Research on intelligent judgment method of natural gas hydrate drilling risk

There are many emergency risks in the process of natural gas hydrate (NGH) drilling. In order to ensure the safe and efficient exploitation of NGH, it is urgent to establish an intelligent judgment method for the risks in the process of NGH drilling. In this paper, the response relationship between monitoring parameters and risk categories of NGH while drilling is established. Based on fuzzy analytic hierarchy process (FAHP), the comprehensive weights of 10 risk monitoring parameters are obtained, including gas production, wellbore instability, hydrate ice barrier, drill string fracture, sticking, bit balling, drilling tool piercement, gas seepage, seabed subsidence and seabed landslide. Besides, the comprehensive judgment weight matrix is constructed, and the reasonable fluctuation range of monitoring parameters is formed. Thus, the intelligent judgment method of NGH drilling risk is established. The intelligent judgment and alarm of NGH drilling risks can be realized quickly and accurately by this method, namely, it can monitor the risks in the process of operation and guarantee the construction safety of NGH drilling.