Research and Application of Novel Acidizing Fluid System in G Oil Reservoir

Abstract

To address the issues of high post-acidizing water cut (>75%) and organic contamination caused by the “thin, multiple, scattered, and heterogeneous” characteristics of the G Oil Reservoir, this study enhances acidizing effectiveness by optimizing acid retardation properties and developing composite plugging removal technology. Methods include: (1) Core dissolution experiments to optimize pre-flush acid (polyhydrogen acid QDQ) and treatment acid (fluoro boric acid/polyhydrogen acid), reducing hydrochloric acid concentration to 6% for dual-retardation; (2) Optimizing additives: corrosion inhibitor (1%), clay stabilizer (1–1.5%), iron ion stabilizer (1.2%), and flowback aid (0.3%); (3) Developing an organic composite plugging remover to degrade contaminants like asphaltene/resin, combined with surfactant (ZC-2) to improve wettability; (4) Employing 12% hydrochloric acid for scale removal in water wells, optimizing corrosion inhibitor (2%) and iron stabilizer (8–12%). Results show: Five field trials of the dual-retardation system significantly reduced post-acidizing water cut (e.g., Well 1 decreased from shut-in to 36.41%); Organic removal techniques increased daily oil production per well by 1.81–2.19 tons; Water well descaling-acidizing extended effective period by 120 days. The dual-retardation system inhibits near-wellbore dissolution, the composite process effectively removes organic blockages, and the surfactant enhances oil displacement efficiency. This work innovates retarded acid structure design and graded organic contaminant removal methodology, providing solutions for efficient development of thin, heterogeneous reservoirs.