固体硝酸解堵技术及在油田的应用

固体硝酸解堵技术解决了硝酸/土酸复合酸化液具有极强腐蚀性及氧化性,对地面设备及管柱具有很大破坏性的问题,可用于解除无机物堵塞和有机物堵塞.室内试验表明,固体硝酸/土酸酸液对滤饼和岩心的12 h溶蚀率分别为10.7%和44.5%,与土酸相比,溶蚀率分别提高了3.54%和14.2%,说明固体硝酸/土酸酸液是一种缓速酸;固体硝酸水解产生的硝酸可与盐酸形成王水,与有机质发生氧化-还原反应,使原油降解、降粘,同时产生大量热,熔化部分沥青及胶质,对解除有机物堵塞具有很大的优势.在葡萄花油田的18口井中采用了该酸化技术.统计结果表明,用固体硝酸/土酸酸液酸化后,注水压力下降了0.9 MPa,视吸水指数提高了1.14 m3/d·MPa.

Plugging removal technology using of solid nitric acid and its oilfield application

The complex acidizing fluid composed of nitric acid and mud acid has extremely strong corrosion and oxidization , and can cause serious damages to surface e-quipment and pipe strings. The solid nitric acid plugging removal technology solves this problem and can be used in both inorganic and organic plugging re-moval. Laboratory tests were conducted on the 12-hour corrosion rate of solid nitric acid/mud acid fluid to the filtrate cake and core samples separately, and the resulting valves were 10. 7% and 44. 5%. As compared with the effect by mud acid, the corrosion rate improved by 3. 54% and 14. 2% respectively, which showed that the solid nitric acid/mud acid fluid could be taken as a retarded acid. Chlorazotic acid is produced from the reaction of hydrated nitric acid with hydrochloric acid, and it further causes the oxidation-reduction reaction with organic matters. This leads to the degradation of crude oil and viscosity reduction, with large amount of heat produced. The heat melts some of the asphalt and gum, which is very good for the removal of organic plugging. This acidizing technology was applied in the 18 wells in the Putaohua oilfield i and statistical results showed that the injection pressure dropped by 0. 9 MPa, and the apparent water injectivity index improved by 1. 14 m3/d.MPa.