Methods of treating a lower-quality water for use as some of the water in the forming and delivering of a treatment fluid into a wellbore

Abstract

The inventions are for methods of forming and delivering a treatment fluid into a wellbore. In one aspect, methods are provided of treating a base aqueous solution to obtain a first aqueous solution, for example, to have a substantially reduced concentration of at least one component relative to the concentration of the component in the base aqueous solution, and using the first aqueous solution and a lower-quality water, such as the base aqueous solution, to form a treatment fluid. The first aqueous solution and the lower-quality water are merged after pumping the fluid portions toward the wellbore. The component is selected for being deleterious to the use or performance of a treatment fluid. More particularly, the component is selected from the group consisting of: a dissolved ion, oil, grease, a production chemical, and suspended, water-insoluble solids. This allows the use of lower-quality water for some of the water required for making up the treatment fluid.

1 . A method of forming and delivering a treatment fluid into a wellbore, the method comprising the steps of:
 (a) treating a base aqueous solution to obtain the first aqueous solution having a substantially reduced concentration of at least one component relative to the concentration of the at least one component in the base aqueous solution, wherein the component is selected from the group consisting of: a dissolved ion, oil, grease, a production chemical, and suspended solids;   (b) pumping a first fluid comprising the first aqueous solution;   (c) pumping a second fluid comprising a second aqueous solution;   (d) merging at least the first and second fluids to form a treatment fluid comprising a merged aqueous solution, wherein the merged aqueous solution comprises at least 25% by weight of the first aqueous solution and at least 25% by weight of the second aqueous solution, and wherein the merged aqueous solution has a merged viscosity of less than 100 cP at 40 l/s and at 25° C. (77° F.); and   (e) directing the treatment fluid into the wellbore;   wherein:
 (i) the merged aqueous solution has a merged concentration of the at least one component; 
 (ii) the first aqueous solution has a concentration of the at least one component that is substantially lower than the merged concentration of the at least one component; and 
 (iii) the second aqueous solution has a concentration of the at least one component that is substantially higher than the merged concentration of the at least one component. 
   
   
   
       2 . The method according to  claim 1 , wherein the merged aqueous solution has a merged viscosity of less than 35 cP. 
   
   
       3 . The method according to  claim 1 , wherein the component is at least one dissolved ion. 
   
   
       4 . The method according to  claim 3 , wherein the step of treating comprises selectively exchanging the at least one dissolved ion for another ion having a different valence. 
   
   
       5 . The method according to  claim 3 , wherein the at least one ion is selected from the group consisting of calcium, magnesium, sulfate, iron, and borate. 
   
   
       6 . The method according to  claim 5 , wherein the second aqueous solution has a substantial concentration of sulfate ions of equal to or greater than 500 ppm; a substantial concentration of calcium or magnesium ions of equal to or greater than a combined total of 1,000 ppm; a substantial concentration of iron ions of equal to or greater than 10 ppm; or a substantial concentration of borate ions of equal to or greater than 5 ppm. 
   
   
       7 . The method according to  claim 1 , further comprising a step of forming the first fluid comprising:
 (i) an unhydrated hydratable additive; and   (ii) the first aqueous solution.   
   
   
       8 . The method according to  claim 7 , further comprising a step of allowing the hydratable additive in the first fluid to reach at least 50% hydration prior to the step of pumping the first fluid. 
   
   
       9 . The method according to  claim 1 , wherein:
 (i) the treatment fluid comprises a merged concentration of a particulate;   (ii) the first fluid comprises a first concentration of the particulate that is substantially higher than the merged concentration of the particulate;   (iii) the second fluid comprises a second concentration of the particulate that is substantially lower than the merged concentration of the particulate; and   (iv) the first fluid is pumped at a substantially lower average bulk fluid velocity than the second fluid.   
   
   
       10 . The method according to  claim 1 , wherein:
 (i) the treatment fluid comprises a merged concentration of a particulate and a merged concentration of the hydratable additive;   (ii) the first fluid comprises a first concentration of the particulate that is substantially higher than the merged concentration of the particulate and a first concentration of the additive that is substantially higher than the merged concentration of the additive; and   (iii) the second fluid comprises a second concentration of the particulate that is substantially lower than the merged concentration of the particulate and a second concentration of the additive that is substantially lower than the merged concentration of the additive.   
   
   
       11 . A method of forming and delivering a treatment fluid into a wellbore, the method comprising the steps of:
 (a) treating a base aqueous solution to obtain the first aqueous solution having a substantially reduced concentration of total dissolved solids relative to the concentration of the total dissolved solids in the base aqueous solution;   (b) pumping a first fluid comprising the first aqueous solution;   (c) pumping a second fluid comprising a second aqueous solution;   (d) merging at least the first and second fluids to form a treatment fluid having a merged aqueous solution, wherein the merged aqueous solution comprises at least 25% by weight of the first aqueous solution and at least 25% by weight of the second aqueous solution, and wherein the merged aqueous solution has a merged viscosity of less than 100 cP at 40 l/s and at 25° C. (77° F.); and   (e) directing the treatment fluid into a wellbore;   wherein:
 (i) the merged aqueous solution has a merged concentration of total dissolved solids; 
 (ii) the first aqueous solution has a concentration of total dissolved solids that is substantially lower than the merged concentration of total dissolved solids; and 
 (iii) the second aqueous solution has a concentration of total dissolved solids that is substantially higher than the merged concentration of total dissolved solids. 
   
   
   
       12 . The method according to  claim 11 , wherein the merged aqueous solution has a merged viscosity of less than 35 cP. 
   
   
       13 . The method according to  claim 11 , wherein the base aqueous solution is selected for having a concentration of total dissolved solids of greater than 40,000 ppm. 
   
   
       14 . The method according to  claim 13 , wherein the first aqueous solution is treated at least sufficiently to have a concentration of total dissolved solids of less than 30,000 ppm. 
   
   
       15 . The method according to  claim 14 , wherein the second aqueous solution is selected for having a concentration of total dissolved solids of greater than 40,000 ppm. 
   
   
       16 . The method according to  claim 11 , wherein the base aqueous solution is selected to be the same as the second aqueous solution. 
   
   
       17 . The method according to  claim 11 , wherein the first fluid is comprised of at least 50% by weight of the first aqueous solution and wherein the second fluid is comprised of at least 50% by weight of the second aqueous solution. 
   
   
       18 . The method according to  claim 11 , wherein the first fluid comprises a first concentration of a hydratable additive and the second fluid has a second concentration of the hydratable additive that is substantially lower than the first concentration of the hydratable additive. 
   
   
       19 . The method according to  claim 11 , further comprising a step of forming the first fluid comprising:
 (i) an unhydrated hydratable additive; and   (ii) the first aqueous solution.   
   
   
       20 . The method according to  claim 19 , further comprising a step of allowing the hydratable additive in the first fluid to reach at least 50% hydration prior to the step of pumping the first fluid.