The qualitative risk assessment of MINI, MIDI and MAXI horizontal directional drilling projects

The differences between uncertainty, risk and hazard in horizontal directional drilling (HDD) technology were described in this paper. Various types of uncertainty in HDD technology were shown on the chosen examples. Due to the increasing complexity of HDD projects, the continuous development in HOD technology, the optional possibility of applying various tools and machines and the diversity in the installation size (MINI, MIDI and MAXI), it was needed to consider the additional risks in HOD projects, as well as identify those risks which have not been considered in previous works. Literature study, scenario analysis, risk interviews with HDD contractors, manufacturers of HDD equipment and mud services, risk brainstorm sessions, expert surveys among HDD contractors and own observations of HDD installations supported the risk identification process. Various types of risks connected with the carrying out of HDD installations were presented. The feedback from expert surveys from 5940 HOD projects carried out in 5 countries, allowed to assess the frequency of occurrence and the influence on project failure of 38 risks in HDD technology and, therefore, proved the need to include them in the risk assessment. Additionally, the survey results allowed to assess the frequency of the occurrence of various types of problems with: the product pipe installation, rig failures, drill pipe failures, the importance of the reasons of drill rig failures and drill pipe failures. The survey results were a basis for the qualitative risk assessment, which was carried out applying Ishikawa diagram. (C) 2014 Elsevier Ltd. All rights reserved.