摘要
鉴于CO_(2)吞吐仅能短期改善反凝析伤害,且存在CO_(2)气源短缺及注入成本昂贵等问题,提出了一种利用热化学流体反应生热增压解除反凝析伤害的新方法。通过开展岩心驱替和吞吐实验,对比评价了2种注入方式下热化学流体改善反凝析伤害的效果,研究了热化学流体对岩心微观孔隙结构和油气两相渗流的影响。结果表明:吞吐注入的最大压差可达25 MPa,最高温度达到329℃,累计4次吞吐凝析油采出程度为63.2%,大于驱替方式的凝析油采出程度49.5%,吞吐效果更好,且最佳吞吐次数为2次;热化学流体注入后能够增大孔隙直径、诱发形成微裂缝、降低毛细管压力和提高油气两相相对渗透率,其中吞吐式注入热化学流体后平均孔径由0.86μm增大至2.54μm,最大孔径由80.11μm增加至690.63μm,但总孔隙度变化较小,平均毛细管压力降幅达到51.2%,最大气相和最大油相相对渗透率分别提高了2.3倍和1.8倍,残余油饱和度下降了29%。研究成果为长期高效解除反凝析伤害提供了方法和借鉴。
Considering that CO_(2) huff-and-puff can only decrease retrograde condensate damage for a short time,and there are problems such as shortage of CO_(2) gas source and high injection cost,a new method is proposed to remove retrograde condensation damage by using thermochemical fluid reaction to generate heat and pressurize.Through core displacement and huff-and-puff experiments,the effects of thermochemical fluid on decreasing retrograde con-densation damage with 2 injection modes are compared and evaluated,and the influence of thermochemical fluid on micro-pore structure of cores and oil and gas flow are studied.Experiment results show that the maximum pressure difference of huff-and-puff injection reaches 25 MPa,and the maximum temperature reaches 329℃.Condensate re-covery degree of cumulative 4 rounds of huff-and-puff is 63.2%,which is 49.5%higher than that of displacement mode,with better huff-and-puff effect and optimal 2 rounds of huff-and-puff.Thermochemical fluid injection in-creases pore diameter,induces micro-fractures,reduces capillary pressure and increases relative permeability of oil and gas.After thermochemical fluid injection by huff-and-puff,average pore size increases from 0.86μm to 2.54μm,and the maximum pore size increases from 80.11μm to 690.63μm,but with less variation of total porosi-ty.Average capillary pressure decreases by 51.2%,and maximum relative permeabilities of gas and oil increase by 2.3 times and 1.8 times respectively.Residual oil saturation decreases by 29%.The research results provide a meth-od and reference for long-term efficient removal of retrograde condensate damage.
作者
宋江峰
SONG Jiangfeng(PetroChina Liaohe Oilfield Construction Co.,Ltd.,Panjin 124010,China)
出处
《大庆石油地质与开发》
CAS
北大核心
2024年第2期78-85,共8页
Petroleum Geology & Oilfield Development in Daqing
基金
国家科技重大专项“大型油气田及煤层气开发”十三五课题“国内油气发展战略研究”(2016ZX05016)。
关键词
凝析气
反凝析
热化学流体(TCM)
致密砂岩
孔隙结构
相对渗透率
微裂缝
condensate gas
retrograde condensation
thermochemical fluid(TCM)
tight sandstone
pore struc-ture
relative permeability
micro-fractures
