海上油田含聚合物污水水质对储层保护技术的影响

Effect of Polymer-contained Sewage Quality on Reservoir Protection in Offshore Oilfield

研究含聚合物(含聚)污水水质对储层的伤害为确定含聚污水回注储层的可行性提供了依据。以渤海绥中36-1油田含聚污水为例,利用偏光显微镜、扫描电镜、核磁共振仪等,通过岩心动态损害实验分别对污水中的乳化油、悬浮物和产出聚合物浓度及粒径中值进行了评价,分析了含聚污水回注对储层的伤害机理。结果表明,含聚污水中油、悬浮物、聚合物三者的协同作用是主要伤害源,且对储层的伤害程度随着单一水质指标的增大而增加;由于聚合物分子的吸附聚集作用而形成高强度的可变形团状集合体,是造成岩心孔隙喉道堵塞的关键因素;含聚污水进入储层对孔喉的堵塞形式是优先堵塞大-中孔喉,并逐步由内滤饼向外滤饼的堵塞形式转化。优化含聚污水水处理工艺及现行加药方式,是解决含聚污水处理问题的关键。

Studying reservoir damage caused by the quality of polymer-contained sewage provided the evidence for the feasibility of reinjecting polymer-contained sewage. Taking the SZ36-1 oilfield of the Bohai Sea as an example,with the help of polarizing microscopy,environmental scanning electron microscope,nuclear magnetic resonance and other means of microscopic analysis,the four significant indexes of water quality including the concentration of emulsified oil,suspended solids and produced polymer,and particle median size,were quantitatively evaluated by the core dynamic damage experiment,and the damage mechanism of reinjecting polymer-contained sewage to reservoir was also discussed. The results showed that the synergy effect between oil,suspended solids and polymer was the main damage source,and the damage degree of reservoir increased with increasing magnitude of single index of water quality. The deformable mass with high strength due to the adsorption and aggregation of polymer molecules,was the key factor to cause the blockage of pore throat. When the polymer-contained sewage invaded into the reservoir,the polymer preferred to block the large and medium-sized throat,and the blocked behavior gradually transformed from the interior to the exterior of filter cake. Optimizing the treatment process of sewage water and the current dosing method was the key to solve the treatment problem of polymer-contained sewage.