天然气井多相流强化携液理论及排液采气关键技术

Ensuring a continuous supply ol gas resources is a crucial requirement lor China's energy security. However, the steady production of gas wells is often hindered by the issue of liquid loading. To maintain a consistent gas production, it is important to implement effective drainage and gas recovery technologies. In China, 60% of the gas wells undergo liquid loading, resulting in production declining by more than 23% per year, and the worse part is that the number of liquid loading wells annually increases by 5%. The conventional method of drainage gas recovery is only appropriate for shallow vertical wells with minimal gas outflow and brings about a low drainage efficiency since the multiphase flow characteristics of gas wells arc not well understood. Therefore, this paper will highlight the current research conducted by our team on the theory of enhanced liquid carrying in multiphase flow and the key technologies of drainage gas recovery in gas wells. We proposed the theory of enhanced liquid carrying, which revolves around the regulation of gas-liquid flow structure. It overcomes the constraint of the traditional critical liquid carrying theory, which is only applicable to annular-mist flow. We developed a set of key technologies for efficient and cost-effective drainage gas recovery that is suitable for various liquid loading states in gas wells under different liquid loading conditions, including oil-resistant and salinity-resistant foam drainage, complex wcllborc velocity string drainage, supersonic nozzle atomization drainage, plunger relay lift drainage, and more. The theoretical and technical achievements have been applied to 11 gas fields and 12 000 gas wells, accounting for more than 30% of all the liquid-loading gas wells in China.