解除低渗凝析气井近井污染研究现状及进展

CURRENT STATUS AND FUTURE DEVELOPMENT OF THE STUDY ON REMOVAL OF NEAR-WELLBORE DAMAGE IN LOW-PERMEABILITY GAS CONDENSATE WELLS

解除近井反凝析堵塞和水锁是深层低渗凝析气藏开发必须解决的难题。通过对国内外文献的调研,分析了凝析气藏近井带反凝析油堵塞和反渗吸水锁形成的机理及其对气井产能的影响,总结了解除凝析气井近井堵塞提高产能的实验和理论研究成果以及形成的主要技术手段。结果认为:低含凝析油的凝析气藏,高渗储层均可能由于反凝析和水锁的存在而严重影响气井产能;高临界凝析油流动饱和度和高含水饱和度导致反凝析影响严重。解除近井反凝析堵塞和反渗吸水锁的主要机理是延缓反凝析出现和加速反凝析油和地层水的蒸发;凝析气注入可反蒸发凝析油中的重烃;注甲醇可有效解除反凝析油和水锁的双重堵塞。将向近井带注入化学溶剂、注气和加热等方法结合起来,可能是解除低渗凝析气井近井堵塞研究的发展趋势。

Removal of the near-wellbore plug and gas lock resulted from retrograde condensation is a key problem to be tackled during the recovery of deep-buried, low-permeable condensate gas reservoirs. Through plenty of investigation and study on literatures worldwide, forming mechanisms and impacts on gas well deliverability of near-wellbore plug and water lock were analyzed for condensate gas reservoirs. Additionally, experimental and theoretical achievements, and also effective technical methods to remove such near-wellbore damage were summarized here. It is concluded that in high-permeability zones of low gas condensate content reservoirs, the deliverability of gas wells can be seriously impacted by retrograde condensation and water lock; the main mechanism of retrograde condensation and water lock mitigation is to slow down the retrograde condensation process and speed up evaporation of the retrograde gas condensate and formation water; injection of condensate gas is helpful for evaporation of heavy hydrocarbons in the gas condensate; and injection of methanol is effective to remove the dual-plug resulted from retrograde gas condensate and water lock. In the end, it is pointed out that combination of chemical solvents injection, gas injection and heating is an effective method for future development to remove near-wellbore damage for low-permeability condensate gas wells.