利用核磁共振技术研究沥青质沉积对低渗储层孔隙结构的影响  

Study on effect of asphaltene precipitation on the pore structure of low permeability reservoir by Nuclear Magnetic Resonance(NMR)

作　　者：王琛[1,2] 李天太[1,2] 赵金省[1,2] 高辉[1,2] 高媛 WANG Chen;LI Tian-tai;ZHAO Jin-sheng;GAO-Hui;GAO Yuan(School of Petroleum Engineering,Xi＇an Shiyou University,Xi＇an 710065,China;Engineering Research Center of Development and Management for Low to Extra-Low Permeability Oil and Gas Reservoirs in West China,Ministry of Education,Xi＇an Shiyou University,Xi＇an 710065,China;Shaanxi Gas Group Company Limited,Xi＇an 710016,China)

机构地区：[1]西安石油大学石油工程学院,西安710065 [2]西安石油大学,西部低渗-特低渗油藏开发与治理教育部工程研究中心,西安710065 [3]陕西燃气集团有限公司,西安710016

出　　处：《地球物理学进展》2018年第4期1700-1706,共7页Progress in Geophysics

基　　金：国家自然科学基金项目“非常规致密砂岩油藏超临界CO2驱CO2-原油-微纳米级孔喉缝系统的相互作用机理研究”(51774236); 中国石油科技创新基金项目“致密砂岩储层有效孔喉缝系统与致密油赋存评价新方法研究”(2017D-5007-0104)联合资助

摘　　要：为揭示CO_2驱过程中沥青质沉积对低渗储层基质孔喉的伤害机理,利用核磁共振技术对岩心样品进行了CO_2驱替前后的T2谱测试.结果表明:沥青质沉积量与驱替压力呈正相关,在CO_2-原油体系达到混相前后,沉积速率最大;渗透率伤害程度则随沥青质沉积量的增加而增大.在驱替初始,较小孔喉(0.1~10 ms)几乎无堵塞,较大孔喉(10~200 ms)出现少量堵塞;注入压力达到最小混相压力,CO_2与原油混相产生大量沥青质沉积,较小孔喉出现45.61%堵塞,较大孔喉堵塞21.31%;在驱替压力继续增大时,较小孔喉堵塞程度严重,最高可达55.22%.对于低渗砂岩储层,基质孔喉尺度越小,沥青质对其的伤害程度就越高.In order to reveal the damage mechanism of asphaltene precipitated in low permeability reservoirs during CO2 flooding,the T2 spectra of core samples were measured by Nuclear Magnetic Resonance（ NMR） before and after CO2 flooding. The results show that the amount of asphaltene is positively correlated with the injection pressure,and the deposition rate is the highest when the CO2-oil system reaches the miscible. The the permeability reduction is positively correlated with the percentage of asphaltene precipitated. At a low injection pressure,a small portion of the large pores（ 10 -200 ms） is filled up with the asphaltene precipitated,while only a tiny part of the smaller pores（ 0. 1 -10 ms） is filled up the with the asphaltene precipitated. When the injection pressure increases above the MMP,more than 45. 61% of the smaller pores（ 0. 1 -10 ms） are clogged,while only 21. 31%of the large pores（ 10 - 200 ms） is affected by the asphaltene. As the pressure further increases,55. 22% of the smaller pores（ 0. 1 -10 ms） are blocked. In the low permeability reservoir,the smaller pores tend to be higher damage degree by the precipitated asphaltene in comparison to the larger pores.

关 键 词：孔喉堵塞率 渗透率伤害 沥青质沉积 CO2驱 低渗储层 

分 类 号：P631[天文地球—地质矿产勘探]