Aqueous solutions which flow at a controlled rate under a given shear stress are required throughout a variety of industrial applications. Such control of viscosity of water is achieved by adding to water agents such as clays, large amounts of polar organic compounds such as polyacrylates or high concentrations of salts With the appropriate additives, these aqueous solutions can suspend large amounts of solid phase and form a thermodynamically stable mixture. These aqueous solutions suspend finely divided solids and will flow slowly when exposed to shear stress Such solutions, free of solids, also flow more uniformly in situations where numerous paths providing different resistances to flow are open to the fluids.
However, each of these conventional agents has attendant disadvantages, particularly when used to recover oil from subterranean wells. The application of these agents to flow control and flocculation-deflocculation control requires careful adjustment of the concentration of an active agent in the solution and control of adsorption of the active agent onto suspended solids or the matrix of a porous media. Such control is impossible when negatively charged agents are introduced into systems containing positively-charged surfaces such as calcite. The negatively-charged agents are completely adsorbed onto the solid Further, if the solution contains divalent cations, the negatively-charged agents associate with the cations and precipitate. Where the treatment or process solution is basic (pH greater than 7.0) there is a tendency of many polymers to hydrolyze to different chemical compositions. Hydrolysis reactions, which convert amides to acids and esters to separated acid-alcohol reagents, are very damaging to the performance of polymers which are susceptible to them. Hence, a need continues to exist for new agents which are capable of suitably thickening water and aqueous solutions to produce aqueous solutions having the desirable properties as outlined below but which are free of attendant disadvantages.
USPTO Backgrounds
USPTO Backgrounds