CONTINUOUS GEOMECHANICALLY STABLE WELLBORE TRAJECTORIES

• US 20100243328A1
• Filed: 03/27/2009
• Published: 09/30/2010
• Est. Priority Date: 03/27/2009
• Status: Active Grant

• Current Assignee: Adrian Enrique Rodriquez Herrera, Schlumberger Technology Corporation (Schlumberger NV)
• Original Assignee: Adrian Enrique Rodriguez Herrera, Schlumberger Technology Corporation (Schlumberger NV)
• Inventors: Rodriguez Herrera, Adrian Enrique
• Granted Patent: US 8,301,382 B2
• Time in Patent Office: Days
• US Class Current: 175/61
• CPC Class Codes: E21B 44/00 Automatic control systems specially adapted for drilling operations, i.e. self-operating systems which function to carry out or modify a drilling operation without intervention of a human operator, e.g. computer-controlled drilling systems; Systems specially adapted for monitoring a plurality of drilling variables or conditions
• CPC Class Codes: E21B 7/04 Directional drilling

Abstract

A continuous geomechanically stable trajectory in a subterranean formation is found by calculating at least one reachable stable position relative to a starting position based on geological data indicative of characteristics of the subterranean formation, and iteratively utilizing the calculated reachable stable position as a new starting position. The calculation may be constrained by a boundary including selected distance and direction relative to the starting position, and selected rate of angle change. Within the constraints of the boundary, the possible new trajectories considered may be discretized. The result of the calculations is a three dimensional tree which defines a stability volume. Pruning of at least some branches of the tree may be employed so that not all stable positions have the preselected number of branches, thereby helping to elongate the tree. Either or both of the tree and stability volume are used to select at least one trajectory. For example, the trajectory may be selected from sets of interconnected stable wellbore positions, or based on some other criteria constrained by the stability volume. The trajectory is then used as the basis for drilling a borehole.

Claims

1. A method for calculation of a continuous geomechanically stable trajectory in a subterranean formation comprising the steps of:

iteratively calculating at least one reachable stable position relative to a starting position by employing geological data indicative of characteristics of the subterranean formation and utilizing the calculated reachable stable position as a new starting position; and

outputting results of the iterative calculations in tangible form.

2. The method of claim 1 including constraining calculating the at least one reachable stable position within a boundary.

3. The method of claim 2 including defining the boundary by selected distance and direction relative to the starting position.

4. The method of claim 3 including defining the boundary by selected rate of angle change.

5. The method of claim 2 including discretizing possible new trajectories within the boundary.

6. The method of claim 1 wherein the calculated stable positions define a tree, and including limiting branching at each stable position to a preselected number.

7. The method of claim 6 including pruning at least some branches of the tree so that not all stable positions have the preselected number of branches.

8. The method of claim 1 including selecting at least one trajectory.

9. The method of claim 8 including selecting the trajectory from sets of interconnected stable wellbore positions.

10. The method of claim 6 including employing the tree to define a stability volume.

11. The method of claim 10 including selecting at least one trajectory within the stability volume.

12. A computer program product, comprising a computer usable medium having a computer readable program code embodied therein, said computer readable program code adapted to be executed to implement a method comprising:

iteratively calculating at least one reachable stable position relative to a starting position by employing geological data indicative of characteristics of the subterranean formation and utilizing the calculated reachable stable position as a new starting position; and

outputting results of the iterative calculations in tangible form.

13. The computer program product of claim 12 including constraining calculating the at least one reachable stable position within a boundary.

14. The computer program product of claim 13 including defining the boundary by selected distance and direction relative to the starting position.

15. The computer program product of claim 14 including defining the boundary by selected rate of angle change.

16. The computer program product of claim 13 including discretizing possible new trajectories within the boundary.

17. The computer program product of claim 12 wherein the calculated stable positions define a tree, and including limiting branching at each stable position to a preselected number.

18. The computer program product of claim 17 including pruning at least some branches of the tree so that not all stable positions have the preselected number of branches.

19. The computer program product of claim 12 including selecting at least one trajectory.

20. The computer program product of claim 19 including selecting the trajectory from sets of interconnected stable wellbore positions.

21. The computer program product of claim 17 including employing the tree to define a stability volume.

22. The computer program product of claim 21 including selecting at least one trajectory within the stability volume.

23. Apparatus for calculation of a continuous geomechanically stable trajectory in a subterranean formation comprising:

a machine that iteratively calculates at least one reachable stable position relative to a starting position by employing geological data indicative of characteristics of the subterranean formation and utilizing the calculated reachable stable position as a new starting position; and

an interface that outputs results of the iterative calculations in tangible form.

24. The apparatus of claim 23 wherein the machine constrains the at least one reachable stable position within a boundary.

25. The apparatus of claim 24 wherein the boundary is characterized by selected distance and direction relative to the starting position.

26. The apparatus of claim 25 wherein the boundary is characterized by selected rate of angle change.

27. The apparatus of claim 24 wherein the machine discretizes possible new trajectories within the boundary.

28. The apparatus of claim 23 wherein the calculated stable positions define a tree, and wherein the machine limits branching at each stable position to a preselected number.

29. The apparatus of claim 28 wherein the machine prunes at least some branches of the tree so that not all stable positions have the preselected number of branches.

30. The apparatus of claim 23 wherein the machine selects at least one trajectory.

31. The apparatus of claim 30 wherein the machine selects the trajectory from sets of interconnected stable wellbore positions.

32. The apparatus of claim 28 wherein the machine employs the tree to define a stability volume.

33. The apparatus of claim 32 wherein the machine selects at least one trajectory within the stability volume.

34. A method of drilling a borehole in a subterranean formation comprising the steps of:

iteratively calculating at least one reachable stable position relative to a starting position by employing geological data indicative of characteristics of the subterranean formation and utilizing the calculated reachable stable position as a new starting position;

selecting at least one trajectory; and

employing a representation of the at least one selected trajectory to drill at least one borehole in the formation.