非瞬时平衡相态对凝析气近井高速流动区动态饱和度的影响研究

INFLUENCE OF NON-INSTANTANEOUS EQUILIBRIUM PHASE STATE ON THE DYNAMIC CONDENSATE SATURATION AT NEAR-WELLBORE HIGH-SPEED FLOW AREA OF CONDENSATE GAS

目前在研究凝析气的渗流和相态问题时 ,当地层压力降低到露点压力以下后 ,采用的都是等温瞬时平衡的概念 ,而在凝析气井生产过程中 ,当近井带压力降至体系露点以下 ,由于气相的高速流动 ,气液相并不充分接触 ,液相析出后运动滞后而逐渐沉积 ,部分液相组分会因高速气流夹带而呈气相运动一段距离后才变成液相析出 ,也就是说液相析出量的多少要受到平衡时间的影响。文章从体系的强度性质出发 ,引入平衡时间因素建立非瞬时平衡相态描述方法 ,利用LHSS方程研究了凝析气井近井地带高速流动区在非瞬时相平衡条件下凝析液的析出和温降。结果表明 ,由于非瞬时平衡作用导致高速流动区液相析出量减少 。

When formation pressure is below dewpoint pressure,an idea of isothermal instantaneous equilibrium is often adopted for studying the problems of the percolation flow and phase state of condensate gas at present.In fact,in the process of condensate gas well production,when the formation pressure near wellbore is below the dewpoint pressure of gas-liquid system,the gas isn't in full contact with the liquid because of gas' flowing with high speed;the liquid released will be gradually deposited owing to lagging movement;and partial liquidus components held by high-speed gas flow will move a certain of distance in gas state,then change into liquid and be separated out.In orther words,the amount of the liquid released will be controlled by gas-liquid equilibrium time.In the paper,in consideration of the strength properties of the components in the system,a non-instantaneous equilibrium phase state describing method is presented through introducing equilibrium time factor,and the release and temperature drop of condensate liquid at near-wellbore high-speed flow area of condensate gas under non-instantaneous phase equilibrium condition are studied by use of LHSS equations.The results indicate that because non-instantaneous equilibrium action can cause the amount of the liquid released at the high-speed flow area to be decreased,the dynamic condensate saturation at the near-wellbore area is lower than that predicted by instantaneous equilibrium method.