Patent Publication Number: US-11649717-B2

Title: Systems and methods for sensing downhole cement sheath parameters

Description:
BACKGROUND 
     1. Field 
     Embodiments of the present disclosure relate to systems and methods for wirelessly monitoring well conditions. 
     2. Description of Related Art 
     Oil and gas wells are high pressure vessels drilled thousands of feet into the ground to gain access to oil and gas reservoirs. The integrity of these wells come from the steel pipes called “casings” that are lowered and lined into the wellbore to support the sides of the wellbore. The casing is designed to withstand high pressures, forces, and environmental factors it will be subjected to in a wellbore, and maintain integrity throughout the production of the well until it is sealed and abandoned. Once the casing is placed in the wellbore, a cement slurry is pumped through the casing and into the annulus to fill the space between the outer diameter of the casing and the well bore wall. Upon curing, the cement permanently seals the casing to the wellbore. 
     Currently there are tools available to accurately evaluate the integrity of cementing jobs. However, these tools have several limitations. This is reflected by several well statistics that show that 2-10% of wells drilled in the last 15 years have integrity issues related to casing and cementing. Casing and cementing failures can result in well blowouts, contamination of aquifers, corrosion of casing and production tubing, contamination of production oil and gas, as well as the cessation of production due to well collapse or threat of well blowout. Moreover, casing and cementing failures can also affect the downhole environment and production potential of other wells in the vicinity. The current tools evaluate cement based on acoustic techniques. The tools are lowered inside the wellbore after cementing operations are completed. The tools depend on ‘knocking on the pipe’ and ‘listening’ for a response. 
     SUMMARY 
     Embodiments disclosed here provide a method of evaluating cement sheath integrity using passive, wireless sensors that are pumped into the wellbore with the cement slurry, and embedded in the cement sheath. The sensors provide information on the elastic constitutive properties of cement sheath such as compressive strength, and also parameters of the cement sheath environment, such as temperature, pressure, humidity, pH, and gases inside the cement sheath. The sensing is performed in situ and the results are transferred wirelessly to a reader that can be lowered into a wellbore through a wireline or as a component of a drilling assembly. Alternatively, the data can be transferred wirelessly to micro-devices that can be circulated through drilling fluids, or to devices that are permanently installed on casing collars. By identifying potential issues about the structural integrity of the cement sheath, timely warnings can be provided to perform remedial actions. 
     Accordingly, one example embodiment is a method for wirelessly sensing downhole cement sheath parameters. The method includes dispersing one or more wireless mobile devices in a cement slurry, pumping the cement slurry including the one or more wireless mobile devices through a casing for cementing the casing to the wellbore wall, sensing one or more cement sheath parameters by the one or more wireless mobile devices, transmitting a signal including the one or more sensed cement sheath parameters, and receiving the signal including the one or more sensed cement sheath parameters by a receiver wirelessly connected to the one or more wireless mobile devices. 
     Another example embodiment is a system for wirelessly sensing downhole cement sheath parameters. The system includes one or more wireless mobile devices embedded in the cement sheath between a casing and the wellbore wall of a subsurface formation. The one or more wireless mobile devices include one or more sensors configured to sense one or more cement sheath parameters. The system also includes a receiver wirelessly connected to the one or more wireless mobile devices. The receiver is configured to receive a signal including the one or more sensed cement sheath parameters. 
     Another example embodiment is a wireless mobile device for wirelessly sensing downhole cement sheath parameters. The device includes a sensor configured to sense a cement sheath parameter, a piezoelectric crystal configured to receive an acoustic wave and convert the acoustic wave into electric energy, and a power management unit configured to receive the electric energy and power the sensor. The device may further include a microcontroller adapted to receive measurement data from the sensor and generate an output signal including the measurement data, and a modulator adapted to receive the signal including the measurement data, and modulate the power or amplitude of the signal. The piezoelectric crystal can be further configured to transmit the modulated signal. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
       For simplicity and clarity of illustration, the drawing figures illustrate the general manner of construction, and descriptions and details of well-known features and techniques may be omitted to avoid unnecessarily obscuring the discussion of the described embodiments. Additionally, elements in the drawing figures are not necessarily drawn to scale. For example, the dimensions of some of the elements in the figures may be exaggerated relative to other elements to help improve understanding of the example embodiments. Like reference numerals refer to like elements throughout the specification. 
         FIG.  1    illustrates a method for wirelessly sensing downhole cement sheath parameters, according to one or more example embodiments. 
         FIGS.  2 A- 2 C  illustrate a schematic of a wireless mobile device in a system for wirelessly sensing downhole cement sheath parameters, according to one or more example embodiments. 
         FIGS.  3 A- 3 D  illustrate a schematic of a wireless mobile device in a system for wirelessly sensing downhole cement sheath parameters, according to one or more example embodiments. 
         FIGS.  4 A- 4 D  illustrate data analysis performed in a system for wirelessly sensing downhole cement sheath parameters, according to one or more example embodiments. 
         FIG.  5    is a schematic of a system for wirelessly sensing downhole cement sheath parameters, according to one or more example embodiments. 
         FIG.  6    is a schematic of a system for wirelessly sensing downhole cement sheath parameters, according to one or more example embodiments. 
         FIG.  7    is a schematic of a system for wirelessly sensing downhole cement sheath parameters, according to one or more example embodiments. 
         FIG.  8    is a schematic of a system for wirelessly sensing downhole cement sheath parameters, according to one or more example embodiments. 
         FIG.  9    is a schematic of a system for wirelessly sensing downhole cement sheath parameters, according to one or more example embodiments. 
         FIGS.  10 A- 10 F  illustrates schematics of a sensor configuration in a wireless mobile device for sensing downhole cement sheath parameters, according to one or more example embodiments. 
         FIG.  11    is a schematic of a sensor configuration in a wireless mobile device for sensing downhole cement sheath parameters, according to one or more example embodiments. 
         FIG.  12    is a schematic of a sensor configuration in a wireless mobile device for sensing downhole cement sheath parameters, according to one or more example embodiments. 
         FIG.  13    is a schematic of a sensor configuration in a wireless mobile device for sensing downhole cement sheath parameters, according to one or more example embodiments. 
         FIG.  14    is a schematic of a sensor configuration in a wireless mobile device for sensing downhole cement sheath parameters, according to one or more example embodiments. 
         FIGS.  15 A- 15 F  illustrate schematics of a sensor configuration in a wireless mobile device for sensing downhole cement sheath parameters, according to one or more example embodiments. 
         FIG.  16    is a schematic of a sensor configuration in a wireless mobile device for sensing downhole cement sheath parameters, according to one or more example embodiments. 
         FIG.  17    is a schematic of a sensor configuration in a wireless mobile device for sensing downhole cement sheath parameters, according to one or more example embodiments. 
     
    
    
     DETAILED DESCRIPTION 
     The methods and systems of the present disclosure will now be described with reference to the accompanying drawings in which embodiments are shown. The methods and systems of the present disclosure may be in many different forms and should not be construed as limited to the illustrated embodiments set forth here; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey its scope to those skilled in the art. 
     The term “wireless mobile device” refers to a micro-chip for sensing one or more downhole cement sheath parameters. The micro-chip may include a sensor, a microcontroller or a microprocessor, and a transceiver. The micro-chip may, in some embodiments, include at least one of a modulator, an amplifier, a power storage unit, a power management unit, a piezoelectric crystal, and a memory unit. The term “high temperature” refers to temperatures greater than 125 degrees Celsius or 257 degrees Fahrenheit unless otherwise noted. The term “high pressure” refers to pressures greater than 15,000 psi unless otherwise noted. The term “high vibration” refers to vibrations over 30 g peak at 50-1000 Hz unless otherwise noted. 
     Turning now to the figures,  FIG.  1    illustrates a method for wirelessly sensing downhole cement sheath parameters, according to one or more example embodiments. In one embodiment, one or more passive, wireless mobile devices  102  are dispersed into and pumped from the surface with a cement slurry into a wellbore  105  to be embedded in the cement sheath  104 . Unlike current tools that have the sensors and actuators outside the cement sheath  104 , this method has information gathering sensors and actuators inside the cement sheath  104 . Moreover, the sensors and actuators in the wireless mobile devices  102  are passive compared to the active sensors used in current tools. Therefore, once embedded, these wireless mobile devices  102  can be activated wirelessly to measure and provide measured properties, such as the compressive strength of cement sheath, as well as properties of the cement sheath environment, such as temperature, pressure, strain, stress, humidity, pH, and gases present in the cement sheath  104 . 
     The wireless mobile devices  102  are pumped through a casing  108  and down a wellbore  105  with the cement slurry in a coordinated manner so that sufficient wireless mobile devices  102  cover the whole column of cement sheath  104  in the wellbore  105 . The cement slurry is preceded and succeeded by pumping of a drilling fluid  106 , both of which flow from inside the casing  108  out into the annulus  110  between the casing  108  and the wellbore wall of the subsurface formation  112 , and back to the surface. Redundancy in a given area of the cement sheath  104  is also important to nullify any attenuation of sensor signals due to irregularities in the cement sheath pathway during the wireless interrogation of sensors, and transmission of sensor signals back to the interrogator or reader. As the cement slurry hardens over a period of time, the wireless mobile devices  102  also set in place and are permanently embedded in the cement sheath  104 . The wireless mobile devices  102  can be spherical or any other shape, such as a cube or a capsule, which does not affect the quality or integrity of the cement sheath  104 . The wireless mobile devices  102  can include a coating (not shown) that can be a polymer such as elastomer or any material that can withstand high pressure, temperature, stress, and strain. The coating can also be made from a material that bonds well with the cement sheath  104  and does not leave any gap between the cement sheath  104  and the wireless mobile device  102 . 
     The wireless mobile devices  102 , once embedded in cement sheath  104 , can remain there indefinitely and provide information about cement sheath properties. The wireless mobile devices  102  do not require a power source, such as a battery for operation, resulting in small sizes, and long lifetimes. Batteries are expensive, have finite lifetimes, and the presence of a significant number of batteries in a well is a critical hazard due to their chemical content, and the possibility of its leakage. Even though the wireless mobile devices  102  are in a difficult to access, harsh environment, they can be powered wirelessly. 
       FIG.  2 A  and  FIG.  2 B  illustrate a system  200  for wirelessly sensing downhole cement sheath parameters, according to one or more example embodiments. In one embodiment, an interrogator or reader  120  transmits acoustic waves  114  to the wireless mobile devices  102  and this acoustic energy  114  is converted to mechanical energy through a vibrating cavity, membrane, diaphragm, or a cantilever, and then converted to electrical energy through a piezoelectric crystal  124 , shown in  FIG.  2 C .  FIG.  2 C  illustrates a cross-sectional view (box with a dotted line) of a wireless mobile device  102 , according to one or more example embodiments. A piezoelectric crystal  124  is used to convert acoustic waves  114  to electrical signals to drive a passive inductor-capacitor (LC) sensor  122 . The wireless activation of the passive LC sensors  122  can be performed by lowering a tool with an acoustic interrogator or reader  120  into the casing  108 . A power management unit  126  performs the role of power conditioning and management by ensuring the unprocessed acoustic power is compatible with the load of the LC circuit. The impedances are matched for power transfer optimization and maximize the efficiency of power consumption. Since the sensors  122  are passive and the capacitive element is self-powered, only an alternating current (AC) waveform needs to be supplied to the LC circuit to obtain its output impedance. The output impedance of the passive LC sensors  122  are then modulated by a modulator  130  and transmitted as an acoustic wave  116  utilizing the piezoelectric crystal  124 . The interrogator or reader  120  now acts as a receiver and reads the acoustic waves  116  from the wireless mobile devices  102  and converts them to intelligible information that gives an indication about the integrity of the cement sheath  104 . Acoustic energy can be transferred at higher efficiencies and over longer distances when compared to electromagnetic energy that can be transferred using transmitters and receivers of the same size. However, in electromagnetic energy transfer, the efficiency drops significantly when the transmission distance becomes larger than the coil diameter. 
     Wireless mobile device  102  may also include a microcontroller  128  to receive measurement data from the sensor and generate an output signal including the measurement data. A power storage unit  132  such as a regular di-electric capacitor de-rated for use at high temperatures, a ceramic, an electrolytic, or a super capacitor can be provided in the wireless mobile device  102  for storing the energy produced. The sinusoidal electrical waveform can be rectified and conditioned by the power management circuit  126  to charge the storage unit  132 . In such a case, the sensors  122  are not limited to passive LC sensors and any active, low-power commercially available sensor can be used in the wireless mobile device  102 , and the power storage unit  132  can be used to provide power to the sensors  122 . If the wireless mobile device  102  includes a power storage component, then active ultrasonic sensors can also be used as a method to evaluate the integrity of cement sheath  104 . 
       FIG.  3 A-D  illustrate a system  300  for wirelessly sensing downhole cement sheath parameters in a subsurface formation  312 , according to one or more example embodiments. Wireless mobile devices  302  may also include a microcontroller  328  to receive measurement data from the sensor and generate an output signal including the measurement data, as shown in  FIG.  3 A . A power storage unit  332  such as a regular di-electric capacitor de-rated for use at high temperatures, a ceramic, an electrolytic, or a super capacitor can be provided in the wireless mobile device  302  for storing the energy produced. The sinusoidal electrical waveform can be rectified and conditioned by the power management circuit  326  to charge the storage unit  332 . In such a case, the sensors are not limited to passive LC sensors and any active, low-power commercially available sensor can be used in the wireless mobile device  302 , and the power storage unit  332  can be used to provide power to the sensors. If the wireless mobile device  302  includes a power storage component, then active ultrasonic sensors can also be used as a method to evaluate integrity of the cement sheath  304 .  FIGS.  3 A and  3 B  show how an omnidirectional ultrasonic transceiver  302  can reveal the integrity of the surrounding cement sheath by generating pulses  316  in different directions by a transmitter  336  and then receiving and evaluating the properties of the echo pulses through a receiver  334 . The acoustic waves are generated by driving the piezoelectric crystal  324  by a power source  332  through an amplifier  330 . The received echo pulses are analyzed by the signal processing unit  326  and stored inside the memory of the microcontroller  328 . By evaluating the time of flight, Doppler shift, and amplitude attenuation properties such as sensing distance, velocity, and directionality, attenuation coefficient can be obtained. In one embodiment as shown in  FIG.  3 C , an interrogator or reader  320  is lowered into the cased hole  306 , which is isolated from the rock formation  312  by a casing  308 . The interrogator or reader  320  transmits acoustic waves to the wireless mobile devices  302  and the acoustic energy contained in the acoustic wave is converted to mechanical energy through a vibrating cavity, membrane, diaphragm, or a cantilever, and then converted to electrical energy through a piezoelectric crystal  324 , shown in  FIG.  3 A . The piezoelectric crystal  324  is used to convert acoustic wave  314  to electrical signals and to send a request to the microcontroller memory to transfer the stored data to the reader. The wireless triggering to obtain data from the memory of the wireless microchip can be performed by lowering a tool with an acoustic interrogator or reader  320  into the casing  308 , as shown in  FIG.  3 D . A signal processing unit  326  performs the role of signal conditioning and management by ensuring the stored data in the microcontroller  328  memory is transferred to the reader as an acoustic wave by utilizing the piezoelectric crystal  324 . The impedances are matched for power transfer optimization and maximize the efficiency of power consumption. As shown in  FIG.  3 D , the interrogator or reader  320 , which may be lowered into wellbore  306 , now acts as a receiver and reads the acoustic waves  316  from the wireless mobile devices  302  and converts them to intelligible information that gives an indication about the integrity of the cement sheath  304 . 
       FIGS.  4 A- 4 D  illustrates data analysis performed in a system for wirelessly sensing downhole cement sheath parameters, according to one or more example embodiments. As illustrated in  FIG.  4 A , the signals  416  transmitted by the transmitter  436 , receiver  434  may be used to determine one or more properties of the cement sheath  404  by analyzing the reflected signal  417 . By evaluating the time of flight, Doppler shift, and amplitude attenuation, properties such as distance, velocity, directionality, and attenuation coefficient can be obtained using the system of the present disclosure. The amplitude of the reflected waveform can be used to measure the temperature of the cement sheath (as shown in  FIG.  4 B ), identify cracks in the cement sheath (as shown in  FIG.  4 C ), and also the quality of the cement sheath (as shown in  FIG.  4 D ). One advantage in having ultrasonic sensors inside the cement sheath is that the coating of the wireless mobile devices can be tuned to match the impedance of the cement sheath so that any wave reflected back to the wireless mobile device will be due to a mismatched boundary in the cement sheath. This way integrity issues such as a crack or a microannulus can be accurately located in the cement sheath as waves are reflected from their boundaries. These signals can be processed by the signal processing electronics, and the microcontroller  128 ,  328 , and stored in a memory (not shown). The interrogator or reader  120 ,  320  can then be used to obtain the signals stored in the memory. 
       FIG.  5    is a schematic of a system  500  for wirelessly sensing downhole cement sheath parameters, according to one or more example embodiments. In this embodiment, the interrogator or reader  520 , which may be lowered into wellbore  506 , is connected to a drilling assembly  522  that may be used to further drill the well deeper. The sensor output signals  516  from the wireless mobile devices  502  can be obtained when the drilling assembly  522  is run inside the wellbore  505  to drill a new formation  512  after cementing the previous formation. The interrogator or reader  520  may send the interrogation acoustic wave  514  to receive the sensor output acoustic wave  516 . The sensor signals  516  received by the interrogator or reader  520  can be transferred to the surface using, for example, mud pulse telemetry. 
       FIG.  6    is a schematic of a system  600  for wirelessly sensing downhole cement sheath parameters, according to one or more example embodiments. System  600  includes wireless transmission rings  610  installed above the interrogator or reader  620 . Wireless mobile devices  602  may transmit signals containing sensor information to the interrogator  620 . The rings  610  are connected in a way to transfer the sensor information from one ring to another, all the way to the surface using low power wireless technologies  608  such as low-power Wi-Fi, Wi-Fi direct, Bluetooth, Bluetooth Low Energy, ZigBee, etc. The power to the rings  610  can be provided by energy harvesting charge pods that contain a mini-turbine and two materials of opposite polarities that are driven towards each other by the motion of the turbine due to the drilling fluid  606  flow. The contact and separation motion of the two materials can produce electricity to power the rings  610 . 
       FIG.  7    is a schematic of a system  700  for wirelessly sensing downhole cement sheath parameters, according to one or more example embodiments. In this embodiment, the wireless mobile devices  702  can be organized as a wireless sensor network  710 . The wireless mobile devices  702  are interrogated from the surface and the interrogation signal  714  is passed down the wireless mobile devices  702  all the way to the bottom of the cement sheath  704 . The wireless mobile devices  702  then send sensor signals  716  with information about depth along the mesh network  710  from the bottom of the cement sheath  704  to the surface where a reader can receive the signals  716 . The signals  716  can then be utilized to obtain a three-dimensional map of the cement sheath  704 . The signal transmission can be RF or acoustic where the transmission distance can be pre-programmed or tuned by the interrogation signal  714 . 
       FIG.  8    is a schematic of a system  800  for wirelessly sensing downhole cement sheath parameters, according to one or more example embodiments. System  800  includes one or more oil or gas rigs  812  that may each include a sensor mesh network  816 . Readers on different wells  814  can be connected to wireless gateways  812  on each well  814 , which in turn can be connected to a remote server  820  to create a regularly updated database of the integrity of the cement sheath in wells in an oil or gas field  818 . Cement sheath integrity data  810  from each of the wells  814  may be transmitted to the remote server  820  for storage and analysis of the data. 
       FIG.  9    is a schematic of a system  900  for wirelessly sensing downhole cement sheath parameters, according to one or more example embodiments. As shown in  FIG.  9   , the wireless mobile devices  910  between different layers of the cement sheath  901 ,  902  can be communicably coupled in a way so that signals  914  sent by the acoustic interrogator or reader embedded in the casings  903 ,  904  can be relayed from one layer of casing  903  to another  904  by the wireless mobile devices  910 , and the sensor signal  916  can be transmitted back from the wireless mobile devices  910  to the interrogator or reader embedded in the casings  903 ,  904 . 
       FIGS.  10 A- 10 F  illustrate a transducer portion of a sensor in a wireless mobile device  102 ,  302 ,  502 ,  602 ,  702 ,  910  for sensing downhole cement sheath parameters, according to one or more example embodiments.  FIG.  10 A  illustrates a sensing device that includes a flexible structure  152  that can expand and compress. This structure  152  is made of a shape-memory material, which can be a shape-memory alloy, polymer, gel, ceramic, or combinations thereof. The main advantage of a shape-memory material is its remarkable property to recover to its original shape after changing shape due to an external stimuli. The external stimuli can be temperature, pressure, stress, strain, current, voltage, magnetic field, pH, humidity, gas or light. Moreover, a shape memory material can be programmed to respond and change shape due to any specific stimulus. The sensor may also include a housing  154 , which will be described in further detail in later parts of the disclosure. 
     The structure  152  can be linked either directly or indirectly to a metal electrode  150  that conducts electricity. Directly below this drive electrode  150  is another metal electrode, the ground electrode  160 , which can be fixed. The drive electrode  150  and the ground electrode  160  act as a parallel-plate capacitor, where the drive electrode  150  and ground electrode  160  are separated by a non-conductive region. Note that the electrode  160  can also act as a drive electrode, in which case the electrode  150  will act as the ground electrode to form the parallel-plate capacitor. When a voltage is applied to the drive electrode  150  an electric field is produced between the drive electrode  150  and the ground electrode  160  and the sensor behaves as a capacitor. The capacitance between the plates increases with decreasing distance between the drive electrode  150  and the ground electrode  160 . For example, if the structure  152  responds to an external stimuli by expanding as shown in  FIG.  10 B , the drive electrode  150  linked to the structure  152  will approach the ground electrode  160  thereby decreasing the distance between the drive electrode  150  and the ground electrode  160 . This change in the distance between the drive electrode  150  and the ground electrode  160  will be reflected by an increase in the capacitance between the drive electrode  150  and the ground electrode  160 . Depending on the shape memory material utilized, the distance between the electrodes may remain the same until a change in the magnitude of the stimulus triggers a further change of its shape. Therefore, they can be programmed to change in steps to different magnitudes of external stimuli.  FIGS.  10 D- 10 F  illustrate cross-sectional views of the structure illustrated in  FIGS.  10 A- 10 C , respectively. 
       FIG.  11    illustrates a transducer portion of a sensor in a wireless mobile device  102 ,  302 ,  502 ,  602 ,  702 ,  910  for sensing downhole cement sheath parameters, according to one or more example embodiments. In this embodiment, the drive electrode  150  and ground electrode  160  can be repeated many times and be designed as an array  156 ,  158 , where the change in distance between the array of electrodes  156 ,  158  gives rise to a change in capacitance. 
       FIG.  12    illustrates a transducer portion of a sensor in a wireless mobile device  102 ,  302 ,  502 ,  602 ,  702 ,  910  for sensing downhole cement sheath parameters, according to one or more example embodiments. In this embodiment, the drive electrode  150  and ground electrode  160  are designed as a flexible, planar interdigital array  162 ,  164 , where the change in the shape of structure  152  will change the distance  166  between the drive electrode  162  and ground electrode  164  leading to a change in the capacitance. 
       FIG.  13    illustrates a transducer portion of a sensor in a wireless mobile device  102 ,  302 ,  502 ,  602 ,  702 ,  910  for sensing downhole cement sheath parameters, according to one or more example embodiments. In this embodiment, the drive electrode  150  is linked to an array of shape-memory alloys  170 , such that when exposed to an external stimuli the shape-memory alloys  170  elongate, thereby driving the drive electrode  150  towards the ground electrode  160 , and changing the capacitance. 
       FIG.  14    illustrates a sensor  122  in a wireless mobile device  102 ,  302 ,  502 ,  602 ,  702 ,  910  for sensing downhole cement sheath parameters, according to one or more example embodiments. In this embodiment, when the capacitor  180  is connected in series with an inductor  168 ,  185  and resistor  190 , the circuit becomes a passive LC resonance sensor circuit. Sensor  122  may include electronic circuitry  172 , which may include the resistor  190 , and other components. Passive LC sensors have low power consumption and operating frequencies, and can be fabricated using microfabrication as microelectromechanical systems (MEMS) devices. They are lightweight, resulting in increased design flexibility, device capability, and reliability. A change in the capacitor response due to an external stimuli shifts the resonance frequency of the LC circuit. In some embodiments, the value of the inductance and any load resistance in the circuit remains the same, and only the capacitor linked to the structure changes as the structure responds to the external stimuli. 
       FIGS.  15 A- 15 C  illustrates a transducer portion of a sensor in a wireless mobile device  102 ,  302 ,  502 ,  602 ,  702 ,  910  for sensing downhole cement sheath parameters, according to one or more example embodiments. In this embodiment, a structure  152  containing shape-memory polymer particles  174  may be used as a transducer. The shape-memory polymer particles  174  expand to external stimuli pushing the drive electrode  150  towards the ground electrode  160 . The cross-section of such a capacitor integrated with an inductor  168  forming an LC circuit is shown in  FIGS.  15 D- 15 F . The sensor in this example changes its resonant frequency according to the change in capacitance. 
       FIG.  16    illustrates a transducer portion of a sensor in a wireless mobile device  102 ,  302 ,  502 ,  602 ,  702 ,  910  for sensing downhole cement sheath parameters, according to one or more example embodiments. In this embodiment, a structure  152  with shape-memory polymer particles  175  that have the ability to cross-link, and change the shape of the structure  152 . An external stimulus leads to physical crosslinking between the particles  175  resulting in larger clusters of polymer particles  175  and a change in the shape of the structure  152 . The level of crosslinking may depend on the magnitude of the stimulus. 
       FIG.  17    illustrates a transducer portion of a sensor in a wireless mobile device  102 ,  302 ,  502 ,  602 ,  702 ,  910  for sensing downhole cement sheath parameters, according to one or more example embodiments. In this embodiment, the LC sensor is shown acting as a gas sensor. The sensor has an opening  176  for the gases  184  to go through, a gas purging outlet  178 , and a structure  152  with shape-memory polymers  174 . When exposed to a given gas  184 , the shape-memory polymers  174  respond by changing their size and therefore, changing the distance between the drive electrode  150  and ground electrode  160 . The structure  152  in the LC sensors can be shape-memory alloys, polymers, gels, ceramics or combinations thereof. The sensor may also include a membrane  182  that may be used to filter the gas  184  between inlet  176  and the structure  152 . 
     In all of the embodiments, the housing that the sensors are enclosed in must be robust enough to withstand the high temperature, high pressure, corrosive and abrasive environments. Packaging and housing is mainly done to protect the micro-chip components from mud and other fluids in the formation, which may degrade its performance. Some materials that can be used for housing include ceramic, steel, titanium, silicon carbide, aluminum silicon carbide, Inconel®, and Pyroflask® or any material that has excellent heat conduction properties and a high Young&#39;s modulus. In order to minimize vibrations in the sensors, electronics they can be mounted and installed in ways to isolate vibrations and placed in a separate compartment within the housing. Chemical coatings can be used to further protect the micro-chip and its components from the harsh downhole environment. They can be polymeric coatings, which can be used to provide a uniform and pinhole free layer on sensor and electronic boards. These coatings can withstand continuous exposure to high temperatures for long periods of time, prevents corrosion of electrodes and is an excellent dielectric. Thermal insulation significantly extends the life and durability of the sensors and electronics. The outer protective shell shields all the components inside from the environment and can be epoxy, resin-based materials, or any material that has good thermal conductivity properties. 
     The sensors and instrumentation system construction should also be designed to withstand the harsh environment downhole, and therefore requires proper housing/encapsulation. The most common approach is packaging the sensors/instrumentation in ceramic or custom ceramic components. The die, where the sensors/instrumentation are fabricated on, is connected to the pins of the IC by a process known as wire bonding. The die is normally silicon (Si), which has excellent thermal conductivity, but the wires used for wire bonding, the pins and the soldering between the pins and a printed circuit board (PCB) and the glue holding the die in the packaging are susceptible to failure. To minimize failure rates gold (Au) and aluminum (Al) are used for wire bonding, high temperature alloy materials are used for soldering, and epoxies or adhesives are used to glue the sensors/instrumentation inside the package. Multi-chip modules (MCMs) such as high temperature co-fired ceramic (HTCC) and alumina boards are used to combine multiple ICs into a single system level unit. They are generally plated with Al and Au for soldering and wire-bonding and the dies on these boards are processed independently and assembled into a single device as a final step. These hybrid boards are interconnected with each other in 2D or 3D layers using ceramic single inline package headers on brazed pins (BeNi contacts). BeNi is commercially available and is a standard technology for high temperature packaging. HTCC packages have excellent mechanical rigidity, thermal dissipation and hermeticity, important features in harsh, high temperature applications. To minimize flexing MCMs a stiffening component such as a bridge over the boards or side rails is incorporated into the assembly. Silicon-on-insulator (SOI) is an alternative technology Si that can be utilized for sensors and instrumentation for harsh environments. Compared to ceramic and bulk Si technology, SOI significantly reduces leakage currents and variations in device parameters, improves carrier mobility, electro-migration between interconnects and dielectric breakdown strength. Silicon carbide (SiC) based electronics is another emerging technology but has superior properties to silicon based electronics that makes it an ideal candidate for harsh environment applications, which are thermally, mechanically and chemically aggressive. One of the advantages of the disclosed embodiments include that MEMS technology has allowed the scaling down of millimeter size devices into the micro-nano range. This provides the opportunity to package and fit sensors into smaller areas, have sensor arrays that increase the resolution of measurements, and to seamlessly integrate with other electronic components, leading to ‘system on chip’ devices that can be mass produced. MEMS devices have low power requirements, and the small size of the sensors makes it more tolerant to mechanical shocks and vibrations experienced in a downhole environment. At the same time, significant advancements in material science have also paved the way for materials that change shape due to their response to stimuli. This property enables them to be self-healing, self-deployable, passive sensors and actuators. 
     The Specification, which includes the Summary, Brief Description of the Drawings and the Detailed Description, and the appended Claims refer to particular features (including process or method steps) of the disclosure. Those of skill in the art understand that the disclosure includes all possible combinations and uses of particular features described in the Specification. Those of skill in the art understand that the disclosure is not limited to or by the description of embodiments given in the Specification. Those of skill in the art also understand that the terminology used for describing particular embodiments does not limit the scope or breadth of the disclosure. In interpreting the Specification and appended Claims, all terms should be interpreted in the broadest possible manner consistent with the context of each term. All technical and scientific terms used in the Specification and appended Claims have the same meaning as commonly understood by one of ordinary skill in the art unless defined otherwise. 
     As used in the Specification and appended Claims, the singular forms “a,” “an,” and “the” include plural references unless the context clearly indicates otherwise. The verb “comprises” and its conjugated forms should be interpreted as referring to elements, components or steps in a non-exclusive manner. The referenced elements, components or steps may be present, utilized or combined with other elements, components or steps not expressly referenced. Conditional language, such as, among others, “can,” “could,” “might,” or “may,” unless specifically stated otherwise, or otherwise understood within the context as used, is generally intended to convey that certain implementations could include, while other implementations do not include, certain features, elements, and/or operations. Thus, such conditional language generally is not intended to imply that features, elements, and/or operations are in any way required for one or more implementations or that one or more implementations necessarily include logic for deciding, with or without user input or prompting, whether these features, elements, and/or operations are included or are to be performed in any particular implementation. 
     The systems and methods described here, therefore, are well adapted to carry out the objects and attain the ends and advantages mentioned, as well as others that may be inherent. While example embodiments of the system and method have been given for purposes of disclosure, numerous changes exist in the details of procedures for accomplishing the desired results. These and other similar modifications may readily suggest themselves to those skilled in the art, and are intended to be encompassed within the spirit of the system and method disclosed here and the scope of the appended claims.