Soluble deverting agents

Abstract

Methods and compositions for stimulating single and multiple intervals in subterranean wells by diverting well treatment fluids into a particular direction or into multiple intervals using water soluble coated diverting agents are described. The water soluble coating of the diverting material is preferably a collagen, poly(alkylene) oxide, poly(lactic acid), polyvinylacetate, polyvinylalcohol, polyvinylacetate/polyvinylalcohol polymer or a mixture thereof applied as a coating on any number of proppants. The method allows for the diverting of the flow of fluids in a downhole formation during a well treatment, such as during a fracturing process. Following completion of a treatment such as a hydraulic stimulation, the soluble diverting agent can be dissolved and removed by the water component of the well production.

1 . A diverting material comprising: 
 a particulate substrate; and    a water-soluble polymer coating,    wherein the water-soluble polymer coating forms a substantial outer coating on the particulate substrate.    
   
   
       2 . The diverting material of  claim 1 , wherein the particulate substrate is selected from the group consisting of natural materials, silica proppants, ceramic proppants, metallic proppants, synthetic organic proppants, and mixtures thereof.  
   
   
       3 . The diverting material of  claim 1 , wherein the particulate substrate is a resin coated proppant.  
   
   
       4 . The diverting material of  claim 1 , wherein the water-soluble polymer is collagen, poly(alkylene) oxide, poly(lactic acid), polyvinylacetate, polyvinylalcohol, polylactone, polyacrylate, latex, polyester, periodic chart elements of group I or II (alkali metal or alkaline earth metal) silicate polymers or admixtures thereof.  
   
   
       5 . The diverting material of  claim 1 , wherein the particulate substrate has a particle size of from about 3 mesh to about 200 mesh.  
   
   
       6 . The diverting material of  claim 4 , wherein the collagen is Type I collagen, Type II collagen, Type III collagen, Type IV collagen, or Type V collagen.  
   
   
       7 . The diverting material of  claim 4 , wherein the water-soluble collagen is crosslinked with a cross-linking agent selected from the group consisting of aldehydes, carbodiimides, isocyanates, and acyl azides.  
   
   
       8 . The diverting material of  claim 1 , further comprising a non-water-soluble polymer in combination with the water-soluble polymer coating.  
   
   
       9 . The diverting material of  claim 8 , wherein the non water-soluble polymer is phenol-aldehyde novolac polymers and phenol-aldehyde resole polymers.  
   
   
       10 . The diverting material of  claim 1 , wherein the water-soluble polymer is poly(alkylene) oxide, poly(lactic acid), polyvinylacetate, polyvinylalcohol, polyvinylacetate/polyvinylalcohol graft polymers or admixtures thereof.  
   
   
       11 . The diverting material of  claim 10 , wherein the poly(alkylene) oxide is poly(ethylene) oxide, poly(propylene) oxide, poly (ethylene oxide)-poly (propylene oxide) block copolymers, or mixtures thereof.  
   
   
       12 . A diverting fluid for diverting oil well treating liquids to progressively less permeable portions of a subterranean formation, said fluid comprising: 
 an aqueous carrier liquid having dispersed therein particulate diverting material of any one of claims  1 - 11 .    
   
   
       13 . The diverting fluid of  claim 12 , wherein the particulate diverting material comprises varying densities greater or less than the density of the carrier fluid.  
   
   
       14 . The diverting fluid of  claim 12 , wherein the diverting material is present in the carrier liquid in an amount from about 0.001 pounds per gallon to about 10 pounds per gallon of the carrier liquid.  
   
   
       15 . The diverting fluid of  claim 12 , wherein the carrier liquid is water, brine, aqueous acid solutions, or gelled acid solutions.  
   
   
       16 . A method of treating a subterranean formation during fracturing treatment so as to increase the stimulation of the subterranean formation, the method comprising: 
 pumping into the subterranean formation a diverting fluid of any one of claims  12 - 15 ;    allowing the carrier liquid to permeate into the formation so as to carry the diverting material into the subterranean formation; and    allowing the diverting material to plug porous portions of the formations thereby diverting flow of treating fluid to less permeable portions of the formation.    
   
   
       17 . The method of  claim 16 , wherein the formation has a temperature from about 75° F. to about 400° F.  
   
   
       18 . The method of  claim 16 , wherein the treating of the subterranean formation is a fracturing treatment, and wherein the stimulation increased is the length of the fractures.  
   
   
       19 . A method treating a cased wellbore to divert flow of fluids from one zone to another, the method comprising: 
 pumping into said wellbore a diverting fluid comprising an aqueous carrier liquid having dispersed therein a particulate form of a water soluble polymer, wherein the particulate polymer has a density greater than or less than the density of the carrier liquid;    allowing the particulate polymer to divert flow of a treating fluid from one zone to another.    
   
   
       20 . The method of  claim 19 , wherein the treating fluid is diverted to flow into a zone of higher pore pressure or lower permeability.  
   
   
       21 . The method of  claim 19 , wherein the wellbore has a temperature from about 75° F. to about 400° F.  
   
   
       22 . The method of  claim 19 , wherein the water-soluble polymer is collagen, poly(alkylene) oxide, poly(lactic acid), polyvinylacetate, polyvinylalcohol, polylactone, polyacrylate, latex, polyester, polyvinylacetate/polyvinylalcohol graft polymer, periodic chart elements of group I or II (alkali metal or alkaline earth metal) silicate polymer, or mixtures thereof.  
   
   
       23 . The method of  claim 19 , wherein the particulate polymer has a particle size of from about 3 mesh to about 70 mesh.  
   
   
       24 . The method of  claim 22 , wherein the poly(alkylene) oxide is poly(ethylene) oxide, poly(propylene) oxide, poly (ethylene oxide)-poly (propylene oxide) block copolymers, or mixtures thereof.  
   
   
       25 . The method of  claim 19 , wherein the particulate polymer is comprised of varying densities greater or less than the density of the carrier fluid.  
   
   
       26 . The method of  claim 19 , wherein the particulate polymer is present in the carrier liquid in an amount from about 0.001 pounds per gallon to about 10 pounds per gallon of the carrier liquid.  
   
   
       27 . The method of  claim 19 , wherein the carrier liquid is water, brine, aqueous acid solutions, or gelled acid solutions.