低渗储层液锁伤害的精确测量与评价

Accurate Measurement and Evaluation of Liquid Blocking Damage for Low Permeability Reservoirs

针对现有液锁伤害测量方法操作复杂、测定数据精度低的问题,设计了高精度注入装置和对应的液锁伤害测定方法,并形成了低渗储层液锁伤害评价方法。研究表明:所设计的注入装置更加精确、实用;液锁伤害主要发生在含水饱和度相对较高的区间上,渗透率伤害率随着含水饱和度的增加而逐渐增加,整体都在50%以上,呈现出“S”形曲线形态,且渗透率越低其曲线的“S”形态越明显;液锁伤害率曲线随渗透率的增加以渗透率为2.2×10^-3μm^2和15.5×10^-3μm^2为拐点而呈现三段式降低,渗透率越高,伤害程度越小;液锁阻塞半径随产量的增加而增加,在产量一定时,阻塞半径随液锁伤害率的增加而增加,并依照阻塞半径变化曲线建立了液锁伤害评价标准,将液锁伤害率在0~27%、27%~43%、43%以上三个区间上的伤害程度分别定义为低伤害、中等伤害和高伤害三个等次,其对应的阻塞半径分别为0~1.5、1.5~6、6 m以上;液锁伤害应以预防为主,适时地采取措施防止液锁伤害的发生,并要建立合理的气井生产制度。所设计的实验装置和实验方法操作性强、数据可靠,为深入研究储层伤害提供了重要依据,为油气田开发及储层保护提供重要的技术参考。

To solve problems of complex operation and low accuracy of the existing methods for measuring the damage caused by liquid lock,a high precision injection device and corresponding methods for measuring the damage caused by liquid lock were designed,and a method for evaluating the damage caused by liquid lock was formed.The results show that the designed injection device and test method are more precise and practical.The damage of liquid lock mainly occurs in the interval with relatively high water saturation,and the damage rate of permeability gradually increases with the increase of water saturation,all of which is more than 50%.It presents S-shape curve,and the lower the permeability,the more obvious the S shape of the curve is.With the increase of permeability,the damage rate curve of liquid lock decreases in three stages with the permeability of 2.2×10^-3μm^2and 15.5×10^-3μm^2 as inflection points.And the higher the permeability is,the smaller the damage degree is.The blocking radius of liquid lock increases with the increase of production,and increases with the increase of the damage rate of liquid lock at a certain output.According to the change curve of blocking radius,the evaluation criteria of liquid lock injury were established.The damage degree of liquid lock injury was divided into three scopes of 0 to 27%,27%to 43%and more than 43%.They were defined as low injury,medium injury and high injury,respectively.The corresponding blocking radius was 0~1.5 m,1.5~6 m and more than 6 m,respectively.Therefore,measures should be taken timely to prevent the occurrence of liquid lock injury,and a reasonable gas well production system should be established.From the above,the experimental device and the designed method is of strong operability and reliable data,which provides an important basis for further study of reservoir damage and an important technical reference for oil and gas field development and reservoir protection.