurement while drilling system, high-strength spiral groove through cable drill rod, bottom motor, core tube, orientation device, circulating water device, etc. Please see the related product introduction or special scheme for details.