Abstract:Shallow gas geological disasters are very easy to induce shallow drilling accidents, which seriously affect the safety of deep water drilling operations. For some shallow gas reservoirs, active blowout of shallow gas through drilling pilot holes can provide guarantee for deep water economic and efficient drilling. Based on the multiphase flow surface tracking technology and turbulence model, a finite element numerical model of deep-water shallow gas active blowout is constructed. The model considers the influence of the size of the blowout channel and the physical properties of the shallow gas reservoir on the blowout process, which can more accurately simulate the whole process of shallow gas blowout. The simulation results show that the initial gas reservoir pressure increases from 20.2MPa to 20.8MPa, and the shallow gas blowout efficiency increases from 75.4% to 84.9%. The size of the guide hole is increased from 812″ to 1214″, and the release degree of shallow gas is increased from 80.9% to 90.7%. The simulation results are in good agreement with the actual observation data, and the error of the calculated value of the maximum escape height is 2.5%. The research results provide theoretical guidance for similar shallow gas active blowout projects in deep water drilling operations in the future.

Key words:deepwater drilling,shallow gas geological disasters,active discharge,gas-water two-phase flow