不同渗透率储层应力敏感性试验对比

针对低渗油气田开发中存在的应力敏感性损害,选取天然储层岩心,开展不同渗透率储层应力敏感性试验对比研究,建立渗透率与有效应力之间的数学关系。对应力敏感性损害机制进行分析。基于平面径向流渗流理论,计算应力敏感性损害对低渗油田产能的影响。结果表明:随有效应力增加,中、高渗储层属于"缓慢下降"型应力敏感性损害模式,储层损害程度较弱;低渗、超低渗储层则属于"先快后慢"型应力敏感性损害模式,储层损害程度较强;储层孔喉结构特征及其尺寸分布是储层应力敏感性损害的主要控制因素;在油井井壁附近存在"渗透率漏斗",一定程度上影响了油井产能。

Experimental study on stress sensitivity in reservoirs with different permeability

Stress sensitivity damage can reduce the permeability of oil and gas reservoirs, especially for low permeability reservoirs. Experimental study on the stress sensitivity was carried out using cores taken from natural rocks with different permeability. The relationship between the permeability and the net stress on rocks was established, and the mechanisms for the stress sensitivity damage were analyzed. The influence of stress sensitivity damage on the productivity of oil wells was studied based on a flow model of radial plane. The results show that the stress sensitivity in ultra-low to low permeability reservoirs is stronger than that in middle to high permeability reservoirs. The damage mode of stress sensitivity in a high permeability reservoir can be described as "gently dipping", while in an ultra-low permeability reservoir it is in a mode of "initially fast then slowly dipping". The damage caused by stress sensitivity is greatly affected by the structure and size distribution of pore throats in the rock. Nevertheless, the stress sensitivity has a negative effect on oil production because a permeability reduction zone can be formed near the wellbore.