Study Of Multi-phased Acidification In Huabei Dawangzhuang Oilfield

Through the research of the geologic reservoir characteristics and the analysis ofreservoir lithology,physical property and fluid characteristics of Shahejie formation inDaWangZhuang oilfield，The blockage type of reservoir had been cleared, the optimumconditions were determined,by means of microscope,SEM and X-ray diffractiontechniques.In addition,we confirmed the construction process parameter based on the coredynamic flow experiments.Studies have shown that the sandstone of Shahejie formation in Dawangzhuang oilfieldis mainly arkose and the content of clay mineral is about10%, The clay mineral is illitemixed layer and then are chlorite, kaolinite and illite. On the basis of the laboratoryexperiment on the penetration acidification, the optimum conditions are determined. Thehydrochloric acid is15%,the hydrofluoric acid is1.5%,the fluoroboric acid is6.0%. theacetic acid is1.0%,And the most optimal concentration of the acid additives aredetermined.The inhibitor LHH is4%,the iron stabilizer LHT is4%,the cleanup additive PZ-7is0.2%,the clay stabbilizer AS-100is1.0%. At the same time, combined with thepermeability recovery experiment and core acidification of the static experiment, the multipleacid acidification subject formula were Selected: the prepad fluid is10％HCl＋1.0％ACH;The first phase of mud acid/organic acid system is10%HCl＋1.5%HF＋1.0%HAC；Thesecond fluoboric acid system is6%HBF4＋10%HCl。The core dynamic flow experiments showed that this acid system had goodcorrosion inhibition and good dissolution ability.and It also has good compatibility andacidification effect. All can satisfy the requirement of solving the injection wells depthacidizing of DaWangZhuang oilfield. Through acidizing test of the A23in DaWangZhuangoilfield, the period of Acidification is more than10months, acidification effect is obvious,which indicat that the multi-phased acidification technology in Dawangzhuang Oilfield issuccessful.