低渗高温油藏聚合物驱研究

Polymer Flooding in High Temperature and Low Permeability Reservoir

王业飞 刘晨 齐自远 潘凌 朱国华 刘华

WANG Ye-Fei LIU Chen QI Zi-Yuan PAN Ling ZHU Guo-Hua LIU Hua

针对江苏油田沙七断块低渗高温中盐储层的特点，通过室内聚合物性能评价及注入性实验，探究了该类型区块聚合物驱应用的可行性。对低相对分子质量的梳形聚合物、磺化聚合物和普通聚合物进行初选，梳形聚合物的抗温耐盐能力良好，1000mg/L聚合物清水溶液的黏度为22.4 mPa·s（25℃）、10.1 mPa·s（83℃），1000mg/L聚合物污水溶液的黏度为10.6 mPa·s（25℃）、5.7 mPa·s（83℃）。对4 种梳形聚合物（M=480×104～1550×104）进行进一步筛选，其剪切黏度保留率为89%～100% ，在83℃老化90d后的黏度保留率为88.5%～95.1%，抗剪切能力和热稳定性均较好。注入性实验表明，聚合物溶液注入压力随聚合物相对分子质量和浓度的增加而增大；相对分子质量1000万的梳形聚合物溶液可以注入到渗透率50×10-3μm2的人造岩心中，随聚合物浓度的增大，低相对分子质量的聚合物溶液也有良好的流度控制能力；相对分子质量1000万的梳形聚合物溶液会堵塞渗透率小于30×10-3μm2的天然岩心，相对分子质量616 万的梳形聚合物溶液可以满足渗透率20×10-3μm2天然岩心的注入性要求。沙七储层聚合物驱宜选用相对分子质量616万的梳形聚合物HF62208。

Block 7 in Jiangsu oilfield was a high temperature and low permeability reservoir. In order to enhance reservoir development effect, the application feasibility of polymer flooding in such reservoirs was studied through the performance evaluation and injection experiment of polymer solution. The comb polymer, sulfonated polymer and regular polymer with low molecular weight were compared through original selection. The results showed that comb polymer had good thermal and salinity resistance. The viscosity of 1000mg/L comb polymer in clean water solutions was 22.4 mPa·s（25℃）and 10.1 mPa·s（83℃）, and that in waste water solutions was 10.6 mPa·s（25℃）and 5.7 mPa·s（83℃）. Four kinds of comb polymers （M=480×104—1550×104）were further screened. The shear viscosity retention rate was of 89%—100%, the viscosity retention rate aging 90d at 83℃ was of 88.5%—95.1%, which indicated that the polymer had good shear and thermal resistance. Injection experiments showed that the injection pressure of polymer solution increased with increasing polymer molecular weight and concentration. The comb polymer solution with molecular weight of 10 million could be injected into artificial core with permeability of 50×10-3μm2. With the increase of polymer concentration, low molecular weight polymer solution also had good flow control ability. The comb polymer with 10 million molecular weight could block natural core with permeability less than 30×10-3μm2, and that with 6.16 million molecular weight could meet the injection requirement of natural core with 20×10-3μm2 permeability. Considering the flow control ability, injection and polymer controlling scope, it was suggested that comb polymer HF 62208 with molecular weight of 6.16 million was suitable for the polymer flooding of Block 7 in Jiangsu oilfield.