Critical Production Pressure and Optimal Gas Production Rate to Avoid Hydrate Reservoir Disturbance

Abstract

Natural gas hydrate is an ice-like crystal formed by methane and water, which is a new type of strategic energy with huge reserves. The exploitation of deep-sea hydrate will cause a large amount of decomposition of hydrate, which will decrease the sediment strength. In this paper, firstly, the influence of three main distribution patterns of hydrate on mechanical parameters is analyzed and the hydrate reservoirs suitable for actual production are judged. Then, reservoir constitutive models and hydrate decomposition and flow models are established based on previous studies. Different distribution patterns of hydrate are established by changing the hydrate content in the reservoir. Finally, simulations are carried out under different production pressure, and parameters such as hydrate saturation are output. Then input those parameters into Mohr-Coulomb model to compare the changes of mechanical properties of reservoir during the exploitation and judge whether the hydrate reservoir is disturbed. Consequently, the critical production pressure is determined. Then, the optimal production rate of different types of reservoir can be determined by adjusting production pressure within the critical bottom hole pressure. The work of this paper will provide a certain reference value for the rational and safe production of hydrate in the future.