Estimating drilling fluid properties and the uncertainties thereof
During drilling operations various drilling mud properties may be measured and predicted. Uncertainties in the measured or predicted values may also be calculated. The estimated uncertainties may then be used to optimize mud sampling interval and/or control a mud mixer. A decision making algorithm may be performed to optimize a surface mud sampling interval such that the uncertainties are maintained within a bounded region with minimal number of sampling times.
1. A method comprising:
circulating a drilling mud through a mud circulation system;
determining a model of drilling mud property dynamics;
measuring a first value for a drilling mud property at a first time;
calculating an uncertainty of the first value at a second time; and
measuring a second value for the drilling mud property once the uncertainty of the first value is greater than an uncertainty limit.
2. The method of claim 1 further comprising: changing the drilling mud property based on the uncertainty.
3. The method of claim 1 further comprising: estimating changes in drilling parameters and conditions, thereby providing estimated drilling parameters and conditions; and changing the drilling mud property based on the uncertainty of the value and the estimated drilling parameters and conditions.
4. The method of claim 2 , wherein changing the drilling mud property involves regulating a feed rate of a chemical into the drilling mud.
5. The method of claim 2 , wherein changing the drilling mud property involves regulating a feed rate of water into the drilling mud.
6. The method of claim 2 , wherein changing the drilling mud property involves regulating a disposal rate of the drilling mud.
7. The method of claim 3 , wherein the drilling parameters and conditions includes at least one of: lithology of a subterranean formation drilling through, trajectory of a drill bit, drilling mud flow rate, drilling mud weight, drilling mud temperature, or drilling mud viscosity.
8. The method of claim 1 , wherein the drilling mud property is mud weight.
9. The method of claim 1 , wherein the drilling mud property is temperature.
10. The method of claim 1 , wherein the drilling mud property is viscosity.
11. A mud circulation system comprising:
a drill string within a wellbore penetrating a subterranean formation;
a pump configured to convey drilling mud through the drill string and the wellbore;
a sensor coupled to the system to measure a drilling condition;
a non-transitory computer-readable medium coupled to the drill string, the pump, or both and encoded with instructions that, when executed, cause the system to perform a method comprising:
circulating a drilling mud through the mud circulation system;
determining a model of drilling mud property dynamics;
measuring a first value for a drilling mud property at a first time;
calculating an uncertainty of the first value at a second time; and
measuring a second value for the drilling mud property once the uncertainty of the first value is greater than an uncertainty limit.
12. The mud circulation system of claim 11 , wherein the method further comprises: changing the drilling mud property based on the uncertainty.
13. The mud circulation system of claim 11 , wherein the method further comprises: estimating changes in drilling parameters and conditions, thereby providing estimated drilling parameters and conditions; and changing the drilling mud property based on the uncertainty of the value and the estimated drilling parameters and conditions.
14. The mud circulation system of claim 12 , wherein changing the drilling mud property involves regulating a feed rate of a chemical into the drilling mud.
15. The mud circulation system of claim 12 , wherein changing the drilling mud property involves regulating a feed rate of water into the drilling mud.
16. The mud circulation system of claim 12 , wherein changing the drilling mud property involves regulating a disposal rate of the drilling mud.
17. The mud circulation system of claim 13 , wherein the drilling parameters and conditions includes at least one of: lithology of a subterranean formation drilling through, trajectory of a drill bit, drilling mud flow rate, drilling mud weight, drilling mud temperature, or drilling mud viscosity.
18. The mud circulation system of claim 11 , wherein the drilling mud property is selected from the group consisting of: mud weight, mud temperature, and mud viscosity.
19. A non-transitory computer-readable medium encoded with instructions that, when executed, cause a mud circulation system to perform a method comprising:
circulating a drilling mud through the mud circulation system;
determining a model of drilling mud property dynamics;
measuring a first value for a drilling mud property at a first time;
calculating an uncertainty of the first value at a second time; and
measuring a second value for the drilling mud property once the uncertainty of the first value is greater than an uncertainty limit.
20. The non-transitory computer-readable medium of claim 19 , wherein the method further comprises: estimating changes in drilling parameters and conditions, thereby providing estimated drilling parameters and conditions; and changing the drilling mud property based on the uncertainty of the value and the estimated drilling parameters and conditions.