Abstract: Chemical flooding has been implemented over twenty years in Shengli oilfield. Because of long time development, from 2016 to 2020, the reservoir conditions have become increasingly harsher, and the composition of the produced water has been becoming more complex, resulting in the viscosity of the injected polymer solution prepared by mother liquor mixed with freshwater and diluted by produced water has been decreasing year by year, which severely affects the effect of development by chemical flooding. To further enhance the organic integration of chemical flooding and green development, this paper systematically analyzes the causes for viscosity decrease throughout the preparation and injection of polymer solution, and the following four low and zero-shear key techniques has been developed for polymer solution through tackling key problems:(1) The biological competition inhibition technique is established to ensure the viscosity of polymer solution, in order to achieve microbial desulfurization and sulfur inhibition by use of probiotics and inhibit the generation of Fe²⁺, which creates a precedent for its large-scale application in the field of chemical flooding. (2) The technique of immediate annihilation of hydroxyl radical via in-situ reservation of polyacrylamide is invented, and a new synthetic treating agent is developed based on DLVO theory of collochemistry, in order to reduce the generation of oil-containing sludge layer that may breeds sulfate-reducing bacteria at its source. (3) The optimization method for the curing parameters of polymer solution is built, and the integrated low-shear device and process is developed for the preparation of mother liquor as well as the mixing and dilution of produced water to form the polymer solution. (4) The simulation method for the structure of large pressure difference and low-shear throttling control unit is established, and a testable and adjustable injection process of the integrated string is also developed. These low and zero shear key techniques of polymer solution have been applied to the chemical flooding project in Shengli oilfield, thus achieving the transformation from the preparation of mother liquid with freshwater to that of produced water, and saving freshwater resources. Moreover, these techniques have achieved the transformation from formaldehyde sterilization to microbial desulfurization and sulfur inhibition by probiotics, which can eliminate occupational health hazards.

Key words: desulfurization and sulfur inhibition, in-situ reservation, annihilation hydroxyl, low shear process, viscosity of polymer solution

摘要： 胜利油田已有20年以上化学驱历史。但由于长时间开采，油藏条件愈加苛刻，产出水成分也愈加复杂，导致淡水配制母液、产出水混配稀释注入的聚合物溶液黏度逐年下降，严重影响了化学驱的开发效果。为了实现化学驱技术的绿色发展，通过系统分析聚合物溶液配制及注入全过程中导致黏度降低的因素，形成了使聚合物溶液低剪切、零剪切的4项关键技术：①生物竞争抑制法保证聚合物溶液黏度技术可以使"益生菌"微生物脱硫抑硫及遏制Fe²⁺产生，并可在化学驱领域大规模应用；②原位保留聚丙烯酰胺即时湮灭羟基自由基技术，该技术基于胶体化学DLVO理论，通过研制新型综合处理剂，从源头减少滋生硫酸盐还原菌的含聚油泥层产生；③聚合物溶液熟化参数优化方法，研发了聚合物溶液产出水母液配制、混配稀释一体化低剪切装置工艺；④大压差低剪切节流控制单元结构仿真模拟方法以及可测试调配一体化管柱注入工艺。聚合物溶液低剪切、零剪切关键技术已成功应用于胜利油田化学驱项目，实现了从淡水配制母液向产出水配制的转变，节约了淡水资源，还实现了甲醛杀菌向"益生菌"微生物脱硫抑硫的转变。

关键词: 脱硫抑硫, 原位保留, 湮灭羟基, 低剪切工艺, 聚合物溶液黏度