含聚污水回注对储层损害机理研究

渤海某油田注水井注入压力高、酸化有效期短等问题突出。结合油田储层地质特征和注水开发历史,系统研究了清水与含聚污水清污配伍性、悬浮物组分、HPAM微观形貌与分子尺寸、注入水与岩心适应性等方面内容。研究表明：悬浮物堵塞是主要的损害形式,悬浮物为产出聚合物与污水处理剂、Ca2＋、Mg2＋等二价离子絮凝的产物,其次为产出聚合物与地层微粒形成的包络物,悬浮物中还含少量CaCO3和FeCO3沉淀。早期注清水导致储层发生强水敏损害,清污混注生成的CaCO3和FeCO3等刚性颗粒加剧了近井地带储层的堵塞程度,产出聚合物的絮凝沉淀等产物对储层深部形成堵塞,是导致注水困难和酸化效果较差的主要原因。

The Mechanism Research on Formation Damage by Reinjection of Polymer-Contained Sewage

The outstanding problems of water injection wells in an oilfield in Bohai are high injection pressure and shorter validity acidification. Combining the geologic feature of reservoir and the waterflooding development histo- ry, the subjects were systematically studied, such as the compatibility of mixed fresh water and polymer-contained sewage, the components of suspended matters, the micro- structures and molecular size of HPAM,the compatibility of injection water and cores,etc. Researches show that suspended solids jam is the main damage forms. Suspended matters are main the flocculation products of the produced polymer with the wastewater treating agents and Ca2+ , Mg2+ bivalent cationic,etc. Secondly,they also contain the precipitation of formation fines and produced polymer. Meanwhile, the suspended matters include a few precipitation of CaCO3 and Fe- CO3. In the early time, serious water sensitivity happened caused by fresh water injection. Rigid granules like CaCO3 and FeCO3, the precipitation of mixed fresh and produced water for reservoir flooding, intensified the obstruction level of formation in wellbore area nearby, the flocculating-dep-osition of produced polymer and other products blocked the deep area of formation, which were the main reasons for the poor waterflood effect and less effective acidification.