METHOD OF TREATING BOTTOM ZONE OF OIL FORMATION Russian patent published in 1999 - IPC

FIELD: oil and gas production. SUBSTANCE: invention relates to wells employing terrigenous low-permeable formations or impairing its running characteristics because of pollution in vicinity of hole. Bottom zone of oil formation with low- and high-permeable reservoirs is treated by injecting chemical reagents with different functionality and depressive effect to achieve hydrodynamic superperfection of wells increasing their productivity. Treatment of bottom zone is accomplished in cyclic action mode including injection of reagents into productive formation zone, process ageing, and return of depleted reagent under depression conditions. After that, acid or acid plus surfactant or demulsifier and organic solvent, or organic solvent plus surfactant or demulsifier are pumped into productive formation zone. Chemical reagents are injected into formation in order, combinations, and volumes determined by conditions of well until filtration resistances in the remote formation zone become superior to those in bottom zone. Process ageing and return of depleted solution are also effected after organic solvent is injected. EFFECT: enhanced bottom zone treatment efficiency. 2 cl, 1 tbl