Sealing/Plugging Capacities of Low Temperature Water Plugging Agent SAMG-I Measured in Core Flow Tests

To solve the troubles connected with highly permeable zones,passages or channellings often created in oil reservoirs at their middle-late stages of water flood,a newly developed low temperature water plugging agent,SAMG-Ⅰ,is investigated in core flow tests for its sealing/plugging capacities.SAMG-Ⅰ is prepared from 5—7% starch,4—7% acrylamide,0.05—0.2% organic crosslinker,0.1—1.0% initiator,and 0.1—0.5% retarder in produced water of Jinlin oil fields and gelates at the reservoir temperature,30℃,in a controllable time to give a strong,stable and shear and ageing resistant gel.SAMG-Ⅰ in ungelled stage can easily transfer in high permeability cores to reach the depth needed and produce strong blockages in the place after gelation with strong adhesion to porous sandstone matrix.A breakthrough pressure of 2.5 MPa and a plugging rate of 99.91% are determined for a core with SAMG-Ⅰ plug 10 cm deep placed and gelled.In paralell core test SAMG-Ⅰ enters selectively into the high permeablity core thus can serve for plugging big passages,highly permeable zones,and channellings in reservoirs.