不同CO_2驱开发方式微纳米级别孔喉适用范围

Applicable Range of Different CO_2 Flooding Methods in Reservoirs with Micron/nano Sized Pore-throat

为了研究不同CO_2驱开发方式在油藏微纳米级别孔喉内适用范围,采用高温高压核磁共振方法,建立核磁共振T2谱与孔喉尺寸的转换关系。定量描述了水驱、CO_2驱、水气交替驱、泡沫驱在天然岩心内驱油范围及增油来源。实验结果表明:水驱可进入0.1μm级别孔喉;CO_2可进入0.01μm级别孔喉;水驱产油以可动油为主,CO_2驱增油以束缚油为主;在多轮次驱替后,岩心出现大孔道,水气交替和泡沫驱可产生封堵,但泡沫驱适应范围更广,在0.1μm级别以下孔喉采出程度高于水气交替30%。

In order to investigate the applicable range of different CO2 flooding methods in reservoirs with micron/nano sized pore-throat, a new evaluation method has been found by and high temperature high pressure nuclear magnetic resonance.The conversion coefficient of NMR T2 relaxation time and pore throat radius was established by using the pore throat distribution data obtained, and the oil displacement range and source of enhanced oil were described by formation-core driving experiments.Experimental results show that： water can enter 0.1 μm scale pore-throat,CO2 can enter 0.01 μm scale pore-throat, water drive oil was mainly movable oil and CO2 flooding increased oil was bound oil.Core macroscopic throats was formed after multiple displacement.The water alternating gas flooding （WAG） and foam flooding could produce block in macroscopic throats, but the adapt of foam flooding was wider than WAG.Below the level of 0.1 μm pore throat, the recovery degree of foam flooding is higher than WAG of 30%.