Study on formation mechanism and prediction of wellbore hydrate in tight sandstone gas reservoir

Abstract

Natural gas hydrate is a crystalline compound composed of water and natural gas. In the process of depressurized production of gas wells, hydrates are usually easy to form in the wellbore. Once these hydrates are formed, they will lead to liquid accumulation at the bottom of the well, which will bring great harm to the normal production of gas wells. Therefore, it is very important to understand the conditions of hydrate formation in wellbore and to predict and prevent hydrate formation. The formation of natural gas hydrate is related to natural gas composition, certain low temperature and high pressure conditions, high speed flow of gas flow, pressure fluctuation and other factors. Through the analysis of physical and chemical properties of natural gas hydrate, various factors affecting the formation and decomposition of natural gas hydrate are summarized in this paper. Taking one breath well as an example, Pipesim software establishes well model, predicts the formation of gas hydrate in wellbore under different tubing sizes, different bottom hole flowing pressure and different gas production. Finally, according to the hydrate control mechanism, the concrete measures to control the formation and decomposition of gas hydrate in wellbore are put forward.