特低渗油藏注CO_2驱油微观机制  

Microscopic Mechanism of CO_2 Flooding in Extra-low Permeability Reservoir

作　　者：张英芝[1,2] 杨正明[3] 唐立根[3] 张硕[3] 刘学伟[3] 

机构地区：[1]中国石油大学(北京)石油工程学院,北京100029 [2]中国大庆油田有限责任公司,黑龙江大庆163712 [3]中国石油勘探开发研究院廊坊分院,河北廊坊065007

出　　处：《科技导报》2012年第35期29-32,共4页Science & Technology Review

基　　金：国家油气重大专项(2011ZX05013-006);中石油重大攻关课题项目(2011B-1203)

摘　　要：利用核磁共振仪、原油气相色谱仪、细管实验和特低渗透岩心物理模拟实验,对细管实验的CO2非混相驱和混相驱驱替原油过程中的产出物和残余油进行取样分析,并结合核磁共振实验分析结果得到特低渗透油藏注CO2微观驱油机制。结果表明,CO2非混相驱主要是萃取C18以前的组分,而CO2混相驱,不但可以萃取C18以前的组分,也能萃取C19—C25的组分,初期主要萃取低碳分子的组分,随着驱替的进行,逐步萃取较高碳分子的组分;与原油组分和非混相驱的残余油组分相比,混相驱的残余油中轻质组分所占比例减少,中间组分和重质组分所占比例较大,导致残余油黏度变大;在非混相气驱和混相气驱时,由于残余油黏度发生变化和胶质沥青沉淀,使岩心孔隙中一部分流体变成不可动流体,核磁共振图谱发生左移。By means of NMR, oil gas chromatography, slim tube experiments, and extra-low permeability core physical simulation experiments, the produced oil and residual oil acquiring from slim tube experiments both in CO2 immiscible flooding and CO2 miscible flooding are analyzed. Combined with the NMR results obtained from the physical simulation experiments for extra-low permeability core, the microscopic mechanism of CO2 flooding in low permeability reservoirs is discovered. It includes three aspects： The components before Cls are mainly extracted by CO2 immiscible flooding, while the CO2 miscible flooding not only could extract the components before C18, but also could extract components Ctg-C~, low-carbon molecules are initially extracted, with the ongoing flooding, higher-carbon molecules are gradually extracted; Compared with crude oil and immiscible flooding residual oil, the components of miscible flooding residual oil consist of smaller proportion of light components and larger proportion of intermediate and heavy components, causing lager residual oil viscosity; The residual oil viscosity changes and the asphaltene precipitates caused by miscible and immiscible gas flooding make a part of pore fluid immobile and the graph of NMR shifted left.

关 键 词：特低渗透油田 非混相气驱 混相气驱 机制 核磁共振 

分 类 号：TE357.45[石油与天然气工程—油气田开发工程]