Dynamic Infill Producer Well Placement

This disclosure relates to computer-implemented methods, computer-readable media and computer systems to determine placement of and control machinery to form wellbores in hydrocarbon fields.

Hydrocarbon entrapped in subsurface reservoirs can be raised to the surface (i.e., produced) by drilling wellbores from the surface to the subsurface reservoirs through a subterranean zone (e.g., a formation, a portion of a formation, multiple formations). The pressure of the subterranean zone causes the hydrocarbons to naturally flow to the surface. Over time, the pressure decreases necessitating secondary and tertiary forms of hydrocarbon recovery (sometimes called enhanced oil recovery or EOR) techniques. One such EOR technique is the formation of injector wells surrounding producer wells, i.e., the wells through which the hydrocarbons are produced to the surface. Injecting fluids (e.g., water) through the injector wells sweeps the hydrocarbons towards the producer wells and ultimately to the surface. Infill drilling is another EOR technique in which additional wells are drilled near existing wells. The infill wells (or infill producer wells) are strategically formed in regions of the subterranean zone in which hydrocarbons are expected to reside.

This disclosure describes technologies relating to computer-implemented methods, computer-readable media and computer systems to dynamically place infill producer wells in a hydrocarbon field and to control machinery to form such wells through the subterranean zone.

The details of one or more implementations of the subject matter described in this specification are set forth in the accompanying drawings and the description below. Other features, aspects, and advantages of the subject matter will become apparent from the description, the drawings, and the claims.

Like reference numbers and designations in the various drawings indicate like elements.

This disclosure describes computer-implemented methods, computer-readable storage media and computer systems that can implement an automated workflow to place infill producer wells at optimal sweet spots (or sweet spot locations) in a hydrocarbon field. The geographic locations of the infill producer wells are selected based on certain criteria that each infill producer well satisfies, e.g., horizontal, vertical or slanted well. The infill producer wells are formed by wellbore drilling machinery that are controlled to automatically drill the wells in response to a trigger event being triggered. For example, the trigger event can be a drop in production flow rate from producer wells, i.e., all producers that are already drilled, below a certain threshold production flow rate. During and after formation of the infill producer wells, the production flow rate from the producer wells and any newly formed infill producer wells can continue to be monitored. Once the production flow rate increases beyond the threshold production flow, the operations of the wellbore drilling machinery can be stopped. A computer system can implement the process of identifying optimal sweet spots to place the infill producer wells. In parallel, the computer system can also implement the process of monitoring the production flow rate from the producer wells and the newly formed infill producer wells. The operations of the wellbore drilling machinery to form the infill producer wells can be automatically (i.e., without human intervention) be performed by the same computer system.

Implementing the techniques described here can yield some advantages. Optimal locations for infill producer wells can be determined computationally and automatically without human intervention. The optimal locations for infill producer wells can change over time due to changes in oil saturation over time. Tracking the changes of the optimal locations at each time step would be very time consuming. By implementing the techniques described here, changes to the optimal locations be determined effectively and more efficiently. Such operations can save computational resources and time. Wellbore drilling machinery to form infill producer wells can be controlled using computer systems that implement simulations to determine optimal locations for infill producer wells. Doing so can reduce human error and can also save computational resources.

are schematic diagrams of a computer systemoperatively coupled to a computer monitorthat shows a computational modelof a hydrocarbon field. The computer system includes a computer-readable storage mediumA and one or more processorsB. The computer-readable storage mediumA (e.g., a non-transitory computer-readable storage medium) can store computer instructions that are executable by the one or more processorsB to perform operations described in this disclosure. A computer monitor(e.g., a display device) can be operatively connected to the computer system. The computer systemcan also be connected to input devices (not shown). The computer systemcan receive input, e.g., from the input devices or from other sources, process the input and display output on the computer monitor.

In some implementations, the computer systemcan run a simulation of the hydrocarbon field with the subsurface hydrocarbon reservoirs. The computer systemcan show the output of the simulation as a model(or a map) on the computer monitor. The computer systemcan implement the simulation to analyze the geographical area covered by the hydrocarbon field. Based on the analysis, the computer systemcan generate the model. The hydrocarbon field can include certain geographic areas that are more saturated with hydrocarbons compared to other geographic areas in the hydrocarbon field. The computer systemcan show such geographic areas as regionsin the model. For example, the computer systemcan show the regionsin a different color compared to a color of the rest of the model. In this manner, the computer systemcan implement the simulation to identify specific geographic areas in the hydrocarbon field that are rich in hydrocarbons.

Producer wells can be formed in such hydrocarbon-rich geographic areas of the hydrocarbon field. For example, wellbore drilling machinery can be used to form each producer well. After completion, each well can be commissioned to produce hydrocarbons from the hydrocarbon-rich geographic areas. Various well and hydrocarbon properties including, for example, a hydrocarbon production flow rate, can be monitored. To do so, various sensors and flowmeters can be deployed above or below the surface of the well and at multiple downhole locations. The values sensed by the sensors and flowmeters including the hydrocarbon production flow rate value can be periodically (e.g., once an hour, once a minute, once per second, more than once per second or other frequency) transmitted to the computer system. The computer systemcan continue to implement the simulation of the hydrocarbon field using the various values received from the various sensors and flowmeters. Alternatively or in addition, the computer systemcan implement the simulation of the hydrocarbon field using simulation data generated by the computer system.

Turning to the computer monitor, each producer well can be represented on the model. For example, a user of the computer systemcan select locations on the modelon which the producer wells are formed. In response, the computer systemcan display representations of the producer well on the model. For example, the computer systemcan display object, object, object, each representing a-producer well, within the regionsrepresenting the hydrocarbon-rich geographic areas of the hydrocarbon field. Thus, the modelinschematically shows hydrocarbon-rich geographic areas in the hydrocarbon field and producer wells formed in those areas during the early stages of wellbore production.

Over time, as more hydrocarbon is produced from the hydrocarbon field, the hydrocarbon saturation levels change. Such change can be due to removal of the hydrocarbons from the hydrocarbon field. Alternatively or in addition, such change can be due to migration of the hydrocarbons within the hydrocarbon field. Migration can also cause hydrocarbons to move away from the hydrocarbon field to adjacent geographic areas and/or cause hydrocarbons from adjacent geographic areas to migrate into the hydrocarbon field. As mentioned above, the computer systemcontinues to implement the simulation of the hydrocarbon field using the various values received from the various sensors and flowmeters over time or using simulation data generated by the computer system(or both).

schematically shows a modified modelthat appears different from the modelschematically shown in. The modified modelis a representation of a change in the hydrocarbon saturation levels in the hydrocarbon field. In some instances, the modified modelshows that geographic areas saturated in hydrocarbons are no longer near the producer wells drilled during early stages of hydrocarbon production. In such instances, production flow rate through the producer wells can decrease, e.g., below threshold production flow rates. In response, secondary or tertiary EOR techniques can be implemented to enhance production through the hydrocarbon field. Such EOR techniques can include forming infill producer wells in strategic locations in the hydrocarbon field to enhance production through the new producer wells.

As described below with reference to, the computer systemcan computationally and automatically (i.e., without human intervention) determine optimal locations for the infill producer wells. To do so, the computer systemcan use data from the simulation that identifies sweet spots in which infill producer wells can be formed. The computer systemcan receive input (e.g., from a user of the computer system) identifying characteristics of the infill producer wells. Based on data received from the simulation and input identifying characteristics of the infill producer wells, the computer systemcan automatically control wellbore drilling machineryto form one or more infill producer wells in the hydrocarbon field. In addition, the computer systemcan display objects (e.g., object, object, object) on the modified model. Each object can represent a corresponding infill producer well formed by the wellbore drilling machinery. An object representing an infill producer well can have a different appearance compared to an object representing a producer well. As described below, the computer systemcan control the wellbore drilling machineryto form the infill producer wells in response to a triggering event (e.g., producer wells' production flow rate dropping below a threshold production flow rate).

is a flowchart of an example of a computer-implemented methodof forming infill producer wells in a hydrocarbon field in response to a trigger event. The infill producer wells can be formed by wellbore drilling machinery. The machinery can be controlled by a computer system (e.g., the computer system) based on hydrocarbon saturation data and based on characteristics of the infill producer wells.

At, an area of interest in a hydrocarbon field is identified. The area of interest represents a geographical area in which multiple infill producer wells are to be formed. The area of interest can be certain layers in the subterranean zone or certain geographic areas in the hydrocarbon field or a combination of them. In some implementations, the area of interest can be determined using the simulation described earlier. The computer systemcan implement the simulations to determine, among other things, hydrocarbon saturation levels in the hydrocarbon field. From the determined hydrocarbon saturation levels, the computer systemcan identify geographical areas with higher hydrocarbon saturation compared to other geographical areas in the hydrocarbon field. For example, the computer systemcan compare hydrocarbon saturation values at different locations in the hydrocarbon field. The computer systemcan determine the hydrocarbon saturation values using data received from multiple sensors deployed across the hydrocarbon field at different depths in the subterranean zone or using simulation data generated by the computer system(or both). The computer systemcan process the received data to determine the hydrocarbon saturation values. The computer systemcan then identify a maximum (or a maximum range) of hydrocarbon saturation values based on the comparison. The computer systemcan then identify the locations at which the maximum (or maximum range) of hydrocarbon saturation values were measured as the area of interest.

Alternatively or in addition, the computer systemcan receive the area of interest from a user of the computer system. For example, as described above, the computer systemcan display a model() or a modified model() that includes representations of geographical areas with hydrocarbon saturation. A user of the computer systemcan select portions of the model that correspond to geographical areas of high hydrocarbon saturation.

At, multiple sweet spot areas can be identified within the area of interest. The computer systemcan identify sweet spot areas by solving sweet spot formulas that identify sweet spot areas. For oil reservoirs, the sweet spot formula is shown in Equation 1.

In Equation 1, Sis the oil saturation and Φ is rock porosity. The oil saturation and rock porosity can be determined based on the simulation implemented by the computer system. In one example, if the output of Equation 1 is ≥30%, then that region is a sweet spot area.

For gas reservoirs, the sweet spot formula is shown in Equation 2.

In Equation 1, Sis the gas saturation and Φ is rock porosity. The gas saturation and rock porosity can be determined based on the simulation implemented by the computer system.

The computer systemcan implement other sweet spot formulas as well. Further, the computer systemcan implement different sweet spot formulas at different instances of implementing the computer-implemented method. For example, an operator of the computer systemcan select a first sweet spot formula at a first instance of implementing the methodand a second, different sweet spot formula at a second, subsequent instance of implementing the method.

In some implementations, to identify the sweet spot areas, the computer systemcan implement a clustering algorithm on the sweet spot areas determined using the sweet spot formula. For example, the clustering algorithm can be a density-based clustering algorithm (e.g., DBSCAN) that segregates data points into high-density regions separated by low density regions. The DBSCAN algorithm can automatically determine clusters based on the density of the data point. The output of the method stepare clustered sweet spot areas in which infill producer wells can be drilled to enhance hydrocarbon recovery through the new producer wells.

At, well criteria associated with the multiple infill producer wells is received. For example, using the input devices, a user of the computer systemcan provide well criteria for each infill producer well. The criteria can include, for example, a well length, azimuth angle, production constraints, collision distance with existing wells in the hydrocarbon field, spacing relative to other infill producer wells, whether the infill producer well is a vertical, horizontal or slanted well, to name a few. Infill producer wells that will be formed in the clustered sweet spot areas will have the criteria received by the computer system in method step.

At, a trigger event to trigger forming the infill producer wells is received. The occurrence of the trigger event indicates that infill producer wells need to be drilled. In some implementations, the trigger event is a decrease in production flow rate from the producer wells. Each producer well can be associated with a threshold production flow rate value. Multiple producer wells can be associated with a similar threshold production flow rate value, which can be a summation of the threshold production flow rate value associated with each producer well. The computer systemcan receive the threshold production flow rate value and store the value in the computer-readable storage mediumB (). Another example of a trigger event is decrease in hydrocarbon production rate (e.g., measured in barrels per day or billions of barrels per day) below a threshold hydrocarbon production rate value.

At, a determination is made that the trigger event has occurred. As described earlier, the computer systemcontinuously receives various values and signals representing well and flow characteristics from various sensors and flowmeters deployed in and around the producer well. Alternatively or in addition, the occurrence of the trigger event can be determined based on simulation data generated by the computer system. The received values include production flow rate from the producer well. The computer systemperiodically compares the received production flow rate value with the threshold production flow rate value stored in the computer-readable storage mediumB (). If the received value is less than the threshold production flow rate value, then the computer systemdetermines that the trigger event has occurred. The determination signifies that the production flow rate from the producer well (or wells) has dropped to a level at which EOR techniques need to be implemented. Specifically and in the context of this disclosure, the determination that the trigger event has occurred signifies that infill producer wells need to be drilled according to the well criteria in the sweet spot areas identified as described earlier.

At, in response to determining that the trigger event has occurred, the wellbore drilling machinery are controlled to form multiple infill producer wells according to the well criteria in the multiple sweet spot areas. In particular, the computer systemautomatically (i.e., without human intervention) controls the wellbore drilling machinery to drill the infill producer wells according to the criteria received at method step.

While drilling the infill producer wells and after the infill producer wells have been drilled, the computer systemcontinues to receive values from the various sensors and flowmeters as described above. The infill producer wells enhance hydrocarbon recovery from the hydrocarbon field by producing hydrocarbons that have migrated through the new producer wells (i.e., the infill producer wells). As the hydrocarbon recovery is enhanced, the values received from the sensors and flowmeters communicate an increase in production flow rate through all producer wells. Alternatively or in addition, the simulation data generated by the computer systemcommunicates an increase in production flow rate through all producer wells. The computer systemcompares the increased production flow rate with the threshold production flow rate. In particular, the computer systemcompares the increased production flow from the existing producer wells and any newly formed infill producer wells through which production has commenced. Upon determining that the increased production flow rate is greater than the threshold production flow rate, the computer systemstops the wellbore drilling machinery from forming more infill producer wells.

In addition, while the infill producer wells are implemented to enhance hydrocarbon recovery from the hydrocarbon reservoir, the computer systemcontinues to implement the simulation of the hydrocarbon field. Over time, the hydrocarbon saturation in the field can change as described above. Such change can once again cause the production flow rate from the producer wells to drop below the threshold production flow rate value (or a different trigger event to be triggered). In response, the computer systemcan once again implement the methodto identify sweet spot areas. The computer systemcan receive criteria for new infill producer wells to be formed in the identified sweet spot areas. The computer systemcan control wellbore drilling machinery to form the new infill producer wells. In this manner, the computer systemcan implement an automated workflow of monitoring the hydrocarbon field and automatically forming inflow producer wells to enhance hydrocarbon recovery from the hydrocarbon field.

illustrates hydrocarbon production operationsthat include both one or more field operationsand one or more computational operations, which exchange information and control exploration for the production of hydrocarbons. In some implementations, outputs of techniques of the present disclosure can be performed before, during, or in combination with the hydrocarbon production operations, specifically, for example, either as field operationsor computational operations, or both.

Examples of field operationsinclude forming/drilling a wellbore, reservoir characterization, hydraulic fracturing, producing through the wellbore, injecting fluids (such as water) through the wellbore, to name a few. In some implementations, methods of the present disclosure can trigger or control the field operations. For example, the methods of the present disclosure can generate data from hardware/software including sensors and physical data gathering equipment (e.g., seismic sensors, well logging tools, flow meters, and temperature and pressure sensors). The methods of the present disclosure can include transmitting the data from the hardware/software to the field operationsand responsively triggering the field operationsincluding, for example, generating plans and signals that provide feedback to and control physical components of the field operations. Alternatively or in addition, the field operationscan trigger the methods of the present disclosure. For example, implementing physical components (including, for example, hardware, such as sensors) deployed in the field operationscan generate plans and signals that can be provided as input or feedback (or both) to the methods of the present disclosure.

Examples of computational operationsinclude one or more computer systemsthat include one or more processors and computer-readable media (e.g., non-transitory computer-readable media) operatively coupled to the one or more processors to execute computer operations to perform the methods of the present disclosure. The computational operationscan be implemented using one or more databases, which store data received from the field operationsand/or generated internally within the computational operations(e.g., by implementing the methods of the present disclosure) or both. For example, the one or more computer systemsprocess inputs from the field operationsto assess conditions in the physical world, the outputs of which are stored in the databases. For example, seismic sensors of the field operationscan be used to perform a seismic survey to map subterranean features, such as facies and faults. In performing a seismic survey, seismic sources (e.g., seismic vibrators or explosions) generate seismic waves that propagate in the earth and seismic receivers (e.g., geophones) measure reflections generated as the seismic waves interact with boundaries between layers of a subsurface formation. The source and received signals are provided to the computational operationswhere they are stored in the databasesand analyzed by the one or more computer systems.

In some implementations, one or more outputsgenerated by the one or more computer systemscan be provided as feedback/input to the field operations(either as direct input or stored in the databases). The field operationscan use the feedback/input to control physical components used to perform the field operationsin the real world.

For example, the computational operationscan process the seismic data to generate three-dimensional (3D) maps of the subsurface formation. The computational operationscan use these 3D maps to provide plans for locating and drilling exploratory wells. In some operations, the exploratory wells are drilled using logging-while-drilling (LWD) techniques which incorporate logging tools into the drill string. LWD techniques can enable the computational operationsto process new information about the formation and control the drilling to adjust to the observed conditions in real-time.

The one or more computer systemscan update the 3D maps of the subsurface formation as information from one exploration well is received and the computational operationscan adjust the location of the next exploration well based on the updated 3D maps. Similarly, the data received from production operations can be used by the computational operationsto control components of the production operations. For example, production well and pipeline data can be analyzed to predict slugging in pipelines leading to a refinery and the computational operationscan control machine operated valves upstream of the refinery to reduce the likelihood of plant disruptions that run the risk of taking the plant offline.

In some implementations of the computational operations, customized user interfaces can present intermediate or final results of the above-described processes to a user. Information can be presented in one or more textual, tabular, or graphical formats, such as through a dashboard. The information can be presented at one or more on-site locations (such as at an oil well or other facility), on the Internet (such as on a webpage), on a mobile application (or app), or at a central processing facility.

The presented information can include feedback, such as changes in parameters or processing inputs, that the user can select to improve a production environment, such as in the exploration, production, and/or testing of petrochemical processes or facilities. For example, the feedback can include parameters that, when selected by the user, can cause a change to, or an improvement in, drilling parameters (including drill bit speed and direction) or overall production of a gas or oil well. The feedback, when implemented by the user, can improve the speed and accuracy of calculations, streamline processes, improve models, and solve problems related to efficiency, performance, safety, reliability, costs, downtime, and the need for human interaction.

In some implementations, the feedback can be implemented in real-time, such as to provide an immediate or near-immediate change in operations or in a model. The term real-time (or similar terms as understood by one of ordinary skill in the art) means that an action and a response are temporally proximate such that an individual perceives the action and the response occurring substantially simultaneously. For example, the time difference for a response to display (or for an initiation of a display) of data following the individual's action to access the data can be less than 1 millisecond (ms), less than 1 second(s), or less than 5 s. While the requested data need not be displayed (or initiated for display) instantaneously, it is displayed (or initiated for display) without any intentional delay, taking into account processing limitations of a described computing system and time required to, for example, gather, accurately measure, analyze, process, store, or transmit the data.

Events can include readings or measurements captured by downhole equipment such as sensors, pumps, bottom hole assemblies, or other equipment. The readings or measurements can be analyzed at the surface, such as by using applications that can include modeling applications and machine learning. The analysis can be used to generate changes to settings of downhole equipment, such as drilling equipment. In some implementations, values of parameters or other variables that are determined can be used automatically (such as through using rules) to implement changes in oil or gas well exploration, production/drilling, or testing. For example, outputs of the present disclosure can be used as inputs to other equipment and/or systems at a facility. This can be especially useful for systems or various pieces of equipment that are located several meters or several miles apart, or are located in different countries or other jurisdictions.

Implementations of the subject matter and the functional operations described in this specification can be implemented in digital electronic circuitry, in tangibly embodied computer software or firmware, in computer hardware, including the structures disclosed in this specification and their structural equivalents, or in combinations of one or more of them. Software implementations of the described subject matter can be implemented as one or more computer programs. Each computer program can include one or more modules of computer program instructions encoded on a tangible, non-transitory, computer-readable computer-storage medium for execution by, or to control the operation of, data processing apparatus. Alternatively, or additionally, the program instructions can be encoded in/on an artificially generated propagated signal. The example, the signal can be a machine-generated electrical, optical, or electromagnetic signal that is generated to encode information for transmission to suitable receiver apparatus for execution by a data processing apparatus. The computer-storage medium can be a machine-readable storage device, a machine-readable storage substrate, a random or serial access memory device, or a combination of computer-storage mediums.

The terms “data processing apparatus,” “computer,” and “electronic computer device” (or equivalent as understood by one of ordinary skill in the art) refer to data processing hardware. For example, a data processing apparatus can encompass all kinds of apparatus, devices, and machines for processing data, including by way of example, a programmable processor, a computer, or multiple processors or computers. The apparatus can also include special purpose logic circuitry including, for example, a central processing unit (CPU), a field programmable gate array (FPGA), or an application specific integrated circuit (ASIC). In some implementations, the data processing apparatus or special purpose logic circuitry (or a combination of the data processing apparatus or special purpose logic circuitry) can be hardware- or software-based (or a combination of both hardware- and software-based). The apparatus can optionally include code that creates an execution environment for computer programs, for example, code that constitutes processor firmware, a protocol stack, a database management system, an operating system, or a combination of execution environments. The present disclosure contemplates the use of data processing apparatuses with or without conventional operating systems, for example, LINUX, UNIX, WINDOWS, MAC OS, ANDROID, or IOS.

A computer program, which can also be referred to or described as a program, software, a software application, a module, a software module, a script, or code, can be written in any form of programming language. Programming languages can include, for example, compiled languages, interpreted languages, declarative languages, or procedural languages. Programs can be deployed in any form, including as stand-alone programs, modules, components, subroutines, or units for use in a computing environment. A computer program can, but need not, correspond to a file in a file system. A program can be stored in a portion of a file that holds other programs or data, for example, one or more scripts stored in a markup language document, in a single file dedicated to the program in question, or in multiple coordinated files storing one or more modules, sub programs, or portions of code. A computer program can be deployed for execution on one computer or on multiple computers that are located, for example, at one site or distributed across multiple sites that are interconnected by a communication network. While portions of the programs illustrated in the various figures may be shown as individual modules that implement the various features and functionality through various objects, methods, or processes, the programs can instead include a number of sub-modules, third-party services, components, and libraries. Conversely, the features and functionality of various components can be combined into single components as appropriate. Thresholds used to make computational determinations can be statically, dynamically, or both statically and dynamically determined.

The methods, processes, or logic flows described in this specification can be performed by one or more programmable computers executing one or more computer programs to perform functions by operating on input data and generating output. The methods, processes, or logic flows can also be performed by, and apparatus can also be implemented as, special purpose logic circuitry, for example, a CPU, an FPGA, or an ASIC.

Computers suitable for the execution of a computer program can be based on one or more of general and special purpose microprocessors and other kinds of CPUs. The elements of a computer are a CPU for performing or executing instructions and one or more memory devices for storing instructions and data. Generally, a CPU can receive instructions and data from (and write data to) a memory. A computer can also include, or be operatively coupled to, one or more mass storage devices for storing data. In some implementations, a computer can receive data from, and transfer data to, the mass storage devices including, for example, magnetic, magneto optical disks, or optical disks. Moreover, a computer can be embedded in another device, for example, a mobile telephone, a personal digital assistant (PDA), a mobile audio or video player, a game console, a global positioning system (GPS) receiver, or a portable storage device such as a universal serial bus (USB) flash drive.

Computer readable media (transitory or non-transitory, as appropriate) suitable for storing computer program instructions and data can include all forms of permanent/non-permanent and volatile/non-volatile memory, media, and memory devices. Computer readable media can include, for example, semiconductor memory devices such as random access memory (RAM), read only memory (ROM), phase change memory (PRAM), static random access memory (SRAM), dynamic random access memory (DRAM), erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), and flash memory devices. Computer readable media can also include, for example, magnetic devices such as tape, cartridges, cassettes, and internal/removable disks. Computer readable media can also include magneto optical disks and optical memory devices and technologies including, for example, digital video disc (DVD), CD ROM, DVD+/−R, DVD-RAM, DVD-ROM, HD-DVD, and BLURAY. The memory can store various objects or data, including caches, classes, frameworks, applications, modules, backup data, jobs, web pages, web page templates, data structures, database tables, repositories, and dynamic information. Types of objects and data stored in memory can include parameters, variables, algorithms, instructions, rules, constraints, and references. Additionally, the memory can include logs, policies, security or access data, and reporting files. The processor and the memory can be supplemented by, or incorporated in, special purpose logic circuitry.

Implementations of the subject matter described in the present disclosure can be implemented on a computer having a display device for providing interaction with a user, including displaying information to (and receiving input from) the user. Types of display devices can include, for example, a cathode ray tube (CRT), a liquid crystal display (LCD), a light-emitting diode (LED), and a plasma monitor. Display devices can include a keyboard and pointing devices including, for example, a mouse, a trackball, or a trackpad. User input can also be provided to the computer through the use of a touchscreen, such as a tablet computer surface with pressure sensitivity or a multi-touch screen using capacitive or electric sensing. Other kinds of devices can be used to provide for interaction with a user, including to receive user feedback including, for example, sensory feedback including visual feedback, auditory feedback, or tactile feedback. Input from the user can be received in the form of acoustic, speech, or tactile input. In addition, a computer can interact with a user by sending documents to, and receiving documents from, a device that is used by the user. For example, the computer can send web pages to a web browser on a user's client device in response to requests received from the web browser.

The term “graphical user interface,” or “GUI,” can be used in the singular or the plural to describe one or more graphical user interfaces and each of the displays of a particular graphical user interface. Therefore, a GUI can represent any graphical user interface, including, but not limited to, a web browser, a touch screen, or a command line interface (CLI) that processes information and efficiently presents the information results to the user. In general, a GUI can include a plurality of user interface (UI) elements, some or all associated with a web browser, such as interactive fields, pull-down lists, and buttons. These and other UI elements can be related to or represent the functions of the web browser.

Implementations of the subject matter described in this specification can be implemented in a computing system that includes a back end component, for example, as a data server, or that includes a middleware component, for example, an application server. Moreover, the computing system can include a front-end component, for example, a client computer having one or both of a graphical user interface or a Web browser through which a user can interact with the computer. The components of the system can be interconnected by any form or medium of wireline or wireless digital data communication (or a combination of data communication) in a communication network. Examples of communication networks include a local area network (LAN), a radio access network (RAN), a metropolitan area network (MAN), a wide area network (WAN), Worldwide Interoperability for Microwave Access (WIMAX), a wireless local area network (WLAN) (for example, using 802.11 a/b/g/n or 802.20 or a combination of protocols), all or a portion of the Internet, or any other communication system or systems at one or more locations (or a combination of communication networks). The network can communicate with, for example, Internet Protocol (IP) packets, frame relay frames, asynchronous transfer mode (ATM) cells, voice, video, data, or a combination of communication types between network addresses.