摘要
为了明确低渗致密气藏发生滑脱效应的压力界限,测试了低渗致密岩样的视渗透率在不同孔隙压力下的变化规律。测试前采用平移法求得了岩样的有效应力系数。测试实验表明,当孔隙压力从地层压力下降到临界压力时,气体流动开始发生滑脱效应,发生滑脱效应的临界压力随着渗透率的增加而降低。得出了定量表征滑脱效应压力界限的公式。当地层压力大于临界压力时,不存在滑脱效应,实验室得出的克氏渗透率小于储层的真实渗透率;当地层压力小于临界压力时,实验室进行气体测量渗透率时应该采用回压阀,此时用回压测得的克氏渗透率值以及求得的滑脱因子更加准确。
In order to determine the pressure limit of slippage effect in low permeability tight gas reservoirs,the apparent permeability of low permeability tight cores is measured under different pore pressures. The effective stress coefficient of the core samples is obtained by graphic shifting method before the apparent permeability of low permeability tight cores is tested. In the testing process of the apparent permeability,keep the effective stresses of the core samples unchanged by adjusting confining pressure to eliminate the effect of stress sensitivity on the test results. The test results show that,the slippage effect occurs when the pore pressure declines to critical pressure,the critical pressure decrease with the increase of the permeability of the core samples. The formula for quantitatively calculating the critical pressure is derived. When formation pressure is higher than the critical pressure,there is no slippage effect,and the tested Klinkenberg permeability is less than the real permeability of the core samples; when formation pressure is lower than the critical pressure,the back-pressure valve should be used in the permeability testing,and thus the obtained Klinkenberg permeability and slippage factor are more accurate.
出处
《西安石油大学学报（自然科学版）》
CAS
北大核心
2015年第4期43-48,共6页
Journal of Xi’an Shiyou University（Natural Science Edition）
基金
国家科技重大专项基金(编号:2011ZX05013-002)
关键词
低渗致密气藏
滑脱效应
压力界限
有效应力
low permeability tight gas reservoir
slippage effect
pressure limit
effective stress
