Effect of Drilling Fluid Invasion on Natural Gas Hydrate Near-Well Reservoirs Drilling in a Horizontal Well

Horizontal wells can significantly improve the gas production and are expected to be an efficient exploitation method for industrialization of natural hydrates (NGHs) in future. However, near-wellbore hydrate is highly prone decomposition during drilling process, owing disturbance aroused by factors such as fluid temperature, pressure, salinity. These issues result engineering accidents bit sticking wellbore instability, which required further investigations. This paper studies characteristics invasion into marine NGH reservoir with varied parameters via numerical simulation. The effects on behavior presented. simulating results show that adjustments density within mud safety window have limited decomposition, meanwhile most sensitive temperature variation. If grows considerably due improper control, range around horizontal well tends expand, then aggravates instability. When salinity varies 3.5–7.5%, increase ion concentration speeds up adverse maintaining stability.