CO_(2)非混相驱前缘运移及气窜规律室内实验研究

Laboratory experiment of front migration and gas channeling of CO_(2) immiscible flooding

目前,前缘运移及气窜规律研究较少通过室内实验手段、从CO_(2)波及角度去探索前缘运移与气窜规律,运用可视化仿真物理模拟装置开展平板岩心CO_(2)非混相驱物理模拟实验,分析原油黏度、储层渗透率、储层非均质性及注入速度等因素对CO_(2)驱前缘运移及气窜规律的影响。研究发现,在注入井定流量注入,生产井定压生产的条件下,原油黏度降低、渗透率降低、储层均质、注入速度变大,可增加CO_(2)非混相驱油采出程度;同时,原油黏度降低、渗透率越低、注入速度增加,也导致油井见气后继续扩大波及的能力增强,即能够缓解气窜。研究结果表明:在注入井定流量注入、生产井定压生产情况下,高注入速度开发能够缓解气窜,并获得较好的开发效果;当注入速度从0.1 mL/min增至2.0 mL/min时,采出程度从15.4%增至35.3%,波及系数差从8.3%增至26.2%。该研究对CO_(2)非混相驱气窜抑制及提高采收率具有重要意义。

Currently,there are few works on the laws of front migration and gas channeling with laboratory experiments from the aspect of CO_(2) sweep efficiency.Therefore,a visual physical simulation device is used to carry out the physical simulation experiment of CO_(2) immiscible flooding of slab core.The influences of factors such as crude oil viscosity,reservoir permeability,reservoir heterogeneity and injection rate on the migration of CO_(2) immiscible flooding front and gas channeling laws are analyzed.The study found that under the conditions of constant flow injection in injection wells and constant pressure production in production wells,the viscosity of crude oil decreases,the permeability decreases,the reservoir is homogeneous,and the injection speed increases,which will lead to an increase in the recovery degree of CO_(2) immiscible flooding.Meanwhile,the decrease in the viscosity of crude oil,the lower the permeability,and the increase in the injection rate,also lead to the enhancement of the ability of the oil well to continue to expand sweep factor after gas breakthrough,that is,it can alleviate gas channeling.It is concluded that under the condition of constant flow injection in injection wells and constant pressure production in production wells,high injection rate development can alleviate gas channeling and obtain better development results.When the injection rate increased from 0.1 mL/min to 2 mL/min,the recovery increased from 15.4%to 35.3%,and the sweep factor difference increased from 8.3%to 26.2%.This research is of great significance for CO_(2) immiscible flooding gas channeling suppression and enhanced oil recovery.