System and method for optimizing tubular running operations using real-time measurements and modelling

1. A method for optimizing a tubular running operation in which a running string is disposed in a wellbore at a wellsite, said method comprising the steps of:

(a) obtaining measurements of a plurality of running string parameters from a plurality of sensors located at the wellsite, wherein said plurality of running string parameters includes an insertion depth of the running string, a running rate of the running string, and a load acting at the top of the running string, wherein said load acting at the top of the running string includes an axial component;

(b) performing torque-and-drag analysis in the top-down direction, by means of one or more processors, using the insertion depth, running rate, and load measurements obtained in step (a) as inputs for the torque-and-drag analysis, to calculate an estimated load on each of a plurality of user-selected components of the running string;

(c) calculating, by means of the one or more processors, a local load limit envelope for each user-selected component of the running string based on each user-selected component's current location in the wellbore;

(d) for each user-selected component of the running string, calculating, by means of the one or more processors, a surface load limit envelope based on the local load limit envelope of the component and the estimated load on the component;

(e) calculating, by means of the one or more processors, a composite surface load limit envelope as the intersection of the surface load limit envelopes of all user-selected components in the running string; and

(f) adjusting the load acting at the top of the running string so that the load acting at the top of the running string remains within the composite surface load limit envelope.

2. The method as in claim 1 wherein steps (a) to (f) in claim 1 are repeated at selected periodic intervals.

3. The method as in claim 1 wherein the method for calculating the surface load limit envelope of a given user-selected component of the running string comprises the steps of:

(a) calculating a surface load adjustment as the difference between the measured load acting at the top of the running string and the estimated load on the component; and

(b) calculating the surface load limit envelope of the component as the sum of the local load limit envelope of the component and the surface load adjustment.

4. The method as in claim 1 wherein the estimated load on a given user-selected component of the running string is assumed to be a virtual load corresponding to the direct output of the torque-and-drag analysis without correction for non-physical results.

5. The method as in claim 1 wherein the local load limit envelope for a given user-selected component of the running string comprises a locus of axial loads and torques.

6. The method as in claim 1 wherein the local load limit envelope for a given user-selected component of the running string is a pessimistic local load limit envelope calculated by the steps of:

(a) performing torque-and-drag analysis in the top-down direction for a range of inputs to obtain a range of possible loads on the component within user-specified measurement and modelling uncertainties; and

(b) calculating the pessimistic local load limit envelope as the largest load limit envelope that contains any nominal load estimate such that the entire range of possible loads is contained within a true local load limit envelope of the component.

7. The method as in claim 1 , further comprising the step of calculating a load ratio for each user-selected component of the running string as the estimated load on that component divided by the local load limit of that component in the direction of loading.

8. The method as in claim 1 wherein the torque-and-drag analysis is repeated for a range of inputs to determine a range of possible loads on each user-selected component of the running string within user-specified measurement and modelling uncertainties.

9. The method as in claim 1 , further comprising the steps of:

(a) measuring one or more of the pressure, the flow rate, and the temperature of a fluid in the wellbore; and

(b) incorporating fluid-induced loading in the estimated load on each user-selected component of the running string.

10. The method as in claim 1 further comprising one or more steps selected from the group consisting of:

(a) changing the running rate of the running string;

(b) changing the a rotation rate of the running string;

(c) adding a lubricant to the wellbore;

(d) adding centralizers to the running string; and

(e) pulling the running string out of the wellbore to perform wellbore cleaning.

11. The method as in claim 1 wherein:

(a) the running string is a rotating running string;

(b) the plurality of running string parameters includes a rotation rate of the running string; and

(c) the load acting at the top of the running string includes a torque component.

12. The method as in claim 1 wherein one or more of the measurements of running string parameters are made indirectly.

13. A method for optimizing a tubular running operation in which a running string is disposed in a wellbore at a wellsite, said method comprising the steps of:

(a) performing torque-and-drag analysis in the bottom-up direction to calculate, by means of one or more processors, an estimated running string load distribution, including a predicted load acting at the top of the running string, at a user-specified future running string insertion depth;

(b) calculating, by means of the one or more processors, a local load limit envelope for each of a plurality of user-selected components of the running string based on each user-selected component's future location in the wellbore for the userspecified future running string insertion depth;

(c) for each user-selected component of the running string, calculating, by means of the one or more processors, a surface load limit envelope based on the local load limit envelope of the component and the estimated load on the component as indicated by the estimated running string load distribution;

(d) calculating, by means of the one or more processors, a composite surface load limit envelope as the intersection of the surface load limit envelopes of all user-selected components in the running string; and

(e) adjusting the predicted load acting at the top of the running string so that the predicted load acting at the top of the running string remains within the composite surface load limit envelope.

14. The method as in claim 13 wherein steps (a) to (e) in claim 13 are repeated at selected periodic intervals.

15. The method as in claim 13 wherein the method for calculating the surface load limit envelope of a given component of the running string comprises the steps of:

(a) calculating a surface load adjustment as the difference between the predicted load acting at the top of the running string and the estimated load on the component; and

(b) calculating the surface load limit envelope of the component as the sum of the local load limit envelope of the component and the surface load adjustment.

16. The method as in claim 13 wherein the local load limit envelope of each user-selected component of the running string comprises a locus of axial loads and torques.

17. The method as in claim 13 wherein the torque-and-drag analysis is repeated for a range of inputs to determine a range of possible loads on each user-selected component of the running string within user-specified modelling uncertainties.

18. The method as in claim 13 wherein the axial load and torque at the bottom of the running string are assumed to be zero in the torque-and-drag analysis.

19. The method as in claim 13 wherein either a non-zero axial load or a non-zero torque is assumed at the bottom of the running string in the torque-and-drag analysis.

20. The method as in claim 13 wherein the predicted load acting at the top of the running string is adjusted by taking one or more steps selected from the group consisting of:

(a) changing a running rate of the running string;

(b) changing a rotation rate of the running string;

(c) adding a lubricant to the wellbore;

(d) adding centralizers to the running string; and

(e) pulling the running string out of the wellbore to perform wellbore cleaning.