This invention relates to improved methods and systems for use in carbon sequestration. In particular, the invention provides methods, apparatuses and systems for more effectively and efficiently assessing risks associated with carbon sequestration, developing a plan to optimize the risks and implementing one or more steps of the plan.
Addition of carbon dioxide (CO2 to be proper, but also referred to herein for ease of formatting as “CO2”) to the atmosphere, for example by burning fossil fuels such as oil, natural gas and coal, is believed to contribute to global warming. Exhausts from petrochemical and other manufacturing plants may also be sources of CO2 additions to the atmosphere. Of course, one could collect the CO2 for commercial use or use it to enhance agricultural production in greenhouses. But sequestering CO2, that is, placing and storing CO2 at a location where the CO2 cannot enter the atmosphere, is a way of mitigating the possible adverse effects of additions of CO2 to the atmosphere. Carbon dioxide sequestration is also referred to as “carbon sequestration.” Carbon capture and storage (CCS) is capture and isolation of carbon dioxide from high carbon-emitting sources, such as power plants, and storage or sequestration in a location where the carbon dioxide will not enter the atmosphere.
One could sequester CO2 using a number of methods and locations. CO2 may be sequestered by placing the CO2 in the depths of the ocean (unless there are unacceptably adverse effects on ocean life) or in the sub-ocean floor such as in basalt formations. But one could also inject the CO2 into underground formations. For example, one could inject CO2 underground in deep saline reservoirs or in depleted hydrocarbon (oil and/or natural gas (gas)) reservoirs. One could inject CO2 into underground coal beds (displacing natural gas, which may then be produced) or into peridotite formations. One could use the CO2 for enhanced oil recovery (EOR) or enhanced gas recovery (EGR) by injecting the CO2 via one or more injection wells into reservoirs containing hydrocarbons and using the CO2 to facilitate mobilization of the hydrocarbons towards one or more producing wells.
A “formation” is a “body of rock that is sufficiently distinctive and continuous that it can be mapped.” (This and other definitions in this paragraph are taken from the Schlumberger Oilfield Glossary (“Glossary”), available online at www.glossary.oilfield.slb.com). Underground formations are comprised of rock which, in turn, are composed of rock grains (of one or more minerals) and pore spaces. (Coal is an exception to this general rule as it is a rock composed of organic material, not minerals which are inorganic.) An underground reservoir is an underground formation “with sufficient porosity and permeability to store and transmit fluids.” A formation suitable for CO2 sequestration would likely be a reservoir (though that might be arguable in the case of a coal seam), but the terms are sometimes used interchangeably. Porosity of a formation is the percentage of space (pores) between the rock grains of the formation, space which may contain fluids (liquids, condensates or gases). Permeability is a measure of how well a rock of a formation allows fluids which occupy the pore space of the rock to flow through the rock. Fracturing, if carefully performed so as not to disturb the trapping mechanism of the reservoir, might be used to enhance injectivity.
Selecting appropriate reservoirs for sequestration pose special challenges. The reservoir would have to have adequate capacity for storage of the desired amount of CO2. The reservoir should have one or preferably more trapping mechanisms to keep the CO2 in place and prevent its migration to the surface. The CO2 may also react to rocks or minerals in the formation and stabilize and become affixed in place.
Analysis of the formation, its composition, porosity and permeability, as well as other characteristics and surrounding lithology, may be important to the selection of an underground formation in which to sequester CO2. The storage formation should be placed with respect to other, preferably impermeable formations so that the CO2 would be trapped within the sequestration formation and not be able to migrate through other formations to the surface. The underground storage formation selected should have sufficient porosity to receive the desired volume of CO2 to be sequestered and should have sufficient permeability so that the CO2 may be injected into the formation and flow through the rock of the formation. (Though as noted above, fracturing, if carefully performed so as not to disturb the trapping mechanism of the reservoir, might be used to enhance injectivity.) Adverse reactions of the CO2 with minerals in the storage formation would preferably be minimized, either by selecting storage formations without minerals the CO2 would likely adversely react with or by taking other steps to minimize such reactions or minimize their adverse effects. On the other hand, it would be advantageous to have a storage formation with minerals that help the CO2 to become affixed in place, such as by crystallizing in place, to minimize or prevent the possibility of the CO2 leaking either to the surface and into the atmosphere or into formations bearing potable water.
In addition, the environment of an underground reservoir used for carbon sequestration might have high temperatures or pressures or have other hazards such as hydrogen sulfide, which might provide challenges to the material selection, well construction and/or placement process. CO2 combined with water can form carbonic acid, which could damage some conventional materials that might be used to transport, place or contain the CO2, so material selection is important.
One may want to prepare surface of the sequestration location in such a way that any leakage of CO2 to the surface after placement is easily detectable and/or mitigated. It is desirable that the site be properly decommissioned after a preferably optimum amount of CO2 is in place and the site monitored for sometime afterwards to ensure that the CO2 placement is stable. It is desirable to ascertain the amount, location and state of the CO2 during the placement process, after the CO2 has been placed and for some period thereafter. Post-decommissioning monitoring may be required by regulatory agencies.
Cost is a consideration throughout the process. Budgets may have to be prepared which make provision for investigating possible sequestration sites, acquiring rights to the desired sequestration site, capturing and treating the CO2, transporting the CO2 if necessary, constructing surface facilities and injection wells, monitoring and measuring the CO2, operating the site, decommissioning the site, posting a bond if necessary to cover any post-decommissioning problems, and monitoring the CO2 after decommissioning the site until the CO2 is determined to be in a stable state of sequestration. Obtaining proper permission from governmental bodies and owners of the space in the reservoir must also be accomplished as part of the process.
There are also many challenges with carbon sequestration that involve the collection, isolation, transport, measurement, placement and post-placement of the CO2. CO2 may have to be isolated, dried and/or collected, for example from the exhaust of power plants or other high volume sources of CO2. CO2 may be compressed for transportation. One could sequester CO2 while in a gaseous state but it would generally be preferable to do so while the CO2 is in a supercritical fluid state or phase, at temperatures above 31.2° C. and pressures above 72.8 atmospheres. CO2 is generally stored in supercritical phase for efficiency reasons. CO2 in a supercritical phase can be very dense which allows more CO2 (in mass units) to be injected into a defined pore space in a formation. Accordingly, CO2 may have to be converted from a gaseous state to a supercritical liquid state. On the other hand, CO2 may also be sequestered in some other state, for example, as a CO2-saturated brine.
In some cases, CO2 may be sequestered close to where it is produced, but in many cases, the CO2 may have to be transported some distance to a suitable sequestration site. Measurement of the CO2 may be needed at different points in the process. One may have to provide for buffering the CO2 (storing the CO2 temporarily, for example, in properly constructed vessels at a surface location) to allow for periods of down-time or disruption in the sequestration process.
There are many sources of CO2 but they can be loosely divided into naturally occurring CO2 (such as CO2 which may be produced along with hydrocarbons in an oil or gas well) or “anthropogenic” CO2 which may be created by burning fossil fuels or by other man-made activities.
One embodiment of the present invention provides a method of facilitating sequestration of naturally occurring carbon dioxide including simulating production of a fluid containing carbon dioxide through an underground reservoir to a production well using a reservoir simulator; simulating production of a fluid containing carbon dioxide from the reservoir to the surface through a production well using a flow simulator; simulating separation of the CO2 from the fluid produced using a process simulator; simulating processing such as compression and dehydration of carbon dioxide at the surface using a process simulator; simulating transport of carbon dioxide from the surface through an injection well and into an underground formation using a second flow simulator; providing economic analysis for all the above activities including carbon sequestration process using an economics modeler; and facilitating an exchange of data among one or more of the reservoir simulator, flow simulator, economics modeler, process simulator and second flow simulator using a software interface.
One embodiment of the present invention provides a method of facilitating sequestration of anthropogenic carbon dioxide including providing economic analysis for the carbon sequestration process using an economics modeler; simulating production, processing and movement of carbon dioxide at the surface using a process simulator; simulating transport of carbon dioxide from the surface through an injection well and into an underground formation using a flow simulator; and facilitating an exchange of data among one or more of the economics modeler, process simulator and injection flow simulator, using a software interface. One or more advantages of the present invention may become apparent to those of skill in art by reference to the figures, the description that follows and the claims.
In the following detailed description of a preferred embodiment and other embodiments of the invention, reference is made to the accompanying drawings. It is to be understood that those of skill in the art will readily see other embodiments and changes may be made without departing from the scope of the invention.
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A software interface, such as Avocet IAM, is used in an embodiment of the invention to facilitate integrated modeling of the carbon sequestration process. Avocet IAM is a commercially available Schlumberger software for oil and gas operations which integrates reservoir, well, surface network and process facility models into a single decision making framework for operations and planning users. Avocet IAM provides valuable production rate information and economic predictions across the entire asset and for the entire asset life. The present invention provides in part an adaptation of a software interface such as Avocet IAM (also known as Avocet Integrated Asset Modeler) so that it can be used in a process to model either naturally occurring CO2 production and sequestration or CO2 production and sequestration process for anthropogenic CO2 or both. One embodiment of the present invention uses a software interface, such as Avocet IAM, to create an interface between one or more various software programs (reservoir modeling which may include phase behavior, flow in wells and pipes; plant systems, and economics evaluation) to allow them to communicate among each other. An embodiment of the present invention so configured to be used for example to predict elevation or subsidence or to determine other things including but not limited to whether sequestered CO2 has become affixed in a sequestration reservoir, whether there has been aquifer contamination or leakage of CO2 to the surface. If problems are detected, steps may be taken to fix the problem and/or improve the problem situation. If inefficiencies are detected, steps can be taken to improve efficiencies.
With this new application of a software interface, such as AVOCET IAM (the best selection the inventors are aware of), it is possible to build a workflow that models the fate of CO2 from its production (anthropogenic or natural) to its injection for sequestration. Patent applications pertinent to AVOCET have been previously filed and are incorporated herein by reference: US Patent Publication No. 20080103743(A1), 20080133194(A1), 20090012765(A1), and 20080262802(A1).
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Specially written software could be used for the simulators and modeling software discussed in the paragraph above, but commercially available software may also be used. To give examples, for the first and second reservoir simulators 315, 350, commercially available software such as FrontSim or ECLIPSE (such as ECLIPSE E300 Dual porosity/permeability model) may be used. Both FrontSim and ECLIPSE are available from Schlumberger. Other commercially available reservoir simulators include Tough2, CMG, VIP, and STOMP. The flow simulator 325 may be commercially available software such as PIPESIM or HYSIS. For the economic modeler software 330 a properly configured Excel file could be used to perform this function. Alternatively, commercially available programs, such as PEEP, could be used as the economic modeler of an embodiment of the present invention if “other” is selected as a component when using PEEP, instead of selecting oil or gas as the component. The process simulator 335 may be commercially available software such as HYSIS. In addition to PIPESIM, other commercial software such as Aspen Plus, Pro II, HYSYS, Pro Max, Winsim could potentially be used as the transportation simulator (not depicted in
The injection flow simulator 340 may be the same as the flow simulator used to model the CO2 being produced through the production well or the injection simulator may be different. As with the flow simulator, commercially available software such as PIPESIM or HYSIS could be used as the injection simulator. The sequestration reservoir 355 may be the same as the producing reservoir 300 (as depicted in
Use of the software interface such as AVOCET IAM with the first 320 and second 350 reservoir simulators, the flow simulator, the economics modeler 330, the a process simulator 335, the injection flow simulator 340, and/or the transportation simulator (collectively “associated simulators”) permits simulation of what-if scenarios, for example a startup on a cold day, an interruption of carbon dioxide supply, a contaminant spike in the stream of produced fluid or CO2 stream, a pressure buildup in a pipeline section, or an examination of limits on water content. Use of the software interface with the associated simulators also permits dynamic simulation under changing conditions as well as fine tuning of the overall model with current operating data. Use of the software interface with the associated simulators also permits process and instrumentation layout, equipment sizing, and/or pipeline sizing. Use of the software interface with the associated simulators could allow adjustments to flow patterns or processing of the CO2 based on conditions or events in the carbon sequestration process. For example, a problem with an injection well might trigger buffering (or if permitted, venting) of processed CO2 upstream of the injection well, choking back or a shut-in of the flow of CO2 upstream of the injection well or a slowdown or shut-in at the carbon processing facility. Simulation of the flow of CO2 within the second reservoir by the second reservoir simulator could monitor the response of the reservoir to the injection of CO2 and might prompt adjustments in the injection rate. Data from the simulation of the flow of CO2 within the second reservoir by the second reservoir simulator sent to the software interface could also help determine whether additional injection wells are needed, whether the second reservoir could be used for additional injection wells or whether a new sequestration reservoir is needed, and well as helping to determine advantageous locations of injection wells or monitoring wells. Problems at the carbon processing facility as monitored by the processing simulator might trigger a shut-in of the production well or buffering of (or if regulations permit, venting of) the CO2 upstream of the carbon processing facility.
There could be a plurality of injection wells each injecting CO2 into one or more reservoirs and/or a plurality of production wells each producing from one or more reservoirs. The plurality of production wells could be associated with one or a plurality of upstream surface production facilities. The plurality of injection wells and/or a plurality of production wells could be associated with one carbon processing facility or a plurality of carbon processing facilities.
For the economic modeler 405 of the embodiment of the present invention depicted in
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Use of the software interface with the associated anthropogenic simulators could allow adjustments to flow patterns or processing of the CO2 based on conditions or events in the carbon sequestration process. For example, a problem with an injection well might trigger buffering (or if permitted, venting) of processed CO2 upstream of the injection well, choking back or a shut-in of the flow of CO2 upstream of the injection well or a slowdown or shut-in at the carbon processing facility. Shut-ins of the carbon processing facility are likely to be strongly disfavored as that might require shut down of the CO2 source, such as a power plant. So in the event of a mechanical problem with an injection well, for example, the processed CO2 intended for the injection well might be diverted to other injection wells. Simulation of the flow of CO2 within the second reservoir by the second reservoir simulator could monitor the response of the reservoir to the injection of CO2 and might prompt adjustments in the injection rate. Data from the simulation of the flow of CO2 within the second reservoir by the second reservoir simulator sent to the software interface could also help determine whether additional injection wells are needed, whether the second reservoir could be used for additional injection wells or whether a new sequestration reservoir is needed, and well as helping to determine advantageous locations of injection wells or monitoring wells. Problems at the carbon processing facility as monitored by the processing simulator might trigger buffering of (or if regulations permit, venting of) the CO2 upstream of the carbon processing facility.
There could be a plurality of injection wells each injecting CO2 into one or more reservoirs and/or a plurality of production wells each producing from one or more reservoirs. The plurality of production wells could be associated with one or a plurality of upstream surface production facilities. The plurality of injection wells and/or a plurality of production wells could be associated with one carbon processing facility or a plurality of carbon processing facilities.
Embodiments of the invention may be implemented on virtually any type of computer regardless of the platform being used. For example, as shown in
Further, those skilled in the art will appreciate that one or more elements of the aforementioned computer system 600 may be located at a remote location and connected to the other elements over a network 614. Further, embodiments of the invention may be implemented on a distributed system having a plurality of nodes, where each portion of the invention may be located on a different node within the distributed system. In one embodiment of the invention, the node corresponds to a computer system. Alternatively, the node may correspond to a processor with associated physical memory. The node may alternatively correspond to a processor with shared memory and/or resources. Further, software instructions to perform embodiments of the invention may be stored on a computer readable medium such as a compact disc (CD), a diskette, a tape, or any other computer readable storage device.
Although the description herein has focused on CO2 sequestration, one or more embodiments of the present invention may be used for sequestration of other substances such as carbon monoxide, sulfur dioxide or other substances where sequestration may be the disposal means of choice.
This application claims priority under 35 U.S.C. §119(e) from Provisional Patent Application Ser. No. 61/169,622 filed Apr. 15, 2009, and is also a continuation in part of co-pending applications initially filed as U.S. Provisional Patent Application No. 60/855,262 filed Oct. 30, 2006, subsequently filed as U.S. application Ser. No. 11/929,811 and U.S. application Ser. No. 11/929,921, both filed Oct. 30, 2007, and entitled “System and Method for Performing Oilfield Simulation Operations” and of International Application No. PCT/US2007/83070 and International Application No. PCT/US2007/83072, both also filed Oct. 30, 2007, having the same title.
Number | Date | Country | |
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61169622 | Apr 2009 | US | |
60855262 | Oct 2006 | US | |
60855262 | Oct 2006 | US |
Number | Date | Country | |
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Parent | 11929811 | Oct 2007 | US |
Child | 12761368 | US | |
Parent | 11929921 | Oct 2007 | US |
Child | 11929811 | US |