Methods and systems for estimating sizes and effects of wellbore obstructions in water injection wells

1. A method to estimate one or more physical dimensions of one or more actual obstructions identified as being in a wellbore of an injection well, the method comprising:

(a) estimating one or more locations within the wellbore and one or more physical dimensions of one or more actual obstructions to thereby define a simulated obstruction within the wellbore;

(b) obtaining two or more sets of actual measurements of two or more characteristics of fluid flow in the wellbore including two or more actual injection rates and two or more actual injection pressures;

(c) calculating a plurality of actual upstream pressure values of the simulated obstruction, the upstream pressure values being responsive to a first outflow performance relationship and a first set of actual measurements of two or more characteristics of fluid flow in the wellbore, the first set of measurements including a first set of actual fluid injection rates and a first set of actual injection pressures;

(d) calculating a plurality of corresponding downstream pressure values across the simulated obstruction, the corresponding downstream pressure values being responsive to a first estimated injectivity index value, one or more actual measurements of one or more characteristics of the reservoir associated with the injection well, and the first set of actual measurements of two or more characteristics of fluid flow in the wellbore;

(e) determining one or more functions to associate a plurality of pressure differentials between the upstream pressure values and the corresponding downstream pressure values with the first set of actual fluid injection rates responsive to a function of estimated downhole choke behavior for the wellbore to thereby model the fluid flow across the simulated obstruction to thereby define the simulated obstruction model;

(f) determining a second outflow performance relationship for the fluid flow through the wellbore responsive to the simulated obstruction model to thereby model well performance with the simulated obstruction;

(g) determining a second estimated injectivity index value responsive to matching a second set of actual measurements of two or more characteristics of fluid flow in the wellbore with a set of simulated fluid flow values obtained from the well performance model with the simulated obstruction, the second set of actual measurements including a second set of actual fluid injection rates and a second set of actual injection pressures;

(h) performing iteratively steps (b) to (g) until the first estimated injectivity index value and the second estimated injectivity index value converge within preselected tolerance limits;

(i) determining one or more physical dimensions of one or more actual obstructions in the wellbore responsive to the simulated obstruction model and a plurality of measurements of one or more characteristics associated with the wellbore when the first estimated injectivity index value and the second estimated injectivity index value converge within preselected tolerance limits; and

(j) implementing one or more changes to well conditions responsive to determining one or more physical dimensions of the one or more actual obstructions in the wellbore, the one or more changes to well conditions including one or more of the following: removal of the actual obstructions, making major skin improvements, and making minor skin improvements.

2. A method as defined in claim 1 , wherein the two or more sets of measurements of two or more characteristics of fluid flow in the wellbore including two or more injection rates and two or more injection pressures are obtained at substantially similar values of reservoir pressure associated with the injection well.

3. A method as defined in claim 2 , wherein the two or more sets of measurements of two or more characteristics of fluid flow in the wellbore are obtained using a solar flowmeter.

4. A method as defined in claim 1 , wherein the plurality of measurements of one or more characteristics associated with the wellbore includes one or more physical dimensions of the wellbore.

5. A method as defined in claim 4 , wherein the one or more physical dimensions of the wellbore includes a diameter of the wellbore.

6. A method as defined in claim 1 , wherein the injection well is a power water injection well.

7. A system to estimate one or more physical dimensions of one or more actual obstructions identified as being in a wellbore of an injection well, the system comprising:

one or more processors;

one or more input and output units in communication with the one or more processors and positioned to receive a user selection of a wellbore of an injection well;

one or more databases in communication with the one or more processors, the one or more databases including a plurality of actual measurements of one or more characteristics of fluid flow in the wellbore of an injection well, a plurality of actual measurements of one or more characteristics of a reservoir associated to the injection well, and a plurality of actual measurements of one or more characteristics of the wellbore of the injection well;

non-transitory computer-readable medium positioned in communication with the one or more processors and having computer program stored thereon including a set of instructions that when executed by one or more processors cause the one or more processors to perform operations of:

(a) estimating one or more locations within the wellbore and one or more physical dimensions of one or more actual obstructions to thereby define a simulated obstruction within the wellbore;

(b) obtaining two or more sets of actual measurements of two or more characteristics of fluid flow in the wellbore including two or more actual injection rates and two or more actual injection pressures;

(c) calculating a plurality of actual upstream pressure values of the simulated obstruction, the upstream pressure values being responsive to a first outflow performance relationship and a first set of actual measurements of two or more characteristics of fluid flow in the wellbore, the first set of measurements including a first set of actual fluid injection rates and a first set of actual injection pressures;

(d) calculating a plurality of corresponding downstream pressure values across the simulated obstruction, the corresponding downstream pressure values being responsive to a first estimated injectivity index value, one or more actual measurements of one or more characteristics of the reservoir associated with the injection well, and the first set of actual measurements of two or more characteristics of fluid flow in the wellbore;

(e) determining one or more functions to associate a plurality of pressure differentials between the upstream pressure values and the corresponding downstream pressure values with the first set of actual fluid injection rates responsive to a function of estimated downhole choke behavior for the wellbore to thereby model the fluid flow across the simulated obstruction to thereby define the simulated obstruction model;

(f) determining a second outflow performance relationship for the fluid flow through the wellbore responsive to the simulated obstruction model to thereby model well performance with the simulated obstruction;

(g) determining a second estimated injectivity index value responsive to matching a second set of actual measurements of two or more characteristics of fluid flow in the wellbore with a set of simulated fluid flow values obtained from the well performance model with the simulated obstruction, the second set of actual measurements including a second set of actual fluid injection rates and a second set of actual injection pressures;

(h) performing iteratively steps (b) to (g) until the first estimated injectivity index value and the second estimated injectivity index value converge within preselected tolerance limits;

(i) determining one or more physical dimensions of one or more actual obstructions in the wellbore responsive to the simulated obstruction model and a plurality of measurements of one or more characteristics associated with the wellbore when the first estimated injectivity index value and the second estimated injectivity index value converge within preselected tolerance limits; and

(j) implementing one or more changes to well conditions responsive to determining one or more physical dimensions of the one or more actual obstructions in the wellbore, the one or more changes to well conditions including one or more of the following: removal of the actual obstructions, making major skin improvements, and making minor skin improvements.

8. A system as defined in claim 7 , wherein the two or more sets of measurements of two or more characteristics of fluid flow in the wellbore including two or more injection rates and two or more injection pressures are obtained at substantially similar values of reservoir pressure associated with the injection well.

9. A system as defined in claim 7 , wherein the plurality of measurements of one or more characteristics associated with the wellbore includes one or more physical dimensions of the wellbore.

10. A system as defined in claim 9 , wherein the one or more physical dimensions of the wellbore includes a diameter of the wellbore.

11. A system as defined in claim 7 , wherein the injection well is a power water injection well.

12. A computer-implemented method to determine dimensions of one or more actual obstructions identified as being in a wellbore of an injection well, the method comprising:

(a) obtaining a plurality of measurements of one or more characteristics of fluid flow in a wellbore of an injection well, a plurality of measurements of one or more characteristics of a reservoir associated with the injection well, and a plurality of measurements of one or more characteristics associated with the wellbore of the injection well;

(b) creating one or more correlations based on a first estimated injectivity index to simulate fluid flow across one or more simulated mechanical obstructions to thereby define a simulated obstruction performance model, the one or more correlations being responsive to the plurality of measurements of one or more characteristics of fluid flow in the wellbore of the injection well, the plurality of measurements of one or more characteristics of the reservoir associated with the injection well, the plurality of measurements of one or more characteristics associated with the wellbore of the injection well, and a plurality of simulated fluid flow measurements across the at least one simulated mechanical obstruction in the wellbore;

(c) determining a second estimated injectivity index, responsive to the simulated obstruction performance model, the plurality of measurements of one or more characteristics of actual fluid flow in the wellbore of the injection well, the plurality of measurements of one or more characteristics of the reservoir associated with the injection well, and the plurality of measurements of one or more characteristics associated with the wellbore of the injection well;

(d) performing iteratively steps (a) to (c) until the first estimated injectivity index value and the second estimated injectivity index value converge within preselected tolerance limits;

(e) determining dimensions of the one or more actual obstruction in the wellbore responsive to the simulated obstruction performance model and the plurality of measurements of one or more characteristics associated with the wellbore of the injection well when the first estimated injectivity index and the second estimated injectivity index converge within acceptable tolerance limits; and

(f) implementing one or more changes to well conditions responsive to determining one or more physical dimensions of the one or more actual obstructions in the wellbore, the one or more changes to well conditions including one or more of the following: removal of the actual obstructions, making major skin improvements, and making minor skin improvements.

13. A method as defined in claim 12 , wherein the simulated obstruction performance model includes at least one of the following: an outflow performance relationship analysis and an inflow performance relationship analysis.

14. A method as defined in claim 13 , wherein the outflow performance relationship analysis is responsive to the plurality of measurements of one or more characteristics of fluid flow in the wellbore of the injection well.

15. A method as defined in claim 13 , wherein the inflow performance relationship analysis is responsive to the plurality of measurements of one or more characteristics of fluid flow in the wellbore of the injection well and the plurality of measurements of one or more characteristics of the reservoir associated with the injection well.

16. A method as defined in claim 12 , wherein the one or more characteristics of fluid flow in the wellbore includes one of the following: injection rate and injection pressure.

17. A method as defined in claim 12 , wherein the plurality of measurements of the one or more characteristics of fluid flow in the wellbore are obtained using a solar flowmeter.

18. A method as defined in claim 12 , wherein the plurality of measurements of one or more characteristics associated with the wellbore includes one or more physical dimensions of the wellbore.

19. A method as defined in claim 12 , wherein the one or more physical dimensions of the wellbore includes a diameter of the wellbore.

20. A method as defined in claim 12 , wherein the injection well is a power water injection well.