Research on the Formation and Plugging Risk of Gas Hydrate in a Deepwater Drilling Wellbore: A Case Study

At present, the formation mechanism of gas hydrate (hereinafter referred to as hydrate) plugging in wellbore during deepwater drilling is not clear, so there are problems such overuse inhibitors and low utilization efficiency inhibitors. Therefore, view risk under different working conditions drilling, research was carried out on area deposition plugging. Taking an atmospheric well South China Sea example, annulus temperature field combined with phase curve analyze region obtained. The effects fluid circulation rate, injection viscosity zone subcooling were predicted. A model developed, based which dynamic predicted quantitatively. results study showed that: (1) Increasing rate fluid, inlet can effectively reduce subcooling, thus reducing formation. (2) by basically does occur normal drilling. (3) Under condition using seawater bentonite slurry safe operating time for stopping 20 h, shutting killing 30 h.