METHOD OF ACID LONGITUDINAL HYDRAULIC FRACTURING OF LOW-PERMEABLE TERRIGENOUS COLLECTOR Russian patent published in 2015 - IPC E21B43/27 

FIELD: oil and gas industry.

SUBSTANCE: in this method of acid longitudinal hydraulic fracturing of low-permeable terrigenous collector to inner cavity of the production casing a slot perforator is run in, walls of the production casing are cut by means of vertical disc cutters of the slot perforator with forming of two longitudinal slots opposed at different height points within the interval from the foot to the roof of the producing formation. Through jet nozzles of the slot perforator hydrocarbon-based process fluid is injected and through longitudinal slots in the production casing the process fluid is washed at pressure that does not exceed pressure of hydraulic fracturing and filtration channels are thus formed in cement stone behind the production casing and ambient rock in the bottom-hole zone of the formation, which pass deep into the producing formation. Upon formation of the filtration channels the slot perforator is removed and downhole equipment consisting of a high-pressure packer and a circulating valve is run in to the well at the flow string. The packer is packed over the roof of the producing formation and filtration channels are washed with hydrochloric acid of 12% concentration with flushing to the producing formation depth of hydrocarbon-based process fluid injected to the well earlier. Thereafter below-packer space of the well is flushed by thickened mud acid consisting of hydrochloric acid of 12% concentration, hydrofluoric acid of 3% concentration and mud thickener of carboxymethyl cellulose to the formation depth as fracturing fluid and proppant material with formation of fractured slot. Upon completion of acid hydraulic fracturing and fixation of fractured slot, the slot is washed by hydrochloric acid of 12% concentration with destruction of mud thickener of carboxymethyl cellulose. Then the over-packer space of the well is washed by creating circulation in annular space and tubing space by means of the circulating valve and influx is induced from the producing formation by reduction of backward pressure. Upon development the well is introduced into operation with remaining downhole equipment, which was run in to the well during process of hydraulic fracturing.

EFFECT: increased square area and depth of the producing formation penetration at elimination of swelling conditions for clays contained in the reservoir.

3 ex, 7 dwg