Low Portland Silica-Lime Cements

Abstract

A system for generating a cement composition comprising: a plurality of cementitious components; and a computer system configured to accept input from a user and generate concentrations of the cementitious components for the cement composition, wherein the computer system is configured to generate the concentrations of the cementitious components based on a target lime to silica correlation.

What is claimed is: 
     
         1 . A system for generating a cement composition comprising:
 a plurality of cementitious components; and   a computer system configured to accept input from a user and generate concentrations of the cementitious components for the cement composition, wherein the computer system is configured to generate the concentrations of the cementitious components based on a target lime to silica correlation.   
     
     
         2 . The system of  claim 1  wherein the computer system is further configured to improve the cement compositions by calculating a lime to silica weight ratio and adjusting a relative amount of each of the cementitious components to meet or exceed the target lime to silica correlation. 
     
     
         3 . The system of  claim 1  further comprising a database, wherein the database comprises the cementitious components, a cost corresponding to each of the cementitious components, an oxide analysis corresponding to each of the cementitious components, and dissolution data corresponding to each of the cementitious components. 
     
     
         4 . The system of  claim 1  wherein the target lime to silica correlation is defined by a user or automatically selected by the computer system. 
     
     
         5 . The system of  claim 1  wherein the cementitious components comprise Portland cement and a silica source, and wherein the Portland cement is present in an amount of 50 wt. % or less in the virtual cement design, and wherein the silica source comprises at least one silica source selected from a group consisting of fly ash, slag, calcined clay, silica fume, crystalline silica, silica flour, cement kiln dust, zeolite, agricultural waste ash, natural pozzolans, and combinations thereof. 
     
     
         6 . The system of  claim 1  wherein the cement composition generated by the system is a virtual cement design. 
     
     
         7 . The system of  claim 1  further comprising an analytical instrument configured to perform an oxide analysis of the cementitious components. 
     
     
         8 . The system of  claim 7  wherein the computer system is further configured to calculate a lime to silica weight ratio from the oxide analysis. 
     
     
         9 . The system of  claim 8  wherein the computer system is further configured to adjust a concentration of at least one of the cementitious components such that the lime to silica weight ratio meets or exceeds a target lime to silica weight ratio. 
     
     
         10 . The system of  claim 9  wherein the input from the user comprises the target lime to silica weight ratio. 
     
     
         11 . The system of  claim 1  wherein the cement composition comprises a Portland cement in an amount of from about 10% to about 50% by weight of the cementitious components. 
     
     
         12 . The system of  claim 1  wherein the cement composition further comprises at least one silica source selected from a group consisting of fly ash, slag, calcined clay, silica fume, crystalline silica, silica flour, cement kiln dust, zeolite, agricultural waste ash, natural pozzolans, and combinations thereof. 
     
     
         13 . The system of  claim 1  wherein the cement composition further comprises one or more additives selected from the group consisting of weighting agents, retarders, accelerators, activators, gas control additives, lightweight additives, gas-generating additives, mechanical-property-enhancing additives, lost-circulation materials, filtration-control additives, fluid-loss-control additives, defoaming agents, defoaming agents, foaming agents, transition time modifiers, dispersants, thixotropic additives, suspending agents, and combinations thereof. 
     
     
         14 . The system of  claim 1  wherein the computer system is further configured to calculate a time dependent concentration of lime and silica and selecting additional cementitious components to include in the cement composition wherein the additional cementitious components are selected based on a dissolution rate for each of the additional cementitious components. 
     
     
         15 . The system of  claim 1  further comprising mixing equipment configured to mix the cement composition. 
     
     
         16 . The system of  claim 15  further comprising a pump configured to pump the cement composition into a wellbore. 
     
     
         17 . A system for generating a cement composition comprising:
 a plurality of cementitious components;   an analytical instrument configured to perform an oxide analysis of the cementitious components;   a computer system configured to accept input from a user and generate concentrations of the cementitious components for the cement composition, wherein the computer system is configured to generate the concentrations of the cementitious components based on a target lime to silica correlation, and wherein the computer system is further configured to calculate a lime to silica weight ratio from the oxide analysis.   
     
     
         18 . The system of  claim 17  further comprising a database, wherein the database comprises the cementitious components, a cost corresponding to each of the cementitious components, an oxide analysis corresponding to each of the cementitious components, and dissolution data corresponding to each of the cementitious components. 
     
     
         19 . The system of  claim 17  wherein the target lime to silica correlation is defined by a user or automatically selected by the computer system. 
     
     
         20 . The system of  claim 17  wherein the input from the user comprises the target lime to silica weight ratio.