注入水中固相颗粒损害地层机理分析

当含有固相颗粒的注入水进入地层时，水中的固相颗粒将不同程度地滞留在孔隙网络中，使地层渗透能力下降。分析胜利油田商三区和胜二区注入水中固相颗粒分布特征、地层孔喉特征，以此为基础，采用实验方法研究注入水中固相颗粒与岩石孔喉的匹配关系，分析固相颗粒损害地层的机理。研究结果表明从水站到注水井，注入水水质沿流程变差；在双对数坐标下，商三区和胜二区岩石孔喉半径与渗透率存在线性关系；当水质一定时，微小粒径的固相颗粒进入岩石孔隙内部形成深部损害，粒径较大的固相颗粒只能在岩石表面和浅表部位附着或桥堵而形成表面(层)损害。根据架桥法则，确定了商三区和胜二区注入水中固相颗粒指标。图3表3参4（秦积舜摘）

Mechanism analysis on the formation damage by retention of particles suspended in injection water

It looks as if a large filter that a porous system of reservoir rocks, which can capture some particles, suspended in injected water when the water is injected into reservoir. This may cause substantial reduction in permeability of reservoir rocks. The authors collect and analyze the distribution of solid particles in injected water and pore throat feature of reservoir rocks in the Unit 3 of Shanghe oil field and the Unit 2 of Shengtuo oil field. For the above mentioned analysis, the authors studied matching relation between size of the particles in the water and one of the pore throats of the rock and analyzed mechanisms of formation damage by retention of particles suspended in injection water. It is found that quality of injection water is become markednessly bad from water treatment station to injection well. There is a liner relation between radius of the pore throat and permeability of the rock in log log coordinate. And there are some differences in various styles of formation damage when injection water quality is fixed and permeability of rock is different. Finally, the authors recommend a new method for quantitatively analyzing formation damage by retention of particles suspended in injection water. By the method, which is based on the information of core, pore structure and the data of the particles we can describe quantitatively mechanism of the damage by the particles in the water and establish the criterions of the water for oilfield.