春风油田排601块水平井蒸汽驱井网类型优化物理模拟实验

蒸汽驱是稠油油藏水平井蒸汽吞吐进入开发后期主要的接替技术，而水平井的井网形式影响着蒸汽驱的开发效果。以春风油田排601块浅薄层稠油油藏为研究对象，依据相似准则，建立了高温高压三维比例物理模型，并开展了排状井网、五点井网、反九点井网条件下蒸汽驱物理模拟实验。研究结果表明:蒸汽驱过程中温度场的发育主要受注入井与生产井间的驱替压差的控制，注入蒸汽主要流向流动阻力小的区域（临近井、高渗条带、高温低黏油带）；蒸汽突破初期，依然有大量的原油从模型产出；实验结束后，蒸汽未波及区域存在大量剩余油。在排601块油藏条件下，排状井网、五点井网和反九点井网蒸汽驱的最终采收率分别为45.10%、41.90%和38.30%；排状井网、五点井网和反九点井网最大累积油汽比分别为0.69、0.63和0.53，综合对比排状井网效果最优。蒸汽驱过程的主要作用机理和现象包括:高温降黏作用、高温体积膨胀、高温蒸汽蒸馏和原油裂解作用、高波及效率和蒸汽超覆。研究结果可以有效支撑春风油田排601块水平井蒸汽驱设计。

Physical simulation experiment for the optimization of steam flooding horizontal well patterns in Pai 601 Block of Chunfeng Oilfield

Steam flooding is the dominant technology replacing horizontal-well steam soaking in the late development stage of heavy oil reservoirs, and its development effect is impacted by the style of horizontal well pattern.In this paper, the heavy oil reservoir in shallow thin layers in Pai 601 Block, Chunfeng Oilfield was taken as the study object.A high temperature/high pressure 3D scaled physical model was established according to the similarity criteria.Then, physical simulation experiment was carried out on steam flooding in row well pattern, five-spot well pattern and inverted nine-spot well pattern.It is indicated that the growth of temperature field in the process of steam flooding is mainly controlled by the displacement pressure difference between injection well and production well.The injected steam mainly flows to the areas of low flow resistance, such as adjacent well, high permeability belt and high-temperature low-viscosity oil band.In the early stage of steam breakthrough, a large amount of crude oil is still produced from the model.After the experiment ends, there is abundant remaining oil in unswept regions.In the oil reservoir conditions of Pai 601 Block, the ultimate recovery factor of steam flooding in row well pattern, five-spot well pattern and inverted nine-spot well pattern is 45.10%, 41.90% and 38.30%, respectively, and their maximum cumulative oil/steam ratio is 0.69, 0.63 and 0.53, respectively.Based on comprehensive comparison, the effect of row well pattern is the best.The main mechanisms and phenomena in the process of steam flooding include high-temperature viscosity reduction, high-temperature volume expansion, high-temperature steam distillation and crude oil cracking, high sweep efficiency and steam overlapping.The research results provide the effective support for the design of horizontal-well steam flooding in Pai 601 Block, Chunfeng Oilfield.