SYSTEM AND METHOD FOR REMAINING RESOURCE MAPPING
A method for mapping remaining hydrocarbon resources in a subsurface reservoir, includes generating a pressure depletion map of the subsurface reservoir based on a pressure depletion dataset representing a pressure change in at least one well over a time interval, obtaining a hydrocarbon pore thickness map of the subsurface reservoir based on a hydrocarbon pore thickness dataset representing hydrocarbon pore thickness substantially at a beginning of the time interval, using the pressure depletion map and the hydrocarbon pore thickness map, generating a remaining resource map of the subsurface reservoir, for each of a plurality of infill wells located in the subsurface reservoir and operated during a portion of the time interval, determining an estimated ultimate recovery value, using each estimated ultimate recovery value with data from the remaining resource map for the locations of the infill wells to determine a correlation, and using the correlations and the remaining resource map, evaluating a location for a proposed infill well.
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The present invention relates generally to mapping resources in a hydrocarbon reservoir and more particularly to the use of pressure data to estimate remaining resources in a producing reservoir.
BACKGROUNDAs a reservoir undergoes resource production, it may be useful to estimate remaining resources in place in order to make decisions regarding future production decisions. Typically, remaining resources are estimated by generating a geologic model of the subsurface region. The model may be upscaled for use in a reservoir simulator. Then the reservoir simulator is run with reference to production data, pressure data and fluid property variability information, for example. Production information is predicted based on the simulator output and the predictions are compared to historical production information. Where the comparison is reasonable, resources may be determined based on the simulation. Where the difference between the prediction and actual production is too great, the model may be refined and re-run until acceptable results are obtained. Simulations of this type tend to have a high computing cost.
SUMMARYA method for mapping remaining hydrocarbon resources in a subsurface reservoir, includes generating a pressure depletion map of the subsurface reservoir based on a pressure depletion dataset representing a pressure change in at least one well over a time interval, obtaining a hydrocarbon pore thickness map of the subsurface reservoir based on a hydrocarbon pore thickness dataset representing hydrocarbon pore thickness substantially at a beginning of the time interval, using the pressure depletion map and the hydrocarbon pore thickness map, generating a remaining resource map of the subsurface reservoir, for each of a plurality of infill wells located in the subsurface reservoir and operated during a portion of the time interval, determining an estimated ultimate recovery value, using each estimated ultimate recovery value with data from the remaining resource map for the locations of the infill wells to determine a correlation, and using the correlations and the remaining resource map, evaluating a location for a proposed infill well.
A system for implementing the foregoing method includes at least one processor and at least one associated memory and modules configured to execute a method including method for mapping remaining hydrocarbon resources in a subsurface reservoir, includes generating a pressure depletion map of the subsurface reservoir based on a pressure depletion dataset representing a pressure change in at least one well over a time interval, obtaining a hydrocarbon pore thickness map of the subsurface reservoir based on a hydrocarbon pore thickness dataset representing hydrocarbon pore thickness substantially at a beginning of the time interval, using the pressure depletion map and the hydrocarbon pore thickness map, generating a remaining resource map of the subsurface reservoir, for each of a plurality of infill wells located in the subsurface reservoir and operated during a portion of the time interval, determining an estimated ultimate recovery value, using each estimated ultimate recovery value with data from the remaining resource map for the locations of the infill wells to determine a correlation, and using the correlations and the remaining resource map, evaluating a location for a proposed infill well.
A non-transitory processor readable medium containing computer readable software instructions used to perform the foregoing method.
Embodiments include methods for estimating remaining resources using measured reservoir pressure in combination with initial hydrocarbon thickness data in accordance with a flowchart as illustrated in
Similarly, initial gas hydrocarbon pore thickness grids may be generated based on seismic imaging and/or well monitoring data. In this regard, the HPT map may be part of an ensemble of different maps which represent different assumptions regarding the initial reservoir state. As will be appreciated, the actual acquisition of seismic data, along with various processing techniques, may be performed by a third-party vendor, such that obtaining data should be understood to encompass direct acquisition as well as retrieval or receipt of data from a storage medium or database. The hydrocarbon thickness grids may then be multiplied by the pressure grids to create grids that are representative of ranges of remaining resources across the reservoir 12. The high and low cases may also be used to generate average cases.
For each of a number of infill wells, an EUR is produced 14. This estimate can be performed in any conventional manner, such as decline curve analysis techniques. Examples of such techniques include exponential or hyperbolic trend analysis on rate versus time plots.
In an embodiment, the estimated remaining resource map may be generated for any given time using historical pressure values. In this approach, a pressure map generated by using pressure values from a time prior to drilling a selected infill well, or wells, combined with the original HPT map are used to develop a correlation factor 16 between remaining resource value from the grid and estimated ultimate recovery for the infill well. Where the correlation factor is high, the remaining resource estimate can be considered to be an accurate estimate.
The resulting remaining resource estimates can then be used to determine which areas in the reservoir are likely to be good candidates for infill or injection well drilling 18. Furthermore, estimates of incremental production vs. accelerated production due to infill well drilling may be produced, and those estimates can further inform decisions relating to further field development activities.
Each of the foregoing steps is discussed in greater detail below.
Once the pressure maps are generated for any given time period, they may be compared to an initial pressure map to produce a pressure depletion map, which may be illustrated as a ratio as illustrated in
An initial hydrocarbon pore thickness map is shown in
Using the initial HPT of
A field manager may use this information as the basis for a decision to conduct drilling operations within the high remaining resource regions 22 in order to increase field output. On the other hand, measuring the existence of these additional available resources may not be a sufficient basis for such decision-making In particular, in the case where the already drilled wells would eventually recover the resources located in regions 22, additional drilling operations may not be merited. In that case, the additional well would represent accelerated production rather than additional (incremental) production. In other words, accelerated production would represent producing hydrocarbons more quickly while additional production would represent a larger amount of hydrocarbons to be produced. While accelerated production may be desirable, for example where a lease is scheduled to end before all of the resources would be produced, it is not necessarily the most efficient use of drilling funds absent a compelling reason to accelerate production.
In this regard, it may be useful to augment the method by estimating, for a given proposed location, a ratio of acceleration to incremental production. In accordance with an embodiment, a method of determining this ratio begins by examining performance of other infill wells in the reservoir, with regard to their impact on existing wells, and estimating what proportion of the production of the infill wells represents acceleration versus incremental production.
The upper trend line 30 in
Similar estimates may be made for each infill well in the field. Once this is completed a series of acceleration impact radii may be determined for each of the wells, based on actual distance between infills and a given group of surrounding pre-existing wells. The radii distances are based on the actual distance measured between infill wells and the offset existing producers that were reviewed for acceleration impact (example of which was illustrated in
For additional proposed infill locations, the field-wide correlation between EUR and RRM value developed from prior analyzed years may be further used to estimate total EUR for that location. The correlation may be determined by plotting EUR v. RRM values for various infill wells and then fitting a line to the data. For example,
Once the estimates are produced, estimate information may be combined with acceleration/incremental production information at each proposed infill site from the map in
The above described methods can be implemented in the general context of instructions executed by a computer. Such computer-executable instructions may include programs, routines, objects, components, data structures, and computer software technologies that can be used to perform particular tasks and process abstract data types. Software implementations of the above described methods may be coded in different languages for application in a variety of computing platforms and environments. It will be appreciated that the scope and underlying principles of the above described methods are not limited to any particular computer software technology.
Moreover, those skilled in the art will appreciate that the above described methods may be practiced using any one or a combination of computer processing system configurations, including, but not limited to, single and multi-processer systems, hand-held devices, programmable consumer electronics, mini-computers, or mainframe computers. The above described methods may also be practiced in distributed computing environments where tasks are performed by servers or other processing devices that are linked through a one or more data communications networks. In a distributed computing environment, program modules may be located in both local and remote computer storage media including memory storage devices.
Also, an article of manufacture for use with a computer processor, such as a CD, pre-recorded disk or other equivalent devices, could include a computer program storage medium and program means recorded thereon for directing the computer processor to facilitate the implementation and practice of the above described methods. Such devices and articles of manufacture also fall within the spirit and scope of the present invention.
As used in this specification and the following claims, the terms “comprise” (as well as forms, derivatives, or variations thereof, such as “comprising” and “comprises”) and “include” (as well as forms, derivatives, or variations thereof, such as “including” and “includes”) are inclusive (i.e., open-ended) and do not exclude additional elements or steps. Accordingly, these terms are intended to not only cover the recited element(s) or step(s), but may also include other elements or steps not expressly recited. Furthermore, as used herein, the use of the terms “a” or “an” when used in conjunction with an element may mean “one,” but it is also consistent with the meaning of “one or more,” “at least one,” and “one or more than one.” Therefore, an element preceded by “a” or “an” does not, without more constraints, preclude the existence of additional identical elements.
While in the foregoing specification this invention has been described in relation to certain preferred embodiments thereof, and many details have been set forth for the purpose of illustration, it will be apparent to those skilled in the art that the invention is susceptible to alteration and that certain other details described herein can vary considerably without departing from the basic principles of the invention. For example, the invention can be implemented in numerous ways, including for example as a method (including a computer-implemented method), a system (including a computer processing system), an apparatus, a computer readable medium, a computer program product, a graphical user interface, a web portal, or a data structure tangibly fixed in a computer readable memory.
Claims
1. A method for mapping remaining hydrocarbon resources in a subsurface reservoir, comprising:
- generating a pressure depletion map of the subsurface reservoir based on a pressure depletion dataset representing a pressure change in at least one well over a time interval;
- obtaining a hydrocarbon pore thickness map of the subsurface reservoir based on a hydrocarbon pore thickness dataset representing a hydrocarbon pore thickness substantially at a beginning of the time interval;
- using the pressure depletion map and the hydrocarbon pore thickness map, generating a remaining resource map of the subsurface reservoir;
- for each of a plurality of infill wells located in the subsurface reservoir and operated during a portion of the time interval, determining an estimated ultimate recovery value;
- using each estimated ultimate recovery value with data from the remaining resource map for the locations of the infill wells to determine a correlation; and
- using the correlations and the remaining resource map, evaluating a location for a proposed infill well.
2. A method as in claim 1, further comprising, estimating, for the proposed infill well location, a proportion of infill well production that represents accelerated production and a proportion of infill well production that represents incremental impact of the infill well, wherein the estimating is based on the remaining resource map and the correlations.
3. A method as in claim 2, wherein the estimating is further used to generate contours of incremental reserves for the subsurface reservoir.
4. A method as in claim 2, wherein an ensemble of estimates of incremental impact is generated.
5. A method as in claim 1, wherein the estimated ultimate recovery value for each well is estimated based, at least in part, on measured pressure decline rate and cumulative production for each well.
6. A method as in claim 1, wherein the estimated ultimate recovery value for each well comprises a range of estimated ultimate recoveries.
7. A method as in claim 1, wherein the generating a pressure depletion map comprises generating high and low case pressure depletion maps.
8. A system for mapping remaining hydrocarbon resources in a subsurface reservoir, comprising:
- a depletion map module configured and arranged to generate a pressure depletion map of the subsurface reservoir based on a pressure depletion dataset representing a pressure change in at least one well over a time interval;
- a pore thickness map module configured and arranged to obtain a hydrocarbon pore thickness map of the subsurface reservoir based on a hydrocarbon pore thickness dataset representing hydrocarbon pore thickness substantially at a beginning of the time interval;
- a remaining resource map module configured and arranged to use the pressure depletion map and the hydrocarbon pore thickness map, to generate a remaining resource map of the subsurface reservoir;
- an estimated ultimate recovery module configured and arranged to, for each of a plurality of infill wells located in the subsurface reservoir and operated during a portion of the time interval, determine an estimated ultimate recovery value;
- a correlation module configured and arranged to use each estimated ultimate recovery value with data from the remaining resource map for the locations of the infill wells to determine a correlation; and
- an evaluation module configured and arranged to, using the correlations and the remaining resource map, evaluate a location for a proposed infill well.
9. A non-transitory processor readable medium containing computer readable software instructions for performing the method comprising:
- generating a pressure depletion map of the subsurface reservoir based on a pressure depletion dataset representing a pressure change in at least one well over a time interval;
- obtaining a hydrocarbon pore thickness map of the subsurface reservoir based on a hydrocarbon pore thickness dataset representing hydrocarbon pore thickness substantially at a beginning of the time interval;
- using the pressure depletion map and the hydrocarbon pore thickness map, generating a remaining resource map of the subsurface reservoir;
- for each of a plurality of infill wells located in the subsurface reservoir and operated during a portion of the time interval, determining an estimated ultimate recovery value;
- using each estimated ultimate recovery value with data from the remaining resource map for the locations of the infill wells to determine a correlation; and
- using the correlations and the remaining resource map, evaluating a location for a proposed infill well.
Type: Application
Filed: Jul 29, 2013
Publication Date: Jan 29, 2015
Applicant: CHEVRON U.S.A. INC. (San Ramon, CA)
Inventors: James McAuliffe (Houston, TX), Allicia Mackensie Davis (Houston, TX)
Application Number: 13/952,783
International Classification: E21B 49/00 (20060101);