低矿化度水驱技术增产机理与适用条件

针对最新提出的注入水低矿化度提高原油采收率问题，展开了对低矿化度水驱技术全方位研究。通过对文献 调研、实验和油田试验数据对比分析，表明低矿化度水驱增产的主要原因是黏土微粒迁移储层微观改造和润湿性转 变，其机理包括微粒迁移、多官能团离子交换、阳离子交换、高价阳离子桥接、双电层离子扩散、pH 值变化、低界面张 力、降低油水流度比、盐溶作用和胶结物溶解等，各种机理相互协同作用增加原油采收率，由于储层条件不同，会出现 某种机理缺失或者某种机理占主导的情况。如果油田具备低矿化度水驱的必备条件，那么控制好注入水的矿化度便 能够提升5%~20% 的原油产量。低矿化度水驱技术不仅成本低、油田施工步骤相对简单和环境污染小，还可以用于开 发海上油田，充分展现了该技术在未来油田开发的潜在价值和广阔空间。

Mechanisms of Low Salinity Waterflooding Enhanced Oil Recovery#br# and Its Application

To explain the reasons why low salinity injection water enhance oil recovery，the low salinity waterflooding is studied thoroughly. Literatures，laboratory and oilfield experimental data are investigated，and research results prove that the main reasons for improved oil recovery by low salinity are clay migration and wettability alteration，its main mechanisms including fine migration，multi-component ionic exchange，cation exchange，multication bridging，electrical diffuse double layers expansion， pH variation，oil-water mobility ratio reduction，salting effect，rock cement dissolution and so on；all mechanisms work collaboratively to improve oil recovery，but some mechanisms may be absent and some mechanisms are the main factors of enhanced oil recovery because of the different oilfield conditions. If the reasonable low salinity is controlled，there are about 5%~20% improvement of oil recovery. Low salinity waterflooding has become an attractive enhanced oil recovery method as it shows more advantages than conventional chemical EOR methods in terms of low costs，low environmental pollution and comparatively easier procedures. This technology is also applicable to onshore and offshore oilfields，which reveals the potential in oilfield development.