EXPERIMENTALSTUDY AND EVALUATION OF COMPOSITE ADDITIVES FOR REINJECTING RESERVOIRS CONTAINING POLYMERIC SEWAGE

摘要

Polymer flooding is an important way to improve oil recovery in oilfields. In recent years, it has been widely used in many oilfields. However, with the expansion of polymer injection scale and the extension of polymer injection time in some oilfields, the polymer concentration in the produced surface fluid gradually increases which caused relatively great pressure on sewage treatment equipment. Even after the treatment, the sewage still contains a large amount of polymers and also a large amount of impurities such as sulfide, bacteria, and oil, which has caused serious pollution to the formation, resulting in a decrease in the permeability of the oil layer. In order to reduce the damage to the physical properties of the reservoir after polymer-containing sewage is reinjected into the formation, a degrading agent with oxidants and surfactants as the main components was developed. At the same time, in order to prevent the anti-blocking agent from causing corrosion on the pipeline and the wellbore, and to prevent the clay minerals in the formation from reacting with the antiblocking agent, a composite deblocking additive was developed with corrosion inhibitor and clay stabilizer as the main components. The research results show that the newly developed anti-blocking agent formula is oil detergent + 0.5% sodium phosphate + 0.5% Rlee, the degradation agent is 0.5% DYNW + 0.3% PMTN + 1% Y-1, and the corrosion agent is 8% HCl + 1.5 % HF + 0.7% DYHS. Through the analysis of core permeability experiments, it can be known that the self-made anti-blocking agent has a significant anti-blocking effect on the simulated core to reach a level of more than 85%. It was verified that the newly developed formula for deblocking polymer-containing sewage can have a good protection effect on the pores and good application value.