Research on deep penetration multi-hydrogen acid plug-removal technology for low permeability sandstone in Yanchang Oilfield
In this paper,the mineral composition and clay composition of the CH-1 and CH-2 reservoirs in Yanchang Oilfield were analyzed,and sensitivity of formation was studied.It is clarified that the increase in injection pressure during water injection development is mainly caused by formation scaling,water sensitivity,and acid sensitivity damage,resulting in low permeability sandstone pore plugging.This article uses dissolution experiments,iron ion stability experiments,and coupon corrosion experiments to optimize the polyhydric acid supply agent,iron ion stabilizer,and corrosion inhibitor.The orthogonal test method is used to optimize the formula,and a deep penetration polyhydric acid solution system is obtained for plugging removal of low permeability sandstone in Yanchang Oilfield.The results show that the acid solution system has a formula of 15％HCl+5％NH4F+5％DTPMP+1％GLDA-Na+2％XCI-1.In the range of 60～90℃,the recovery rate of reservoir core permeability can reach over 400％,and the acid rock reaction time can reach over 180 minutes at 90℃,and the acid rock reaction time can reach over 300 minutes at 60℃.
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