稠油油藏水平井泡沫酸解堵技术

Foamed Acid Plug-Removal Technique for Horizontal Wells in Heavy Oil Reservoirs

为解除稠油油藏水平井钻井和生产过程中产生的近井污染、提高酸化解堵效果,开展了水平井泡沫酸解堵技术研究。以胜利油田郑411西区稠油油藏为研究对象,采用泡沫性能评价试验和近井污染物溶蚀试验筛选了泡沫酸体系配方,采用填砂管携砂试验和泡沫酸黏度试验研究了泡沫酸的携砂、悬砂性能。筛选出的泡沫酸体系发泡体积和半衰期分别为380mL和450s,具有很强的溶蚀能力和携砂能力;泡沫最大黏度2 629mPa·s,砂粒在泡沫酸中的沉降速度可以忽略。该技术在郑411西区应用12井次,生产周期平均延长71d,周期产油量增加1 080t。研究结果表明,泡沫酸解堵技术可以有效解除稠油油藏水平井近井地带的污染,大幅提高原油产量。

In this paper,a series of studies was conducted on the foamed acid plug-removal technique used to to remove near wellbore contaminants in horizontal wells in heavy oil reservoirs.The studies were conducted drilling and production to improve plug removal effects.Based on foam performance evaluation experiments and near wellbore contaminant corrosion tests,the formula of foamed acid system was optimized with the heavy oil reservoirs in the west of Block Zheng 411 as the examples.The sand pack core flooding experiment and foamed acid viscosity test were conducted on foamed acid to study its sand carrying and suspending capacities.The optimized formula was good in foaming properties with foaming volume of380 mL and half-life time of 450 s.It was excellent in terms of sand carrying and suspension capacity.Its maximum viscosity was 2 629mPa·s,and the sand settling velocity in the foamed acid could be ignored.This technique was applied in 12 wells in the west of Block Zheng 411.Thus,production cycle was extended by 71 dand the oil incremental per cycle averaged 1 080 t.It was shown that this technique could remove the near wellbore contaminants of horizontal wells in heavy oil reservoirs efficiently and greatly increase oil production.