METHOD FOR PERFORMING OILFIELD PRODUCTION OPERATIONS

• US 20080140369A1
• Filed: 12/06/2007
• Published: 06/12/2008
• Est. Priority Date: 12/07/2006
• Status: Active Grant

• Current Assignee: Schlumberger Technology Corporation (Schlumberger NV)
• Original Assignee: Schlumberger Technology Corporation (Schlumberger NV)
• Inventors: Lucas-Clements, Daniel, Tonkin, Trevor, Shand, Andrew, Letizia, Luca, Rashid, Kashif, Howell, Andrew John
• Granted Patent: US 8,078,444 B2
• Time in Patent Office: Days
• US Class Current: 703/10
• CPC Class Codes: E21B 43/00 Methods or apparatus for obtaining oil, gas, water, soluble or meltable materials or a slurry of minerals from wells applicable only to water E03B
• CPC Class Codes: E21B 43/122 Gas lift

Abstract

A method is disclosed for optimal lift resource allocation, which includes optimally allocating lift resource under a total lift resource constraint or a total production constraint, the allocating step including distributing lift resource among all lifted wells in a network so as to maximize a liquid/oil rate at a sink.

Claims

1. A method for performing operations of an oilfield having at least one process facilities and at least one wellsite operatively connected thereto, each at least one wellsite having a wellbore penetrating a subterranean formation for extracting fluid from an underground reservoir therein, the method comprising:

optimally allocating lift resource under at least one selected from a group consisting of a total lift resource constraint and a total produced gas constraint to generate a lift resource allocation, the allocating step comprising distributing the lift resource among a plurality of lifted wells in a network so as to maximize a liquid/oil rate at a sink.

2. The method of claim 1, wherein the allocating step comprises:

using lift performance curve data generated at a pre-processing step to solve lift resource allocation;

converting a system of N-wells with a linear inequality constraint into a constraint into a single variable with a linear equality constraint using Newton decomposition to generate a solution; and

determining if the solution is in agreement with an actual network model for wellhead pressure of the plurality of lifted wells using a network simulator.

3. The method of claim 1, wherein the allocating step comprises:

using an offline-online optimization procedure, comprising;

extracting lift performance curves,

solving an offline optimal allocation procedure to determine an optimal allocation of the lift resource,

solving a real network problem including the plurality of lifted wells using said optimal allocation of the lift resource to obtain updated well head pressures of the plurality of lifted wells; and

repeating said offline optimal allocation procedure using said updated wellhead pressures.

4. The method of claim 1, wherein a network model comprises the plurality of lifted wells, and wherein the allocating step comprises:

(a) in a pre-processing step, generating a plurality of lift performance curves for at least one well in the network, the plurality of lift performance curves adapted for describing an expected liquid flow rate for a given amount of lift resource application at given wellhead pressures;

(b) obtaining a first wellhead pressure for the at least one well in the network, the first wellhead pressure adapted for setting an operating curve for said at least one well;

(c) implementing an allocation procedure to generate optimal lift resource values in response to the first wellhead pressure;

(d) generating a second wellhead pressure using a real network model with the optimal lift resource values assigned to the plurality of lifted wells of the network model; and

(e) repeating steps (b) through (d) until there is convergence between the first wellhead pressure and the second wellhead pressure.

5. A method for performing operations of an oilfield having at least one process facilities and at least one wellsite operatively connected thereto, each at least one wellsite having a wellbore penetrating a subterranean formation for extracting fluid from an underground reservoir therein, the method comprising:

optimally allocating lift resource under at least one selected from a group consisting of a total lift resource constraint and a total produced gas constraint to generate a lift resource allocation, the allocating step comprising distributing the lift resource among a plurality of lifted wells in a network so as to maximize a liquid/oil rate at a sink, the allocating step further comprising;

using lift performance curve data generated at a pre-processing step to solve lift resource allocation;

converting a system of N-wells with a linear inequality constraint into a constraint into a single variable with a linear equality constraint using Newton decomposition to generate a solution; and

determining if the solution is in agreement with an actual network model for wellhead pressure of the plurality of lifted wells using a network simulator.

6. The method of claim 5, wherein the allocating step further comprises:

using an offline-online optimization procedure, comprising;

extracting lift performance curves,

solving an offline optimal allocation procedure to determine an optimal allocation of the lift resource,

solving a real network problem including the plurality of lifted wells using said optimal allocation of the lift resource to obtain updated well head pressures of the plurality of lifted wells; and

repeating said offline optimal allocation procedure using said updated wellhead pressures.

7. The method of claim 5, wherein a network model comprises the plurality of lifted wells, and wherein the allocating step further comprises:

(a) in a pre-processing step, generating a plurality of lift performance curves for at least one well in the network, the plurality of lift performance curves adapted for describing an expected liquid flow rate for a given amount of lift resource application at given wellhead pressures;

(b) obtaining a first wellhead pressure for the at least one well in the network, the first wellhead pressure adapted for setting an operating curve for said at least one well;

(c) implementing an allocation procedure to generate optimal lift resource values in response to the first wellhead pressure;

(d) generating a second wellhead pressure using a real network model with the optimal lift resource values assigned to the plurality of lifted wells of the network model; and

(e) repeating steps (b) through (d) until there is convergence between the first wellhead pressure and the second wellhead pressure.

8. A method for performing operations of an oilfield having at least one process facilities and at least one wellsite operatively connected thereto, each at least one wellsite having a wellbore penetrating a subterranean formation for extracting fluid from an underground reservoir therein, the method comprising:

optimally allocating lift resource under at least one selected from a group consisting of a total lift resource constraint and a total produced gas constraint to generate a lift resource allocation, the allocating step comprising distributing the lift resource among a plurality of lifted wells in a network so as to maximize a liquid/oil rate at a sink, a network model comprising the plurality of lifted wells, the allocating step further comprising;

(a) in a pre-processing step, generating a plurality of lift performance curves for at least one well in the network, the plurality of lift performance curves adapted for describing an expected liquid flow rate for a given amount of lift resource application at given wellhead pressures;

(b) obtaining a first wellhead pressure for the at least one well in the network, the first wellhead pressure adapted for setting an operating curve for said at least one well;

(c) implementing an allocation procedure to generate optimal lift resource values in response to the first wellhead pressure;

(d) generating a second wellhead pressure using a real network model with the optimal lift resource values assigned to the plurality of lifted wells of the network model; and

(e) repeating steps (b) through (d) until there is convergence between the first wellhead pressure and the second wellhead pressure.

9. A computer program adapted to be executed by a processor, said computer program, when executed by the processor, conducting a process for optimal resource allocation, said process comprising:

optimally allocating lift resource under at least one selected from a group consisting of a total lift resource constraint and a total produced gas constraint to generate a lift resource allocation, the allocating step comprising distributing the lift resource among a plurality of lifted wells in a network so as to maximize a liquid/oil rate at a sink.

10. The computer program of claim 9, wherein the allocating step comprises:

using lift performance curve data generated at a pre-processing step to solve lift resource allocation;

converting a system of N-wells with a linear inequality constraint into a constraint into a single variable with a linear equality constraint using Newton decomposition to generate a solution; and

determining if the solution is in agreement with an actual network model for wellhead pressure of the plurality of lifted wells using a network simulator.

11. The computer program of claim 9, wherein the allocating step comprises:

using an offline-online optimization procedure, comprising;

extracting lift performance curves,

solving an offline optimal allocation procedure to determine an optimal allocation of the lift resource,

solving a real network problem including the plurality of lifted wells using said optimal allocation of the lift resource to obtain updated well head pressures of the plurality of lifted wells; and

repeating said offline optimal allocation procedure using said updated wellhead pressures.

12. The computer program of claim 9, wherein a network model comprises the plurality of lifted wells, and wherein the allocating step comprises:

(a) in a pre-processing step, generating a plurality of lift performance curves for at least one well in the network, the plurality of lift performance curves adapted for describing an expected liquid flow rate for a given amount of lift resource application at given wellhead pressures;

(b) obtaining a first wellhead pressure for the at least one well in the network, the first wellhead pressure adapted for setting an operating curve for said at least one well;

(c) implementing an allocation procedure to generate optimal lift resource values in response to the first wellhead pressure;

(d) generating a second wellhead pressure using a real network model with the optimal lift resource values assigned to the plurality of lifted wells of the network model; and

(e) repeating steps (b) through (d) until there is convergence between the first wellhead pressure and the second wellhead pressure.

13. A computer program adapted to be executed by a processor, said computer program, when executed by the processor, conducting a process for optimal resource allocation, said process comprising:

optimally allocating lift resource under at least one selected from a group consisting of a total lift resource constraint and a total produced gas constraint to generate a lift resource allocation, the allocating step comprising distributing the lift resource among a plurality of lifted wells in a network so as to maximize a liquid/oil rate at a sink, the allocating step further comprising;

using lift performance curve data generated at a pre-processing step to solve lift resource allocation;

converting a system of N-wells with a linear inequality constraint into a constraint into a single variable with a linear equality constraint using Newton decomposition to generate a solution; and

determining if the solution is in agreement with an actual network model for wellhead pressure of the plurality of lifted wells using a network simulator.

14. The computer program of claim 13, wherein the allocating step further comprises:

using an offline-online optimization procedure, comprising;

extracting lift performance curves,

solving an offline optimal allocation procedure to determine an optimal allocation of the lift resource,

solving a real network problem including the plurality of lifted wells using said optimal allocation of the lift resource to obtain updated well head pressures of the plurality of lifted wells; and

repeating said offline optimal allocation procedure using said updated wellhead pressures.

15. The computer program of claim 13, wherein a network model comprises the plurality of lifted wells, and wherein the allocating step further comprises:

(a) in a pre-processing step, generating a plurality of lift performance curves for at least one well in the network, the plurality of lift performance curves adapted for describing an expected liquid flow rate for a given amount of lift resource application at given wellhead pressures;

(b) obtaining a first wellhead pressure for the at least one well in the network, the first wellhead pressure adapted for setting an operating curve for said at least one well;

(c) implementing an allocation procedure to generate optimal lift resource values in response to the first wellhead pressure;

(d) generating a second wellhead pressure using a real network model with the optimal lift resource values assigned to the plurality of lifted wells of the network model; and

(e) repeating steps (b) through (d) until there is convergence between the first wellhead pressure and the second wellhead pressure.

16. A computer program adapted to be executed by a processor, said computer program, when executed by the processor, conducting a process for optimal resource allocation, said process comprising:

optimally allocating lift resource under at least one selected from a group consisting of a total lift resource constraint and a total produced gas constraint to generate a lift resource allocation, the allocating step comprising distributing the lift resource among a plurality of lifted wells in a network so as to maximize a liquid/oil rate at a sink, a network model comprising the plurality of lifted wells, the allocating step further comprising;

(a) in a pre-processing step, generating a plurality of lift performance curves for at least one well in the network, the plurality of lift performance curves adapted for describing an expected liquid flow rate for a given amount of lift resource application at given wellhead pressures;

(b) obtaining a first wellhead pressure for the at least one well in the network, the first wellhead pressure adapted for setting an operating curve for said at least one well;

(c) implementing an allocation procedure to generate optimal lift resource values in response to the first wellhead pressure;

(d) generating a second wellhead pressure using a real network model with the optimal lift resource values assigned to the plurality of lifted wells of the network model; and

(e) repeating steps (b) through (d) until there is convergence between the first wellhead pressure and the second wellhead pressure.

17. A program storage device readable by a machine tangibly embodying a program of instructions executable by the machine to perform method steps for optimal resource allocation, said method steps comprising:

optimally allocating lift resource under at least one selected from a group consisting of a total lift resource constraint and a total produced gas constraint to generate a lift resource allocation, the allocating step comprising distributing the lift resource among a plurality of lifted wells in a network so as to maximize a liquid/oil rate at a sink.

18. The program storage device of claim 17, wherein the allocating step comprises:

using lift performance curve data generated at a pre-processing step to solve lift resource allocation;

converting a system of N-wells with a linear inequality constraint into a constraint into a single variable with a linear equality constraint using Newton decomposition to generate a solution; and

determining if the solution is in agreement with an actual network model for wellhead pressure of the plurality of lifted wells using a network simulator.

19. The program storage device of claim 17, wherein the allocating step comprises:

using an offline-online optimization procedure, comprising;

extracting lift performance curves,

solving an offline optimal allocation procedure to determine an optimal allocation of the lift resource,

solving a real network problem including the plurality of lifted wells using said optimal allocation of the lift resource to obtain updated well head pressures of the plurality of lifted wells; and

repeating said offline optimal allocation procedure using said updated wellhead pressures.

20. The program storage device of claim 17, wherein a network model comprises the plurality of lifted wells, and wherein the allocating step comprises:

(a) in a pre-processing step, generating a plurality of lift performance curves for at least one well in the network, the plurality of lift performance curves adapted for describing an expected liquid flow rate for a given amount of lift resource application at given wellhead pressures;

(b) obtaining a first wellhead pressure for the at least one well in the network, the first wellhead pressure adapted for setting an operating curve for said at least one well;

(c) implementing an allocation procedure to generate optimal lift resource values in response to the first wellhead pressure;

(d) generating a second wellhead pressure using a real network model with the optimal lift resource values assigned to the plurality of lifted wells of the network model; and

(e) repeating steps (b) through (d) until there is convergence between the first wellhead pressure and the second wellhead pressure.

21. A system adapted for optimal lift gas allocation, comprising:

apparatus adapted for optimally allocating lift resource under at least one selected from a group consisting of a total lift resource constraint and a total produced gas constraint, the apparatus comprising further apparatus adapted for distributing the lift resource among a plurality of lifted wells in a network so as to maximize a liquid/oil rate at a sink.

22. The system of claim 21, the apparatus comprising further apparatus adapted for:

using lift performance curve data generated at a pre-processing step to solve lift resource allocation;

converting a system of N-wells with a linear inequality constraint into a constraint into a single variable with a linear equality constraint using Newton decomposition to generate a solution; and

determining if the solution is in agreement with an actual network model for wellhead pressure of the plurality of lifted wells using a network simulator.

23. The system of claim 21, the apparatus comprising further apparatus adapted for:

using an offline-online optimization procedure, comprising;

extracting lift performance curves,

solving an offline optimal allocation procedure to determine an optimal allocation of the lift resource,

solving a real network problem including the plurality of lifted wells using said optimal allocation of the lift resource to obtain updated well head pressures of the plurality of lifted wells; and

repeating said offline optimal allocation procedure using said updated wellhead pressures.

24. The system of claim 21, wherein a network model comprises the plurality of lifted wells, the apparatus comprising further apparatus adapted for:

(a) in a pre-processing step, generating a plurality of lift performance curves for at least one well in the network, the plurality of lift performance curves adapted for describing an expected liquid flow rate for a given amount of lift resource application at given wellhead pressures;

(b) obtaining a first wellhead pressure for the at least one well in the network, the first wellhead pressure adapted for setting an operating curve for said at least one well;

(c) implementing an allocation procedure to generate optimal lift resource values in response to the first wellhead pressure;

(d) generating a second wellhead pressure using a real network model with the optimal lift resource values assigned to the plurality of lifted wells of the network model; and

(e) repeating steps (b) through (d) until there is convergence between the first wellhead pressure and the second wellhead pressure.

25. A system adapted for optimal resource allocation, comprising:

apparatus adapted for optimally allocating lift resource under at least one selected from a group consisting of a total lift resource constraint and a total produced gas constraint the apparatus comprising further apparatus adapted for distributing the lift resource among a plurality of lifted wells in a network so as to maximize a liquid/oil rate at a sink, a network model comprising the plurality of lifted wells, the apparatus comprising further apparatus adapted for;

(a) in a pre-processing step, generating a plurality of lift performance curves for at least one well in the network, the plurality of lift performance curves adapted for describing an expected liquid flow rate for a given amount of lift resource application at given wellhead pressures;

(b) obtaining a first wellhead pressure for the at least one well in the network, the first wellhead pressure adapted for setting an operating curve for said at least one well;

(c) implementing an allocation procedure to generate optimal lift resource values in response to the first wellhead pressure;

(d) generating a second wellhead pressure using a real network model with the optimal lift resource values assigned to the plurality of lifted wells of the network model; and

(e) repeating steps (b) through (d) until there is convergence between the first wellhead pressure and the second wellhead pressure.