METHOD FOR REAGENT-WAVE HYDROPERCUSSION TREATMENT OF BOREHOLE ZONE OF RESERVOIRS WITH HARD-TO-RECOVER OIL RESERVES Russian patent published in 2022 - IPC E21B43/27 E21B43/18 E21B47/06 

FIELD: oil, gas and coke-chemical industry.

SUBSTANCE: invention relates to methods for intensification of oil production and water injection. Method of reagent-wave hydropercussion treatment of well zone of reservoirs with hard-to-recover oil reserves includes selection of wells with low-permeable screened or non-screened productive reservoirs with formation thickness of not less than 5 m and with injectivity of 0.1–0.5 m³/h. In the shielded collectors, the allowable pressure is determined on the interstratal bridge P_add; a hydropercussion device is lowered into the well with pressure accumulation in the pipe string in the form of a shutoff valve of multi-cycle action. Cyclic injection of the chemical is carried out in the following sequence: pressure is accumulated in the pipe string to the value of P_fhf and higher by pumping liquid into the pipe string with the shutoff valve closed, shutoff valve is opened and pressure is released into the formation with creation of a hydraulic shock with a pulse of hydrodynamic pressure with steepness of the leading edge of the pulse of not less than 30 atm/s, pumping is continued with flushing into the formation at pressure of not more than P_add until the formation is saturated for 5–15 minutes. Cycle is completed by releasing pressure and pouring liquid from the formation into the pipe string until the liquid is completely discharged from the well, but not more than the volume of the chemical reagent pumped in the cycle. Pulse pumping cycles are repeated with forcing and spouting till injectivity stabilization. In non-shielded reservoirs, the above hydropercussion device and pressure concentrator are lowered into the well, the annular space is shut off in the middle of the treated interval with a pressure concentrator. Cyclic injection of the chemical is carried out in the following sequence: accumulating pressure in the pipe string to the value of P_fhf and higher by pumping liquid into the pipe string with the shutoff valve closed, opening the shutoff valve and releasing pressure into the formation with the creation of a hydraulic shock by a pressure pulse with a steepness of the leading edge of the pulse of not less than 30 atm/s, wherein pressure pulse amplitudes are controlled at wellhead caused by reflected wave of hydraulic shock. Operations of pressure accumulation in pipes and its release into formation are repeated until pressure pulse amplitude of reflected wave of hydraulic shock is stabilized, but not for more than 30 minutes. Cycle is completed by releasing pressure and pouring liquid from the formation into the annular space until the liquid is outflowed from the well in the volume of not more than the volume of the chemical reagent pumped in the cycle. After injectivity stabilization, pressure release and fluid outflow from the formation is carried out into the annular space. In shielded and unshielded reservoirs, operations are repeated until injectivity is more than 1 m³/h, the operations are completed by pumping the planned volume of chemicals into the formation, waiting for the reaction and removing reaction products from the wellbore zone of the formation.

EFFECT: possibility of establishing hydrodynamic connection in conditions of low-permeability formation, high viscosity and heterogeneity, dense colmatation of the formation in the borehole zone.

1 cl, 3 dwg