Well drilling methods with event detection

1. A well drilling method, comprising:

assigning a value to a behavior of each of multiple drilling parameters during a drilling operation, wherein the drilling parameters are derived at least in part from whether at least one precursor event has occurred;

forming multiple parameter signatures, each of the parameter signatures comprising a respective combination of the values;

comparing the parameter signatures to multiple event signatures, each of the event signatures being indicative of a respective drilling event; and

controlling the drilling operation in response to a partial match resulting from comparing the parameter signatures to the event signatures.

2. The method of claim 1 , further comprising drilling a wellbore, and wherein the drilling operation is performed in furtherance of drilling the wellbore.

3. The method of claim 1 , further comprising alerting an operator in response to the partial match resulting from comparing the parameter signatures to the event signatures.

4. The method of claim 1 , wherein at least one of the behaviors comprises an increasing trend.

5. The method of claim 1 , wherein at least one of the behaviors comprises a trend increasing at greater than a predetermined rate.

6. The method of claim 1 , wherein at least one of the behaviors comprises a decreasing trend.

7. The method of claim 1 , wherein at least one of the behaviors comprises a trend decreasing at greater than a predetermined rate.

8. The method of claim 1 , wherein controlling the drilling operation further comprises controlling flow through a drilling fluid return line.

9. The method of claim 1 , wherein controlling the drilling operation further comprises controlling flow through a drilling fluid injection line.

10. The method of claim 1 , wherein the drilling parameters are derived at least in part from drilling properties sensed by sensors during the drilling operation.

11. The method of claim 1 , wherein the drilling parameters are derived at least in part from offset well data.

12. The method of claim 1 , wherein the drilling parameters are derived at least in part from operator input.

13. The method of claim 1 , wherein the drilling parameters are derived at least in part from whether multiple precursor events have occurred.

14. The method of claim 1 , further comprising, in response to the partial match resulting from comparing the parameter signatures to the event signatures, indicating that an event will occur.

15. A well system, comprising:

a control system including machine-readable code and a processor which a) assigns a value to a behavior of each of multiple drilling parameters during the drilling operation, b) forms multiple parameter signatures, each of the parameter signatures comprising a respective combination of the values, and c) compares the parameter signatures to multiple event signatures, each of the event signatures being indicative of a respective drilling event, wherein the drilling parameters are derived at least in part from whether at least one precursor event has occurred; and

a controller which controls the drilling operation in response to a partial match resulting from comparing the parameter signatures to the event signatures.

16. The system of claim 15 , wherein the drilling operation comprises drilling the wellbore.

17. The system of claim 15 , wherein the control system alerts an operator in response to the partial match resulting from comparing the parameter signatures to the event signatures.

18. The system of claim 15 , wherein at least one of the behaviors comprises an increasing trend.

19. The system of claim 15 , wherein at least one of the behaviors comprises a trend increasing at greater than a predetermined rate.

20. The system of claim 15 , wherein at least one of the behaviors comprises a decreasing trend.

21. The system of claim 15 , wherein at least one of the behaviors comprises a trend decreasing at greater than a predetermined rate.

22. The system of claim 15 , wherein the controller controls the drilling operation at least in part by controlling flow through a drilling fluid return line.

23. The system of claim 15 , wherein the controller controls the drilling operation at least in part by controlling flow through a drilling fluid injection line.

24. The system of claim 15 , wherein the drilling parameters are derived at least in part from drilling properties sensed by sensors during the drilling operation.

25. The system of claim 15 , wherein the drilling parameters are derived at least in part from offset well data.

26. The system of claim 15 , wherein the drilling parameters are derived at least in part from operator input.

27. The system of claim 15 , wherein the drilling parameters are derived at least in part from whether multiple precursor events have occurred.

28. The system of claim 15 , wherein the control system, in response to the partial match resulting from comparing the parameter signatures to the event signatures, indicates that an event will occur.

29. A well drilling method, comprising:

defining an event signature comprising a unique combination of a behavior of each of multiple drilling parameters, the event signature being indicative of a drilling event;

accessing data from each of multiple sensors which sense respective drilling properties during a drilling operation;

determining multiple parameter signature segments from the respective drilling properties;

combining the parameter signature segments, thereby forming a parameter signature;

comparing the parameter signature to the event signature;

controlling the drilling operation in response to a partial match resulting from comparing the parameter signature to the event signature; and

indicating a probability of the event when the parameter signature partially matches the event signature.

30. The method of claim 29 , further comprising indicating the event when the parameter signature partially matches the event signature.

31. The method of claim 30 , wherein indicating the event further comprises indicating that a future event will occur.

32. The method of claim 29 , wherein determining the multiple signature segments further comprises determining a trend of at least one of the drilling parameters.

33. The method of claim 29 , wherein determining the multiple signature segments further comprises determining a ratio of selected ones of the drilling parameters.

34. The method of claim 29 , wherein determining the multiple signature segments further comprises determining a difference between selected ones of the drilling parameters.

35. The method of claim 29 , wherein determining the multiple signature segments further comprises determining whether at least one of the drilling parameters is within a predetermined range.

36. The method of claim 29 , wherein determining the multiple signature segments further comprises determining whether at least one of the drilling parameters is greater than a predetermined value.

37. The method of claim 29 , wherein determining the multiple signature segments further comprises determining whether at least one of the drilling parameters is less than a predetermined value.

38. The method of claim 29 , wherein the event comprises an undesired abnormal event.

39. The method of claim 29 , wherein controlling the drilling operation further comprises controlling flow through a drilling fluid return line.

40. The method of claim 29 , wherein controlling the drilling operation further comprises controlling flow through a drilling fluid injection line.

41. The method of claim 29 , wherein controlling the drilling operation further comprises controlling flow from a drilling fluid injection line to a drilling fluid return line.

42. The method of claim 29 , wherein accessing data further comprises inputting offset well data indicative of respective drilling properties.

43. The method of claim 29 , wherein accessing data further comprises inputting operator experience indicative of respective drilling properties.

44. The method of claim 29 , wherein accessing data further comprises accessing whether at least one prior event has occurred.