Diverting agents based on thermoplastic polyvinyl alcohol pellets
AssigneeKuraray Co., Ltd.
InventorsGhebrehiwet Ghebremeskel, Keisuke Morikawa, Richard Cazares
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Abstract
A biodegradable and substantially water-soluble thermoplastic polyvinyl alcohol-based diverting agent is provided which comprises pellets of a specified polyvinyl alcohol optionally with certain specified additives, which pellets are made in an extruder and cut to a specified size.
Claims19
A particulate diverting agent composition comprising pellets of a melt-extrudable, thermoplastic polyvinyl alcohol composition comprising:
- (1) a polyvinyl alcohol component comprising a polyvinyl alcohol resin which is a hydrolyzed polymer of vinyl acetate and optionally minor amounts of one or more comonomers, and (2) a plasticizer, wherein:
- (a) the thermoplastic polyvinyl alcohol composition has a melt flow index in the range of from about 0.5 to about 60 g/10 min (190° C., 21.6 kg);
- (b) the polyvinyl alcohol resin has degree of hydrolysis is in the range of from about 60 mol % to 100 mol %, and a viscosity-average degree of polymerization of from about 200 to about 3000;
- (c) the diverting agent composition has a D(90) pellet size of a length of from about 2 mm to about 6 mm, and a diameter of from about 2 mm to about 5 mm;
- and
- (d) the polyvinyl alcohol resin has a methanol content of less than 2 wt % based on the total weight of the polyvinyl alcohol resin.
A method of making the particulate diverting agent, comprising the step of extruding the melt-extrudable, thermoplastic polyvinyl alcohol composition in a twin-screw extruder to a strand, and cutting the strand to the pellet size, wherein the melt-extrudable, thermoplastic polyvinyl alcohol composition comprises:
- (1) a polyvinyl alcohol component comprising a polyvinyl alcohol resin which is a hydrolyzed polymer of vinyl acetate and optionally minor amounts of one or more comonomers, and (2) a plasticizer, wherein:
- (a) the thermoplastic polyvinyl alcohol composition has a melt flow index in the range of from about 0.5 to about 60 g/10 min (190° C., 21.6 kg);
- (b) the polyvinyl alcohol resin has degree of hydrolysis is in the range of from about 60 mol % to 100 mol %, and a viscosity-average degree of polymerization of from about 200 to about 3000;
- (c) the diverting agent composition has a D(90) pellet size of a length of from about 2 mm to about 6 mm, and a diameter of from about 2 mm to about 5 mm;
- and
- (d) the polyvinyl alcohol resin has a methanol content of less than 2 wt % based on the total weight of the polyvinyl alcohol resin.
A method of treating a subsurface formation to divert flow of a fluid from one zone of the subsurface formation to another, by pumping into the subsurface formation an aqueous carrier liquid having dispersed therein a particulate diverting agent, wherein the particulate diverting agent is a particulate diverting agent composition comprising pellets of a melt-extrudable, thermoplastic polyvinyl alcohol composition comprising:
- (1) a polyvinyl alcohol component comprising a polyvinyl alcohol resin which is a hydrolyzed polymer of vinyl acetate and optionally minor amounts of one or more comonomers, and (2) a plasticizer, wherein:
- (a) the thermoplastic polyvinyl alcohol composition has a melt flow index in the range of from about 0.5 to about 60 g/10 min (190° C., 21.6 kg);
- (b) the polyvinyl alcohol resin has degree of hydrolysis is in the range of from about 60 mol % to 100 mol %, and a viscosity-average degree of polymerization of from about 200 to about 3000;
- (c) the diverting agent composition has a D(90) pellet size of a length of from about 2 mm to about 6 mm, and a diameter of from about 2 mm to about 5 mm;
- and
- (d) the polyvinyl alcohol resin has a methanol content of less than 2 wt % based on the total weight of the polyvinyl alcohol resin.
Dependencies are inferred from the claim text.