Study on an emulsion-type blockage removal agent for heavy oil recovery enhanced by polymer

In polymer flooding process, the poor solubility of polymer and the wrap of incompletely dissolved polymer particles with heavy oil lead to the generation of complicated blockage, which seriously affects the normal production of wells. Therefore, how to fabricate an effective blockage removal agent is particularly important. Based on the blockage from Bohai Offshore Oilfield in China, a blockage removal agent composed of (0.5wt% potassium persulfate+kerosene (the ratio of kerosene: blockage is 3:5)+0.3wt% OP-10, the oil-water ratio is 1:9) was developed. The removal effect and mechanism were characterized by weight loss method and core test. Moreover, the emulsification property of the removal agent was also evaluated by microscopic appearance. The results showed that the blockage removal agent can be formulated as an O/W emulsion and had good stability for more than 72h. Core test showed that the permeability had a significant improvement after injection of removal agent. The emulsion-type removal agent can demulsify after contact with the blockage, then the oil-soluble detergent as internal phase in emulsion can be released which contributes to the wash off of heavy oil. Accompanied with the polymer degradation by the oxidant, this agent realized the effective dissolution and removal of blockage.