Study On Self-diverting Acid Of The Long-well Section In Buried Hill Reservoir

This article studies the long well section of a horizontal well penetrating the Xing BuriedHill reservoir located in Liaohe Oil Field. The reservoir suffers from severe heterogeneity,low permeability, low natural productivity and vulnerable to external fluid pollution etc. Thispaper suggests a new method which is targeted homogeneous acidification transformationprocess that named new acidification self-diverting technology, and synthesizes a betainesurfactants which has acidification self-diverting capacity, it’s called VWN. Tests on VWNhave been completed under laboratory condition. The result confirms its good performance inresistance to temperature and diverting, and ensure the formula of diverting acid in front thatis fit the Xing buried hill reservoir:12%HCl+5%VWN. The composition of acidizing liquidis chosen based on the mineralogy and damage level of the reservoir. Addictives are chosen tomatch the requirement of homogeneous acidification as well as to optimize acid’sperformance. As a result, the main acid system formula of homogeneous acidification used inlong well section of Xing buried hill reservoir is established as follow:5%D+5%FS+3%YES+7.5%HCl+1%corrosion B+1.5%QS-2+1%DQ-6. Meanwhile, by using artificial coreswhich combine real cores and clay minerals, the performance of the acidizing liquid isevaluated in short-core flow and core parallel experiments. The core flow experiment showsthat the main acid system can increase the permeability, reduce secondary damage to theformation, and achieve the purpose of increasing production and injection, which is proved tobe suitable for Xing buried hill reservoir acidizing. According to the core parallel experiment,it is clear that the steering effect of simulated injection field self-diverting acid system (frontdiverting acid+main acid) is obvious. It can temporarily block the high permeability core,and effectively improve low permeability core. Thus, self-diverting acid system can beeffectively applied to the acidification of Xing Buried Hill Reservoir.