4/29/2023 0 Comments Underground directional drilling![]() As with most trenching operations the impact on local surroundings can be massive and extremely unpleasing on the eye whilst also bringing very high installation costs. Directional Drilling prevents the need for costly and inefficient trenching methods which is are harmful to the environment and create massive amounts of waste materials. With this method pipelines of almost any material, with diameters of up to 1000mm and lengths to 1000m can be installed in one single operation. We at SW Directional Drilling are one of the market leaders within the UK Directional Drilling industry. 1993, A calculation method for earth pressures on directionally drilled pipelines, Pipeline conference 1993, Belgium.What we can achieve with Directional Drilling 2005, Stability of a borehole during horizontal directional drilling, Proc. No dig conference Rotterdam Viehofer, T., Linthof, T. A., 2005 Modelling installation loads for pipes in horizontal directional drilling, Proc. Bisschop, F., 1995 transport processes in borehole and pipeline (In Dutch), Drilling of tunnels and pipelines research group, Delft. H.J.A.M, and Kruse H.M.G 2007, Soil Related Risks during the Pull-back-phase of a Horizontal Directional Drilling (HDD), Proc. H.J.A.M., and Spiekhout J., 2007, Design guidelines for the bending radius of large diameter steel pipes for HDD construction, submitted for publication in 3R international. Brink H.J., Kruse H.M.G., Luebers, H., Hergarden. Scientific series, Ann Arbor, University of Michigan press. Hetényi, M., 1946 Beams on elastic foundations. A high pulling force caused by bore hole instability due to erroneous chosen drilling fluid.A high pulling force caused by bore hole instability due to soil and groundwater conditions.A high pulling force caused by an irregular shaped bore hole with small 3D-bending radii.Damage of the coating of the pipeline caused by wrong choice of the coating of the pipeline in relation to the forces in between the pipeline and the obstacles.Damage of the coating of the pipeline caused by occurrence of obstacles of man made origin.Damage of the coating of the pipeline caused by unawareness of obstacles of natural origin due to misinterpretation of the results of the soil investigation.High radial displacements may lead to breakage of drill pipes. ![]() Higher normal forces on the bore hole wall and higher radial displacements of the pipeline during the pull back operation are also caused by a small design bending radius. A high pulling force caused by a small design bending radius.A high pulling force caused by wrong ballasting with respect to the weight of the drilling fluid.The consideration of the described aspects is used for a global risk analysis for future horizontal directional drillings. The complex pipeline soil interaction can be divided in a several aspects (processes and phenomena) which are described in the previous paragraphs. The pipeline soil interaction during the pull back operation has a major influence on the success of the pull back operation. The risk analysis resulted in a series of risk reducing measures for future horizontal directional drillings. Besides high normal forces on the bore hole wall in case of small bending radii or irregular shaped bore holes, occurrence of obstacles and bore hole instability are identified as major risks during the pull back operation. Consideration of all aspects of the combined pipeline soil behaviour formed the bases of a global risk analysis of the pull back operation. The pipeline soil interaction can be defined as the combined behaviour of the pipeline and the surrounding soil in terms of stresses and deformations. The nature of these problems is related to the pipeline-soil interaction. The problems, which might occur during a pull back operation, are varying from high pulling forces to uncompleted pull back operations and from slight coating damages to deteriorated pipelines. The success of the pull back operation of horizontal directional drilling can be increased by performance of a risk analysis.
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