STUDY OF REFRACTURING TECHNOLOGY IN LOW-PERMEABILITY SANDSTONE RESERVOIR

The propped fracture generated during primary fracturing induces a stress field that changes original stress field and further reorients new fracture during refracturing,the extension direction is still controlled by stress status.By means of altering confining pressure,hydraulic fracturing simulation experiment proves the possibility of new fracture generation during refracturing.Temporarily blocked refracturing is applied in the Ansai oilfield of the Ordos Basin: a temporary blocking agent is injected during old fractures reopening to form a high-pressure environment and newly generated fracture connects the natural micro fractures which establishes new high-conduction fracture system with later added proppant and enlarges the oil-draining area.Pilot fracture monitor and effect analysis prove the generation of new fractures during refracturing.