The Research Of Measures For Increasing Injection Base On Qijia Oilfield Reservoir Protection

Qijia oilfield is a typical low permeability oilfield. After production, appear high injection pressureand difficult injection phenomenon. Currently, there is no systematic analysis about variety factors and theirinteractions about the effect of flood effectiveness. Solve the problems of water flood development relatedto the increase of oilfield development effectiveness and economic efficiency. Therefore it is of greatimportance for us to carry out measures for increasing injection base on reservoir protection for complexformation conditions of Qijia oilfield.This thesis based on analysis of injected water quality, compatibility determination of injected waterand formation water, measurement of core dissolution rate, reservoir sensitivity evaluation and scalesimulation experiments, defines the pollution mechanism of water injection reservoir. The result shows thatit must be exists a stoppage cause by oil pollution near well bore in water injection reservoir, whileinjecting water containing oil. It must be produce scale sediment caused by poor compatibility betweeninjected water and formation water. Low salinity of injected water may cause swelling of clay minerals, andthen plug the reservoir pore. While reservoir rocks show weak velocity sensitivity or moderate to weakvelocity sensitivity, critical velocity range between3mL/min~4mL/min, reservoir show weak watersensitivity or moderate to weak water sensitivity，critical salinity range from8000mg/L to10000mg/L,reservoir rock shows severe acid sensitivity.After clear the mechanism of water injection reservoir pollution, we launch many pharmacon selectionexperiments include Anti-swelling Agent，Chelon and Permeate Agent, compatibility of pharmaconexperiments and core flooding experiment，then determine stimulation measures recipe base on Qijiaoilfield reservoir protection：DIA3%，EDTA2.5%， DY1%， DY-ST0.4%，osmotic agentPT-10.4%，Simulated injection experiments show that core permeability decreased about7.88%, improved the impacton the formation permeability effectively.