用相平衡理论评价注气吞吐消除凝析气井反凝析污染机理

为了评价注气吞吐消除凝析气井近井带反凝析污染的相态机理，文章基于油气两相相平衡热力学理论和PR状态方程，建立了静态零维组分模型。运用该模型，对一个实例凝析气井注气吞吐的相态机理进行了评价，研究了注入气组成、气藏衰竭压力水平以及注气量对消除凝析气井近井带反凝析污染的影响规律。结果显示：在最大反凝析压力之前注气效果更好；注气量越大效果越好，注气量过小反而将增大反凝析损失；注入气降低反凝析液量和露点压力有利于成功的注气吞吐，在相同注入条件下，不同气体吞吐效果为C₃>C₂>CO₂>烟道气>C₁>N₂。

EVALUATING MECHANISM OF HUFF AND PUFF TO ELIMINATE RETROGRADE CONDENSATE POLLUTION FOR CONDENSATE WELLS BY PHASE EQUILIBRIUM THEORY 1)

To evaluate the phase-state mechanism of huff and puff to eliminate retrograde condensate pollution of the zones near the borehole for condensate wells, based on the thermodynamic theory and PR EOS of oil/gas bi-phase equilibrium, the static compositional model with zero dimension is developed. With the model, the phase-state mechanism of huff and puff is evaluated for a real condensate well. The effect of the gas injecting composition, the reservoir pressure depleting level and the gas injecting volume on the eliminating retrograde condensate pollution of the zones near the borehole is studied. The results show the huff and puff is more effective before the maximum liquid dropout is reached. The more the gas injecting volume is, the better the result is. The insufficient gas injecting volume will increase the retrograde condensate loss. The gas injection will decrease the retrograde condensate liquid volume and the dew point pressure, which is favorable for successful huff and puff. Under the same injecting conditions, the rank of the results from the different injecting gas is as follows: C_3>C_2>CO_2>flue gas>C_1>N_2.