摘要
基于松辽盆地砂岩油藏岩样,进行CO_(2)驱替饱和原油岩心实验,结合核磁共振和油组分分析,研究CO_(2)驱油机理。选取松辽盆地中渗、低渗、特低渗和致密岩样,分析渗透率对CO_(2)驱替的影响效果;分成三个阶段进行驱替实验,分析注入量对CO_(2)驱替的影响效果。以特低渗岩样和致密岩样的大注入量CO_(2)驱替作为研究重点,通过控制变量的方法,研究松辽盆地特低渗致密油藏大注入量CO_(2)驱油机理。实验表明,对于特低渗致密油藏,大注入量CO_(2)驱替可以获得很好的驱油效果。小注入量驱替后,低渗和中渗样的平均采出程度为30.56%,特低渗岩样和致密岩样的平均采出程度为26.21%;在大注入量驱替后,低渗和中渗样的平均采出程度为55.92%,特低渗岩样和致密岩样的平均采出程度为67.00%。说明大注入量CO_(2)驱替可以有效提高油藏采出程度,且提高幅度对于特低渗致密油藏更为明显。大注入量完全混相的CO_(2)驱替可以获得很好的最终采出程度,最高可达到67.49%;完全混相驱替可以很好驱替出原油中包含重质组分在内的各种组分,不同驱替阶段的油样族组分区别很小,但仍存在明显的抽提轻质组分的效果,油样组分峰值从前期C_(12)附近逐步偏移到后期C_(17)附近。CO_(2)的抽提作用会使得原油中重质组分滞留于孔喉表面,在小注入量时滞留现象在特低渗致密油藏中更为明显,低渗与中渗油藏滞留现象较弱;在大注入量CO_(2)驱替后,特低渗致密油藏中的重质组分被很好采出,其重质组分最终采出程度和低渗及中渗油藏相当,说明大注入量CO_(2)驱替更适用于特低渗致密油藏。研究结果很好地补充了特低渗致密油藏CO_(2)驱油理论,可为松辽盆地后续的CO_(2)驱油工程建设提供理论参考。
Based on sandstone reservoir samples from Songliao Basin,we conducted carbon dioxide displacement experiments on saturated crude oil cores.These experiments were combined with nuclear magnetic resonance and oil component analysis to study the mechanism of carbon dioxide oil recovery.We selected rock samples with varying permeability,including medium,low,ultra-low,and tight permeability in Songliao Basin,to analyze the effect of permeability on carbon dioxide displacement.The displacement experiment was divided into three stages to analyze the effect of injected volume on CO_(2)displacement.Our research focused on high CO_(2)injection carbon dioxide flooding of ultra-low and tight permeability rock samples.The mechanism of high CO_(2)injection flooding of ultra-low permeability and dense reservoirs in Songliao Basin is studied using the method of controlling variables.Experiments show that high CO_(2)injection flooding can result in good recovery for ultra-low permeability and dense reservoirs.After low injection volume displacement,the average harvesting degree of low-permeability and medium-permeability samples was 30.56%,and that of ultra-low-permeability and dense samples was 26.21%.After high injection displacement,the average recovery degree of low-permeability and medium-permeability samples was 55.92%,while the average recovery degree of ultra-low-permeability and dense samples increased to 67.00%.This indicates that high CO_(2)injection flooding can effectively improve reservoir recovery,particularly for ultra-low permeability and dense reservoirs.In fact,high injection complete miscible CO_(2)displacement can achieve a final recovery degree up to 67.49%.Complete miscible displacement can well displace various components of crude oil including heavy components.While there is little difference in the oil family components in different displacement stages,there is still an obvious effect on extracting light components.The peak value of oil components gradually shifts from near C_(12) in the early stage to near C_(17) in the late stage.The carbon dioxide extraction leads to the deposition of heavy components on the pore throat surface.The deposition phenomenon is more pronounced in ultra-low permeability and dense reservoirs when injected with low injection volume,but it is weaker in medium and low permeability oil reservoirs.After high CO_(2)injection flooding,heavy components in ultra-low permeability and dense reservoirs are well recovered,and the final recovery degree of heavy components is similar to that of medium and low permeability oil reservoirs.This indicates that high CO_(2)injection flooding is more suitable for ultra-low permeability and dense reservoirs.The research results complement the theory of CO_(2)flooding in ultra-low permeability and dense reservoirs and provide theoretical reference for the subsequent construction of CO_(2)flooding projects in Songliao Basin.
作者
徐锐
沈瑞
周体尧
李海波
孙盈盈
邹新源
罗燕
XU Rui;SHEN Rui;ZHOU Tiyao;LI Haibo;SUN Yingying;ZOU Xinyuan;LUO Yan(College of Engineering Sciences,University of Chinese Academy of Sciences,Beijing,100049,China;Institute of Flow and Fluid Mechanics,Chinese Academy of Sciences,Langfang,Hebei,065007,China;PetroChina Research Institute of Petroleum Exploration and Development,Beijing,100083,China;Process Research Institute of No.1 Oil Production Plant of Daqing Oilfield,Daqing,Heilongjiang,163000,China)
出处
《天然气与石油》
2023年第4期55-66,共12页
Natural Gas and Oil
基金
中国石油天然气集团有限公司前瞻性基础性科技专项“页岩油气开发机理与体积开发技术”(2023ZZ08)。
关键词
砂岩油藏
CO_(2)
特低渗致密
核磁共振
组分分析
Sandstone reservoir
CO_(2)
Ultra-low permeability and dense
Nuclear magnetic resonance(NMR)
Component analysis
