Research and application of blockage removal technology for low-pressure gas well in eastern Sichuan carboniferous formation

These are different degrees of wellbore blockage which affects productivity due to long time production in gas well of eastern Sichuan carboniferous formation. Perennial acidizing stimulation leads to the formation of large acid-corrosion channels around wellbore. The acid flowed away directly without any effect, resulting in poor acidification efficiency and short stable production period. The analysis shows that the blockages are mainly composed of iron oxide, carbonate, barium sulfate, silica, and lauryl alcohol polyether organics. The dissolution rate of the blockage removal acid solution to scale at formation temperature is up to 77.6%(15%HCl+1% corrosion inhibitor +2% iron stabilizer +3% surfactant).Specific blockage removal technologies are proposed for different blockage place, coiled tubing or tubing injection for tubing blockage removal, vacuum backposition sand pumping process for casing blockage, the foam acidizing technology for formation plugging. Field tests were carried out in 6 wells, the effective rate was 100%, which provides an effective technical means for blockage removal of low-pressure gas wells in this area and the same type.