Estimation of optimum tripping schedules

Patent metadata

Field	Value
Publication number	US-10794134-B2
Application number	US-201615228220-A
Country	US
Kind code	B2
Filing date	Aug 4, 2016
Priority date	Aug 4, 2016
Publication date	Oct 6, 2020
Grant date	Oct 6, 2020

Abstract

An embodiment of a method for evaluating a schedule for removing a core sample includes generating a model of the core by applying a value of each of the input parameters, one or more of the input parameter values associated with an uncertainty range, and defining a proposed tripping schedule, and performing an evaluation including applying the proposed tripping schedule and a set of expected input parameter values to the model, estimating a core parameter and determining whether the tripping schedule is predicted to be successful by comparing the core parameter to selected core damage criteria. The method also includes iteratively repeating the evaluation, each evaluation being performed using a different combination of input parameter values than any other evaluation, and calculating a probability of success (POS) of the proposed tripping schedule based on a number of evaluations that result in the tripping schedule being predicted to be successful.

First claim

The invention claimed is:

1. A method for evaluating a schedule for removing a core sample from a borehole, the method comprising:
taking the core sample within the borehole with a sampling tool;
generating a model of the core sample based on a plurality of input parameters, the generating including applying a value of each of the input parameters, wherein one or more of the input parameter values is associated with an uncertainty range;
defining a proposed tripping schedule, and performing, by a processor, an evaluation of the proposed tripping schedule, the evaluation including applying the proposed tripping schedule and a set of expected input parameter values to the model, estimating a core parameter and determining whether the tripping schedule is predicted to be successful by comparing the core parameter to selected core damage criteria;
iteratively repeating the evaluation by applying the proposed tripping schedule and a different set of input parameter values to the model, estimating the core parameter and determining whether the tripping schedule is predicted to be successful by comparing the core parameter to the selected core damage criteria, the different set of input parameter values including a value of at least one parameter that is different than a previous value of the at least one parameter in a previous evaluation, the value of the at least one parameter and the previous value of the at least one parameter selected from a range of parameter values within an uncertainty associated with the at least one parameter, each evaluation being performed using a different combination of input parameter values than any other evaluation;
calculating a probability of success (POS) of the proposed tripping schedule based on a number of evaluations that result in the tripping schedule being predicted to be successful, the POS having a value based on a proportion of a total number of evaluations that are being predicted to be successful; and
removing the core sample through the borehole according to the proposed tripping schedule based on the calculated POS.

2. The method of claim 1 , wherein repeating the evaluation includes iteratively performing the evaluation using a plurality of different sets of input parameter values, each different set of input parameter values having a value of at least one parameter that is adjusted relative to a previous evaluation within the uncertainty associated with the at least one parameter.

3. The method of claim 1 , further comprising calculating a POS of a plurality of proposed tripping schedules.

4. The method of claim 3 , further comprising generating a POS curve indicating the POS of each tripping schedule.

5. The method of claim 3 , further comprising selecting one of the plurality of proposed tripping schedules, and removing the core sample according to the selected proposed tripping schedule.

6. The method of claim 1 , wherein the model is a finite-element model of the core sample, and applying the proposed tripping schedule includes applying a boundary condition to the model at each increment of the proposed tripping schedule based on a depth of the core sample at each increment.

7. The method of claim 6 , wherein the core parameter includes a differential pore pressure in the core sample based on external stress and pore pressure incident on the core sample at each increment.

8. The method of claim 7 , wherein determining whether the tripping schedule is predicted to be successful includes comparing the differential pore pressure to a threshold pressure estimated based on tensile rock strength.

9. The method of claim 1 , wherein the proposed tripping schedule prescribes an at least substantially constant tripping speed along a selected interval of the borehole.

10. A system for evaluating a schedule for removing a core sample from a borehole, the system comprising:
a carrier configured to transport the core sample through at least part of the borehole; and
a processor configured to evaluate a tripping schedule for removing the core sample, the processor configured to perform:
generating a model of the core sample based on a plurality of input parameters, the generating including applying a value of each of the input parameters, wherein one or more of the input parameter values is associated with an uncertainty range;
defining a proposed tripping schedule, and performing an evaluation of the proposed tripping schedule, the evaluation including applying the proposed tripping schedule and a set of expected input parameter values to the model, estimating a core parameter and determining whether the tripping schedule is predicted to be successful by comparing the core parameter to selected core damage criteria;
repeating the evaluation by applying the proposed tripping schedule and a different set of input parameter values to the model, estimating the core parameter and determining whether the tripping schedule is predicted to be successful by comparing the core parameter to the selected core damage criteria, the different set of input parameter values including a value of at least one parameter that is different than a value of the at least one parameter in a previous evaluation, the value of the at least one parameter and the previous value of the at least one parameter selected from a range of parameter values within an uncertainty associated with the at least one parameter, each evaluation being performed using a different combination of input parameter values than any other evaluation;
calculating a probability of success (POS) of the proposed tripping schedule based on a number of evaluations that result in the tripping schedule being predicted to be successful, the POS having a value based on a proportion of a total number of evaluations that are being predicted to be successful; and
controlling removal of the core sample through the borehole according to the proposed tripping schedule based on the calculated POS.

11. The system of claim 10 , wherein repeating the evaluation includes iteratively performing the evaluation using a plurality of different sets of input parameter values, each different set of input parameter values having a value of at least one parameter that is adjusted relative to a previous evaluation within the uncertainty associated with the at least one parameter.

12. The system of claim 11 , wherein the evaluation is repeatedly performing according to a Monte Carlo algorithm.

13. The system of claim 10 , wherein the processor is configured to calculate a POS of a plurality of proposed tripping schedules.

14. The system of claim 13 , wherein the processor is configured to generate a POS curve indicating the POS of each tripping schedule.

15. The system of claim 13 , wherein the processor is configured to select one of the plurality of proposed tripping schedules, and control removal of the core sample according to the selected proposed tripping schedule.

16. The system of claim 10 , wherein the model is a finite-element model of the core sample, and applying the proposed tripping schedule includes applying a boundary condition to the model at each increment of the proposed tripping schedule based on a depth of the core sample at each increment.

17. The system of claim 16 , wherein the core parameter includes a differential pore pressure in the core sample based on external stress and pore pressure incident on the core sample at each increment.

18. The system of claim 17 , wherein determining whether the tripping schedule is predicted to be successful includes comparing the differential pore

Assignees

• Hoeink Tobias
• Van Der Zee Wouter E
• Baker Hughes A Ge Co Llc

Inventors

• Hoeink Tobias
• Van Der Zee Wouter E

Classifications

• E21B25/005 Primary

  Above ground means for handling the core, e.g. for extracting the core from the core barrel · CPC title