COMPOSITION FOR UNCLAYING OF FORMATION BOTTOM ZONE (VERSIONS) Russian patent published in 2001 - IPC

FIELD: oil and gas production. SUBSTANCE: invention, in particular, relates to unclaying of bottom zone of formation of both production and injection wells, formation being characterized by low-productivity terrigenic clayey oil reservoir in which reduced productivity is due to mudding of pores with clayey material. Unclaying composition contains, %: hydrochloric acid, 7.0-20.0; nitrilotrimethylphosphonic acid, 1-hydroxyethylidenediphosphonic acid, ammonium nitrate, or diphonate, 0.5-5.0; water-methanol fraction (solvent), 33.0-66.0; and water, the balance. Alternatively, composition can additionally include surfactant and thereby contains, wt.%: hydrochloric acid, 7.0-20.0; nitrilotrimethylphosphonic acid, 1-hydroxyethylidenediphosphonic acid, ammonium nitrate, or diphonate, 0.5-5.0; surfactant, 0.1-2.0; water-methanol fraction, 33.0-66.0; and water, the balance. Another composition can further contain 0.5 to 5.0% of hydrofluoric acid. The following composition is also possible, wt.%: hydrochloric acid, 7.0-20.0; diphonate-urea peroxyhydrate mixture, 5.0-15.0; water-methanol fraction, 33.0-66.0; and water, the balance. The latter composition can also be completed by 0.1 to 2.0% of surfactant. EFFECT: increased permeability of formation bottom zone and enabled effective reuse of large-scale petrochemical industry wastes. 5 cl, 1 tbl, 48 ex