Scale treatment in a heterogeneous reservoir using a non-newtonian fluid

Abstract

The technology relates to a method of treating inorganic scale in a well that is drilled in a heterogeneous reservoir matrix. A heterogeneous reservoir matrix has varying permeabilities. The varying permeabilities can cause a change in the shear rate as a fluid flows through it. A shear thinning nanofluid that includes a nanoparticle functionalized with a scale inhibitor and an aqueous solvent is injected into the heterogeneous reservoir matrix. The shear thinning behavior of the nanofluid causes a self-diversion of the nanofluid from a high permeability zone towards the low permeability zone due to a change in the viscosities. The self-diversion causes the scale inhibitor to be delivered to the low permeability zone.

1 . A scale treatment method comprising:
 pre-flushing a heterogeneous reservoir matrix with an aqueous solvent, wherein the aqueous solvent is injected through a well;   injecting a shear thinning nanofluid into the heterogeneous reservoir matrix through the well, wherein the shear thinning nanofluid comprises:
 a nanoparticle functionalized by loading with a scale inhibitor; and 
 an aquifer water; 
   self-diverting the shear thinning nanofluid from a first zone comprising a first shear rate to a second zone comprising a second shear rate of the heterogeneous reservoir matrix, wherein the first zone has a permeability higher than the second zone, causing the scale inhibitor to reach the second zone;   shutting in the well for a time period to enhance retention of the scale inhibitor by the second zone; and   resuming a production of a produced water stream through the well, wherein the produced water stream comprises the scale inhibitor.   
     
     
         2 . The method of  claim 1 , wherein the nanoparticle comprises a metal oxide functionalized with a scale inhibitor. 
     
     
         3 . The method of  claim 1 , wherein the nanoparticle comprises a carbon nanotube or graphene oxide loaded with a scale inhibitor. 
     
     
         4 . The method of  claim 1 , wherein the nanoparticle comprises a scale inhibitor and a divalent cation. 
     
     
         5 . The method of  claim 1 , wherein the nanoparticle comprises a carboxyl-modified quantum dots (CCQDs). 
     
     
         6 . The method of  claim 1 , wherein the scale inhibitor comprises amino trimethylene phosphonate (ATMP), bishexamethylene triamine pentamethylene phosphonate (BHPMP), hexamethylenediamine tetramethylene phosphonate (HDTMP), diethylenetriamine pentamethylene phosphonate (DETPMP), ethylene diamine tetramethylene phosphonate (EDTMP), 1-hydroxyethylidene-1,1-diphosphonate (HEDP), polyamino polyether methylene phosphonate (PAPEMP), 2-phosphonobutane-1,2,4-tricarboxylic acid (PBTC), or phosphate esters. 
     
     
         7 . The method of  claim 1 , wherein the shear thinning nanofluid exhibits a first viscosity in the first zone, wherein the first viscosity at least partially impedes the flow of the shear thinning nanofluid in the first zone and diverts the shear thinning nanofluid into the second zone, wherein the first viscosity is higher than the second viscosity. 
     
     
         8 .- 10 . (canceled) 
     
     
         11 . The method of  claim 1 , wherein shutting in the well comprises the time periods of 4-50 hours. 
     
     
         12 . A method of scale inhibitor displacement in a heterogeneous reservoir comprising:
 injecting a shear thinning nanofluid into the heterogeneous reservoir through a well, wherein the shear thinning nanofluid comprises a nanoparticle functionalized by loading with a scale inhibitor and an aqueous solvent;   self-diverting the shear thinning nanofluid into the heterogeneous reservoir from a first zone comprising a first permeability to a second zone comprising a second permeability, the first permeability is higher than the second permeability, wherein the self-diverting comprises:
 flowing the shear thinning nanofluid into the first zone, wherein the shear thinning nanofluid exhibits a first viscosity in the first zone, wherein the first viscosity at least partially impedes the flow of the shear thinning nanofluid in the first zone; and 
 diverting the shear thinning nanofluid from the first zone into the second zone, causing the scale inhibitor to reach the second zone, wherein the shear thinning nanofluid exhibits a second viscosity in the second zone, wherein the second viscosity is lower than the first viscosity; 
   and   producing, through the well, a produced water stream from the heterogeneous reservoir comprising the scale inhibitor.   
     
     
         13 . The method of  claim 12 , wherein the nanoparticle comprises a metal oxide functionalized with a scale inhibitor and the aqueous solvent comprises an aquifer water. 
     
     
         14 . The method of  claim 13 , wherein the scale inhibitor comprises amino trimethylene phosphonate (ATMP), bishexamethylene triamine pentamethylene phosphonate (BHPMP), hexamethylenediamine tetramethylene phosphonate (HDTMP), diethylenetriamine pentamethylene phosphonate (DETPMP), ethylene diamine tetramethylene phosphonate (EDTMP), 1-hydroxyethylidene-1,1-diphosphonate (HEDP), polyamino polyether methylene phosphonate (PAPEMP), 2-phosphonobutane-1,2,4-tricarboxylic acid (PBTC), or phosphate esters. 
     
     
         15 . The method of  claim 14 , wherein the scale inhibitor comprises DETPMP or phosphate esters. 
     
     
         16 . The method of  claim 12 , wherein the shear thinning nanofluid has a viscosity ranging between 100-2500 cP measured by a rotational viscometer. 
     
     
         17 . (canceled) 
     
     
         18 . (canceled) 
     
     
         19 . A system of scale treatment comprising:
 a heterogeneous well through which a shear thinning nanofluid comprising a nanoparticle functionalized with a scale inhibitor is injected into a subterranean formation comprising a plurality of permeabilities, wherein the plurality of permeabilities causes a self-diversion of the shear thinning nanofluid from a first zone comprising a first permeability to a second zone comprising a second permeability, causing the scale inhibitor to reach the second zone, wherein the first permeability is higher than the second permeability; and   a bullhead pump, which is used to pump the shear thinning nanofluid into the heterogeneous well.   
     
     
         20 . The system of  claim 19 , wherein the shear thinning nanofluid comprises a metal oxide nanoparticle functionalized with a scale inhibitor and an aquifer water.