Abstract: By means of simulation experiments in sandstone micromodels,scaling mechanism and formation damage due to scaling of BaSO₄ and CaCO₃ are studied respectively. The results show:1)Formation scaling is formed in the repeated heterogeneous-phase nucleation and crystal growth. The crystal can grow both in pores and at throats. 2)The characteristics of scaling are different for different scales. BaSO₄ scaling develops intermittently in the alternate process of water mixing and scaling, the morphology of the scale crystals develops poorly and the crystals are fine.While CaCO₃ scaling develops continuously,the morpholgy of the scale crystals develops perfectly and the crystals are large. 3)The formation damage due to scaling is a complex problem,even if effects of temperature and multiphase flow are excluded,it is still affected by the amount of scale and formation permeability. In general,the larger the amount of scale is or the lower the permeability is, the severer the formation damage is. As the permeability of formation decreases, the difference of formation damage decreases due to different amount of scale. As the amount of scale increase, the difference of formation damage decreases in formations with different permeability.

Key words: scaling mechanism, formation, formation damage due to scaling, simulation experiment, sandstone micromodel, waterflooding oil field

摘要： 通过砂岩微观孔隙模型模拟实验,分别对BaSO₄和CaCO₃结垢机理及结垢油层伤害规律进行了研究。研究结果表明:①油层结垢是在多次的异相成核-晶体生长过程形成的,晶体生长在孔隙中和喉道处均可发生;②不同类型结垢,其结垢特点不同。BaSO₄结垢呈现出水混合-结垢交替间断进行及垢晶体晶形发育差、晶粒细小之特点,而BaSO₃结垢呈现出连续进行及垢晶体晶形发育好、晶粒粗大之特点;③结垢油层伤害是一复杂问题,即使不考虑温度及多相渗流的影响,其仍受到结垢量和油层渗透性的双重影响。一般结垢量越大,油层渗透性越差,结垢对油层的伤害越严重。随油层渗透性变差,结垢量不同引起的结垢油层伤害程度的差异减小;随结垢量增大,渗透性不同,油层结垢伤害程度的差异减小。

关键词: 结垢机理, 油层, 结垢油层伤害, 模拟实验, 砂岩微观孔隙模型, 注水开发油田