Control system for downhole operations

1. A method of controlling a downhole operation, comprising:

deploying a work string into a wellbore, the work string comprising a deployment string and a bottomhole assembly (BHA);

generating a digital mark in a controller according to a depth of the BHA when an operational parameter reaches a threshold value; and

using the digital mark as a reference point to generate target values for operational parameters of the downhole operation.

2. The method of claim 1 ,

further comprising engaging the BHA with an object in the wellbore and detecting the engagement by monitoring whether the operational parameter reaches the threshold value,

wherein the deployment string is digitally marked in response to detection of the engagement.

3. The method of claim 1 , where the threshold value corresponds to one of an engagement of the BHA engaging with a whipstock anchored in the wellbore, an engagement of an anchor on the workstring with a casing, an engagement of a deflector on the workstring with the wellbore, an engagement of a liner hanger on the workstring with a casing, an engagement of a drill bit on the BHA with a casing, an engagement of a fishing tool on the workstring with a stuck portion in the wellbore, and an engagement of a drill bit or mill bit on the BHA with a bridge plug or a packer in the wellbore.

4. The method of claim 1 , wherein the threshold value corresponds to an engagement of the BHA with an stationary object in the wellbore.

5. A method of controlling a downhole operation, comprising:

deploying a work string into a wellbore, the work string comprising a deployment string and a bottomhole assembly (BHA);

engaging the BHA with an object in the wellbore and detecting the engagement;

in response to detection of the engagement, generating a digital mark in a controller according to a depth of the BHA; and

using the digital mark to perform the downhole operation comprising:

correlating a first set of minimum and maximum first target values to the digital mark; and

while performing the downhole operation:

monitoring a first operational parameter of the downhole operation; and

comparing the first monitored parameter to the first set of the first target values.

6. The method of claim 5 , wherein:

the first set of the first target values is correlated to a first event or region of the downhole operation, and

the method further comprises:

correlating a second set of minimum and maximum first target values to a second event or region of the downhole operation; and

comparing the first monitored parameter to the second set of the first target values while performing the downhole operation.

7. The method of claim 5 , further comprising:

correlating a first set of minimum and maximum second target values to the digital mark; and

while performing the downhole operation:

monitoring a second operational parameter of the downhole operation; and

comparing the second monitored parameter to the first set of the second target values.

8. The method of claim 7 , wherein:

the first sets of the target values are correlated to a first event or region of the downhole operation, and

the method further comprises:

correlating second sets of minimum and maximum first and second target values to a second event or region of the downhole operation; and

comparing the first and second monitored parameters to the second sets of the respective target values while performing the downhole operation.

9. The method of claim 7 , further comprising controlling the second operational parameter by adjusting the first operational parameter while performing the downhole operation.

10. The method of claim 7 , further comprising, while performing the downhole operation:

displaying the target values as windows on respective graphs; and

plotting the operational parameters on respective graphs.

11. The method of claim 10 , further comprising displaying an animation of the downhole operation while performing the downhole operation.

12. The method of claim 7 , further comprising:

correlating a set of minimum and maximum third target values to the digital mark; and

while performing the downhole operation:

monitoring a third operational parameter of the downhole operation; and

comparing the third monitored parameter to the set of the third target values,

wherein:

the first operational parameter is rate of penetration,

the second operational parameter is rotational speed of the BHA; and

the third operational parameter is weight exerted on a bit of the BHA.

13. A method of performing a downhole operation in a wellbore, comprising:

monitoring operational parameters associated with the downhole operation performed by a workstring;

detecting an engagement of the workstring with an object in the wellbore according to one or more monitored operational parameters;

marking a reference point in a monitoring system when engagement of the workstring with the object is detected;

in response to marking the reference point, using the monitoring system to provide target values for selected operational parameters for execution of the downhole operation; and

controlling the execution of the downhole operation according to the target values.

14. The method of claim 13 , wherein controlling the execution of the downhole operation is automated.

15. The method of claim 13 , wherein controlling the execution of the downhole operation is manual.

16. The method of claim 13 , further comprising:

using the monitoring system to provide a forecast for a change in one or more target value based upon continuing monitoring of the operational parameters.

17. The method of claim 16 , wherein the forecast is generated by:

monitoring progress of the downhole operation; and

correlating one or more preprogrammed future target values with the progress of the downhole operation.

18. The method of claim 16 , wherein the forecast is generated by:

monitoring progress of the downhole operation; and

correlating one or more preprogrammed future target values with the actual values of the parameters being monitored.

19. The method of claim 13 , wherein providing target values is based upon a set of pre-programmed instructions or values.

20. The method of claim 13 , wherein the parameters include at least one of weight-on-bit, rate-of-penetration, and rotational velocity, and depth.

21. The method of claim 13 , wherein the downhole operation is at least one of drilling, milling, fishing, and operating a downhole tool.

22. The method of claim 13 , wherein marking the reference point in the monitoring system corresponds to a depth reference.

23. The method of claim 13 , wherein a comparison between the target values and the actual monitored values provides an indication of the quality of the execution.

24. The method of claim 13 , wherein at least one of the target values comprises an acceptable range of values.

25. The method of claim 13 , wherein marking the reference point in the monitoring system corresponds to a time reference.

26. The method of claim 13 , where the engagement is one of a bottomhole assembly on the workstring engaging with a whipstock anchored in the wellbore, an anchor on the workstring engaging with a casing, a deflector on the workstring engaging with the wellbore, a liner hanger on the workstring engaging with a casing, a drill bit on a bottomhole assembly on the workstring engaging with a casing, a fishing tool on the workstring engaging with a stuck portion in the wellbore, and a drill bit or mill bit on a bottom hole assembly on the workstring engaging with a bridge plug or a packer in the wellbore.

27. The method of claim 13 , wherein the object is a stationary object to the wellbore.