带油环凝析气藏注气吞吐采出流体特征

Characteristics of Produced Fluid From Condensate Gas Reservoirs With Oil Rings Developed by Gas-Injection Huff and Puff

凝析气藏注气吞吐可提高采收率,但凝析气藏注气吞吐实验一般多研究注气量、注气速度及采收率的变化,而缺乏对注气后采出流体组分变化规律的研究。在建立带油环凝析气藏多次注气吞吐室内物理模拟评价方法的基础上,开展了带油环凝析气藏衰竭式开采后注气吞吐开采实验。结果表明:凝析气注气吞吐开采过程中,随注气吞吐次数增多,产出流体N_(2)+C_(1)含量降低,C_(2)—C_(4)和C_(5)^(+)含量升高;随着注气吞吐次数增加,采出流体组成变化越来越小,至第4次注气吞吐后流体组成基本不变。油环油注气吞吐过程中,产出流体N_(2)+C_(1)含量高,而C_(2)—C_(6)和C_(7)^(+)含量低;随着注气吞吐次数增加,采出流体N_(2)+C_(1)在初始几次注气吞吐中升高较明显,C_(2)—C_(6)和C_(7)^(+)含量明显降低,注气吞吐达到9次时,采出流体组成趋于稳定。

Gas⁃injection huff and puff development can improve the recovery of condensate gas reservoirs.Experiments on gas⁃injection huff and puff in condensate gas reservoirs generally focus on the changes in gas injection volume,gas injection rate and recovery rate,but less on the changes in the composition of the produced fluid.After establishing an indoor physical simulation method for evaluating condensate gas reservoirs with oil rings developed by gas⁃injection huff and puff,a gas⁃injection huff and puff experiment was carried out on a condensate gas reservoir with an oil ring after depletion development.The results show that,as the rounds of gas⁃injection huff and puff increase in the condensate gas reservoir,the content of N_(2)+C_(1)decreases while the contents of C_(2)-C_(4)and C_(5)^(+)increase in the produced fluid,and the composition of the produced fluid changes less and less,until to almost stable after the fourth round of gas⁃injection huff and puff;during the gas⁃injection huff and puff development for the oil from the oil ring,there are more N_(2)+C_(1)but less C_(2)-C_(6)and C_(7)^(+)in the produced fluid,and as the rounds of gas⁃injection huff and puff increase,N_(2)+C_(1)increase obviously while C_(2)-C_(6)and C_(7)^(+)decrease significantly during the first several rounds,finally the composition becomes stable after 9 rounds.