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西峰油田长8油层单井注采能力较低,根据长8油层酸化施工情况,酸处理的效果存在井间差异,一些井酸化效果较差或无效,酸化后注水压力依然很高,达不到配注要求。通过X—射线衍射和能谱分析,了解到储层富铁绿泥石含量高是酸化效果欠佳的关键原因之一。利用扫描电镜等测试手段,系统对比酸化流动实验前后绿泥石微观结构特征的变化,指出酸化过程中绿泥石能被大量溶蚀,研究表明存在三方面原因导致酸化效果差:绿泥石呈等厚环边状、绒球状赋存,与外来流体接触面积最大化,酸消耗过快,pH值快速升高,残酸形成不溶性沉淀或胶体堵塞喉道;酸化过程中地层微粒间结合力减弱,导致微粒被大量释放;储层渗透率过低,返排困难等。通过毛管流动孔隙结构仪(PM I)测试酸化前后孔隙结构参数表明,酸化后储层有效喉道大小没有得到明显改善。
The single well of Chang 8 reservoir in Xifeng Oilfield has a low injection and injection capacity. According to the acidizing construction of Chang 8 reservoir, there are differences in the effect of acid treatment. In some wells, the acidification effect is poor or ineffective, and the injection pressure after acidification is still still high, With note requirements. Through X-ray diffraction and energy spectrum analysis, we know that the high content of iron-rich chlorite in reservoirs is one of the key reasons for poor acidification. By means of scanning electron microscopy and other testing methods, the system compares the changes of chlorite microstructure before and after the acidizing flow experiment, and points out that chlorite can be corroded in a large amount during the acidification process. Studies have shown that there are three reasons that lead to poor acidification: Thick ring edge, pompon shape, with the maximum contact area of foreign fluid, acid consumption too fast, rapid increase in pH, residual acid to form insoluble precipitate or colloidal plug throat; during acidification weakened the binding force between the formation particles, Resulting in a large number of particles are released; reservoir permeability is too low, back row difficulties. The pore structure parameters before and after acidification were measured by capillary flow pore structure analyzer (PM I). The effective throat size of the reservoir after acidification has not been significantly improved.