The Model of Cohesionless Sediment Blowout with an Increase in the Methane Flow Rate

Abstract

Dissociation of methane hydrates in the Arctic permafrost may lead to explosive gas emission. Methane blowout may be triggered by increasing gas flow rate at a certain depth. The mechanism of rock failure and blowout under the effect of pressurized gas was studied numerically and in laboratory experiments. The problem was formulated for the unsteady flow of compressed gas depending on the flow rate at a given depth, and pore gas pressure variations were calculated as a function of depth and time. The model parameters were chosen with reference to field data. According to the model, the input of gas to friable material at an increasing rate may lead to gas blowout and density loss propagating downward as the gas pressure exceeds the overburden pressure at some depth. The laboratory system was of the type of a Hele-Shaw cell, with small glass balls as friable material confined between two glass panels. The results of physical modeling and calculations show good agreement.