Study on Formula of Retarded Acid for Acidizing and Blocking of Coalbed Methane Wells

Abstract

Acid plugging removal technology is an effective measure to remove the pollution in the near-well zone of oil and gas reservoirs and restore the productivity of oil and gas wells. It is to use the chemical dissolution of acid solution to dissolve formation plugs, expand or extend formation fractures and holes, so as to restore and improve formation permeability, reduce oil inflow resistance or water injection resistance, thus achieving the purpose of increasing oil well production and water injection. Therefore, the acid formula is particularly important. The commonly used acid formula is the soil acid formula. However, due to the shortcomings of the Soil Acid Formula itself, as well as higher safety risks and construction costs, this paper has studied a new acid formula. X-ray diffraction analysis was carried out on the experimental slime samples from 8 wells in Linfen block of Shanxi province, and it was found that the main mineral composition of the blockage was a mineral that can react with acid. The dissolution rate and corrosion rate of the blockage were tested with Southwest Solid Acid and Soil Acid Formula. The advantages and usability of Southwest Solid Acid were found by comparing the experimental results. Through a large number of experiments, the formula of retarded acid liquor with excellent performance, economy and effectiveness has been selected.