文章详细信息

利用热化学流体反应生热增压解除致密砂岩凝析气反凝析伤害的新方法
A new method of heat generation and pressurization by thermochemical fluid to remove retrograde condensate damage of tight sandstone condensate gas

宋江峰
SONG Jiangfeng

1:中国石油辽河油田建设有限公司

摘要(Abstract)：

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 condensation 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 recovery 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 increases 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 0.86 μm to 2.54 μm, and the maximum pore size increases from 80.11 μm to 690.63 μm, but with less variation of total porosity. 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 method and reference for long-term efficient removal of retrograde condensate damage.

关键词(KeyWords)： 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 structure;relative permeability;micro-fractures

基金项目(Foundation): 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）

作者(Author): 宋江峰
SONG Jiangfeng

DOI: 10.19597/J.ISSN.1000-3754.202301039