Using the specific heat capacity of a drilling fluid to determine other properties thereof

Abstract

A method of monitoring and controlling one or more properties of a drilling fluid used in drilling a well is provided. The method comprises circulating the drilling fluid through the wellbore, measuring the specific heat capacity of the drilling fluid, and determining the value of an additional property of the drilling fluid based at least in part on the measured specific heat capacity of the drilling fluid. For example, the additional property of the drilling fluid can be the oil-to-water ratio of the drilling fluid. As another example, the additional property of the drilling fluid can be average specific gravity of the solids in the drilling fluid.

What is claimed is: 
     
         1 . A method of monitoring and controlling one or more properties of a drilling fluid used in drilling a well, comprising:
 circulating the drilling fluid through a wellbore;   after circulating the drilling fluid through the wellbore, measuring the specific heat capacity of the drilling fluid; and   determining the value of an additional property of the drilling fluid based at least in part on the measured specific heat capacity of the drilling fluid.   
     
     
         2 . The method of  claim 1 , wherein said drilling fluid is circulated through the wellbore and a fluid processing unit. 
     
     
         3 . The method of  claim 2 , wherein said fluid processing unit is located on a surface adjacent to said wellbore. 
     
     
         4 . The method of  claim 3 , wherein said drilling fluid is circulated through the wellbore, said fluid processing unit and a mud retention pit that is also located on the surface adjacent to said wellbore, and wherein said fluid processing unit is located upstream of said mud retention pit. 
     
     
         5 . The method of  claim 3 , wherein said drilling fluid is circulated through the wellbore, said fluid processing unit and a mud retention pit also located on the surface adjacent to the wellbore, and wherein said fluid processing unit is located in said mud retention pit. 
     
     
         6 . The method of  claim 3 , wherein said drilling fluid is circulated through the wellbore, said fluid processing unit, a mud retention pit also located on the surface adjacent to the wellbore, and a mixer also located on the surface adjacent to said wellbore and located downstream of said mud retention pit, and wherein said fluid processing unit is located downstream of said mixer. 
     
     
         7 . The method of  claim 1 , wherein the specific heat capacity of the drilling fluid is measured at two or more fluid pressures, and wherein said additional property of the drilling fluid is determined based at least in part on said measured specific heat capacity at each fluid pressure. 
     
     
         8 . The method of  claim 1 , wherein the specific heat capacity of the drilling fluid is measured at a temperature that is above or below ambient temperature. 
     
     
         9 . The method of  claim 1 , further comprising providing a representation including multiple potential values of said additional property of the drilling fluid, each potential value corresponding to a predetermined specific heat capacity of the drilling fluid, and wherein said additional property of the drilling fluid is determined by comparing said measured specific heat capacity of the drilling fluid to the predetermined specific heat capacities of said representation and selecting the potential value of the additional property that corresponds to the predetermined specific heat capacity that most closely matches said measured specific heat capacity of the drilling fluid. 
     
     
         10 . The method of  claim 1 , wherein said value of the additional property of the drilling fluid that is determined is the oil-to-water ratio of the drilling fluid. 
     
     
         11 . The method of  claim 1 , wherein said value of the additional property of the drilling fluid that is determined is the average specific gravity of solids in the drilling fluid. 
     
     
         12 . The method of  claim 1 , wherein the value of a first additional property of the drilling fluid and the value of a second additional property of the drilling fluid are determined based at least in part on the measured specific heat capacity of the drilling fluid. 
     
     
         13 . The method of  claim 12 , further comprising providing a separate representation for each of said first and second additional properties, each representation including multiple potential values of the corresponding additional property of the drilling fluid, each potential value corresponding to a predetermined specific heat capacity of said additional property of the drilling fluid, and wherein each of said first and second additional properties of the drilling fluid are determined by comparing said measured specific heat capacity of the drilling fluid to the predetermined specific heat capacities of the corresponding representation and selecting the potential value of the additional property that corresponds to the predetermined specific heat capacity that most closely matches the measured specific heat capacity of the drilling fluid. 
     
     
         14 . The method of  claim 13 , wherein said first additional property of the drilling fluid is the oil-to-water ratio of the drilling fluid, and the second additional property of the drilling fluid is the average specific gravity of solids in the drilling fluid. 
     
     
         15 . The method of  claim 1 , further comprising adjusting at least one property of the drilling fluid in response to said determined additional property of the drilling fluid. 
     
     
         16 . The method of  claim 15 , further comprising adjusting one or more of the oil-to-water ratio of the drilling fluid, the composition of the drilling fluid, the solids content of the drilling fluid, and the average specific gravity of solids in the drilling fluid in response to said determined additional property of the drilling fluid. 
     
     
         17 . The method of  claim 14 , further comprising adjusting at least one property of the drilling fluid in response to the determined oil-to-water ratio of the drilling fluid and the determined average specific gravity of the solids in the drilling fluid. 
     
     
         18 . The method of  claim 2 , wherein said fluid processing unit comprises:
 a specific heat capacity sensor; and   a computer associated with said specific heat capacity sensor.   
     
     
         19 . A method of monitoring and controlling the oil-to-water ratio of a drilling fluid used in drilling a well, comprising:
 circulating the drilling fluid through a wellbore;   after circulating the drilling fluid through the wellbore, measuring the specific heat capacity of the drilling fluid;   providing a representation including multiple potential values of the oil-to-water ratio of the drilling fluid, each potential value corresponding to a predetermined specific heat capacity of the drilling fluid;   determining the oil-to-water ratio of the drilling fluid based at least in part on the measured specific heat capacity of the drilling fluid by comparing said measured specific heat capacity of the drilling fluid to the predetermined specific heat capacities of said representation and selecting the oil-to-water ratio that corresponds to the predetermined specific heat capacity that most closely matches said measured specific heat capacity of the drilling fluid; and   adjusting at least one property of the drilling fluid in response to the determined additional property of the drilling fluid.   
     
     
         20 . A method of monitoring and controlling the average specific gravity of the solids in a drilling fluid used in drilling a well, comprising:
 circulating the drilling fluid through a wellbore;   after circulating the drilling fluid through the wellbore, measuring the specific heat capacity of the drilling fluid;   providing a representation including multiple potential values of the of the drilling fluid, each potential value corresponding to a predetermined specific heat capacity of the drilling fluid;   determining the average specific gravity of solids in the drilling fluid based at least in part on the measured specific heat capacity of the drilling fluid by comparing said measured specific heat capacity of the drilling fluid to the predetermined specific heat capacities of said representation and selecting the oil-to-water ratio that corresponds to the predetermined specific heat capacity that most closely matches said measured specific heat capacity of the drilling fluid; and   adjusting at least one property of the drilling fluid in response to the determined additional property of the drilling fluid.   
     
     
         21 . The method of  claim 20 , wherein the drilling fluid is circulated through the wellbore using pumping equipment.