Multiphase Flow Law and Well Control Risk Analysis in Deep Water Gas Hydrate Horizontal Well While Drilling

Natural gas hydrate is an important clean energy in the future because of its high energy density, clean and pollution-free, large amount of resources and wide distribution. However, the gas hydrate reservoir in the sea area has the characteristics of deep water depth and shallow reservoir buried depth. It is difficult to develop, and the development cost is high, so it is difficult to meet the needs of commercial exploitation. Horizontal well drilling can ensure reservoir drilling rate, increase reservoir drainage area and improve development efficiency. During the drilling process of deep water gas hydrate horizontal wells, the gas hydrate is decomposed into gaseous gas due to the change of temperature and pressure environment. The multiphase transient flow of gas in the wellbore will affect the wellbore temperature and pressure environment and cause well control risk. The calculation model of multiphase transient flow and temperature field in drilling wellbore of deepwater gas hydrate horizontal well and the model of gas hydrate formation were established. The gas distribution, migration law and temperature and pressure distribution in wellbore were analyzed, and the variation of wellbore pressure, surface flow law and temperature and pressure range of gas hydrate formation were grasped, which will provide theoretical basis and construction reference for deep water gas hydrate horizontal well drilling.