特低渗透油藏气驱启动压力实验研究

Experimental study on threshold pressure of extra low permeability reservoir
during gas injection

李爱芬 张磊 李春芹 刘敏

中国石油大学，山东 东营 257061 2．胜利油田分公司纯梁采油厂，山东 博兴 256504

低渗透油藏主要采用注水开发，但一些特低渗油藏，由于渗透率低、水敏较严重，往往因注水困难而无法正常开发，而注气开发则是唯一可行的方法，但能否正常注气，目前尚无可行的论证方法。以纯梁油田特低渗油藏为例，通过岩心实验分析，研究了出口压力为大气压力及不同回压时不同渗透率岩心的气驱油启动压力及其变化规律。研究结果表明，气驱油启动压力随岩心渗透率的增加而降低，进口压力随回压的增加而增加，但启动压力梯度随回压的增加而减小。该实验结果对低渗油藏注气开发方案的制订具有重要的指导意义。

Waterflooding is the major method to develop the low permeability reservoir. But it is usually ineffective for some low  permeability reservoirs because of the serious water sensitivity and the low permeability. Gas injection is the only feasible method  for such reservoirs, but it can not be demonstrated if this method can be used or if the gas can be injected into the reservoir with the  current gas injection equipment. This paper takes the low permeability reservoir in Chunliang Oilfield as an example and studies the  threshold pressure during gas injection into the low permeability rock at different back pressure of rock. The results show that the
threshold pressure decreases with the increase of permeability and the entrance pressure increases with the increase of back  pressure, but the pressure gradient decreases with the increase of back pressure. This experimental result can be used to gas  injection design and has great instruction meanings for the low permeability reservoir development.