Numerical simulation analysis and optimization of process parameters in the cementing process of gas hydrate-bearing sediments in deep water oil and gas wells

Abstract:

The South China Sea has been confirmed to be rich in oil and gas resources as well as natural gas hydrate resources. However， hydrate-bearing formations are often encountered during the drilling of oil and gas wells. Cementing is a critical step in oil and gas development. In deepwater drilling， the heat released during cement hydration can potentially induce hydrate decomposition， compromising formation stability and even affecting cementing quality. This study utilized numerical simulation methods， focusing on the hydrate-bearing formation at the SH7 site in the Shenhu area of the South China Sea GMGS-1 project. A numerical model for cementing was established to analyze the issues caused by cement slurry invasion into hydrate-bearing formations and the impact of cementing process parameters. The study found that an increase in cement hydration heat release rate significantly advanced the onset of gas and water influx， as well as increased its volume. The cementing pressure differential had a minor impact on the influx phenomenon， but it suppressed the influx when exceeding a certain threshold. Prolonging the pressure maintenance period significantly delayed the initiation of influx and reduced its volume. Therefore， it is recommended in practical engineering to use low-heat cement， extend the pressure maintenance period， and avoid excessively high cementing pressure differentials in the early stages to minimize hydrate decomposition and mitigate the occurrence of influx. This research provides a theoretical foundation for the cementing of hydrate-bearing formations， which is of great significance for enhancing the safety and efficiency of cementing operations.