摘要
以鄂尔多斯盆地长7致密油藏岩心(K<0.1 m D)为研究对象,采用煤油和氮气作为实验流体,开展了应力敏感实验,结合铸体薄片、扫描电镜和恒速压汞实验结果,分析了致密油藏应力敏感特征的微观作用机理。从实验结果发现,致密油藏孔喉越细微,铁方解石胶结和石英加大作用越强烈,对孔喉的支撑作用越明显,因此液测应力敏感渗透率损失程度随着岩心渗透率的降低先增大后减小,但是恢复程度一直减小,最终出现完全不恢复的现象。同时,由于边界层的作用导致液体的临界孔喉半径远大于气体,而临界孔喉的影响导致液测应力敏感的渗透率损失程度和恢复程度与气测的差异随着渗透率的降低而增大。本文实验结果可为致密油藏产能预测及开发策略制定提供依据。
Stress sensitivity experiments were conducted using cores with permeability less than 0. 1 m D which were taken from Chang 7 tight oil reservoir in Ordos Basin. The fluids used in the experiments are kerosene and nitrogen. In addition,casting thin section,SEM and constant-speed mercury injection experiments were performed to analyze the mechanism of the stress sensitivity. It was found that the effects of secondary cementing of ferrocalcite and secondary enlargement of quartz become more severe with decrease in throat sizes of tight oil reservoirs. However,the supporting effects on throats are more significant. Therefore,in the beginning the fraction of permeability reduction increases and then decrease with the permeability of the cores decreasing. But the fraction of permeabil-ity recovery of liquid-measured stress sensitivity decreases all the time. At worst,the process of recovery disappears. In addition,due to the effect of boundary layers,the critical throat size of liquid is far larger than that of gas,resulting in the fact that the differences of fraction of permeability reduction and recovery become larger as permeability decreases. The experiment results can be the basis for predicting production and establishing strategies for tight oil reservoirs.
出处
《中国海上油气》
CAS
CSCD
北大核心
2015年第2期63-67,共5页
China Offshore Oil and Gas
基金
国家自然科学基金"特低渗油藏天然缝与人工缝耦合作用的渗流机理与模型(编号:51174215/E0403)"
高等学校博士学科点专项科研基金"致密油藏亚微米-超纳米级孔喉渗流机理研究(编号:20130007120014)"部分研究成果
关键词
致密油藏
应力敏感
液测
渗透率损失
渗透率恢复
孔喉结构
作用机理
tight oil reservoir
stress sensitivity
liquid measurement method
permeability reduction
permeability recovery
micro-pore-throat structure
mechanism
