Abstract:
A sensing transducer apparatus measures specific chemicals or classes of chemicals. The apparatus includes an electromagnetic transducer comprising at least two electrodes wherein at least one of the electrodes is on an electrically and mechanically stable substrate, and a chemically sensitive material having an affinity for a dispersed chemical or class of chemicals in a single or multiphase analyte, the chemically sensitive material disposed on or adjacent to the electromagnetic transducer.

Description:
CROSS-REFERENCE TO RELATED APPLICATION(S) AND CLAIM OF PRIORITY 
       [0001]    The present application claims priority to U.S. Provisional Patent Application Ser. No. 61/738,926 filed Dec. 18, 2012, entitled “PRODUCTION RESERVOIR AND WELL MANAGEMENT SYSTEM USING CONTINUOUS CHEMICAL MEASUREMENT”. The content of the above-identified patent document is incorporated herein by reference. The present application also includes some common text and/or figures as, but is otherwise unrelated to, concurrently filed U.S. patent application Ser. No. ______ (Docket Number NEOT01-00002), which is hereby incorporated by reference. 
     
    
     TECHNICAL FIELD 
       [0002]    The present disclosure relates to direct chemical detection in a complex single-phase or multiphase flow from a well or in a pipeline. The present disclosure also relates to real-time chemical sensing utilizing temporary or permanent apparatuses, such as logging tools, with electronics for measuring the chemical properties of a single-phase or multiphase flow in one or more wells. The present disclosure further relates to a real-time chemical sensor network system and method to gather chemical flow data, both subterranean and at the surface. In addition, the present disclosure relates to the management of underground reservoirs, such as oil, natural gas, water and geothermal reservoirs, for production optimization. 
       BACKGROUND 
       [0003]    Oil, natural gas, water, or other wells can be likened to sophisticated high pressure, high temperature factories. Well and reservoir management often requires a system-level approach with direct knowledge of the processes and their outcomes for the most effectively optimized production. Geochemical modeling capabilities are fairly advanced, but applications to field problems remain challenging due to limited availability of relevant and timely field data and the scale dependence of parameters. Current approaches often only allow snapshots of the outcomes and, not being continuous, can only guess at the processes. This causes inefficient remediation efforts that are sometimes even destructive. 
       SUMMARY 
       [0004]    In some embodiments, the present disclosure provides a continuous method and system for reservoir and well management based on direct in-well chemical measurements for a reservoir fluid composed of liquid, gas or supercritical fluid components with dissolved or dispersed solids, coupled with pre-production or other production data on the reservoir. By continuous processing of chemical data delivered from remote sites, some embodiments of the present disclosure can identify and respond quickly when wells go offline or move outside normal operating conditions. This can have huge benefits in preventing hazardous outcomes, improving safety and environmental management, and progressively reduce uncertainty, which can ultimately lead to reduced operating costs. 
         [0005]    Various advantages can be obtained depending on the implementation. For example, some embodiments of the present disclosure reduce uncertainty in a broad sense to allow production extension through optimum reservoir management. Some embodiments of the present disclosure also provide for more cost effective monitoring and production of a well or reservoir. Some embodiments of the present disclosure further decrease the time it takes to obtain a real-time dynamic fluid flow full-field multiphase reservoir simulation model that fits obtained data and that can be used for timely interpretation of the simulation model for prediction of future situations. Moreover, some embodiments of the present disclosure provide a direct chemical measurement system for surface or sub-surface deployment that can be used in the harsh environment of a well. In addition, some embodiments of the present disclosure provide a chemical sensor whose data processing for classification, identification and concentration is completely self-contained so that its external communication requirements for data transportation are reduced or minimized. 
         [0006]    In particular embodiments, the technologies described here and the information they provide can be integrated with standard reservoir and production management tools, databases and models to contribute information to guide real-time reservoir optimization models. 
         [0007]    In one embodiment, a sensing transducer apparatus for measuring specific chemicals or classes of chemicals is provided. The apparatus includes an electromagnetic transducer comprising at least two electrodes wherein at least one of the electrodes is on an electrically and mechanically stable substrate, and a chemically sensitive material having an affinity for a dispersed chemical or class of chemicals in a single or multiphase analyte, the chemically sensitive material disposed on or adjacent to the electromagnetic transducer. 
         [0008]    In another embodiment, a sensing apparatus for continuous measuring of chemicals or classes of chemicals is provided. The sensing apparatus includes an electromagnetic transducer comprising at least two electrodes wherein at least one of the electrodes is on an electrically and mechanically stable substrate, a chemically sensitive material having an affinity for a dispersed chemical or class of chemicals in a single or multiphase analyte, the chemically sensitive material disposed on or adjacent to the electromagnetic transducer, a temperature sensor, a pressure sensor, a flow sensor, a signal generator configured to generate an electromagnetic signal into the transducer at one or more frequencies so as to generate a field that penetrates the chemically sensitive material, a detector configured to detect a change in impedance or resonant frequency of the transducer and chemically sensitive material when immersed in the analyte, and a microcontroller configured to control the signal generator and the detector. 
         [0009]    In yet another embodiment, a sensing system for continuous measurement of specific chemicals or classes of chemicals is provided. The sensing system includes an array of two or more sensing transducer apparatuses, each sensing transducer apparatus comprising a electromagnetic transducer comprising at least two electrodes wherein at least one of the electrodes is on an electrically and mechanically stable substrate, and a chemically sensitive material having an affinity for a dispersed chemical or class of chemicals in a single or multiphase analyte, the chemically sensitive material disposed on or adjacent to the electromagnetic transducer. The sensing system also includes a signal generator configured to generate an electromagnetic signal into each electromagnetic transducer at one or more frequencies so as to generate a field that penetrates the chemically sensitive material for each transducer, a detector configured to detect a change in complex impedance, resistive impedance or resonant frequency of each transducer when immersed in the analyte, a temperature sensor placed in the array, a pressure sensor, a flow sensor, a signal processor configured to control the signal generator and the detector, and a housing. 
         [0010]    In still another embodiment, a wellhead fluid analyzer for continuously monitoring a chemical composition in a well having a flow line through which a single or multiphase analyte is flowing is provided. The wellhead fluid analyzer includes a housing inserted into the well flow line, and a sensing apparatus disposed within the housing, the sensing apparatus comprising an array of two or more sensing transducer apparatuses. Each sensing transducer apparatus includes an electromagnetic transducer comprising at least two electrodes on an electrically and mechanically stable substrate, and a chemically sensitive material having an affinity for a dispersed chemical or class of chemicals in the single or multiphase analyte, the chemically sensitive material disposed on or adjacent to the electromagnetic transducer. The wellhead fluid analyzer also includes a flow sensor disposed in the housing and configured to measure the flow rate in a main pipe of the well flow line, a mixing device in the housing, and a communications connection. 
         [0011]    Other technical features may be readily apparent to one skilled in the art from the following figures, descriptions, and claims. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0012]    For a more complete understanding of this disclosure and its features, reference is now made to the following description, taken in conjunction with the accompanying drawings, in which like reference numerals represent like parts: 
           [0013]      FIG. 1  illustrates an example Production Reservoir Management System based on direct chemical measurements in accordance with this disclosure; 
           [0014]      FIG. 2  illustrates example inputs to the Production Reservoir Management System in accordance with this disclosure; 
           [0015]      FIG. 3  illustrates an example Knowledge Engine in the Production Reservoir Management System in accordance with this disclosure; 
           [0016]      FIG. 4  illustrates an example generalized topology engine within the Knowledge Engine in accordance with this disclosure; 
           [0017]      FIG. 5  illustrates an example rule for an alert engine within the Knowledge Engine in accordance with this disclosure; 
           [0018]      FIG. 6  illustrates example outputs of the Production Reservoir Management System in accordance with this disclosure; 
           [0019]      FIG. 7  illustrates an example use where the Production Reservoir Management System&#39;s knowledge engine and outputs are remote from a reservoir in accordance with this disclosure; 
           [0020]      FIGS. 8A-8D  illustrate example chemical sensor transducers in accordance with this disclosure; 
           [0021]      FIGS. 9A-9C  illustrate example chemical sensor transducer electrodes in accordance with this disclosure; 
           [0022]      FIG. 10  illustrates a chemical sensor transducer with multilayer structure in accordance with this disclosure; 
           [0023]      FIG. 11  illustrates alternative electrode designs with rounded geometries in accordance with this disclosure; 
           [0024]      FIG. 12  illustrates an example of chemical sensor performance with fouling present in accordance with this disclosure; 
           [0025]      FIGS. 13A-13B  illustrate an example chemical sensor transducer array in accordance with this disclosure; 
           [0026]      FIGS. 14A-14B  illustrate example chemical sensor schematics and electronics in accordance with this disclosure; 
           [0027]      FIG. 15  illustrates an example surface fluid analyzer chemical sensor in accordance with this disclosure; 
           [0028]      FIGS. 16A-16B  illustrate an example transducer array assembly in the surface fluid analyzer chemical sensor in accordance with this disclosure; 
           [0029]      FIG. 17  illustrates multiple sensor chemical sensing data in response to a multistep analyte fluid change over time in accordance with this disclosure; 
           [0030]      FIGS. 18A-18C  illustrate sensor performance with respect to temperature of a chemical in accordance with this disclosure; 
           [0031]      FIG. 19  illustrates an example acoustic communication system for use with a chemical sensor in sub-surface applications in accordance with this disclosure; 
           [0032]      FIG. 20  illustrates an example chemical sensor in a sub-surface application in accordance with this disclosure; 
           [0033]      FIGS. 21A-21C  illustrate an example surface fluid analyzer for surface applications in accordance with this disclosure; 
           [0034]      FIGS. 22A-22C  illustrate example chemical sensors employed for sensing of an individual well as part of the Production Reservoir Management System in accordance with this disclosure; 
           [0035]      FIG. 23  illustrates an example chemical sensor placement for a well having a multiplicity of production zones using a multiplicity of downhole sensors in accordance with this disclosure; 
           [0036]      FIG. 24  illustrates an example chemical sensor placement for a production zone which has been perforated with a set of perforations in accordance with this disclosure; 
           [0037]      FIG. 25  illustrates example sensor placements in a well with multiple zones including a horizontal well bore in accordance with this disclosure; and 
           [0038]      FIGS. 26A-26B  illustrate example earthmode transmissions for closely (locally) located wells and wells that are beyond the subterranean communications range in accordance with this disclosure. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0039]      FIGS. 1 through 26B , described below, and the various embodiments used to describe the principles of the present disclosure in this patent document are by way of illustration only and should not be construed in any way to limit the scope of this disclosure. Those skilled in the art will understand that the principles of the present disclosure may be implemented in any type of suitably arranged device or system. 
         [0040]    The following documents are hereby incorporated into the present disclosure as if fully set forth herein: 
         [0041]    U.S. Patent Documents:
   U.S. Pat. No. 4,969,130 to Wason et al. entitled “System for Monitoring the Changes in Fluid Content of a Petroleum Reservoir;”   U.S. Pat. No. 7,478,024 to Gurpinar et al. entitled “Integrated Reservoir Optimization;”   U.S. Pat. No. 5,680,899 to Waid et al. entitled “Electronic Wellhead Apparatus for measuring properties of Multiphase Flow;”   U.S. Pat. No. 3,995,488 to Crawley entitled “Dielectric Change Sensing Device;”   U.S. Pat. No. 5,055,784 to Jaeger et al. entitled “Bridgeless System for Directly Measuring Complex Impedance of an Eddy Current Probe;”   U.S. Pat. No. 5,514,337 to Groger et al. entitled “Chemical Sensor Using Current or Resonant Electromagnetic Circuit Detection;”   U.S. Pat. No. 5,227,342 to Anderson et al. entitled “Process of Making Porous Ceramic Materials with Controlled Porosity;”   U.S. Pat. No. 6,370,965 to Knapp entitled “Capacitive Sensing Array Devices;” and   U.S. Pat. No. 8,165,986 to Niu et al. entitled “Method and System for Real Time Production Management and Reservoir Characterization.”   
 
         [0051]    Additional References:
   Smith et al., “The Road Ahead to Real-Time Oil &amp; Gas Reservoir Management,” Transactions of the Institution of Chemical Engineers: Chemical Engineering Research and Design, Vol. 76A, pp. 539-552, 1998;   Mukhopadhyay, “Novel Planar Electromagnetic Sensors: Modeling and Performance Evaluation,” Sensors 2005, 5, pp. 546-579;   Konishi, “Microwave Integrated Circuits,” CRC Press, 1991 ISBN 0-8247-8199-6;   Shida, “A New Multifunctional Sensor for Measuring the Concentration and Temperature of Dielectric Solution,” SICE 2002, Proceedings of the 41st SICE Annual Conference, 5-7 Aug. 2002, page 575;   Bakar et al., “New Contactless Eddy Current Sensor for the Measurement of Concentration of Electrolyte Solution,” SICE &#39;97, Proceedings of the 36th SICE Annual Conference, International Session Papers, pp. 937-940, 29-31 Jul. 1997, doi: 10.1109/SICE. 1997.624882;   Pallas-Areny et al., “Sensor and Signal Conditioning,” 2nd ed. NY, USA: John Wiley &amp; Sons, 2001;   Bhat, “Salinity (Conductivity) Sensor Based on Parallel Plate Capacitors,” Graduate School Theses and Dissertations, University of South Florida, paper 2784, 2005;   Tulliani et al., “Porous Alumina and Zirconia Bodies Obtained by a Novel Gel Casting Process,” Advances in Bioceramics and Porous Ceramics: Ceramic Engineering and Science Proceedings, Volume 29, Issue 7, John Wiley &amp; Sons, 2009;   Igreja et al., “Dielectric Response of Interdigital Chemocapacitors: The Role of the Sensitive Layer Thickness,” Sensors and Actuators B: Chemical, Vol. 115 (1), May 23, 2006; and   Staginus et al., “Surface-Engineered Sensors: Polymer-based Sensors for the Capacitive Detection of Organic Pollutants in Water,” Proceedings of IMCS 2012—The 14th International Meeting on Chemical Sensors, pp. 1141-1144.   
 
         [0062]    For years, oil and gas company operators have been trying to integrate data, interpretations, models, simulations, and effects of development and production decisions in such a way as to optimally deplete a reservoir according to a business model and economic constraints. Oil and gas wells can be likened to high pressure, high temperature tubular reactors whose geometry and sophistication is complex. As stated by Smith and Geoffrey in “The Road Ahead to Real-Time Oil &amp; Gas Reservoir Management,” a reservoir “can be viewed as an underground factory whose overall efficiency in producing saleable products is determined by the way that its individual production units are deployed and coupled in the light of market needs.” Chemicals and chemical processes are the chief factor affecting well and reservoir operation and sustainability. The simultaneous flow of oil, gas and water in porous media affects practically every aspect of the reservoir engineer&#39;s job of optimizing the recovery from a well and from a reservoir. 
         [0063]    Optimized reservoir management and operation typically involves a determination of which formations are producing, which fractures are flowing, what is specifically flowing and what the individual flow rates are. Seismic exploration reveals regional geology that indicates geometry, internal architecture, rock properties and their variability, as well as hinting at potential mechanical processes that will be triggered as the well is produced. Logging can also reveal porosity and permeability for each lithologic environment found within each well. Coring provides general trends, identifying the azimuth of a fracture plane. Pressure is another commonly used metric, but even very low-permeability sites show that pressure varies widely within the same wellbore, thus reservoir pressure is generally not well known. A “good” reservoir may deteriorate as a consequence of fluid circulation because injected fluids may self-enhance short-circuiting pathways and because the solvent properties of water and other fluids used at injection wells to improve production can induce mineral dissolution and precipitation at geothermal temperatures. 
         [0064]    Various approaches have been taken in the oil and gas industry to combat these issues. For example, hybrid self-learning reservoir models have been developed and utilized when data is scarce, which is often the case in early reservoir development. These models balance accuracy of data fitting with predictive ability by appropriate selection of model algorithms. Reservoir models may employ a first-principles structure along with empirical constitutive related equations (such as Darcy&#39;s law, ideal gas law, and pressure-drop relationships) to the chemical processes that are actually occurring. They often rely on incoming data to identify and regularly update values of many of the algorithms&#39; parameters as they try to estimate the actual situation in a reservoir. 
         [0065]    In systems with hundreds of wells, first-principles models may fall apart because there is not enough processing power to calculate solutions. There is an overwhelming amount of data used to make reasonable inferences, either directly or through comparison, since direct measurement of the actual processes and their results downhole are not available. Simpler solutions yield results that decisions can be based on; although there is great potential for error, the results usually provide reasonable solutions at that specific moment. In practice, engineers and operators have sophisticated models available but still make most of their subjective decisions based on simple EXCEL spreadsheets because there is not enough time to run the complex models before making a decision. 
         [0066]    Chemical sensing has played a part in the development of wells and reservoirs during production, but it is limited in nature due to inaccuracies and timeliness. During production, fluid samples are occasionally analyzed at an offsite laboratory to determine their chemical content and help determine the production capability of the well. As these samples are removed from the individual wells, the temperature and pressure of the samples change from what is found downhole or even at the wellhead. This changes the composition as (i) the bubble point is reached at lower pressures causing out-gassing, (ii) various chemicals co-precipitate at lower temperatures as they come out of saturation and (iii) are often chemically recombined to create new compounds that were non-existent under the original conditions in the well. 
         [0067]    Methods in current use involve measuring indirect properties of these chemicals or occasionally measuring them directly on a sampled basis with long times between samples. This information is then compared with models, which are continuously revamped to match the current data. If a reservoir simulation model is not frequently updated with new data and new history matches conducted, the “optimized” solutions rapidly become irrelevant and may then be put aside to return to traditional tried and tested decline-curve and water-cut analysis. Those analyses provide the reservoir managers with an understanding of what is actually happening in active wells but offer little in terms of optimization solutions. 
         [0068]    Continuously-monitored chemical-based sensors could reveal changes in the production quality and quantity in relation to changes in underground fluid flow and geological structure not visible to seismic and other sensors with various chemicals present in the reservoir moving along the flow-paths. These chemicals serve as tracers to reveal when and where water intrusion is happening, identify the start of channeling, visualize distribution of the flood to determine how well an injection sweep is performing, or even detect precursors to the corrosion such as caused by hydrogen sulfide and naphthenic acids or formation of waxes and asphaltenes well before any restriction to a production flow happens. 
         [0069]    In enhanced oil recovery (EOR), chemical disequilibrium between injected fluid and the reservoir lithology is a major issue. To maintain production rates, rock/fluid interactions are monitored for scale production in the reservoir that reduces permeability or for the creation of preferred pathways reducing extraction efficiency. Monitoring a breakthrough of the EOR agent such as carbon dioxide from an injection to production wells is critical for achieving better sweep efficiencies and subsequently higher production flows and overall reservoir depletion rate. 
         [0070]    There is a need to provide a more accurate, efficient and effective process for the managing of wells and reservoirs. Providing real-time continuous predictive chemical analytics allow well interventions to be managed proactively ahead of serious well or reservoir damage. Current tools do not provide this and are based on algorithmically connecting “guesstimates” obtained through indirect measurements. There is also a need to continuously capture direct measurements of these chemicals with a sensor that can be used in real-time for a wide range of chemicals and that reacts quickly to changes, while still being able to sense a wide range of chemical concentrations in three phase flows. 
         [0071]    Reference is now made in detail to various embodiments of this disclosure, examples of which are illustrated in the figures. Each example is provided by way of explanation and is not meant as a limitation. For example, features illustrated or described as part of one embodiment can be used on or in conjunction with other embodiments to yield yet further embodiments. It is intended that the present disclosure include such modifications and variations. Although specific features of various embodiments of the disclosure may be shown in some drawings and not in others, this is for convenience only. In accordance with the principles of the disclosure, any feature of a drawing may be referenced and/or claimed in combination with any feature of any other drawing. 
         [0072]    As used here, the term “microcontroller” is not limited to integrated circuits referred to in the art as a computer but broadly refers to a controller, microprocessor, microcomputer, programmable logic controller (PLC), digital signal processor (DSP), application specific integrated circuit, and other programmable circuits, and these terms are used interchangeably herein. It should be understood that a processor and/or a control system can also include memory, input channels, and/or output channels and peripherals. Peripherals may include, without limitation, analog to digital converters (ADCs), digital to analog converters (DACs), pulse width modulators (PWMs), universal serial bus (USB) interfaces, and RS-232 transceivers. Memories may include, without limitation, computer-readable volatile media such as a random access memory (RAM) and computer-readable non-volatile media such as flash memory. 
         [0073]    Processors described herein process information transmitted from a plurality of electrical and electronic devices that may include, without limitation, sensors, actuators, compressors, control systems, and/or monitoring devices. Such processors may be physically located in, for example, a control system, a sensor, a monitoring device, a desktop computer, a laptop computer, and/or a programmable logic controller (PLC). RAM and other storage devices store and transfer information and instructions to be executed by the processor(s). RAM and other storage devices can also be used to store and provide temporary variables, static (i.e., non-changing) information and instructions, or other intermediate information to the processors during execution of instructions by the processor(s). Instructions that are executed may include, without limitation, system control commands, data parsing and mathematical algorithms. The execution of sequences of instructions is not limited to any specific combination of hardware circuitry and software instructions. 
         [0074]    Some embodiments of a Production Reservoir Management System (PRMS) of the present disclosure include or support a process involving continuous or near-continuous chemical monitoring of one or more wells in a reservoir, an apparatus to provide the continuous or near-continuous monitoring, analysis of the measured data, and output and storage of the analysis results. Some embodiments of the present disclosure also utilize chemical sensors resident in various well flows (at the surface or sub-surface) and utilize a communication network to communicate data to a central location. Well flows are a multi-component mixture with the components having a specific set of chemical and physical attributes (such as phases) and each component having additional characteristics relative to other components (such as concentrations) or in time (such as flow rates) or space (such as positioning along the wellbore). 
         [0075]    Production Reservoir Management System 
         [0076]      FIG. 1  illustrates an example Production Reservoir Management System (PRMS)  1000  based on direct chemical measurements in accordance with this disclosure. The embodiment of the PRMS  1000  shown in  FIG. 1  is for illustration only. Other embodiments of the PRMS  1000  may be used without departing from the scope of this disclosure. 
         [0077]    The PRMS  1000  of  FIG. 1  includes inputs  1 , a knowledge engine  2 , outputs  3 , and communications  4 . The inputs  1  can relate to one or more individual wells or to an entire reservoir. The knowledge engine  2  processes the inputs  1  and derives actionable information. The outputs  3  are made available to users, such as via display devices, as parameters to reservoir models or searchable databases, or in other ways. The communications  4  provide data transport between various locations. 
         [0078]      FIG. 2  illustrates example inputs  1  to the Production Reservoir Management System  1000  in accordance with this disclosure. The embodiment of the inputs  1  shown in  FIG. 2  is for illustration only. Other embodiments of the inputs  1  may be used without departing from the scope of this disclosure. 
         [0079]    Inputs that are snapshots of specific points in time and have been measured external to the system are called “prior measured data”  5 . This data can be obtained for either the entire reservoir or on an individual well basis. The data  5  can include data obtained from seismic surveys, data taken while drilling, and logging measurements from various common tools that provide information on temperature, pressure, porosity, flow rate, water cut, and other common parameters. The PRMS  1000  can utilize available additional data to further optimize and extend its outputs. Continuous chemical sensing data  6 , taken at the surface or sub-surface or both by apparatuses disclosed herein, provides chemical presence indication and concentration data for a single-phase or multiphase flow, such as is found in an oil, gas, water or geothermal well. The PRMS  1000  can also utilize current process data  7 , such as what chemicals are utilized and their concentration for injector wells located in the reservoir. Additionally, this data can include the geo-location of the injector wells. 
         [0080]      FIG. 3  illustrates an example of the Knowledge Engine (KE)  2  in the Production Reservoir Management System  1000  in accordance with this disclosure. The embodiment of the KE  2  shown in  FIG. 3  is for illustration only. Other embodiments of the KE  2  may be used without departing from the scope of this disclosure. 
         [0081]    The KE  2  supports the operational rule set to provide reservoir operational optimization. The KE  2  includes a set of inference engines  8 , a common database  9 , and a visual analytic display engine  10 . The common database  9  is an incoming storage repository for prior measured data, continuously obtained chemical sensing data  6 , and current process data  7 . It also is a repository for output results generated by the inference engine set  8 . The inference engine set  8  includes an engine  11  for each specific chemical or characteristic of interest that is being sensed. The inference engine set  8  also includes alert engines  12  that can use a default set of rules based on standard industry practice (such as operational pressure and the formation of waxes) or user-defined rules (such as related to the breakthrough of CO 2  on a single well or multiple wells during an injection sweep). A remedy prescription engine  13  can be used to identify solutions to various problems that can be encountered. 
         [0082]    Chemical measurements are fused with other co-existing or prior measured data  5  in the topology engines  11 , whose output is combined with geographic information system (GIS) data in the visual analytic display engine  10  to allow the determination of flow patterns and chemical contour mapping over time. This allows the reservoir to be viewed on an actual dynamic basis. The molecular characteristics of the individual chemical components produced, along with the identification of subterranean rock formation boundaries and formation porosity (which can be determined from the prior measured data  5 ), allows for the topographical mapping of multi-component chemical flows. 
         [0083]      FIG. 4  illustrates an example generalized topology engine  11  for use within the Knowledge Engine  2  in accordance with this disclosure. The embodiment of the engine  11  shown in  FIG. 4  is for illustration only. Other embodiments of the engine  11  may be used without departing from the scope of this disclosure. 
         [0084]    The engine  11  performs various mathematical operations, in whole or in part and individually or in combination, using the prior measured data  5 , continuous chemical sensing data  6  and/or the current process stream  7 . These operations may include, but are not limited to, feature extraction operations  14  resulting in output feature sets  15 , feature fusion operations  16 , feature delineation operations  17  resulting in decision sets  18 , and pattern processing  19  including pattern matching used in a situation assessment  20 . The desired features that have been extracted, along with those that have been obtained from the mathematical operations and the situation assessment, are used to develop a final decision as to the current state and possible actions to be taken pertinent to the specific function of the engine. These decisions and actions become outputs  21  of the engine  11  for use by the visual analytics display engine  10 , storage in the common database  9 , input to reservoir models, or display to the user. 
         [0085]      FIG. 5  illustrates an example rule for an alert engine  12  within the Knowledge Engine  2  in accordance with this disclosure. The embodiment of the rule shown in  FIG. 5  is for illustration only. Other embodiments of the rule may be used without departing from the scope of this disclosure. 
         [0086]    Inputs  22  for specific chemical measurements, such as presence, concentration and flow rate, are combined with external data  23  through mathematical algorithmic operations  24 . The operations are performed on individual input data elements/streams or combinations of input data elements/streams as required by the specific information to be obtained. Outputs from the mathematical operations  24  are fed to an appropriate test rule  25 , of which there can be a single rule or multiple rules applying to a specific data element/stream or set of data elements/streams and the appropriate mathematical operations. The output results of the test rule  25  can trigger an alert event  26 , an update of the database event  27 , and the output of data to a user. 
         [0087]      FIG. 6  illustrates example outputs  28  of the Production Reservoir Management System  1000  in accordance with this disclosure. The embodiment of the outputs  28  shown in  FIG. 6  is for illustration only. Other embodiments of the outputs  28  may be used without departing from the scope of this disclosure. In some embodiments, the outputs  28  may represent the outputs  3  of  FIG. 1 . 
         [0088]    The outputs  28  provide for reservoir production optimization through presentation of reduced and analyzed data from the knowledge engine  2 . Visualization of data occurs on a User Data Interface (UDI)  29 , which can be implemented on a data terminal, personal computer (PC), or handheld mobile device. The dynamic monitoring of individual wells and topological breakthrough times and patterns in the reservoir can also be monitored. Optimized reservoir management occurs due to specific knowledge of where problems are occurring in a well as defined by individual system and user defined alerts  30 . This provides better remediation techniques via prescriptive remedies  31  tailored to the problem occurring, which can take into consideration the remedy&#39;s effect on the local set of wells as well as the entire reservoir. As an example, water intrusion can be detected by the present disclosure at an early stage prior to causing significant damage to an oil or gas well, allowing a simple prescriptive remedy of decreasing pressure. However, if the production rate is desired to be kept constant (so the pressure cannot be decreased), the effect can also be monitored more globally to see possible changes to reservoir dynamics related to this issue. 
         [0089]    Continuous chemical measurements of the chemical factory of a reservoir and dynamic topographical mapping of reservoir flows on a chemical basis or class of chemical bases can be used to improve a reservoir model  32 . This allows better determination of where infield drilling is most productive from an overall reservoir standpoint, allowing the possibility of fewer infield wells drilled. The model structure for interaction with the PRMS  1000  can support a self-learning adaptive scheme that optimizes multiphase fluid migration in reservoirs while integrating wellhead restrictions and business constraints and continuously optimizing reservoir performance while satisfying surface and sub-surface constraints. 
         [0090]      FIG. 7  illustrates an example use where the knowledge engine  2  and outputs  3  of the Production Reservoir Management System  1000  are remote from a reservoir in accordance with this disclosure. The embodiment of the shown in  FIG. 7  is for illustration only. Other embodiments may be used without departing from the scope of this disclosure. 
         [0091]    Here, the knowledge engine  2  and outputs  3  are at a remote locale  33  from a reservoir  34  and chemical sensors  35 . A communication network  36  allows the monitoring of a producing reservoir by production engineers at an off-site location as well as data aggregation within a field. This allows the production engineer to easily monitor multiple reservoirs using real-time alerts of the present disclosure whose rules are defined by the reservoir engineer to quickly react to problems that impact production and would otherwise be unnoticed for days. Additionally, information that is monitored but pertinent to local immediate well operations derived by the knowledge engine  2  is available locally via a local display  37 , which can be tied into the communication network  36 . 
         [0092]    Chemical Sensors 
         [0093]    Being able to detect chemicals in a well flow may require sensors that are selectively sensitive to individual chemical components and can withstand the harsh environment of a well with its high temperature, high pressure, and (for some wells) abrasive nature of the flow. There have been many commercial chemical sensors developed on the principle of interaction of a chemically-sensitive material with an electromagnetic signal, such as eddy current induction or resistance-inductance-capacitance (RLC) circuits. However, current sensors typically do not stand up to the environmental conditions found downhole, especially the abrasiveness of the flow, making them useless for permanent installations. Additionally, current sensors typically are not sufficiently differentiating and accurate to provide a true chemical analysis including an indication of abundance. 
         [0094]    Eddy current systems date back to the 1920s with the advent of the grid dip meter. They are usually used to provide a non-contact probe that measures a material property in a non-destructive manner. The probe is a separate component from the material, which is usually part of another component. 
         [0095]    The present disclosure provides chemical sensors that use a combination of mechanical structures, sensing material selectivity for specific chemicals or class of chemicals, and sensor dynamic range geometry and measurement technique. The present disclosure also includes a mechanical configuration that makes it useful in harsh environments. 
         [0096]      FIGS. 8A-8D  illustrate example chemical sensor transducers in accordance with this disclosure. The embodiments of the transducers  38  shown in  FIGS. 8A-8D  are for illustration only. Other embodiments of the transducers  38  may be used without departing from the scope of this disclosure. 
         [0097]      FIG. 8A  shows a mechanical depiction of a chemical sensor transducer  38 .  FIG. 8B  shows the constituent parts of the transducer  38 , including an induction and reader platform  39 , field electrodes  40 , plated through vias  41 , and a chemically-sensitive and selective sensing material  42 . This mechanical format lends itself to harsh environments as the structure forms a “sandwich” that exposes only the sensing material and the platform to the harsh environment but not the printed circuitry or any electronics. This can be seen in  FIG. 8C  where the sensing material  42  fully covers and encapsulates the field electrodes  40  and the plated through vias  41 . 
         [0098]    An alternate embodiment of the transducer  38  is shown in  FIG. 8D , which adds a conductive grid  43  on top of the sensing material  42  with additional secondary plated through vias  44  for connection to the backside of the platform  39 . The grid  43  can be charged positively or negatively to provide additional chemical selectivity based on the ionic charge of the molecules in the analyte stream. The grid  43  can also be used to effectively turn off a sensor whose natural ionic charge affinity can be negated by an opposite charge on the grid. 
         [0099]      FIGS. 9A-9C  illustrate example chemical sensor transducer electrodes  45 - 46  in accordance with this disclosure. The embodiments of the electrodes  45 - 46  shown in  FIGS. 9A-9C  are for illustration only. Other embodiments of the electrodes  45 - 46  may be used without departing from the scope of this disclosure. 
         [0100]    Each electrode  45 - 46  includes two sets of interdigital fingers  47  and is coupled to plated through vias  41 . This example shows two electrodes  45 - 46 , although more electrodes could also be used. This structure allows selective driving of the various interdigital fingers  47  to provide variation in penetration of an electromagnetic field, from wholly-contained within the transducer sensing material  42  to beyond the sensing material  42  and into the analyte, with the same total applied electromotive force applied at the electrodes. 
         [0101]      FIG. 9B  shows details of the mechanical structure of the electrodes  45 - 46 , each with two separate sets of fingers  47 .  FIG. 9C  shows the vertical structure of the electrodes, where a dielectric insulator  48  is placed between the metallization layers forming the electrodes  45 - 46  at the points where they would overlap. The fingers  47  of both sets are co-planer. This structure may be extended to a larger number of electrodes to form additional driving points. When both sets of fingers  47  are driven, this results in a more tightly coupled electrode structure, and the electric field may not penetrate outside of the sensing material  42  shown in  FIGS. 8B and 8C . If only one set of fingers  47  is driven, a looser electrically coupled structure is created, and the field can penetrate farther outside the sensing material  42 . The electrode structure density used (finger spacing) relates to the thickness of the sensing material to be used with (deposited on) the electrode. The use of interlaced fingers  47  is just one technique for forming the electrode. Other techniques could also be used, such as concentric rings. 
         [0102]    To withstand harsh environments, in some embodiments the induction and reader platform  39  can be made of a single crystal form of AL 2 O 3  or similar ceramic material. This material is insulative, abrasion resistant, and can withstand high pressure. It also has a low coefficient of thermal expansion but is readily processed using standard industry processes found in the manufacture of printed circuit boards. 
         [0103]    The chemical sensing material  42  can have a multi-component make up. A base material can be formed from a material that is neutral or mostly neutral from a chemical selectivity standpoint. In many cases, it is composed of a cross-linked backbone of inorganic and organic polymers. The backbone material structure can be derivatized for chemical sensitivity and selectivity in order to obtain its final functional form. The resulting sensing material&#39;s permeability, chemical polarity, and dielectric properties are selectable and controllable by choice of both the backbone precursors and functional groups. The base material&#39;s hardness can provide abrasion resistance, and its compressible strength can provide the ability to withstand pressure. Both may be needed for long term operation downhole. 
         [0104]    In the present disclosure, the property of controlled nano-porosity can be used to influence sensor response time, increase the available magnitude of the response, and enhance chemical selectivity. Total pore volume influences the sensor response time and dynamic range. The higher the total pore volume, the longer the time analyte takes to diffuse into the material, thus desirably averaging the sensor response to sudden variations due to turbulence of the flow. Also, the higher the total pore volume, the greater the change in the material property that can occur, thus increasing the available magnitude and available dynamic range of the measurement. In some embodiments of this disclosure, the sensing materials have an open-pore structure that permits a fluid component to move freely or be selectively obstructed from one surface to an opposing surface of the material through a convoluted pathway of interconnecting networked channels. 
         [0105]    In some embodiments of this disclosure, the nano-porosity is controlled through a combination of pores engineered into the chemical sensing material  42  and pores that do not pre-exist but are formed in interaction with an analyte. 
         [0106]    A combination of permeability and chemical polarity of the functional material cause the material to become chemically sensitive and selective. The present disclosure uses a variety of precursors and derivatization agents to create chemically sensitive materials, which can be polymers, ceramics, silicones, metal oxides, or ferroelectric, magnetic, or composites materials that show an affinity and sensitivity for a particular chemical or class of chemical. The resulting functional materials are designed and optimized for certain properties, such as being hydrophilic, hydrophobic, lyophobic, lyophilic, oleophobic, or oleophilic and their specific affinity for a particular class of chemical. 
         [0107]    The specific dielectric constant of the base material can also influence the magnitude of the material property relative to the analyte property and thus the magnitude of the measured response for the specific analyte. For example, in some embodiments, a material of low dielectric constant is preferably used to detect a fluid component of high dielectric constant, and vice-versa. 
         [0108]    In addition to the primary selectivity based on matching chemical polarities between the selective material and the chemical component of the analyte fluid within a specific class of chemical such as hydrocarbons of generic chemical formula C n H 2n+2 , molecular selectivity can be enhanced by selection of the base material porosity so that its pore size matches the desired chemical within the class that is to be detected within the analyte. The base material therefore acts like a sieve, allowing only a certain size molecule or smaller to diffuse into the base material. Thus, a base material can be made or selected with a pore size that would allow, for example, C 5 H 12  (pentane) to diffuse into the material but block the diffusion of C 8 H 18  (octane). Further decreasing of the effective pore size results in natural gas selective materials and stops at the cut-off value of n=1 representing the selectivity for CH 4  (methane) only. 
         [0109]    The base material therefore can make up the bulk of the sensing material, so its environmental properties can be controlled by the choice of base material and its selectivity can be controlled by the choice of derivatization agents. The two-part nature of the transducer provides independence between basic chemical affinity (sensitivity) and differentiation power (selectivity) of the material, allowing each to be manipulated independently. 
         [0110]    In the present disclosure, the thickness of the induction and reader platform  39 , the thickness of the sensing material  42 , the dimensions and spacing of the electrode fingers  47 , and the selective driving of the electrodes  45 - 46  can be varied to produce an optimal-strength voltage readout from a bridge measurement circuit when excited by a specific input. The output voltage can be proportional to the abundance of the chemical being sensed at a given instant in time. 
         [0111]    Both environmental properties and selectivity of the transducer  38  can be further improved by a multilayer structure, as shown in  FIG. 10 . Each of the selective layers can have an additional functionality. For example, the bottom layer  49  can be impermeable or the least permeable to provide protection from direct contact between the selected fluid component and the substrate and field electrodes  40 . The middle layer  50  can be semi-permeable to provide selectivity based on its specific porosity, while the top layer  51  could be the most permeable but pre-selecting the chemicals by its chemical polarity. Alternatively, the middle layer  50  can be of different dielectric relative to that of detected chemical to provide high contrast in the electrical property and of high permeability to generate strong response, while the top layer  51  can serve as a primary selector by chemical polarity. 
         [0112]      FIG. 10  also shows that the interdigitated field electrodes  40  enable control of the electrical field protrusion, i.e. from which selective layer to read the signal. In the example shown in  FIG. 10 , the field  52  from adjacent electrodes penetrates the bottom layer  49  but reaches only up to the middle selective layer  50 . The field  53  from the relatively close but not adjacent electrodes, for example every other or interspersed with several electrodes, can penetrate all of the selective layers up to the top layer  51 , thus reading the signal composed of all material properties and chemical selected by the materials. Finally, the field  54  generated by distant electrodes protrudes out of the selective materials and provides the signal from the complex fluid mixture above. The field protrusion and overall materials thickness may need to be in a close relation in order to maximize both sensitivity and selectivity of the transducer&#39;s response. 
         [0113]    In one embodiment, the signal from the field contained with a non-selective material is considered as a reference and the signal from the field reaching out of the selective materials determines the upper limit of the dynamic range for the specific transducer and fluid environment in contact with this transducer. 
         [0114]    The electrical field can be further controlled by the field electrode  40  design, and more specifically by the geometry, distance between the excitation and reading electrodes, and their thicknesses.  FIG. 11  shows some examples of geometries with rounded shapes that help to contain the field within the selective materials such as straight interdigital electrode  55 , coiled interdigital electrode  56 , and a rounded multi-T interdigital  57  electrode. The geometries shown in  FIG. 11  are for illustration only. Other geometries may be used without departing from the scope of this disclosure. 
         [0115]    The environment found in typical wells may produce material compounds that foul sensors by being deposited on the sensing material, such as inorganic scale, asphaltenes or waxes, which drastically alter their ability to provide accurate measurements if they can measure at all.  FIG. 12  shows the projected sensor response  58  and actual sensor response without scale  59  to changes in analyte composition  60  along with the actual sensor response when covered with scale  61  (a 59 mil coating of calcite scale). One effect of the scale deposit is a delay in response as changes in the analyte composition  60  occur. The chemical sensor transducer  38  accomplishes sensing at the molecular level, which makes it particularly insensitive to build up of fouling materials on the surface of the chemical sensing material  42 , as the fouling materials are actually porous media with their effective pore sizes much larger that the sizes of the analytes at the molecular level. This porosity allows the analyte to pass through the fouling material to the chemical sensing material  42 . 
         [0116]    A particular embodiment of the transducer  38  uses a ceramic with a low dielectric constant (such as magnesium aluminum silicate and magnesium silicate compounds) or a material such as quartz glass, cordierite, or borosilicate glass or other similar types of material as the base material. These materials have the ability to withstand high temperatures, high compressive pressures, and abrasion due to a Mhos hardness of 7 or above. Additionally, they possess both ionic and covalent bonding sites, yielding a multiplicity of ways in which the material structure can be manipulated to obtain the desired response. Using a material with a low dielectric constant can improve sensitivity since a smaller concentration of a chemical can be sensed than if a higher dielectric constant material is used. Additionally, a material with a low dielectric constant can provide a low coefficient of thermal expansion, ensuring good adhesion during the temperature changes encountered from manufacturing to in-well usage. 
         [0117]    In particular embodiments, the sensing material  42  is initially in the form of a slurry or paste with controlled rheology and is screen-printed or spin coated on the platform  39 , which has pre-printed field electrodes  40 . This is followed by chemical cross-linking via exposure to radiation, a reagent and/or curing by high-temperature annealing to harden the sensing material  42 . Utilization of a thin film fabrication process and micromachining, based on well-defined IC deposition and etching processes, yields high reproducibility and achieves a practical mass production capability allowing multiple transducers  38  of the same sensing material  42  to be manufactured simultaneously. 
         [0118]    In other embodiments, the present disclosure uses the ability of electromagnetic fields penetrating into the analyte itself to provide the capability to produce a secondary response type. The secondary response type is based on a comparison of measurements when one measurement is made with the electromagnetic field fully contained within the sensing material  42  and another measurement is made with the electromagnetic field penetrating beyond the sensing material  42 . This can be used to enhance the accuracy of the chemical measurement as the signal from outside of the material can be used to normalize the signal from inside of the material for a drift caused by external conditions changes unrelated to the fluid flow composition. 
         [0119]    In yet other embodiments, the present disclosure uses differential measurements to provide in-situ calibration of the transducer. The use of this type of electrode may not require controlling the geometry of the transducer sensing material, such as when the sensing material&#39;s thickness would ordinarily be controlled to prevent the electromagnetic field from passing substantially outside the transducer itself. Instead, the present disclosure allows controlling the transducer&#39;s geometry to vary the dynamic range and response time of the transducer. 
         [0120]    To be more useful in a reservoir environment, a chemical sensor could sense more than one chemical, typically in a multiphase flow within the wells of the reservoir. Each chemical typically possesses different concentrations, from very small to very large, as a percentage of the total. 
         [0121]      FIGS. 13A-13B  illustrate example chemical sensor transducer arrays  62  in accordance with this disclosure. The embodiments of the arrays  62  shown in  FIGS. 13A-13B  are for illustration only. Other embodiments of the arrays  62  may be used without departing from the scope of this disclosure. 
         [0122]    As shown in  FIG. 13A , the transducer array  62  allows the sensing of multiple chemicals using different sensing materials, each of them sensitive to a different chemical component of the fluid flow. The mix of sensing materials can be optimized for the specific application. The transducer array  62  includes the induction/reader platform with an array of transducers  38 , with multiple sensing materials  64 - 66  mounted on a motherboard  63  that has backside electronics  67  and interconnects  68 . Plated through vias  41  connect the chemical sensor transducers  38  to the backside electronics  67  through the interconnects  68 . The sensing materials  64 - 66  could represent different materials and/or common materials with different thicknesses. Plated through vias  41  provide a signal path from the backside electronics  67  to the field electrodes  40 .  FIG. 13B  shows another embodiment, where the motherboard  63  serves as the induction/reader platform for all the field electrodes  40  in the array, with the multiple sensing materials  64 - 66  deposited directly on the motherboard  63 . 
         [0123]    Sensing materials formed from the same material but having different thicknesses create transducers with different saturation points, allowing different maximum concentrations to be sensed. Additionally, the speed of response of a transducer can be affected by the sensing material&#39;s thickness. Thicker materials respond more slowly due to the time it takes for an analyte to diffuse significantly into the sensing material and make a material property change measurable. For ultra-thin or nano-particle depositions of sensing materials, the sensitivity increases dramatically when the thickness becomes comparable to the depletion layer thickness of the material. Thus, the array  62  can include sensing materials formed from the same material but having different thicknesses, with at least one thin layer of sensing material providing a quicker response and at least one thick layer of sensing material providing a slower response but extending the concentration range that can be identified. 
         [0124]      FIGS. 14A-14B  illustrate an example chemical sensor  1400  in accordance with this disclosure. The embodiment of the chemical sensor  1400  shown in  FIGS. 14A-14B  is for illustration only. Other embodiments of the chemical sensor  1400  may be used without departing from the scope of this disclosure. 
         [0125]    As shown in  FIG. 14A , the chemical sensor  1400  includes an impedance bridge circuit  69  having the chemical sensing transducer  38 , sensor electronics  70 , a communication circuit  71 , and a pressure sensor  72 . The sensor electronics  70  include a microcontroller  73 , a driver amplifier  74 , and a differential instrumentation amplifier  75 . The transducer  38  forms one arm of the bridge circuit  69 , allowing changes in its electrical properties to be measured. The impedance bridge circuit  69  can provide noise immunity to the noise-generating environments found downhole. The bridge circuit  69  may be implemented as a two wire circuit as shown in  FIG. 14A  or as four wire circuit to further improve accuracy. The pressure sensor  72  may be an absolute pressure sensor type or a differential sensor type to measure differential pressure across a mixing plate  117 , which is shown in  FIG. 21 . The mixing plate  117  provides a restriction in the flow allowing fluid properties (e.g., density and the velocity of the fluid) to be measured and calculated. 
         [0126]    The sensor electronics  70  provide both the excitation and sensing of the impedance bridge circuit  69 , aided by the differential driver amplifier  74  for excitation and the differential instrumentation amplifier  75  for sensing. The microcontroller  73  provides an analog signal for excitation of the impedance bridge circuit  69  and reads the response of the bridge circuit  69  at the output of the differential instrumentation amplifier  75 . The communication circuit  71  can be duplex in nature, relaying information from the sensor to the knowledge engine  2  and relaying commands and reprogramming from the knowledge engine  2  to the sensor. In some embodiments, the communication circuit  71  is a wireless radio for use in surface applications or an acoustic/ultrasonic wireless radio for use in sub-surface applications. Other possible implementations use wired circuitry such as RS-232, RS-485 and Ethernet interfaces. The radio protocol in one implementation is a ZIGBEE protocol, but it may be any radio network, point-to-point, point-to-multipoint, or other wireless protocol (such as IEEE 802.11 or ANT). In particular implementations, the protocol used over the communication circuit  71  is MODBUS, but it may be any other standard or proprietary protocol, such as IPV4, IPV6, UDP, TCP, Fieldbus or HART. 
         [0127]      FIG. 14B  shows additional details of the sensor electronics  70 , which includes an excitation filter  76 , a reading filter  77 , and the microcontroller  73 . The microcontroller  73  may include pulse width modulator (PWM)  78 , digital to analog converter  79 , analog to digital converter  80 , digital input/output  81 , FSK modulator  82 , general purpose input/output (GPIO)  83 , and memory  84 . The sensor electronics  70  also include a temperature sensor  85  and a differential amplifier  86  used for temperature compensation. Various components shown outside the microcontroller  73  in  FIG. 14B  could be integrated into the microcontroller  73 . Similarly, various components shown inside the microcontroller  73  in  FIG. 14B  could be placed outside the microcontroller  73 . 
         [0128]    The microcontroller  73  provides an analog signal for excitation of the impedance bridge circuit  69  using the pulse width modulator  78 , whose frequency and wave shape can be varied via programming in the microcontroller  73 . Example excitation frequencies could range from 10 Hz to 10 MHz, and example wave shapes can include sinusoidal, square, triangular, ramp, or narrow pulse shapes or a combination of one or more of these shapes. The frequency and pulse shape may vary in step with each other or independently such that one pulse shape may occur at different frequencies. The excitation filter  76  provides wave shaping to the signal generated by the PWM  78 . The temperature sensor  85  can be collocated with an array of transducers  87  so that a calibration of the output of the impedance bridge circuit  69  versus temperature in each transducer  38  can be made if needed. Such calibration may be triggered, for example, due to changes in the sensing material&#39;s electrical properties caused by variation in temperature. 
         [0129]    In another implementation, the impedance bridge circuit  69 , driver amplifier  74 , differential instrumentation amplifier  75 , excitation filter  76 , reading filter  77 , and PWM  78  are replaced by an integrated circuit specifically designed to measure complex impedance of a component. The microcontroller  73  then provides the communication functions and controls the integrated circuit. 
         [0130]      FIG. 14B  also shows that the sensor electronics  70  are used with the array of chemical transducers  87  via multiplexers  88 . The multiplexers  88  allow particular transducers  38  with particular sensing materials to be coupled to the remaining components of the impedance bridge circuit  69  at desired times. This reduces the need for separate sensor electronics  70 , driver amplifiers  74 , and differential instrumentation amplifiers  75  to be provided for each transducer  38  (although this could be done). In other implementations, each transducer  38  could form part of its own impedance bridge circuit  69 , and the multiplexers  88  could couple different impedance bridge circuits to the amplifiers  74 - 75 . In the configuration here, a single temperature sensor  85  is used with the array of chemical transducers  87 , although separate temperature sensors  85  could be used for each transducer  38 . The same or a similar implementation using multiplexers  88  can be used with an integrated circuit specifically designed to measure complex impedance. 
         [0131]    Some configurations use comparisons of data when a single sensor of a single sensing material is operated over a range of frequencies to maximize conductivity of the sensing material. This may be a time consuming process, taking hundreds of microseconds for each measurement. It may place strict property matching requirements on each arm of the multiplexers  88  to switch the sensing material, or it may require a complex calibration procedure. Since materials and circuits drift differently with application of high temperatures and pressures and since they cannot be truly physically collocated, significant errors might be introduced with this method. 
         [0132]    The present disclosure, while capable of operating over a range of frequencies, can also operate at a single frequency/measured parameter combination that is optimized for each specific transducer patch. This can provide increased measurement speed and reduced calibration requirements. The specific measured parameter, capacitance, inductivity, resistivity, resonance, or other chemically-affected property can be chosen to provide the highest output from the bridge circuit to produce the best signal-to-noise ratio (SNR) possible in the noisy environment of a well. This combination of measured parameter and frequency can be specific to the sensing material and chemical to be detected. There may also be cases in which multiple combinations of parameter measured and frequency produce acceptable results for the same material, but there is often only one combination that produces optimum results for a given sensing material thickness. 
         [0133]      FIG. 15  illustrates an example surface fluid analyzer chemical sensor  89  in accordance with this disclosure. The embodiment of the surface fluid analyzer chemical sensor  89  shown in  FIG. 15  is for illustration only. Other embodiments of the surface fluid analyzer chemical sensor  89  may be used without departing from the scope of this disclosure. In some embodiments, the surface fluid analyzer chemical sensor  89  may represent the chemical sensor  1400  shown in  FIGS. 14A-14B . 
         [0134]    The chemical sensor  89  here could be used in a wellhead or other surface location. The sensor  89  includes a tubular housing  90 , which contains a sensor electronics board  91  and a power supply  92 . A transducer array assembly  93  is located at one end of the tubular housing  90 , and a closed cap  94  is located at the other end of the tubular housing  90 . A connection  95  for external communications extrudes through the cap  94 . The housing  90  can be made of any suitable material(s), such as stainless steel, and can have any suitable standard or non-standard size. The size can be chosen to match the size of logging tools so that the internal components can also be used for chemical sensing as part of a logging tool. 
         [0135]    The housing  90  can be threaded at one or both ends. For example, the bottom end can be internally threaded to accept the transducer array assembly  93  while making a liquid- and gas-tight seal with or without the use of O-rings. The bottom end can also be externally threaded to allow it to be screwed into a production pipe section, which positions the transducer array assembly  93  in the production flow. The top end of the housing  90  can be externally threaded to allow the cap  94  to screw onto the housing  90  and seal the housing against the elements. The cap  94  also provides easy access for replacement of parts within the housing  90 , such as the power supply  92  (which may be a battery or a power converter for an external source). The connection  95  is located through the cap  94 . If wireless communications are utilized in the unit, an antenna may be directly connected to the connection  95 , or a socket may exist if wired communications are used. Alternately, the connection  95  may host a direct connection to a data storage device, such as a hard drive or a USB or other solid-state drive. 
         [0136]      FIGS. 16A-16B  illustrate an example transducer array assembly  93  in the surface fluid analyzer chemical sensor  89  in accordance with this disclosure. The embodiment of the transducer array assembly  93  shown in  FIGS. 16A-16B  is for illustration only. Other embodiments of the transducer array assembly  93  may be used without departing from the scope of this disclosure. 
         [0137]      FIG. 16A  shows the transducer array assembly  93  with an array housing  96 .  FIG. 16B  shows an exploded view of the transducer array assembly  93 . An array housing cavity  97  serves to protect the electronics that it contains, and connections may pass through a slot  99 . This allows connection to the electronics using, for example, a flexible interconnect cable or individual wires. A hot wire flow sensor  98  can be embedded in the array housing  96 . The hot wire flow sensor  98  provides flow rate input so that, when coupled with the known diameter of the pipe in which the sensor is placed, a chemical concentration can be calculated from the abundance measurement the array provides. This calculation could take place in the microcontroller  73 . Alternately, the flow sensor could be implemented as a spinner, turbine, or other type of flow sensor instead of the hot wire type. Any of these implementations can be placed outside of the array housing  96 , such as in a location in the main pipe of the flanged nipple assembly  116  shown in  FIG. 21A . 
         [0138]    The use of filled plated through vias  41 , which are covered by sensing material  42  to make electrical connections with backside electronics  67 , allows the chemical sensor transducer array  62  to be sealed to the array housing  96 . Taken in its entirety, the backside electronics  67  are completely shielded from the environment. Flat surfaces can ensure the ability to achieve an excellent bond without leaks. Thus, only the topside of the array  62  and the array housing  96  itself are exposed to the environment. Both structures can be made from materials that can withstand the temperatures, pressures and chemically caustic environments downhole. This provides the capability to operate the sensor in harsh environments while ensuring operational reliability of the electronics. 
         [0139]    In a specific embodiment, optimized transducers  38 , each selective to different relevant components of a complex fluid, are arranged into an array  62 , where one of them is intentionally non-selective to serve as a reference, a second one is selective to hydrocarbons to provide an oil-sensitive response, a third one is selective to water, and a fourth one is sensitive to the salinity level in the aqueous phase.  FIG. 17  shows the set of four data traces from measurements of such a transducer array  62 , the reference response  100 , oil-sensitive response  101 , water sensitive response  102 , and salinity level in the aqueous phase response  103 . Each of the transducers responds selectively to the fluid component they were designed for, and promptly follow the injections of brine into a stirred oil  104 , equilibrating after the multiphase mixture becomes well mixed. 
         [0140]    In another embodiment, an optimized array of transducers  62  is installed at an example wellhead in the Permian Basin with limited production of crude oil and gas, contacted by gas only with an increasing level of moisture at varying temperature. Temperature is one of the environmental parameters that affects the transducer&#39;s  38  response.  FIGS. 18A-18C  show the individual measured response traces from this transducer array collected across a single day. The temperature trace  105  in  FIG. 18A  shows an example daily variation of temperatures at an example wellhead at Permian Basin. As shown in  FIG. 18B , two transducer traces, one being a chemically non-selective transducer trace  106  and the other being a water sensitive transducer trace  107 , provide an mirror image of the temperature profile. After the temperature normalization, the reference trace becomes flat, while the water-selective transducer monitors the increasing moisture level as shown in  FIG. 18C . 
         [0141]    As an alternative to using an independent temperature sensor and the post-detection temperature compensation, the interdigitated electrode design provides a method for active temperature control directly at the transducer, with one of the electrodes with an optimized resistance serving as a heater and the whole non-selective transducer serving as a temperature sensor. The temperature response can immediately be used to tune the power for the heating element, so the resulting temperature is kept constant regardless of the environmental temperature. 
         [0142]      FIG. 19  illustrates an example acoustic communication system  108  for use with a chemical sensor in sub-surface applications in accordance with this disclosure. The embodiment of the acoustic communication system  108  shown in  FIG. 19  is for illustration only. Other embodiments of the acoustic communication system  108  may be used without departing from the scope of this disclosure. 
         [0143]    The acoustic communication system  108  employs a transmitter  109  and a receiver  110 , which could collectively form a transceiver. The transceiver is electronically connected to array electronics  111  to provide for communications of data from the sensor array  62 , as well as for commanding and reprogramming the sensor. A dual-frequency transceiver could be used, with one band including higher ranges of an acoustic band and the other band including an ultrasonic band. 
         [0144]    In subterranean applications, transmitted and received signals travel through confined fluids, which may contain pockets or slugs of trapped gases, as well as through sections of pipe that are coupled together. The pockets of gas and the coupling sections of pipe disturb the communications, making them less reliable and lowering the available data rate due to interference. Dual-band transmissions can help to provide reliable transmissions while maintaining a higher data rate since the different frequency bands have different properties with respect to the electromagnetic index of refraction. Thus, while the acoustic band is “bent” more by a gas pocket (causing significant multipath interference), the ultrasonic band is “bent” less, so it causes less multipath interference and increases the reliability of the transmission. The opposite is true in the case of a pipe coupling, where the size of the coupling is more significant in relation to the wavelength of the ultrasonic band than to the acoustic band. 
         [0145]      FIG. 20  illustrates an example chemical sensor  2000  in a sub-surface application in accordance with this disclosure. The embodiment of the chemical sensor  2000  shown in  FIG. 20  is for illustration only. Other embodiments of the chemical sensor  2000  may be used without departing from the scope of this disclosure. In some embodiments, the chemical sensor  2000  may represent the chemical sensor  1400  shown in  FIGS. 14A-14B  or the surface fluid analyzer chemical sensor  89  shown in  FIG. 15 . 
         [0146]    In this example, a housing  112  of the chemical sensor  2000  resides within a side pocked mandrel  113  that has been inserted in the production string (such as with a SLICKLINE using standard methods). The mechanical configuration positions the transducer array assembly  93  so that it is immersed in the fluid or gas flow, and a communication interface  114  (such as system  108 ) is able to communicate up the pipe. The mechanical configuration is similar to that of  FIG. 15 , with the closed cap  94  containing the communication interface  114 . 
         [0147]      FIGS. 21A-21C  illustrate an example wellhead fluid analyzer  115  for surface applications in accordance with this disclosure. The embodiment of the wellhead fluid analyzer  115  shown in  FIGS. 21A-21C  is for illustration only. Other embodiments of the wellhead fluid analyzer  115  may be used without departing from the scope of this disclosure. 
         [0148]    In  FIG. 21A , the wellhead fluid analyzer (WFA)  115  includes a flanged nipple assembly  116 , a surface chemical sensor  89 , and a mixing plate  117 . The surface chemical sensor  89  is inserted so that its transducer array assembly  93  is placed vertically in the fluid or gas flow. The transducer array assembly  93  is positioned so that the flow is parallel to the face of the individual transducers to minimize the probability of the transducers being struck by objects embedded in the flow, such as rocks. The transducer array assembly  93  can also be positioned such that it directly impacted by the flow, turned so that it is facing away from the flow, or positioned at any angle in between as may be advantageous. Since the diameter of the main pipe of the flanged nipple assembly  116  of the WFA  115  is fixed and known, each chemical&#39;s concentration can be computed in the sensor for forwarding to the knowledge engine  2 . A communications connection  118  is attached to the surface chemical sensor  89 . The connection  118  supports a hardwired connection to a data exfiltration system, such as a supervisory control and data acquisition (SCADA) system or other system. In other embodiments, a wireless radio is used in the surface chemical sensor  89 , and an antenna is instead attached to the surface chemical sensor  89 . 
         [0149]      FIG. 21B  shows another embodiment in which the sensor&#39;s mechanical configuration has been altered to make the transducer array assembly  93  parallel to the fluid flow. The mixing plate  117  stirs the flow to provide a homogeneous flow instead of a laminar flow to ensure the accuracy of the sensing. If a single sensor is placed in a laminar flow, placement of the sensor would determine what chemicals could be found, as only those chemicals that were in the strata in which the sensor is placed would be sensed. Multiple sensor placements at different relative positions around the perimeter can then provide information on phase-separated streams of different fluid components, for example gas flowing on top, oil in the middle and aqueous phase at the bottom of the stratified production flow. 
         [0150]      FIG. 21C  shows an example mixing plate  117 , which represents a solid plate with holes  119 . In other embodiments, the mixing plate could be replaced with a ramp or a set of tubes that are twisted together. 
         [0151]    Chemical Sensor Networks &amp; Management Systems 
         [0152]    The PRMS  1000  uses inputs from chemical sensors to provide data for the knowledge engine  2 . Current methods and apparatuses often include a test separator, which provides an oil, gas and water ratio but operates at atmospheric temperatures and pressures. This can cause inaccuracies in measurements due to exceeding the bubble point for gases, precipitation due to saturation as temperature decreases, and other similar physical phenomena. Sampling chemical sensors operate at well pressures and temperatures but do not provide continuous information. The present disclosure&#39;s chemical sensors operate in a continuous manner at well pressures and temperatures, providing continuous information directly about well conditions. This allows even rapidly-changing conditions to be measured and information to be provided to the system user. 
         [0153]      FIGS. 22A-22C  illustrate example chemical sensors employed for sensing of an individual well as part of a Production Reservoir Management System in accordance with this disclosure. The embodiments shown in  FIGS. 22A-22C  are for illustration only. Other embodiments may be used without departing from the scope of this disclosure. 
         [0154]    In  FIG. 22A , a fluid analyzer  115  with a chemical sensor is employed for surface sensing of an individual well&#39;s flow. The fluid analyzer  115  is placed in the production flow path of wellhead equipment  120 , and the fluid analyzer  115  provides data to a SCADA system  121  or other data exfiltration system. This embodiment is useful for wells with a single production zone, and it can also be used to obtain an overall operational picture of a well with multiple producing zones. 
         [0155]    In other embodiments, such as shown in  FIG. 22B , a chemical sensor  35  is placed in the mandrel  113  as part of a production string pipe  122 . This places the sensor directly in the fluid flow  123  at a point with a known pipe diameter. This embodiment is useful in wells having more than one active production zone. Since the pipe diameter is known, a simple flow measurement allows the calculation of chemical concentrations. A wellhead transceiver  124  can be placed in the wellhead equipment to allow extraction of data transmitted from the chemical sensor using the communication system  108 . 
         [0156]      FIG. 22C  shows a combination of both sensors from  FIGS. 22A and 22B . Here, both surface and subterranean sensing in the same well is supported by the PRMS. 
         [0157]      FIG. 23  illustrates an example chemical sensor placement for a well having a multiplicity of production zones  125  using a multiplicity of downhole sensors  35  in accordance with this disclosure. The embodiment shown in  FIG. 23  is for illustration only. Other embodiments may be used without departing from the scope of this disclosure. Here, a chemical sensor  35  is placed in each zone so that information can be obtained from each of the producing zones of interest. If a zone is packed off, no sensor is required, as it is not producing. 
         [0158]      FIG. 24  illustrates an example chemical sensor placement for a production zone  125 , which has been perforated with a set of perforations  126  in accordance with this disclosure. The embodiment shown in  FIG. 24  is for illustration only. Other embodiments may be used without departing from the scope of this disclosure. 
         [0159]    Again, the sensors  35  are placed in side mandrels  113  within production string pipes  122 . As can be seen in  FIG. 24 , the sensors  35  are placed above and below the perforation(s) of interest. For determination of specific chemical information from a specific production zone  125 , the difference between the compositions measured by the two sensors  35  can be compared. This can be done for all producing zones, and chemical sensors  35  can be placed above and below each producing zone for all but the lowest zone. This information can be processed by the knowledge engine  2  to extract zone-specific analyses for each zone. Further, information about all wells in the reservoir can be captured using WFAs  115  or subterranean emplacements and can be processed by the knowledge engine  2  to provide an overall operational reservoir picture. This can include, but is not limited to, topographical analysis on a chemical by chemical basis, sweep effectivity for injection sweeps commonly used in EOR, and well to well communication. 
         [0160]      FIG. 25  illustrates example sensor placements in a well with multiple zones  125  including a horizontal well bore  127  in accordance with this disclosure. The embodiment shown in  FIG. 25  is for illustration only. Other embodiments may be used without departing from the scope of this disclosure. 
         [0161]    Sensors  35  can be placed inside the bore  127 . Two or more chemical sensors  35  can also be placed so that they span the vertical height of the horizontal well bore  127  (or production string pipe  122 , if present) since laminar flow is typical in horizontal bores and the various phases of the flow would separate out due to their different specific gravities. The placement of multiple chemical sensors  35  ensures an accurate determination of chemical concentrations can be made. Alternately, a single linear array of any number of chemical sensor transducers  38  can be assembled into a single chemical sensor  35  to span the horizontal bore  127 . 
         [0162]      FIGS. 26A-26B  illustrate example earthmode transmissions for closely (locally) located wells and wells that are beyond the subterranean communications range in accordance with this disclosure. The embodiments shown in  FIGS. 26A-26B  are for illustration only. Other embodiments may be used without departing from the scope of this disclosure. 
         [0163]    These embodiments use portions of the earth  128  (earthmode) as a transmission medium for closely located wells and for wells that are beyond the subterranean communications range. Here, a chemical sensor  35  is connected to an earthmode radio and antenna  129  that are embedded into the earth  128  in the side of a wellbore  130 . An electromagnetic signal  131 , such as in the acoustic or ultrasonic range, is relayed through the earth  128  to establish communications with a surface transceiver  132  located on the surface, but having its antenna  133  embedded in the earth to form a wireless underground sensor network (WUSN). Communication frequencies are not limited to the acoustic or ultrasonic range, and other frequencies (such as high as the 169 MHz bands) can be useful with a more limited range. This range may be more appropriate for intra-well communication hopping  134 , which relays a signal up the wellbore  130  from one sensor radio and antenna  129  to another where it is regenerated to maximize the SNR of the signal before being retransmitted. The final hop of the network is between the radio and antenna  129  and the surface transceiver  132  and its antenna  133 , minimizing the transmitter power requirements. The surface transceiver  132  is attached to a SCADA communication system  121  or other system for communications external to the reservoir. 
         [0164]    The transceiver  132  can also communicate with additional wells  135  within signal propagation range.  FIG. 26B  shows an embodiment when communications for some wells are outside of direct in-earth signal propagation range. Wireless local area network nodes  136  are added to establish communication links  137  using air as the transmission medium. 
         [0165]    Note that in the description above, reference is made to “continuous” measuring, monitoring, or other operations. In other embodiments, near-continuous measuring, monitoring, or other operations could be used to obtain the same or similar benefits described above. 
         [0166]    Although these figures illustrate examples of devices, systems, and methods for reservoir and well management based on direct in-well chemical measurements, various changes may be made to any of these figures. For example, the structural arrangements of various devices and systems are for illustration only. Various components in each figure could be moved, combined, further sub-divided, or omitted and additional components could be added according to particular needs. Also, a component or group of components in a figure could be replaced by another component or group of components that performs the same or similar function. 
         [0167]    In some embodiments, various functions described above are implemented or supported by a computer program that is formed from computer readable program code and that is embodied in a computer readable medium. The phrase “computer readable program code” includes any type of computer code, including source code, object code, and executable code. The phrase “computer readable medium” includes any type of medium capable of being accessed by a computer, such as read only memory (ROM), random access memory (RAM), a hard disk drive, a compact disc (CD), a digital video disc (DVD), or any other type of memory. A “non-transitory” computer readable medium excludes wired, wireless, optical, or other communication links that transport transitory electrical or other signals. A non-transitory computer readable medium includes media where data can be permanently stored and media where data can be stored and later overwritten, such as a rewritable optical disc or an erasable memory device. 
         [0168]    It may be advantageous to set forth definitions of certain words and phrases used throughout this patent document. The terms “include” and “comprise,” as well as derivatives thereof, mean inclusion without limitation. The term “or” is inclusive, meaning and/or. The phrase “associated with,” as well as derivatives thereof, may mean to include, be included within, interconnect with, contain, be contained within, connect to or with, couple to or with, be communicable with, cooperate with, interleave, juxtapose, be proximate to, be bound to or with, have, have a property of, have a relationship to or with, or the like. The term “fluids” may include liquids, gases, or any combination thereof. 
         [0169]    While this disclosure has described certain embodiments and generally associated methods, alterations and permutations of these embodiments and methods will be apparent to those skilled in the art. Accordingly, the above description of example embodiments does not define or constrain this disclosure. Other changes, substitutions, and alterations are also possible without departing from the spirit and scope of this disclosure, as defined by the following claims.