METHOD AND SYSTEM FOR HEAT MANAGEMENT OF AN OIL FIELD
The present invention includes a method and system for heat management in an oil field, the method including the steps of, on a first time interval: determine a thermal maturity for each subsurface region associated with a pattern of oil wells in the oil field, input the thermal maturity output from step (a)(i) and determine a latent heat target and steam injection target for each subsurface region; and input the latent heat target and steam injection target output from step (a)(ii) and a subsurface region development plan and recalibrate a steam optimizer policy engine, on a second time interval: using the recalibrated steam optimizer policy engine from step (a)(iii) and operating data, determine steam injection schedules; and collect operating data; and on a third time interval: input the thermal maturity output from step (i) and perform a periodic look-back process, thereby producing deviations from latent heat targets; and input the deviations from latent heat targets from step (c)(i) and re-determine the subsurface region development plan.
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This patent document contains material which is subject to copyright protection.
(C) Copyright 2007. Chevron U.S.A. Inc. All rights reserved,
With respect to this material which is subject to copyright protection. The 8 owner, Chevron U.S.A, Inc., has no objection to the facsimile reproduction by any one of the patent disclosure, as it appears in the Patent and Trademark Office patent files or records of any country, but otherwise reserves all rights whatsoever.
II. FIELD OF THE INVENTIONThe present invention relates to heat management of an oil field,
III. BACKGROUND OF THE INVENTIONSteam flooding is a method of increasing oil recovery from an oil field where the oil has a high viscosity. The high viscosity slows or prevents flow of oil thus inhibiting its recovery. Steam flooding greatly reduces the viscosity of the crude oil so that it can flow from the reservoir into the production wells.
Typically, in steam flood operations the steam generators are not completely automated. Additionally, there is no steam flood operation where the latent heat targets are used for the control of steam generation or steam distribution, and there is no place where steam generation and distribution controls are integrated. In summary, a need exists for complete integration and automation of the controls of steam generation and distribution driven by heat management design. Throughout the life of a steam flood project, steam generation and distribution need to be optimized to ensure that each injection well rate (and cyclic heat delivered to the reservoir to promote production) proceeds along the trajectory necessary to provide the appropriate latent heat to each part of the reservoir. Executing this reliably and efficiently, day in and day out, will increase the probability that a steam flood project achieves its planned operational efficiency and production.
This invention overcomes the above-described shortcomings of known methods and systems.
IV. SUMMARY OF THE INVENTIONIn one aspect, the present invention is a method for heat management in an oil field, the method including the steps of, on a first time interval: determine a thermal maturity for each subsurface region associated with a pattern of oil wells in the oil field; input the thermal maturity output and determine a latent heat target and steam injection target for each subsurface region; and input the latent heat target and steam injection target output and a subsurface region development plan and recalibrate a steam optimizer policy engine on a second time interval: using the recalibrated steam optimizer policy engine and operating data, determine steam injection schedules; and collect operating data, and on a third time interval: input the thermal maturity output and perform a periodic look-back process thereby producing, deviations from latent heat targets; and input the deviations from latent heat targets and re-determine the subsurface region development plan,
In another aspect, the invention provides A system for heat management in an oil field, the method including a CPU; a memory operatively connected to the CPU, the memory containing a program adapted to be executed by the CPU and the CPU and memory cooperatively adapted for heat management of an oil field; the program including a first code segment configured and adapted for, upon a first pre-determined time interval: determining a thermal maturity for a subsurface region associated with a pattern of oil wells in the oil field; inputting the thermal maturity output from step (a)(i) and determining a latent heat target and steam injection target for each subsurface region; and inputting the latent heat target and steam injection target output from and a subsurface region development plan and recalibrate a steam optimizer policy engine, the program including a second code segment configured and adapted for upon on a second pre-determined time interval; using the recalibrated steam optimizer policy engine and operating data, determining steam injection schedules; and collecting operating data, and the program including a third code segment configured and adapted for upon on a third pre-determined time interval; inputting the thermal maturity output and performing a periodic look-back process including comparing latent heat target and steam injection target outputs to collected operating and calculating deviations of actual heat delivery results from scheduled heat delivery results; and inputting the deviations from latent heat targets and re-determining the subsurface region development plan, wherein the re-determined subsurface region development plan is sufficient to overcome the latent heat target deficiencies output
So that the above recited features and advantages of the present invention can be understood in detail, a more particular description of the invention, briefly summarized above, may be had by reference to the embodiments thereof that are illustrated in the appended drawings. It is to be noted, however, that the appended drawings illustrate only typical embodiments of this invention and are therefore not to be considered limiting of its scope, for the invention may admit to other equally effective embodiments.
A. Overview
The major components (also interchangeably called aspects, subsystems, modules, functions, services) of the system and method of the invention, and examples of advantages they provide, are described below with reference to the figures. For figures including process/means blocks, each block, separately or in combination, is alternatively computer implemented, computer assisted, and/or human implemented Computer implementation optionally includes one or more conventional general purpose computers having a processor, memory, storage, input devices, output devices and/or conventional networking devices, protocols, and/or conventional client-server hardware and software. Where any block or combination of blocks is computer implemented, it is done optional[y by conventional means, whereby one skilled in the art of computer implementation could utilize conventional algorithms, components, and devices to implement the requirements and design of the invention provided herein. However, the invention also includes any new unconventional implementation means.
B. The System/Method
The process of the invention in one embodiment is a continuous process having a closed loop. The process of the invention can be viewed as beginning at Determine Subsurface region Development Plan 125. A development plan is output and consists of a set of subsurface regions to be developed over the next planning time period and a set of decision policies, i.e., rules for the policy engine to apply, for carrying out the development plan. The schedule for development includes overall system constraints, e.g., of steam availability or rig availability. The development plan is passed to Recalibrate Steam Optimizer Policy Engine process 140 which also uses input of the latent heat target and steam injection schedule from step 135 to recalibrate the Policy Engine. Control then passes to step 150 where the Policy Engine is applied to determine steam plant delivery schedules, water plant delivery schedules, and injection schedules, both continuous and cyclic injection schedules, and data collection schedules, or any individual or subset of the above schedules.
Application of the Policy Engine 150 is as follows: The Policy Engine extracts a large amount of information about the current state of operations from Collect Operating Data process 155. This information (collected operating data) includes current and historic production rates and accumulated production rates, current and historic injection rates and accumulated infection rates, facility value such a steam generator status and availability, fresh water delivery capability, and well status information such as thermal maturity state and availability status.
This information is gathered into a field model. The various wells and equipment are aggregated into separate clusters, each cluster having a distinct operational strategy and corresponding set of policies. For each cluster:
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- 1. Override policies are triggered by the high level heat management strategies. These in turn set initial action, constraint, and priority policies generating one possible solution.
- 2. A simulation of this operational solution is performed and a steam supply/demand balance is established at each step across the active field.
- 3. Conflicts within this solution are identified during the simulation, thus triggering hierarchy policies that attempt to resolve the conflicts.
- 4. Unresolved conflicts are passed through a user interface to a modeling expert to resolve.
- 5. The modeler changes the existing policies or creates new policies to resolve the conflicts.
- 6. Steps 2-5 above are repeated until all conflicts have been resolved.
- 7. A series of schedules are generated and output from process 150 to operations for implementation. The output includes the steam system and water plant delivery schedules.
Collect Operating Data Process 7.0 (155) collects operational data, including but not limited to steam injection rates, production rates, and steam generation rates as well has historical data and current and historical capacities. The data collected is combined with the schedule information and reconciliation is performed to set either new system constraints or to adjust schedule targets to realistically achievable rates. The new rates are fed back into the Apply Policy Engine step 6.0 (150) during its next run. The operational data is also fed to the Determine Thermal Maturity process 3.0 and to Periodic Look-back Review process 1.0.
Actual development rates are then gathered from the field data in step 1.2. This data includes the time series of injection and production and maintenance activity done to wells or the distribution system that may have impacted the development schedules Then in step 1.3 the data is analyzed to determine actual steam rate cuts from noise in the injection system. The plan data is then reconciled in step 1.4 against the actual field performances. Then the planning inputs are adjusted to describe the target reservoir until the plan would have matched the field actual. Then these planning inputs are used for future planning in step 1.5.
FIG, 3 depicts a schematic level I data flow diagram of the processes and logical data flow for the Determine Subsurface region Development process 2.0. First, in step 2.1, inputs are gathered describing the target reservoir. These include area and volume of pattern/region, initial reservoir temperature, reservoir pressure, dip of overburden and parameters related to water scavenging. Initially these inputs are developed by the field geologist or reservoir engineer. Later these inputs are taken from the look-back process (
If the look-back process has been conducted the above values should be adjusted to create more realistic inputs based upon actual field responses (step 2.5). Finally, in step 2.6, the new development plan is published. The plan consists of a set of subsurface regions along with the start up dates and initial injection rates. A schedule for steam cuts is also included in the development plan.
In
After getting the temperature data from well logging data (step 440), determine if the temperature is above a pre-determined threshold (step 445). If not, then this indicates pores are filled with air and there is no steam chest, thus the subsurface region is not thermally mature (step 450). If the temperature is above a pre-determined threshold (step 445), then the subsurface region potentially thermally mature and the indicator status should be identified (step 445) and combined (step 450) by averaging them with appropriate weights. “Indicator status” refers to the indicator supporting the pattern being mature or immature.
Then determine if the combined indicator value is at least at a pre-determined threshold (step 465). If not, then this indicates there is not enough evidence of a steam chest and the subsurface region is at most of mixed maturity (step 470). If yes, the there is sufficient evidence of thermal maturity (step 475).
If yes, this indicates thermal maturity 505. If not then determine if low temperature and high saturation or not flat temperature for thick sands (step 520). If yes, then this indicates a mixed maturity 510. The determination of whether there is a high temperature and low saturation is by user specified thresholds. “High” temperature means higher than the user specified threshold. “Low” saturation means lower than the user specified threshold.
The next listed indicator is to determine if the flow line or wellhead temperature is elevated (step 525). This is determined by measuring the temperature of flowing fluid at the wellhead. An “elevated” wellhead temperature in this context means higher than the user specified threshold. If yes, this indicates thermal maturity 505. If not, this indicates mixed thermal maturity 510. The next listed indicator is to determine if production has peaked (step 530). If yes, this indicates thermal maturity 505, if not, this indicates mixed thermal maturity 510. The next listed indicator is to determine if case vent rates are high (step 540). This is determined by user specified thresholds. “High” case vent rates in this context means higher than the user specified threshold. If yes, this indicates thermal maturity 505. If not, this indicates mixed thermal maturity 510. The next listed indicator is to determine if a steam chest has developed (step 545). This is determined by the earth model. A “developed” steam chest means presence of steam at the top of the zone of consideration. If yes, this indicates thermal maturity 505. If not, then check if there are pockets in the steam chest (step 550). If not, this indicates mixed thermal maturity 510.
Prior to entering the process 1100 the Policy Engine retrieves a large block Of data called the Field Model. The Field Model contains information about the current state of field operations that could influence the policy decisions. The Field Model includes information about the current status of subsurface regions associated with a pattern of wells such as their thermal maturity and availability for steam. The subsurface regions' current and historic production rates are gathered. For any injection wells associated with a subsurface region, the current and historic injection rates are retrieved along with cumulative injected heat values for every well that has been used to inject steam into the reservoir. The Field Model information is separated into Clusters (1125), each Cluster representing a separate collection of wells and field equipment. The planning period can be divided into separate Stages, if desired. In the most complex application, the modeler can set different strategies for each Cluster and Stage of the planning period.
The Policy Engine consists of a set of rules called Policies, unlike a typical rules engine the Policy Engine has several different types of rules.
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- Action Policies (1145)—Do This or Don't Do This statements that tend to have starts and endpoints
- Constraint Policies (1145)—Deal with limits on resources (steam) or equipment and tend to be long standing
- Priority Policies (1145)—help focus the allocation of steam when supply is less than demand by prioritizing its distribution.
- Hierarchy Policies (1155)—State that Activity A is more important than Activity B. These are useful to resolve other conflicting policies
- Override Policies (1140)—State that under certain conditions, other policies may be activated or deactivated
At the outset, a number of policies will be provided to the modeler. Modelers can build their own policies by specifying policies categories and the appropriate poll elements. For any run of the Policy Engine, the user updates the Field Model and identifies the active policies and the time frame and supplies the constants required by the policies. The Policy Engine determines which Override policies (1140) are in effect for which time periods resolves resource conflicts, and calculates the appropriate set points. Any unresolved conflicts are highlighted for the modeler. The modeler can easily visualize the results and change the policy list to improve the next run.
For any given stage the following steps are preformed.
-
- The current selected Strategy (1130 or 1135) triggers Override policies (1140) which set the initial list of active Action and Constraint policies (1145).
- The simulation is performed and a steam supply/demand balance is established at each time step.
- Hierarchy policies (1155) are used to resolve as many conflicts (1150) as possible. Any unresolved conflicts are passed through the user interface to a modeler for resolution (1165).
- The modeler resolves conflicts by changing or creating new policies (1165).
- The process steps are repeated until all conflicts are resolved for every stage.
Finally all system schedules are published to operations for implementation (1170).
B. Other Implementations
Other embodiments of the present invention and its individual components will become readily apparent to those skilled in the art from the foregoing detailed description. As will be realized, the invention is capable of other and different embodiments and its several details are capable of modifications in various obvious respects, all without departing from the spirit and the scope of the present invention. Accordingly the drawings and detailed description are to be regarded as illustrative in nature and not as restrictive. It is therefore not intended that the invention be limited except as indicated by the appended claims.
Claims
1. A method for heat managements in an oil field, the method comprising the steps of:
- (a) on a first time interval: i) determine a thermal maturity for each subsurface region associated with a pattern of oil wells in the oil field; ii) input the thermal maturity output from step (a)(i) and determine a latent heat target and steam injection target for each oil well in the subsurface region; and iii) input the latent heat target and steam injection target output from step (a)(ii) and a subsurface region development plan and recalibrate a steam optimizer policy engine,
- (b) on a second time interval: i) using the recalibrated steam optimizer policy engine from step (a)(iii) and operating data, determine steam injection schedules; and ii) collect operating data; and
- (c) on a third time interval: i) input the thermal maturity output from step (i) and perform a periodic look-back process, thereby producing deviations from latent heat targets; and ii) input the deviations from latent heat targets from step (c)(i) and re-determine the subsurface region development plan.
2. The method of claim 1 wherein the periodic look-back process in step (c)(i) comprises comparing latent heat target and steam injection target outputs from step (a)(ii) above to collected operating data from step (b)(ii) above, calculate deviations of actual heat delivery results from scheduled heat delivery results.
3. The method of claim 1, wherein the re-determined subsurface region development plan from step (c)(ii) is sufficient to overcome the latent heat target deficiencies output from step (c)(i).
4. The method of claim 1, whereby the revised subsurface region development plan from step (c)(ii) is used in step (a)(iii) upon its next execution on the first pre-determined time interval.
5. The method of claim 1, wherein the collected operating data from step (b)(ii) comprises injection rates, steam generation rates, steam generation capacity production rates and water delivery capacity.
6. The method of claim 1, wherein steam injection schedules determined in step (b)(i) comprise continuous steam injection schedules and cyclic steam injection schedules.
7. The method of claim 1, wherein the first time interval, second time interval, and third time interval are pre-determined.
8. The method of claim 1, wherein the first time interval is from about nine months to fifteen months, the second time interval is from about one month to six months, and third time interval is from about one hour to one week.
9. The method of claim 1, wherein the first time interval is about one year, the second time interval is three months, and third time interval is about one day.
10. The method for heat management in an oil field, the method comprising the steps of:
- (a) on a first pre-determined time interval: i) determine a thermal maturity for each subsurface region associated with a pattern of oil wells in the oil field; ii) input the thermal maturity output from step (a)(i) and determine a latent heat target and steam injection target for each subsurface region; and iii) input the latent heat target and steam injection target output from step (a)(ii) and a subsurface region development plan and recalibrate a steam optimizer policy engine,
- (b) on a second pre-determined time interval, i) using the recalibrated steam optimizer policy engine from step (a)(iii) and operating data, determine continuous and cyclic steam injection schedules; and ii) collect operating data comprising injection rates, steam generation rates, steam generation capacity, production rates, and water delivery capacity; and
- (c) on a third pre-determined time interval: i) input the thermal maturity output from step (i) and perform a periodic look-back process comprising comparing latent heat target and steam injection target outputs from step (ac)(ii) above to collected operating data from step (b)(ii) above and calculating deviations of actual heat delivery results from scheduled heat delivery results, and ii) input the deviations from latent heat targets from step (c)(i) and re-determine the subsurface region development plan, wherein the re-determined subsurface region development plan is sufficient to overcome the latent heat target deficiencies outputs from step (c)(i).
11. The method of claim 10, wherein the first the interval is from about nine months to fifteen months, the second time interval is from about one month to six months, and third time interval is from about one hour to one week.
12. The method of claim 11, wherein the first time interval is about one year, the second time interval is three months, and third time interval is about one day.
13. The method of claim 11, whereby the revised subsurface region development plan from step (c)(ii) is used in step (a)(iii) upon its next execution on the first pre-determined time interval.
14. A system for heat management in an oil field, the method comprising:
- (a) a CPU.
- (b) a memory operatively connected to the CPU, the memory containing a program adapted to be executed by the CPU and the CPU and memory cooperatively adapted for heat management of an oil field;
- (c) the program comprising a first code segment configured and adapted for, upon a first pre-determined time interval: i) determining a thermal maturity for each subsurface region associated with a pattern of oil welts in the, oil field; ii) inputting the thermal maturity output from step (a)(i) and determining a latent heat target and steam injection target for each subsurface region, and iii) inputting the latent heat target and steam injection target output from step (a)(ii) and a subsurface region development plan and recalibrate a steam optimizer policy engine,
- (d) the program comprising a second code segment configured and adapted for, upon on a second pre-determined time interval: i) using the recalibrated steam optimizer policy engine from step (a)(iii) and operating data, determining steam injection schedules, and ii) collecting operating data; and
- (e) the program comprising a third code segment configured and adapted for, upon on a third pre-determined time interval: i) inputting the thermal maturity output from step (i) and performing a 8 periodic look-back process comprising comparing latent heat target and steam injection target outputs from step (a)(ii) above to collected operating data from step (b)(ii) above and calculating deviations of actual heat delivery results from scheduled heat delivery results; and ii) inputting the deviations from latent heat targets from step (c)(i) and re-determining the subsurface region development plan, wherein the re-determined subsurface region development plan is sufficient to overcome the latent heat target deficiencies output from step (c)(i).
15. The system of claim 14, wherein the periodic look-back process comprises comparing latent heat target and steam injection target outputs to collected operating data, and calculating deviations of actual heat delivery results from scheduled heat delivery results.
16. The system of claim 14, wherein the re-determined subsurface region development plan is sufficient to overcome the latent heat target deficiencies.
17. The system of claim 14, wherein the collected operating data comprises injection rates, steam generation rates, steam generation capacity, production rates, and water delivery capacity.
18. The system of claim 14, wherein steam injection schedules determined comprise continuous steam injection schedules and cyclic steam injection schedules.
19. The system of claim 14, wherein the first time interval is from about nine months to fifteen months, the second time interval is from about one month to six months, and third time interval is from about one hour to one week.
20. The system of claim 14, wherein the first time interval is about one year, the second time interval is three months and third time interval is about one day.
Type: Application
Filed: May 16, 2007
Publication Date: Nov 20, 2008
Applicant:
Inventors: David Tuk (Fairfield, CA), Anilkumar Patel (Fremont, CA), Charles Guthrie (Richmond, CA), Richard Cullip (Bakersfield, CA), Mike Riddle (Napa, CA)
Application Number: 11/749,628
International Classification: E21B 43/24 (20060101);