A New Method to Predict and Assessment the Risk of Shallow Water Flow in Deep-Water Drilling

Abstract Shallow water flow is one of the geological disasters faced by deep water drilling operations. The common way to predict shallow water flow is applying qualitative prediction of seismic profiles and the accuracy is low. This paper proposes a new approach based on simulation experiment to quantitative predict the shallow water flow in deep water. Based on the characteristics of propagation velocity of acoustic wave in deepwater and rock media, the simulation experiments of acoustic wave characteristics of shallow water flow have been conducted. The influence of shallow water flow in seabed soil on the propagation velocity of acoustic wave in rock and soil is revealed. The simulation experiments also show the relationship between the pressure and porosity changes in shallow water formation and the propagation velocity of acoustic wave. As a result, a template for predicting and identifying shallow water flow by acoustic wave is established, and the risk grade of shallow water flow to drilling is evaluated. The results show that the greater the detected acoustic velocity, the greater the shallow water flow pressure in the formation and the greater the risk of drilling. The pressure and porosity of shallow water flow stratum are in a power exponential function relationship with the acoustic wave velocity. According to the site application results, the accuracy of this prediction model is more than 80%, meet the requirement of deepwater drilling design and site construction.