稠油油藏气体-泡沫辅助注蒸汽实验与数值模拟

Numerical simulation and tests of gas-foam assisted steam-flooding for heavy oil development

针对蒸汽吞吐过程中由于能量不足以及严重汽窜等导致热效率低、吞吐效果变差的问题,从室内物理模拟以及数值模拟两方面,开展了在蒸汽中添加气体及高温泡沫以改善蒸汽吞吐开发效果的研究。首先,通过引入泡沫综合指数,筛选了合适的发泡剂;其次,进行了4组室内平行双管实验,分别为单纯蒸汽驱、蒸汽-烟道气泡沫驱、蒸汽-氮气泡沫驱以及蒸汽-氮气驱。实验结果表明:在注入条件相同的情况下,蒸汽-烟道气泡沫驱和蒸汽-氮气泡沫驱均能够有效地封堵高渗管,启动低渗管,与单纯蒸汽驱相比,采出程度最高分别提高了28.98%和26.04%;蒸汽-氮气驱调剖效果有限,不能有效地启动低渗管,采出程度比单纯蒸汽驱提高了10.56%。结合物理模拟的结果,采用数值模拟方法,分析了地层参数对烟道气-泡沫辅助吞吐和单纯蒸汽吞吐开发效果的影响,结果显示,对于层薄、油稠的非均质油藏,烟道气-泡沫辅助吞吐与单纯蒸汽吞吐相比具有显著的优势,能够有效地提高蒸汽吞吐开发效果。对河南油田井楼零区烟道气-泡沫辅助蒸汽吞吐方案进行了参数优化,得到最佳日注汽量为100 m^3,最佳气汽比为12,最佳焖井时间为7 d。

With consideration of low thermal conducting efficiency induced by insufficiency in energy and severe steam channeling during steam stimulation, researches have been conducted through indoor physical simulation and numerical simulation by adding gas and high-temperature foam to enhance performances of steam stimulation. First of all, comprehensive foam indicators have been introduced to identify the optimal foaming agent. Secondly, four indoor parallel dual-pipe tests, namely pure steam flooding, steam-flue gas foam flooding, steam-nitrogen foam flooding and steam-nitrogen flooding, were performed. Test results show under identical flooding conditions, both steam-flue gas foam flooding and steam-nitrogen foam flooding can effectively seal off high-permeability channelsto mobilize low-permeability channels. Compared with pure steam flooding, the new technique can enhance oil recovery by 28.98%and 26.04%, respectively. The steam-nitrogen flooding displayed limited profile-control performances because it failed to mobilize lowpermeability channels effectively. It has improved oil recovery by 10.56% higher than that of pure steam flooding. With consideration of the results of physical simulation, numerical simulation has been performed to study the impact of formation parameters on the productionperformances of flue gas-foam assisted stimulation and pure steam stimulation. Test results show flue gas-foam assisted stimulation has outstanding advantages over pure steam stimulation for development of thin and heterogeneous heavy oil reservoirs because it may effectively enhance performances of steam stimulation. After optimization of the parameters for flue gas-foam assisted steam stimulation in Jinglouling Block, Henan Oilfield, the daily steam injection volume has been up to100 m3, gas/steam ratio to 12 and soaking time to 7 days.