China University of Petroleum, China
Title: Study on gas hydrate blocking mechanism and precaution in wellbore of deep water drilling
Xiangfang Li is a Professor from China University of Petroleum, China.
When natural gas reservoir is broached, gas hydrate is easy to assemble on throttle fill upline, marine riser, blowout preventer and well head in sea floor etc., which bring greataffection to petroleum exploration drilling in deep water. For this reason, study on theblocking mechanism of hydrate in annular of deep water drilling pit shaft, and advisableprevention bring important and profound sense to deepwater exploration drilling in future. When gas influx happens during deepwater drilling, most researchers thought the hydrate could be formed due to the high pressure, low temperature and predicted the formation area.However it is wrong during the deepwater drilling according to the real gas kick conditions. The kineticsof gas hydrate should also be considered, such as the hydrate formation time. In generation, when the pressure and temperature of hydrate formation is reached, the generation speed is slow. There will be nucleation and growth. During this process, the fluid which may form the hydrate has flowed out of the wellbore and the blocking will not happen. Based on the gas liquid two phase flow in wellbore annuli, the gas hydrate formation and blocking mechanism are studied. The hydrate formation model are established based on the PVT equation, the flash theory, multiphase flow theory and kinetic theory. The effects of flow pattern, fluid velocity, the gas fraction are considered. Then the gas hydrate formation and blocking area are predicted.