Prediction model of strength properties of marine gas-bearing sediments based on compressional wave velocity

Abstract

The strength properties of marine sediments are closely related to the spudcan penetration and jacket installation of offshore oil platforms. However, gas affects the properties of sediments to a certain extent and poses certain hidden dangers to the operation. Therefore, rapid and accurate determination of the strength properties of gas-bearing sediments has become an important issue. In this study, a series of acoustic and mechanical experiments were conducted in the laboratory by replicating marine gas-bearing sediments. Based on the two acoustic wave propagation theories, the calculated compressional wave velocity was compared with the measured wave velocity, and it was found that the result of the porous media model (P-M) is consistent with the actual situation. Laboratory mechanical property tests showed that cohesion and internal friction angle were positively correlated with density and negatively correlated with water content. The bubble fractional volume affects the undrained shear strength of the sediment, and the multi-parameter equation of the strength properties and physical properties of the marine sediment is fitted by the multivariate nonlinear regression method. On this basis, a single-parameter strength property prediction model of marine gas-bearing sediments based on compressional wave velocity was established with physical properties as a bridge, and the strength properties of gas-bearing sediments were accurately predicted. This prediction model avoids the disturbance of sediments measured by in-situ sampling and improves the accuracy of the strength properties of gas-bearing sediments in marine areas that cannot be sampled.