延长油田低渗油藏长岩心二氧化碳吞吐参数优化

Optimization of Long Core CO_2 Huff-n-Puff Experimental Parameters in Low Permeability Reservoir,Yanchang Oilfield

以延长油田低渗油藏长岩心为实验样品,研究CO2吞吐中周期注入量、焖井时间、压力衰竭速度、注气方式和注气速度等对低渗油藏开发效果的影响。实验分析得出:CO2吞吐过程中,第一周期在整个CO2吞吐过程中起关键作用;第一周期应当焖井到压力稳定再开井生产,之后的吞吐周期无需等压力稳定后再开井生产;适当低的注气速度能够较好地克服油藏非均质性的影响,减弱气体指进给油藏开采带来的负面影响。

By experiment of long core samples from low permeability reservoir in Yanchang oilfield,the effects of cyclic injection volume,soak time,pressure decline rate,gas injection process and gas injection rate on low-permeability reservoir development by CO2huff-n-puffprocess were studied.The results show that the first cyclic CO2huff-n-puff is the key of production,its soak time should keep stable pres-sure followed by opening well for production,after which the production can be conducted without keeping stable pressure at any cycle.And appropriate low gas-injection rate may well overcome the influence of the model heterogeneity,hence reducing the negative impact ofgas fingering on reservoir exploitation.