Deep Plug Removal Technology Of Retarded Acid About Low Permeability Reservoir In Xingshugang Oil Field

The low permeable layers in Xingshugang oil field are characteristics of low permeability,low abundance and low productivity of single well.Conventional acidifications failed to achieve the desirable purpose because of the problems as quick acid-rock reaction rate and short effective acidification distance.Therefore,in order to solve these problems,it is necessary to perform the research of retarded acidification and optimize the retarded acid formula to improve the acidification effect.Aiming at the acidification problems appeared in Xingshugang low permeability sandstone,this paper has screened the main agent of retarded acid formula and optimized its concentration by means of measuring the variation of pH value and corrosion rate with the increment of time.The additives including corrosion inhibitor,clay stabilizer have also been selected so that the retarded acid formula system for these low permeable layers was eventually developed.Then this formula system has been evaluated by means of plugging and unplugging simulation experiment with natural cores.And the results indicate that this formula possesses the advantages as low acid-rock reaction rate,long penetration distance and good corrosion effect when comparing to the traditional mud acid under the formation temperature and could achieve the purpose of retarded acidification.