低渗透油藏两相渗流参数及驱油效率的应力敏感性研究

储层物性参数及渗流参数受作用在岩石上的应力状态的影响。开发过程中由于地层压力的下降而导致应力状态变化,这种变化会带来岩石的不可逆伤害而影响物性参数、渗流参数及开发效果。建立了室内模拟地层压力变化的实验技术。定量研究了地层压力下降过程中油水两相渗流特征以及水驱油效率的变化规律。借助压汞、核磁共振等测试手段,分析地层压力下降过程中岩石孔喉结构特征参数的变化规律,定性研究了低渗透油藏两相渗流参数及水驱油效率的应力敏感性作用机制。研究结果表明,低渗透油藏岩石的油水两相渗流参数及水驱油效率具有应力敏感性,且岩石的渗透率越低,应力敏感性越强。不同渗透率级别岩石孔喉尺寸的差别决定两相渗流参数及水驱油效率的应力敏感程度。研究结果可为低渗透油藏的储层保护和水驱高效开发提供理论指导。

Research on Stress Sensitivity of Water/Oil Displacement Characteristics and Displacement Efficiency in Low Permeability Reservoir

Because reservoir physical properties and flowing characteristics is depended on stress states acting on rocks,reservoir pressure decline induces irreversible damages to rock which influences physical properties,flowing characteristics as well as water flooding development process.Through established test technique simulating change of reservoir pressure,the impact of pressure decline on oil / water relative permeability as well as displacement efficiency was quantitatively studied.With mercury-injection test and nuclear magnetic resonance spectrometry analysis,effect of pressure decline on characteristic parameters of pore-throat was quantitatively studied and changing mechanism for flowing parameters and displacement efficiency in changing process of reservoir pressure was qualitatively analyzed.It is shown that two phase flowing characteristics including relative permeability as well as displacement efficiency varies with effective overburden pressure acted on rock.Also it is concluded that the lower the permeability,the stronger the changing degree of flowing parameters and displacement efficiency.The results can be a theoretical guidance for low permeability reservoir prevent from damage and water flooding development effectively.