天然气井多相流强化携液理论及排液采气关键技术

Theory of Enhanced Liquid Carrying with Multiphase Flow and Key Technologies of Drainage Gas Recovery in Gas Wells

天然气田稳产是保障我国能源安全的重大需求,气井积液是制约稳产的瓶颈,排液采气是保障稳产的关键。我国60%气井因积液年均产气量递减23%以上,且积液井数以年均5%的速率快速递增。由于对气井多相流动特性认识不足,传统排液采气技术仅适用于积液轻微的浅直井且排液率较低。研究团队近年来聚焦天然气井排液采气难题,构建了基于气液流动结构调控的强化携液理论,突破了经典临界流速携液理论仅适用于环雾状流的局限;发明了抗油耐矿化度泡沫排液、复杂井筒速度管柱排液、超声速喷嘴雾化排液、气举柱塞接力举升排液等适用气井不同积液状态的高效低成本排液采气系列关键技术。研究成果已推广至长庆气田、中外合作开发区等11个气区,累计应用近12000口气井,占我国积液气井总数的30%以上。

Ensuring a continuous supply of gas resources is a crucial requirement for 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 are 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 wellbore 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 12000 gas wells,accounting for more than 30%of all the liquid-loading gas wells in China.