Research Of Strong Penetration Chemical Blocking Removal Technology In Injection Wells Of Niuxintuo Oil Field

Niuxintuo layer is a typical low permeability reservoir, which presents small rock pore and low permeability. With the extension of development, water flooding pressure is gradually rising, and displacement effect is declining. The problem must be resolved. Common acidification and blocking removal measures, which had been used before many times, did not achieve the desired results because of the difficulty of injection, small treated radius and short durability. So it is necessary to study formation damage mechanism of injection wells and research a new type of blocking removal technology.In this paper, rock mineral compositions in Niuxintuo oilfield reservoir were determined by means of XRD. And petrophysics analysis, injection water quality analysis, composition analysis of injection wells flowback blocking materials, compatibility of injected water and formation water and reservoir sensitivity examination were developed based on lab test, the types and causes of formation damage in injection wells of Niuxintuo oilfield were confirmed, including suspended material plugging, bacterial jam, oil drop plugging, inorganic scaling and clay swelling. According to the damage causes and types, through experiment, a new type of blockage removal agent that is appropriate for the injection wells of Niuxintuo oilfield has been developed. In the remover, the strong penetration agent can significantly reduce the surface tension, and can penetrate into the core of plugging materials easily and open channel for the blocking removal agents so that increase the treatment distance.By the monolayer preferential adsorption of reservoir pore protection agent, a resist film deposits on the pore wall, and which prevents the subsequent deposition of pollutants in the pore wall, and increase the term of validity. Using natural cores, on which flooding microscopic displacement were carried out. The results showed that, compared to the conventional acidification method, this new blocking removal technology can improve blocking removal effect 20 ~ 30% and reduce plugging about 20%.