WO2010107879A1

WO2010107879A1 - Sensor, sensor array, and sensor system for sensing a characteristic of an environment and method of sensing the characteristic

Info

Publication number: WO2010107879A1
Application number: PCT/US2010/027616
Authority: WO
Inventors: Miroslav Petro; Thomas Harding Mcwaid
Original assignee: Freeslate, Inc.
Priority date: 2009-03-18
Filing date: 2010-03-17
Publication date: 2010-09-23

Abstract

Sensors, sensing systems and methods of sensing at least one characteristic of interest of an environment are disclosed. The sensors include one or more conductors enclosed in a dielectric material. The dielectric materials are configured such that electromagnetic fields associated with any and all of the conductors that pass outside the conductors do not substantially pass beyond the dielectric material into the environment. The sensors feature geometries that remain substantially unchanged when exposed to the environment. The dielectric material has a dielectric function that changes in response to a change in the at least one characteristic of interest of the environment.

Description

SENSOR, SENSOR ARRAY, AND SENSOR SYSTEM

FOR SENSING A CHARACTERISTIC OF AN

ENVIRONMENT AND METHOD OF SENSING THE

CHARACTERISTIC

BACKGROUND

[0001] The field of this disclosure relates generally to sensors, sensor arrays, and sensor systems for sensing one or more characteristics of an environment and more particularly to sensors, sensor arrays, and sensor systems adapted for sensing one or more characteristics of a harsh environment.

[0002] Many known sensors, sensor arrays, and sensor systems are based on electrical components such as capacitors, inductors, and resistors. When the capacitors, inductors, and resistors are intended for use as components in electronic equipment (i.e. not for use as sensors), the capacitors, inductors, and resistors are typically designed to be unaffected by their environment. That is, their environment does not influence or has little influence on how they operate. However, it is possible to configure capacitors, inductors, and resistor in such a way that they are influenced by their environment and therefore can be used as sensors, sensor arrays, and sensor systems to sense changes in their environment.

[0003] Sensors, sensor arrays, and sensor systems using capacitors or inductors are often configured to maximize the effect of so-called "fringing fields" on the measured capacitance or inductance. By using specific geometries that encourage the passage of electromagnetic fields outside of the device, the capacitance or inductance caused by the electromagnetic fields passing through the environment can be measured. A change in the environment is measured as a change in capacitance or inductance due to the substantial effect of fringing fields on the observed measurement.

[0004] In passing outside the physical boundaries of the device and into the environment being sensed, electromagnetic fields are modified by any change in the dielectric function or magnetic permeability of the substance or environment being tested, including changes in composition, temperature, density, phase assemblage, and the like. Changes in phase assemblage can include: presence or absence of a second, third, fourth, or larger number of phases (e.g. bubbles or solid particles), changes in size of different phase domains (e.g. larger or smaller bubbles), changes in orientation of phase domains (e.g. alignment of anisotropic particles), or other changes. Moreover, the environment can simultaneously change in multiple ways (e.g. bubble size and chemical composition), creating a convoluted change in measured capacitance, inductance, or other electrical characteristic. This phenomenon complicates the interpretation of the measurement because the measured capacitance, inductance, resistance, or other electrical characteristic can change for numerous reasons. In other words, sensors based on capacitance, inductance, resistance, or other electrical characteristic often lack selectivity.

[0005] The lack of selectivity has been the subject of extensive work in sensor development and use since many sensors show some response to multiple properties. In sensing an environment, for example, many of these properties can be excluded using knowledge about the environment. Consider a hypothetical in-vivo sensor used to monitor blood sugar in a human. In addition to the human's blood sugar level, the sensor might also respond to temperature, e.g., a 10 degree Celsius increase in body temperature might create the same response as a 10% increase in blood sugar. However, a 10 degree Celsius increase in the body temperature of the human is such a low probability occurrence (ostensibly impossible for a living human) that the response of the sensor can be confidently interpreted to be a response to the human's blood sugar level. Although the sensor responds to multiple properties, knowledge of the environment can be used to interpret the response.

[0006] Accurate sensing often requires the use of additional information about the environment, and/or multiple sensors to discriminate among the various factors that might lead to a response. An array or other combination of sensors can be used to discriminate among a variety of changes in an environment. Similarly, time dependent measurements, frequency sweeping, complicated driving and reading algorithms, equivalent circuit analysis, numerical simulation, and the like, can all be used to provide or enhance the ability to sense an environment. However, these components often add cost, reduce robustness, and make the sensor less applicable to remote environments, such as environments in which power supply is limited, geometry is constrained, sufficient computing power is unavailable, or a user is inaccessible.

[0007] One of the fundamental challenges with the design of any sensor is the tradeoff between sensitivity, selectivity, and robustness. The sensor must somehow be exposed to the environment but should not be so exposed that it is degraded or destroyed by the environment. The sensor's response should correlate with one or more characteristics of the environment, and the user should be able to distinguish any response due to other properties (e.g. by using other sensors or knowledge about the environment). Highly sensitive sensors are often not robust against deviations from the target environment in which they have been designed to operate, and for particularly harsh environments, the durability of even the most insensitive sensor is often insufficient.

[0008] In harsh environments, many known sensing technologies can suffer premature (or even immediate) failure due to extremes in temperature, pressure, reactive chemistry, or other characteristics. Thus, for example, substantial effort may be required to prevent chemical attack on sensors in corrosive environments. Other harsh environments include pressures and temperatures sufficiently different from ambient that equipment developed for ambient use ceases to function. These environments often require the placement of a measurement apparatus far from the environment, such as in fluid communication with a probe immersed in the environment.

[0009] Another requirement of a sensor is that its operational characteristics (including but not limited to size, power requirements, cooling or heating requirements, isolation (magnetic, electrical, radiative) requirements and the like) must be of a scale that is practical for use in the application for which the sensor was designed. This requirement precludes the use of many types of large or high powered measurement equipment in sensing small or remote regions. These characteristics may also exclude many methods of protecting the measurement equipment from the environment. [0010] Particularly sensitive environments, such as environments that are adversely affected by typical sensing technologies, can also be challenging to sense. Thus, for example, in-vitro sensing in humans can be a challenging sensing environment because of the sensitivity of the subject to the method of sensing.

[0011] As a result, many industries are in need of sensors that can endure harsh or otherwise challenging environments, detect a change in one or more characteristic of interest of the environment, transmit the change to a user in usable format, remain benign to the environment, and not respond to changes in characteristics not of interest. In one example, there is a need for these types of sensor for the characterization or monitoring of conditions at or near the bottom of deep, subsurface borings, such as those used for the exploitation of clean water, fossil fuels (i.e., oil, gas), or other underground materials. These borings can be remote, spatially constrained, under high pressures, at high temperatures, and subject to complex and varied chemical conditions.

[0012] Of particular importance in deep borings is the sensing of gases dissolved in flowable media or fluids. Deep borings are created by using a drill rig to rotate a bit via a drill string which causes the bit to cut into or otherwise dislodge underlying bedrock and thereby advance the boring. Drilling fluid (or drilling mud) is pumped into the boring during operation of the drill rig to cool the bit, lift the rock cuttings to the surface, prevent the destabilization of the bedrock defining the boring, and prevent fluid and/or gas contained within the bedrock from entering the boring.

[0013] A "kick" or blowout can occur during operation of the drill rig if fluid and/or gas contained within the bedrock are allowed to uncontrollably enter the boring. The reduction in pressure associated with the ascension of fluid from deep within the earth to the earth's surface can result in the rapid evolution of gas out of solution. This rapid evolution, or "kick" of gas, can significantly disrupt the exploitation process, and can also be dangerous. Thus, the ability to sense, before the fluid reaches the surface, the fluidic conditions (e.g. composition) that might lead to a "kick" upon reaching the surface is a useful feature of a sensor. The "kick" sensor could monitor gas entry in a measurement-while-drilling arrangement with the sensor being a part of the drilling hardware or by monitoring dissolved gases in drilling fluids at pressure (downhole or even at surface but still under pressure).

[0014] Another important compositional change in downhole fluid is the multiphase composition such as a proportional ratio of oil, gas, and water. Specifying the location where the change occurs with a high spatial resolution is of particular importance. Other aspects, such as a direction and a shape of the compositional gradient within a boring could be of particular importance as well.

[0015] The ability to sense differences in the overall chemical qualities of individual phases, related to molecular size and polarity distributions, for example light versus heavy oil or salt water (brine) versus clean water, is also of high importance.

[0016] Sensing a number of specific molecular species that may cause undesired effects on the oil/gas/water well and the related infrastructure is of a specific importance. Some potentially important sensing target may include asphaltenes and waxes creating organic deposits, or naphtenic acids and hydrogen sulfide causing corrosion.

[0017] Profiling compositional changes along the boring can also serve to detect and identify a type of interaction between the well fluids and the surrounding geological formations or strata. For example, dissolution of solid minerals, influx of other reservoir fluids, and leaks or exchanges of fluids between different locations along the length of a well could be of particular importance.

[0018] In addition to understanding the characteristics of a specific well, a cross-correlation of the information from multiple wells allows assessment of the value of individual streams and an understanding of the mobility of fluids with and around the well and, in a broader sense, the inter-connectivity and overall fluid dynamics of different fluid containing portions of a reservoir or whole field.

[0019] This section is intended to introduce the reader to various aspects of art that may be related to various aspects of the disclosure, which are described and/or claimed below. This discussion is believed to be helpful in providing the reader with background information to facilitate a better understanding of the various aspects of the present disclosure. Accordingly, it should be understood that these statements are to be read in this light, and not as admissions of prior art.

BRIEF DESCRIPTION

[0020] One aspect of the disclosure is directed to a sensor that is configured such that the electromagnetic fields associated with the sensor pass through one or more materials having a complex dielectric function and/or complex magnetic permeability function that change in response to a change in the condition of the environment. Sensors are designed with a geometry that ensures that the electromagnetic fields associated with the sensor do not substantially pass outside the sensor itself, and thus do not substantially penetrate the environment being sensed. Rather, the electromagnetic fields are essentially entirely contained within the sensor itself. Moreover, the sensor geometries and materials are specified such that the measurement is only affected by electromagnetic fields that pass through materials having a selectively changing dielectric function and/or magnetic permeability function. Other aspects provide for arrays of sensors, sensing systems, and methods for sensing conditions of target environments that take advantage of the enhanced sensitivity to the condition provided by such sensors.

[0021] Another aspect is directed to a sensor for sensing a condition of an environment. The sensor includes a first conductor enclosed in a dielectric material. The dielectric material is configured such that the electromagnetic fields associated with the conductor that pass outside the conductor do not substantially pass beyond the dielectric material into the environment. The sensor has a geometry that remains substantially unchanged when exposed to the environment. The dielectric material has a dielectric function that changes in response to a change in the characteristic of interest.

[0022] Still another aspect is directed to a sensor for sensing a condition of an environment that includes two or more conductors. All of the conductors are enclosed in one or more dielectric materials, and each dielectric material is configured such that electromagnetic fields associated with any of the conductors that pass outside the conductors remain substantially within the dielectric materials and do not traverse the environment beyond the sensor. The spacing between any two of the conductors remains substantially unchanged when the sensor is exposed to the environment, and each dielectric material has a dielectric function that changes in response to a change in the condition of the environment. This type of sensor can also be operated as a capacitor, and the sensing response can be measured as a change in capacitance.

[0023] The sensor can include two or more conductors and have geometries in which electromagnetic fields between any two conductors pass outside the region disposed directly between the two conductors. The sensor can be operated at a variety of frequencies, which may provide increased information content relative to operation at a single frequency or zero frequency. Many frequencies can result in the dielectric material displaying substantial conductivity. The sensor can include a cladding that substantially surrounds and/or encloses any and/or all of the dielectric materials. The cladding can provide chemical, thermal, physical or any other type of protection. The cladding can also provide or increase the ability of the dielectric material to selectively respond to the condition of the environment.

[0024] Yet other aspects are directed to a sensing system, sensors based on such a system, and an array of such sensors including sensors and apparatus for interaction with, control of, and response to the sensors. Such systems can include apparatus for sending an input signal to the sensor and receiving an output signal from the sensor. Signals and responses from individual sensors within an array can be treated individually (reduced) or, by comparing the individual signals before sending the input or output to/from the whole array (for example, two identical sensors), can be tuned to different dynamic ranges and sensitivities and thereby send different signals out.

[0025] Still another aspect is directed to a method for sensing a condition of an environment that includes providing a sensor or a sensing system that includes a sensor. The sensor includes a first conductor and optionally one or more second conductors enclosed in one or more dielectric materials. Each dielectric material is configured such that an electromagnetic field associated with any conductor that passes outside the conductor does not substantially pass beyond the dielectric material into the environment. The sensor has a geometry that remains substantially unchanged when exposed to the environment. The dielectric material has a dielectric function that changes in response to a change in the condition of the environment. The sensor or sensing system is then operated to monitor the environment for a change in the condition. The sensors can be operated as inductors or capacitors or in other ways. They can be operated at a range of frequencies, including a fixed frequency or zero frequency. The sensors can be operated at frequencies such that a particularly chosen dielectric material has a substantial conductivity at the frequencies of interest. Sensors can also be operated as resistors, with current passing through the dielectric from one conductor to another.

[0026] Yet another aspect is directed to a method for sensing a characteristic of interest of an environment. The method comprises providing a sensor or sensing system that uses a sensor. The sensor comprises a first conductor enclosed in a dielectric material, the dielectric material being configured such that any electromagnetic field associated with the conductor but passing outside the conductor does not substantially pass beyond the dielectric material. The sensor has a geometry that remains substantially unchanged when exposed to the environment. The dielectric material has a dielectric function that changes in response to a change in the characteristic of interest of the environment. The method further comprises exposing the sensor to the environment, monitoring the dielectric function of the dielectric material, detecting a change in the dielectric function of the dielectric material, and determining a change in the characteristic of interest of the environment based on the detected change.

[0027] The utilization of electromagnetic fields can provide a nondestructive way to measure a condition of the environment. The use of a dielectric material whose dielectric function has an enhanced dependence on the condition increases the sensitivity of the sensor to changes in the condition. In one suitable embodiment, the sensors can be exposed to fluids being extracted from a deep well and adapted to sense an incipient kick of gas in the fluids being extracted, to sense changes in a ratio between water and hydrocarbons, or to sense changes in a ratio between oil, gas, and water. In another embodiment, the sensors can be exposed to a fluid in an in-vivo environment and adapted to sense changes in a concentration of a component of the fluid. [0028] Various refinements exist of the features noted above in relation to the various aspects of the present disclosure. Further features may also be incorporated in these various aspects as well. These refinements and additional features may exist individually or in any combination. For instance, various features discussed below in relation to one or more of the illustrated embodiments may be incorporated into any of the above-described aspects of the present disclosure alone or in any combination. Again, the brief summary presented above is intended only to familiarize the reader with certain aspects and contexts of the present disclosure without limitation of the claimed subject matter.

BRIEF DESCRIPTION OF THE DRAWINGS

[0029] FIG. 1 is a perspective of one embodiment of a sensor.

[0030] FIG. 2A is a perspective of another embodiment of a sensor.

[0031 ] FIG. 2B is a cross-section taken along line 2B-2B of FIG. 2A.

[0032] FIG. 3 is a schematic showing an embodiment of a sensing system.

[0033] FIG. 4 is a top plan of yet another embodiment of a sensor.

[0034] FIG. 5 is an enlarged, fragmentary top plan of still another embodiment of a sensor.

[0035] FIG. 6 is a plot illustrating response versus dielectric constant of a further embodiment of a sensor.

[0036] FIG. 7 is plot illustrating response versus time of another embodiment of a sensor.

[0037] FIG. 8 is an enlarged, fragmentary elevation of a drilling string and a drill bit being used to penetrate bedrock and a sensor mounted to the drill string.

[0038] FIG. 9 is an enlarged, fragmentary elevation of a logging tool having a plurality of sensors and being used to log an open borehole. [0039] FIG. 10 is an enlarged, fragmentary elevation of a cased borehole with a casing having sensors coupled thereto.

[0040] FIG. 11 is a schematic showing an embodiment of a sensor array.

[0041] FIG. 12 is a plot illustrating potentially suitable dielectric materials with respect to their size-base selectivity, polarity-based selectively, and robustness/durability.

[0042] Like reference symbols in the various drawings indicate like elements.

DETAILED DESCRIPTION

[0043] The present disclosure is directed to sensors, sensor arrays, sensing systems, and methods of sensing that use electromagnetic fields to sense one or more characteristics of an environment. For the purposes of this specification, the characteristic of the environment comprises one or more properties of interest in the environment, and can include any aspect of the environment of interest to the user, including, but without limitation, the concentration of one or more chemical species, pressure, density, and temperature. Sensing refers to the measurement of the characteristic or of a change in the characteristic.

[0044] Unlike electronic devices that have been designed to remain inert or insensitive to the environment, the sensors described herein are designed to maximize the interaction of the electromagnetic fields emitted by the sensor with the environment. The sensors' interaction with the environment is selective for the characteristic being measured, such that the sensor exhibits a response to the characteristic that is measurably greater than, or at least measurably different from, the sensor's baseline response and/or response to properties that are unrelated to the characteristic. In particular implementations, this selective interaction results from a combination of sensor geometry and the choice of dielectric material or materials used in the sensor thus representing an equilibrium between the dielectric material and the environment in contact with the material. In addition to sensor geometry and dielectric materials, selectivity can be provided or enhanced for the sensors described herein in a variety of ways, including the use of additional sensors (e.g., an array), additional data, and/or knowledge about the environment being sensed.

[0045] As used in this specification, a dielectric material is a material that exhibits dielectric properties when interacting with electromagnetic fields. In the sensors described herein, the dielectric material can be a composite material, and can even comprise several separate materials. The dielectric material has a dielectric function and/or magnetic permeability function (hereinafter referred to collectively as a "dielectric function" unless otherwise noted) that is selectively modified by the condition of the environment. Suitable dielectric materials include organic, inorganic and hybrid materials that are cross-linked or cured into an interconnected or interpenetrated network of (macro) molecular chains with a selective accessibility via partitioning or nanoporosity. The molecular chains can be held together using any suitable bonds, such as, carbon-carbon (C- C) bonds, silicon-oxygen (Si-O) bonds, carbon-oxygen (C-O) bonds, carbon-nitrogen (C- N) bonds, silicon-carbon (Si-C) bonds, aluminum-oxygen (Al-O), and zirconium-oxygen (Zr-O). Examples of suitable dielectric materials include organic polymers, silicones, ceramics, carbon metal oxide particulates, and combinations thereof.

[0046] Sensor geometry refers to the physical shape and arrangement of the components of a sensor or system, including without limitation distances, spacings, thicknesses, volumes, sizes, or other physical descriptors. The sensors described herein have a geometry that ensures that the electromagnetic fields associated with the sensor do not substantially pass outside the sensor itself, and thus do not substantially traverse the environment being sensed. Rather, the electromagnetic fields are essentially entirely contained within the sensor itself. In addition, the sensor geometry and materials ensure that only electromagnetic fields passing through material having a characteristic -dependent dielectric function affect the measurement (i.e. are changed as the environment changes). As a result, the electromagnetic fields traversing the material are selectively modified by the environmental characteristic of interest. The sensor geometry remains substantially unchanged when exposed to the environment being sensed. [0047] FIG. 1 illustrates a sensor, indicated generally at 100, adapted for sensing a characteristic of interest in an environment 102. The sensor 100 comprises an inductor, indicated generally at 104, including a conductive wire 110 that is enclosed in a suitable dielectric material 120. The wire 110 has a coiled portion 130, which defines a generally cylindrical internal volume 134, and a pair of leads 136 with one of the leads extending outward from one end of the coiled portion and the other lead extending outward from the opposite end of the coiled portion. In one suitable embodiment, the conductive wire 110 can be made of platinum. It is understood, however, that the wire 110 can be made from other suitable conductive materials (e.g., copper, gold).

[0048] As seen in FIG. 1, the dielectric material 120 completely encloses the coiled portion 130 of the wire 110. Specifically, the dielectric material 120 fills the internal volume 134 defined by the coiled portion 130 and surrounds the exterior of the coiled portion. As a result, the dielectric material 120 is disposed both inside and outside the coiled portion 130. As illustrated in FIG. 1, the dielectric material 120 extends beyond the coiled portion 130 of the wire 110 and has a diameter 140 that is sufficient to ensure that an electromagnetic field 150 created by the inductor 104 is substantially contained within the dielectric material. That is, the electromagnetic field 150 created by the inductor 104 does not extend beyond the extent of the dielectric material 120. The dielectric material 120 exhibits substantial electrical conductivity at one or more frequencies.

[0049] In the illustrated embodiment and as seen in FIG. 1, the coiled portion 130 of the wire 110 has a coil diameter 132 that substantially less than the diameter 140 of the dielectric material 120. It is contemplated, however, that the relative diameters 132, 140 of the wire 110 and the dielectric material 120 can be different than those illustrated. In one example, the dielectric material 120 can have a diameter that is only slightly greater than the diameter 132 of the wire 110, such as, a thickness corresponding to a gauge of the wire 110. In another example, the dielectric material 120 can have a diameter that is significantly greater (e.g., more than twice the size) than the diameter 132 of the wire 110. [0050] In another suitable embodiment, which is illustrated in FIGS. 2 A and 2B, a sensor, indicated generally at 200, comprises a capacitor, indicated generally at 204, enclosed in a dielectric material 220. The illustrated capacitor 204 includes a first conductor 210 and a second conductor 212 that are separated by a gap 229 between the conductors. The gap 229 between first and second conductors 210, 212 defines a gap distance 230. The gap distance 230 remains substantially unchanged when the sensor 200 is exposed to the environment. The geometry (e.g., size, shape) of each of the first and second conductors 210, 212 is selected so that they can each carry current or be controlled to have desired voltages. In the illustrated embodiment, the first and second conductors 210, 212 are affixed to a substrate 215. The substrate can be made from any suitable material include silicon, glass, metal, plastic, and metal-oxide.

[0051] As seen in FIGS. 2A and 2B, the first and second conductors 210, 212 are surrounded by the dielectric material 220, which has a dielectric function that is sensitive to one or more characteristics of interest of the environment. The dielectric material 220 can enclose the entire capacitor 204 (as illustrated in FIGS. 2 A and 2B) or be provided as a cover that overlies the first and second conductors 210, 212 and the substrate 215 (not shown).

[0052] With reference to FIG. 2B, which is a cross-section of the sensor 200 illustrated in FIG. 2A, the dielectric material 220 has a thickness 225 that is sufficiently larger than electromagnetic fields 250 created by the first and second conductor 210, 212 so that during operation of the sensor 200, the electromagnetic fields 250 remain substantially within the dielectric material. In one suitable embodiment, the electromagnetic fields 250 pass outside the region defined by the gap distance 230. The relatively large thickness 225 of dielectric material 220 creates an active region 227, in which changes in the electromagnetic fields have a measurable effect on the response of the device, and an inactive region 228 in which changes do not have a measurable effect on the device. In one example, the inactive region 228 within the dielectric material 220 is one or more portions of the dielectric material that are not contacted by the electromagnetic fields. [0053] In a suitable embodiment, the thickness 225 of the dielectric material 220 is at least twice as large as the gap distance 230 between the first and second conductors 210, 212, at least 10 times the gap distance, at least 100 time the gap distance, or at least 1000 times the gap distance. In other suitable embodiments, the thickness 225 of the dielectric material 220 can be made relatively small by making gap distance 230 short relative to the overall size of the sensor 200. In particular, the thickness 225 of the dielectric material 220 should not be so large that the speed at which dielectric material 220 responds to the sensing environment is adversely affected (e.g., by unduly slowing the speed that chemical components in the environment can diffuse from the environment into the dielectric material).

[0054] The substrate 215 to which the first and second conductors 210, 212 are attached can be fabricated from the same material as the dielectric material 220, or from a different material. In some embodiments, the substrate 215 is configured to contain the electromagnetic fields within the sensor. For example, the substrate 215 may be made from a substantially inert material (e.g., a material having a dielectric function that does not change in the environment being sensed) and can have a thickness sufficient to substantially prevent the passage of electromagnetic fields through the substrate. In other embodiments, one or more electromagnetic shielding components 240 can be used to prevent the passage of electromagnetic fields into undesired regions of the sensor 200. In the illustrated embodiment, the planar shield 240 is disposed within the substrate 215. The shield 240 is suitably positioned close to the first and second conductors 210, 212 but without direct contact therewith. It is contemplated that the shield 240 can be electrically conductive and can be maintained at ground potential, can be ungrounded, or can be maintained at another desired potential (e.g., the potential of one of the conductors in certain implementations). In still another embodiment, an electromagnetic shielding component (not shown) can be used to minimize the intrusion of external electromagnetic fields into the sensor.

[0055] In the embodiment illustrated in FIGS. 2A and 2B, the first conductor 210 is served by a first pair of leads 270, 272 and the second conductor 212 is served by a second pair of leads 274, 276. The illustrated configuration allows each of the first and second conductors 210, 212 to be used as a current source, a current sink, a voltage source, or a voltage sink. For implementations requiring only voltage measurements (e.g., a capacitance measurement), the sensor 200 can be constructed with first and second conductors 210, 212 being serviced by a single lead each. Sensor 200 can also be constructed with first and second conductors 210, 212 having multiple leads for providing alternate paths in case of lead breakage.

[0056] As seen in FIGS. 2 A and 2B, a cladding 290 can be used to surround at least a portion of the sensor 200. The entire sensor 200 is surrounded by the cladding 290 in FIGS. 2A and 2B. The cladding 290 can comprise one or more materials, and can be applied in a configuration that improves the performance of sensor 200. In one suitable embodiment, the cladding 290 is chemically inert to one or more components of the environment to provide chemical protection to the sensor from these components while allowing the passage of other components of the environment. In another embodiment, the cladding 290 can be used to increase the selectivity of the dielectric material 220, for example, by minimizing the passage of one or more undesired components of the environment to the to dielectric material. In other words, the cladding 290 can filter components of the environment as they pass through the cladding to the dielectric material 220. It is understood that the cladding can be formed from a single layer of material, multiple layers of material (e.g., a composite, a laminate). In another embodiment, the cladding 290 can also provide thermal protection or otherwise minimize thermal effects on the sensor 200.

[0057] In one suitable embodiment, the thickness 225 of dielectric material 220 is large enough so that the electromagnetic field 250 does not extend beyond the dielectric material during use of the sensor, is such that the extent to which the electromagnetic field 250 extends beyond dielectric material is minimized. This inhibits characteristics of the environment that are not of interest and are disposed outside of the dielectric material 250 from adversely affecting the accuracy of the sensor 200. Any portion of the electromagnetic field 250 that extends beyond the dielectric material 220 may potentially be influenced by characteristics of the environment that are not of interest which adversely affects the accuracy of the sensor 200. It is understood that the extent of the electromagnetic field 250 can be manipulated or otherwise managed by varying the gap distance 230 between the first and second conductors 210, 212, by changing the thickness 225 of the dielectric material 250, by using one or more shielding components 240, and/or changing the shape or material of the conductors 210, 212. The strength of the electromagnetic field 250 can be calculated and is dependent on each of these variables. As a result, this calculation can be used to properly size and configure the sensor 200.

[0058] In one suitable embodiment, the dielectric material 220 includes an active region 227 (i.e., a region of the dielectric material 220 containing the electromagnetic field during operation of the sensor 200), and inactive region 228 (i.e., a region of the dielectric material 220 outside the influence of the electromagnetic field during operation of the sensor 200), and a boundary region between the active region and the inactive region. The location of the boundary region may vary somewhat during use. To ensure that the electromagnetic field 250 does not extend beyond the dielectric material 220 during use of the sensor 200, the thickness 225 of the dielectric material can be twice, three times, or even ten times the distance from the conductors to the boundary of the electromagnetic field 250 (in the same direction). In one suitable embodiment, the substrate 215 can be formed with a suitable thickness to substantially contain the electromagnetic field 250. That is, the substrate 215 can have a predetermined thickness to prevent the electromagnetic field 250 from penetrating the substrate.

[0059] In some implementations, it may be convenient to fabricate a sensor 200 that is selective for a particular condition by constructing multiple sensors with differing geometries and/or dielectric materials, and testing each sensor to identify a particular sensor or combination of sensors that exhibit desirable sensing characteristics. For example, a device can be tested after fabrication to determine if dielectric material 220 depends on a condition of interest, is sufficiently thick and is sufficiently independent of other properties of the environment. Similarly, confirmation that electromagnetic fields created by the sensor do not pass outside the sensor at a level that affects the measurement can be obtained by testing the fabricated device. [0060] In another embodiment, sensors can be configured with more than two conductors, such as in arrays or other arrangements of multiple conductors. The sensor configuration can be constant across the sensor in such multi-conductor implementations, or one or more characteristics such as gap distances 228 can vary between individual conductors or groups of conductors. In particular multi-conductor implementations, each conductor can interact with any other conductor. However, in each such implementation, the thickness 225 should be large enough that the largest active region (typically associated with the largest gap distance between any two interacting conductors) remains entirely within dielectric 220. In implementations where different dielectric materials are used, electromagnetic fields should only be modified by selective modification of the dielectric function of any of the dielectric materials.

[0061] Libraries (e.g. arrays or other multiples) of possible sensors can be created to test diverse geometries, conductors, dielectric materials, substrate materials, claddings, testing protocols and other factors. Proxies of different environments to be sensed can also be created in library format. Screening libraries of potential sensors against libraries of representative environments can be an efficient way to discover appropriate combinations of geometric and materials factors for sensing in different environments. Similar testing methods can be used to determine cladding compositions that may enhance selectivity, improve protection, or otherwise improve performance. Such libraries of sensors can also be used to increase the information content or information quality provided by the sensors.

[0062] FIG. 3 illustrates one embodiment of a sensing system, indicated generally at 300, for sensing one or more characteristic of interest of an environment 302. The sensing system 300 includes a sensor 310, which can be any of the various sensors described herein. In one suitable embodiment, the sensor 310 is immersed in the environment 302, as shown in Fig. 3. In other embodiments, the sensor 310 can also be partially immersed, adjacent to, affixed to, in optical, acoustic, or electromagnetic communication with, or otherwise operatively connected to the environment 302. The placement of the sensor 310 relative to the environment 302 can be determined based on, for example, accessibility, the nature of the environment, or the nature of the characteristic of interest being sensed.

[0063] The sensor 310 is operatively connected to a controller 330 (e.g., a computer) via a communication path 320. The communication path 320 is the path along which information is transferred between the sensor 310 and controller 330, and may also serve to transmit power to the sensor 310. In other words, the communication path enables sending an input signal to one or more sensors (such as sensor 310) and receiving an output signal from the one or more sensors. The communications path 320 can be, for example, acoustic, electronic, optical, radio frequency, or a combination thereof. The controller 330 serves to drive, power, control, or otherwise activate the sensor 310, as well as process any information transferred from the sensor 310 via the communication path 320. Depending upon the nature of the sensor 310 and the communication path 320, the controller 330 may also control the rate at which data is collected.

[0064] In one embodiment, the system 300 includes at least one data storage apparatus 340 (e.g., flash memory), a user interface 350 (e.g., keyboard, monitor), and response/activation apparatus 360. Some or all of components 340, 350, and 360 may communicate with the controller 330 via additional communication paths 335, which may be electronic, radio frequency, optical frequency, and/or acoustic communication paths. One or several of these communication paths 335 may also transmit power to the controller 330. The illustrated system 300 also include a power supply 370 (e.g., a battery, a fuel cell, or other power generation device) for powering the system. It is contemplated that the system 300 can be powered using an external power supply, such as, using a plug and a standard outlet. The power supply 370 can be integrated with the sensor 310, the controller 330, or any other component of the system 300. In an embodiment where the system 300 includes more than one power supply 370, one power supply can be integrated with the sensor and another power supply can be integrated with the controller. The later embodiment enables the use of wireless communication methods for one or more of the communication paths 320, 335. EXAMPLE 1

[0065] In this example, a sensor, indicated generally at 400, comprises a substrate 410 supporting two interdigitated comb conductors 420, 430. The combination of the conductors 420, 430 affixed to the substrate 410 (prior to coating with a dielectric material) is referred herein as a "die". The illustrated die for the sensor 400 was prepared using standard methods for fabricating printed circuit boards (PCB 's) for packaging microelectronic devices. The substrate 410 was formed from a generally square piece of glass fiber reinforced epoxy (Garolite) having a thickness of about 0.06 inches, a length of about 1.25 inches, and a width of about 1.25 inches. Both of the conductors 420, 430 are copper and have a thickness of about 0.0014 inches. Each of the conductors 420, 430 has a comb with seven teeth, a pitch width 440 of about 0.1 inches, and a gap distance between adjacent conductors 420, 430 of about 0.01 inches. The die also features a 0.0014 inch thick planar layer of copper (not shown) on the surface of the substrate 410 opposite the surface upon which the conductors 420, 430 are disposed, usable as a ground plane.

[0066] Two of the interdigitated-conductor dies were prepared. One die was then coated on all sides with a polymer dielectric material 460 (Adhesive Paste # 800 available from Master Bond, Inc. of Hackensack, New Jersey) to a thickness of approximately 0.15 millimeters. The polymer dielectric material 460 was allowed to cure overnight in air and at ambient temperature. The dielectric material 460 substantially encloses the sensor 400, and the electrical connectivity to the conductors 420, 430 is via insulated leads 421, 431, respectively. The other die was left uncoated.

[0067] The sensor 400 having the dielectric material 460 thereon was tested along with the uncoated die to compare the difference in response to solvents having differing polarities. The coated and uncoated dies were separately tested, and were operated as capacitors. Their responses were monitored using an SR720 LCR meter, which is available from Stanford Research Systems of Sunnyvale, CA, at IV peak to peak, at 100 kHz frequency. Data was acquired using a LabJack data acquisition module (available from LabJack Corporation of Lakewood, CO) that was interfaced with a personal computer (PC) using Lab View software (National Instruments Corporation of Austin, TX). [0068] The coated and uncoated dies were washed in three successive isopropanol baths (100 rnL each) for 1, 3, and 12 hours, respectively. The initially fluctuating response stabilized during the wash, showing no detectable drift in time after completion of the washing procedure. The washed dies were wiped using a chemically clean paper napkin, air-dried for about 1 min, and tested as follows.

[0069] In order to compare the responses of the coated and uncoated dies, each was separately immersed in the following sequence of solvents (100 mL) having different polarities: cyclohexane, hexane, pentane, toluene, ethyl acetate, tetrahydrofuran, acetonitrile, isopropyl alcohol, and deionized water. Each die was paper-wiped and air- dried between each solvent immersion. The response in each solvent environment was recorded after it had stabilized, which took a few seconds in non-polar solvents, several minutes in the more polar solvents, and about 30 minutes in the final water environment.

[0070] The measured capacitance response in pF was plotted against the known dielectric constants of the solvents, as shown in Figure 6. For the uncoated die, the capacitance response increased continuously with increasing solvent dielectric constant within the whole range of the solvent environments used. The capacitance response of the coated die (i.e., the sensor 400 having the dielectric material 460) showed an increase with increased dielectric constant only for the less polar solvents (dielectric constant < 20) while the solvents with higher dielectric constants yielded a flat response. The result suggests that the uncoated die is sensitive to the whole range of solvent polarities tested while the coated die is more sensitive to non-polar than polar environments, suggesting that the coated die could be used to selectively sense compositional changes among non-polar molecules in an otherwise interfering more polar environment. Thus, the sensor 400 can be used to differentiate water and oil or linear polarity differentiation by comparing pure hydrocarbons versus components like asphaltenes and naphtenates.

EXAMPLE 2

[0071] Figure 5 shows another embodiment, featuring multiple gap distances between conductors in a single sensor, indicated generally at 500. The sensor 500 includes a substrate 510 and four independent interdigitated comb conductors 520, 530, 540, 550. The substrate 510 was formed from a generally square piece of glass fiber reinforced epoxy (Garolite) with thickness of about 0.06 inches, a length of about 1.25 inches, and a width of about 1.25 inches. The die for sensor 500 was prepared using standard methods for fabricating printed circuit boards (PCB 's) for packaging microelectronic devices. Each comb conductor 520, 530, 540, 550 has 12 teeth (only six of the forty-eight total teeth being shown in Figure 5), and is fabricated from copper. The thickness of each of the comb conductors 520, 530, 540, 550 is about 0.0014 inches. The teeth of two of the conductors 520, 530 are connected adjacent respective sides of substrate 510 as shown in Figure 5, which is the side of substrate 510 upon which all the conductors are disposed, while the teeth of the conductors 540, 550 are similarly connected on the opposite surface of the substrate 510.

[0072] The conductors 520, 530, 540, 550 of the sensor 500 are separated by two different gap distances: a first gap distance 560 between proximal teeth, and a second gap distance 570 between distal teeth as shown in Figure 5. In this example, the sensor 500 is constructed with a first gap distance 560 of about 0.01 inches, and a second gap distance 570 of about 0.03 inch. Each tooth is about 0.01 inches wide and about 0.75 inch long. A pitch width 580 for sensor 500 is about 0.08 inches.

[0073] Two dies were fabricated. One of the dies was kept uncoated for use as a control. The other dies was coated on all sides with a polymer dielectric material 590 (Adhesive Paste # 800 available from Master Bond, Inc. of Hackensack, NJ) to a thickness of approximately 0.15 millimeters. The polymer was cured overnight in air and at ambient temperature.

[0074] The coated and uncoated dies were washed in three successive isopropanol baths (100 mL each) for 1, 3, and 12 hours, respectively. The initially fluctuating response stabilized during the wash, showing no detectable drift in time after completion of the washing procedure. The washed dies were wiped using a chemically clean paper napkin, air-dried for about 1 min, and tested as follows. [0075] The sensor 500 having the dielectric material 590 thereon and the uncoated control die were tested by operation as capacitors. Their responses were monitored using an SR720 LCR meter, which is available from Stanford Research Systems of Sunnyvale, CA, at IV peak to peak, at 100 kHz frequency. Data was acquired using a LabJack data acquisition module (available from LabJack Corporation of Lakewood, CO) that was interfaced with a personal computer (PC) using Lab View software (National Instruments Corporation of Austin, TX).

[0076] For the experiments on both the uncoated die and the coated die (i.e., sensor 500), two of the conductors 520, 540 were operatively connected to each other, and the other two conductors 530, 550 were operatively connected to each other. The coated and uncoated dies were immersed simultaneously in a beaker containing 80 mL of Arabian crude oil at 50 degrees Celsius and continuously stirred at 200 rpm. Beginning after about 1 hour of equilibration, the response over time was monitored in the form of the inverse value of capacitance (1/pF). The initial response was considered to be of 100% with the zero to be a response at an infinite capacitance. For each die, the value for inverse capacitance at time t=0 was used to normalize the subsequent response, allowing the comparison of both devices on a single plot. After several minutes of data collection, 20 milliliters of water was added and allowed to blend with the crude oil. The resulting mixture was continuously stirred. Then, in order to simulate an influx of low-molecular- weight hydrocarbons such as solubilized/liquidified methane, 2 milliliters of pentane was injected into the mixture. The data recording was stopped after several more minutes.

[0077] Figure 7 is a plot of the resulting data. The vertical axis shows normalized inverse capacitance (i.e., a smaller value on the vertical axis corresponds to an increased capacitance) and the horizontal axis shows time in seconds. As shown in the response trace, the addition of water resulted in a rapid change in the response of the uncoated die, fluctuating as the heterogeneous oil/water blend contacted the conductors. In contrast, the addition of water did not yield any significant response from the coated die (i.e., sensor 500). However, the subsequent injection of pentane into the water/oil mixture did result in a clearly detectable response by the coated die. This suggests that the coated die could be used to detect small hydrocarbon influxes into a crude oil stream, and that the coated and uncoated dies could be used in combination to recognize more complex compositional changes.

[0078] With reference to Figure 8, one suitable use of any of the sensors, sensor arrays, and sensor systems described herein is for well drilling and more particularly for deep well drilling. Deep well drilling can be conducted for a number of reasons but is often conducted for the exploration of natural gas and/or petroleum. For purposes of this specification, deep well drilling means drilling to a total depth of 10,000 feet or more below ground surface. Deep well drilling is conducted using a drill rig (not shown) that is adapted for rotating and advancing a dill bit B. The bit B is operatively connected to the drill rig via a drill string DS and is configured to cut through bedrock R to form a borehole H. During drilling, drilling fluid (or mud) is pumped downward through the drill string DS, out one or more nozzles formed in the bit B, and upward through an annulus A where it exits the borehole at the surface. The annulus is defined as the interior space of the borehole H excluding the drill string DS, The drilling fluid is used, for example, to remove cuttings (e.g., dislodged pieces of bedrock B) from the borehole H, maintain acceptable formation pressures, stabilize the borehole above the bit B, cool and lubricate the bit, and to transmit hydraulic energy to bit.

[0079] One or more sensors can be mounted on or adjacent to the drill bit B. In one embodiment shown in Figure 8, an array of sensors 600 is mounted on the drill string DS adjacent the drill bit B. As a result, the sensors 600 can be used during the drilling operations (measurement-while-drilling) to collect data related to the borehole H environment near the bit B. It is understood that the sensors 600 can be free from mounting to the drill string DS or bit B. That is, the sensors 600 can be placed into the borehole H independent of the drill string DS and bit B and used during the drilling operations (logging-while-drilling) or with the drill string and bit removed from the borehole (open-hole logging). For example, FIG. 9 illustrates a down-hole logging tool (LT) having a plurality of sensors 700 mounted thereon being used to sense the borehole H environment. The sensors can also be used before and/or after a stimulation processes (e.g., perforation, fracturing) or a well-intervention process (liquid lifting, deposit removal, plugging, cementation) is conducted in the borehole H. The sensors 600 can also be used to permanently, continuously monitor, or to intermittently monitor production of the resulting well. In one example, as illustrated in FIG. 10, a plurality of sensors 800 are mounted to a casing C used to case off the borehole H. The sensors 800 can be used to monitor the environment within the casing C during subsequent drilling operations, stimulation processes, well-intervention processes, and/or well production.

[0080] As explained above, a "kick" or blowout can occur during operation of the drill rig if fluid and/or gas contained within the bedrock B uncontrollably enter the borehole H. The reduction in pressure associated with the ascension of fluid from deep within the earth to the earth's surface can result in the rapid evolution of gas out of solution. This rapid evolution, or "kick" of gas, can significantly disrupt the exploitation process, and can also be dangerous. With reference again to FIG. 8, one or more of the sensors 600 can be configured to detect a rapid or sudden change in pressure in the borehole H near the bit B. Any pressure change detected by the sensors 600 can be communicated (as discussed above) to the drillers operating the drill rig. The drillers, knowing a potential "kick" has been detected, can take evasive measures to minimize or prevent damage caused by the "kick". Thus, the ability to sense, before the fluid reaches the surface, the fluidic conditions (e.g. composition) that might lead to a "kick" upon reaching the surface is a useful feature of a sensor.

[0081] Another important compositional change in downhole fluid is their multiphase composition such as a proportional ratio of oil, gas, and water. Thus, the sensors 600 can be configured to detect changes in the proportional ratios of oil, gas, and water. That is, the sensors 600 can be configured to detect increases or decreases (fluctuations) in the amount of oil and/or gas present in the borehole H adjacent the bit B compared to the amount of water. The sensors 600 can also be configured to sense changes in the overall chemical qualities of oil, gas, and/or water that relate to molecular size and polarity distributions. For example, the sensors 600 can be configured to sense light versus heavy oil or salt water (brine) versus clean water. The sensors 600 can also be configured to sense changes in the number of specific molecular species, such as asphaltenes and waxes creating organic deposits, or naphthenic acids and hydrogen sulfide causing corrosion. Thus, the sensors 600 are sensitive to changes in multiphase fluid composition and molecular size or polarity distribution within individual phases.

[0082] It is contemplated that the array of sensors 600 can be configured to sense changes in numerous characteristics of interest within the borehole H environment. Information about these characteristics can aid in the drilling process or in the production of the resulting well. It is also contemplated that a plurality of arrays of sensors 600 can be used. For example a plurality of arrays may be used to collect data from a number of wells throughout an oil field, and this data may be used to assist in analysis of the field.

[0083] FIG. 11 illustrates one embodiment of an array of sensors, indicated generally at 900, comprising a plurality of individual sensors 910, 912, 914, 916, 920, 922, 924, 926, 930, 932, 934, 936, 940, 942, 944, and 946 (hereinafter collectively referred to as "910-946"). The illustrated array of sensors 900 includes sixteen individual sensors 910-946 but it is understood that the array can include more or fewer individual sensors but no fewer than two sensors.

[0084] In one configuration of the array 900, each of the individual sensors 910-946 is configured to operate independent of the other sensors. That is, each of the individual sensors 910-946 is configured to sense a change in a single characteristic of interest in the environment that is unrelated to the other characteristics of interest being sensed by the other sensors.

[0085] In another configuration of the array 900, at least some of the individual sensors 910-946 are configured to be dependent or operative in conjunction with one or more of the other individual sensors. For example, one of the sensors 910 may be able to sense a change in a collective group of characteristics of interest (e.g., compounds 1, 2, 3, and 4); another sensor 912 may be slightly more sensitive and be able to sense a change in a smaller group of characteristics of interest (e.g., compounds 2, 3, and 4); another sensor 914 may be slightly more sensitive yet and able to sense a change in still a smaller group of characteristics of interest (e.g., compounds 3 and 4); and another sensor 916 may be configured to sense a single characteristic of interest (e.g., compound 4). In this example, the data collected from each of these four sensors 910, 912, 914, 916 can be processed, such as by a PC, to ascertain information regarding all four compounds. It is understood that more or fewer sensors can be dependent or operative in conjunction with the other individual sensors 910-946.

[0086] In another example wherein at least some of the individual sensors 910-946 are interdependent, one of the sensors 920 may detect a change in pressure and another sensor 922 may detect a change in temperature. The data regarding temperature and/or pressure changes can be used to correct or at least equilibrate data collected from one or more of the other sensors if the sensors are configured to sense changes in characteristics of interest that are effected by changes in pressure or temperature.

[0087] In still another configuration of the array 900, some of the sensors are configured to sense a change in a single characteristic of the environment that is unrelated to the characteristics being sensed by the other sensors and some of the sensors may be configured to be dependent upon or operate in conjunction with one or more of the other individual sensors.

[0088] The dielectric material for the various sensors described herein can be selected based upon one or more characteristics of interest of the environment. For example, as illustrated in FIG. 12, suitable dielectric materials include metals, ceramics, organic polymers, and inorganic/organic hybrids. As shown based on the size of the circle, metals are typically more robust and durable than the others and the inorganic/organic hybrids are typically more robust and durable than the ceramics and organic polymers. The ceramics are typically more robust and durable than the organic polymers. Metals, however, typically have less size-based and polarity-based selectivity than the others. Ceramics typically have greater size-based selectively but lower polarity-based selectivity as compared to organic polymers and inorganic/organic hybrids. Organic polymers typically have higher polarity-based selectivity but lower size-based selectively than the others. Inorganic/organic hybrids typically have high size-based and polarity-based selectivity than the others. In this example, inorganic/organic hybrids have a greater range of environments and characteristics of interest for which they can suitably be used as dielectric materials, as compared to metals, ceramics and organic polymers. It is understood, however, that metals, ceramics and organic polymers can be used as dielectric materials in some environments and in sensing some characteristics of interest. These materials are listed as examples and should not be construed as limiting.

[0089] A number of embodiments of the invention have been described. Nevertheless, it will be understood that various modifications may be made without departing from the spirit and scope of the invention. Accordingly, other embodiments are within the scope of the following claims.

[0090] When introducing elements of various embodiments, the articles "a", "an", "the", and "said" are intended to mean that there are one or more of the elements. The terms "comprising", "including", and "having" are intended to be inclusive and mean that there may be additional elements other than the listed elements. Moreover, the use of "top", "bottom", "above", "below" and variations of these terms is made for convenience, but does not require any particular orientation of the components.

[0091] While the invention may be susceptible to various modifications and alternative forms, specific embodiments have been shown by way of example in the figures and have been described in detail herein. However, it should be understood that the invention is not intended to be limited to the particular forms or embodiments disclosed. Rather, the invention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention as defined by the following claims.

Claims

WHAT IS CLAIMED IS:

1. A sensor for sensing at least one characteristic of interest of an environment, the sensor comprising a conductor and a dielectric material enclosing the conductor, the dielectric material being configured such that any electromagnetic field associated with the conductor and passing outside the conductor does not substantially pass beyond the dielectric material, the sensor having a geometry that remains substantially unchanged when exposed to the environment, the dielectric material having a dielectric function that changes in response to a change in the characteristic of interest.

2. The sensor of claim 1 wherein the conductor is a first conductor, and the sensor further comprises a second conductor spaced from the first conductor, the first and second conductors being enclosed by the dielectric material, the dielectric material being configured such that any electromagnetic fields associated with either of the conductors and passing outside the conductors remain substantially within the dielectric material, the spacing between the conductors remaining substantially unchanged when exposed to the environment.

3. The sensor of either of claims 1 and 2 wherein the sensor comprises a capacitor.

4. The sensor of claim 2 wherein at least a portion of the electromagnetic field passes outside the region disposed directly between the conductors.

5. The sensor of either of claims 1 and 2 wherein the dielectric material exhibits substantial electrical conductivity at one or more frequencies.

6. The sensor of either of claims 1 and 2 further comprising a cladding enclosing the dielectric material and the conductors enclosed therein.

7. An array comprising two or more of the sensors of either of claims 1 and 2.

8. A sensing system, comprising:

one or more of the sensors of either of claims 1 and 2; and

an apparatus for interaction with the one or more sensors.

9. The system of claim 8 further comprising an apparatus for sending an input signal to the one or more sensors and receiving an output signal from the one or more sensors.

10. The sensor of either of claims 1 and 2 wherein the sensor is sensitive to changes in multiphase fluid composition and molecular size or polarity distribution within individual phases.

11. The system of claim 8 wherein the sensor is sensitive to changes in multiphase fluid composition and molecular size or polarity distribution within individual phases.

12. A method for sensing a characteristic of interest of an environment, the method comprising:

providing a sensor or sensing system that uses a sensor, the sensor comprising a first conductor enclosed in a dielectric material, the dielectric material being configured such that any electromagnetic field associated with the conductor but passing outside the conductor does not substantially pass beyond the dielectric material, the sensor having a geometry that remains substantially unchanged when exposed to the environment, the dielectric material having a dielectric function that changes in response to a change in the characteristic of interest of the environment;

exposing the sensor to the environment;

monitoring the dielectric function of the dielectric material;

detecting a change in the dielectric function of the dielectric material; and

determining a change in the characteristic of interest of the environment based on the detected change.

13. The method of claim 12 wherein the step of providing a sensor or sensing system that uses a sensor comprises providing a sensor that includes a first conductor and one or more second conductors, the first and second conductors being enclosed by the dielectric material, the dielectric material being configured such that any electromagnetic fields associated with any of the first and/or second conductors, but passing outside the first and/or second conductors, remain substantially within the dielectric material, the spacing between any two of the first and/or second conductors remaining substantially unchanged when exposed to the environment, the dielectric material having a dielectric function that changes in response to a change in the characteristic of interest.

14. The method of claim 13 wherein the dielectric material comprises one or more dielectric materials, the dielectric materials being configured such that any electromagnetic fields associated with any of the first and second conductors, but passing outside the first or second conductors, remain substantially within the dielectric materials, the spacing between any two of the first and second conductors remaining substantially unchanged when exposed to the environment, each dielectric material having a dielectric function that changes in response to a change in the condition, and wherein:

monitoring the dielectric function comprises monitoring the dielectric function of each of the dielectric materials; and

detecting a change comprises detecting a change in the dielectric function of any of the dielectric materials.

15. The method of any of claims 12 to 14 wherein:

monitoring the dielectric function comprises monitoring the dielectric function over a range of frequencies.

16. The method of any of claims 12 to 14 wherein:

the change in condition is an incipient kick of gas in fluids being extracted from a deep well; and

exposing the sensor to the environment comprises exposing the sensor to the fluids being extracted from the deep well.

17. The method of any of claims 12 to 14 wherein:

the change in condition is a change in concentration of a component of a fluid; and exposing the sensor comprises exposing the sensor to the fluid in an in-vivo environment.

18. The method of any of claims 12 to 14 wherein:

the change in condition is a change in concentration of a component of a fluid; and

exposing the sensor comprises exposing the sensor to the fluid in a deep well.

19. The method of claim 18 wherein the change in condition is a change in a ratio between water and hydrocarbons.

20. The method of claim 18 wherein the change in condition is a change in a ratio between oil, gas, and water.