Patent Application
20120175510
1. Field
This patent relates generally to devices and methods for measuring fluid properties for oilfield and other industrial applications. In particular, the patent relates to measuring one or more fluid properties such as density.
2. Background
Ability to measure fluid density and other fluid properties downhole is paramount to petroleum exploration as it enables one to differentiate between oil, gas and water [W. D. McCain, Jr., The Properties of Petroleum Fluids, 2nd ed. (1990)]. The relative amounts of oil and gas produced have a direct impact on reservoir development cost. Furthermore, it allows one to locate the oil-water contact line and hence the thickness of the pay zone of a formation. The ability hinges upon availability of an accurate and robust sensor that works reliably in the harsh environment found in an oilwell. Oilfield pressures downhole may be as high as 25,000 psi with temperatures up to 175° C. or higher. There are wells with even more extreme conditions, especially offshore. A further challenge in downhole fluid analysis is that acquiring large quantities of representative downhole fluids is difficult due to the ever-present contamination, such as drilling mud or formation water [O. C. Mullins, M. Hashem, H. Elshahawi, G. Fujisawa, C. Dong, S. Betancourt, T. Terabayashi, Petrophysics 46, 302 (2005)].
Fluid density provides a means of fluid typing. Water has a density of 1.0 g/cm3. Densities of liquid-rich hydrocarbons vary between 0.5 to 0.9 g/cm3, and dry gas or condensate formations have a significantly lower density. The above values are understood to vary with reservoir pressure and temperature. Further, an understanding of the heterogeneity of the reservoir may require that densities be measured at several depths so that the compositional variation can be fully deduced. Such information can aid in identifying zones with the highest economic value; for example a dry gas may be preferred if the well is drilled in a gas field with existing infrastructure to handle gas transport through pipelines. Furthermore, for a given gas composition, the amount of standard cubic feet (SCF's) of gas producible is directly proportional to the density. Knowledge of the fluid density is essential for avoiding costly economic errors in applications, by non-limiting example, oilfield applications.
It is straight-forward to measure a liquid density at ambient pressure and temperature in a laboratory setting. Typically a flask of well-defined volume (volumetric flask) is filled with the fluid of interest and it is weighed on a scale. The density is obtained by dividing the fluidic mass by the known volume. Measurements at elevated pressure and temperature, however, require more sophisticated techniques. Gaseous fluids and heterogeneous liquids further complicate the measurement task. There are some known measurement methods employed for pressure/temperature density measurements, but they have limitations for downhole implementation.
For example, a known method includes a resonating sensor such as resonating tube densitometer and Coriolis flow meter, however, this method is not well-suited for subterranean applications. Firstly, the sizes of such flow meters in many cases are too large to fit in downhole tools, by non-limiting example, oilfield applications. Secondly, mud can be omnipresent at the beginning of a job (i.e., an oilfield application job), and it is unclear that mud can be completely cleaned from the two flow lines of the sensor. Thirdly, the method operates at pressures in the order of 1,000 psi, which makes such method unusable at pressures much higher than 1,000 psi.
Furthermore, there are special fluid conditions that can present problems for resonating sensors to measure fluid properties, such as density. For example, some of the problems for resonating sensors include inaccurate measurements of the fluid properties such as density due to special fluid conditions, i.e., gaseous fluids, emulsions, non-Newtonian fluids, supercritical fluids or multiphase Fluids.
Therefore, there is a need for a device, method and system that can measure the fluid properties such as density for oilfield applications and other industries that can overcome the above noted problems either above ground or in a subterranean environment.
According to some embodiments of the disclosed subject matter, a device for measuring one or more property of a fluid including density. The device comprising: a pressure housing having one or more window formed in the pressure housing. The device includes a flow device arranged in the pressure housing for the fluid to flow through the flow device, and one or more radiation source mounted within the pressure housing approximate a first source window of the one or more window that is configured to generate particles into the fluid. Finally, the device has one or more detectors supported by the pressure housing and positioned approximate a first detector window of the one or more window, the first detector window located between the one or more detector and the flow device. It is noted that the one or more detector can be from a group consisting of one of a solid state detector, radiation detector, a scintillator detector or a gas detector, a solid state charged beta particle detector, a beta particle ionization detector, a wide band gap solid state detector such as a diamond detector or an another radiation detecting device.
According to some aspects of the disclosed subject matter, the fluid can be from the group consisting of at least one liquid, at least one solid mixed with the at least one liquid, at least one gas or some combination thereof. Measurements can be made while the fluid temperature is one of at least −150 Celsius or greater, at least −50 Celsius or greater, at least 50 Celsius, at least 100 Celsius or at least 175 Celsius. The fluid can be one of flowing or not flowing through the flow device while measuring the one or more property of the fluid which includes density. Further, the fluid may be a supercritical fluid such as carbon dioxide (CO2) that is in a supercritical condition which is approximate to a downhole application. The fluid can be one of an emulsified fluid, a drilling fluid or a multiphase fluid.
According to some other aspects of the disclosed subject matter, the one or more radiation source may be from the group consisting of a beta particle source, a strontium source, a strontium 90 source or a positron source. The one or more radiation source can produce beta particles within a energy range of 2 MeV to 3 MeV. The generated beta particles of the one or more radiation source can be emitted through the first source window, into the flow device containing the fluid, out of the flow device and through the first detector window to be detected by the one or more detector, so at least one electronic device such as a processor is in communication with the one or more detector for receiving a pulsed signal from the one or more detector in one of a downhole environment, a reservoir, a borehole, inside a surface metering device or testing device. The one or more detector may be from the group consisting of one of a solid state detector, a radiation detector, a scintillator detector, a gas detector, a solid state charged beta particle detector, a beta particle ionization detector, a wide band gap solid state detector such as a diamond detector or an another radiation detecting device.
According to some other aspects of the disclosed subject matter, a wide band gap solid state detector may include one of a band gap of approximately 5.45 eV, a approximate density of 3.51 g/cm3 or a approximate dimension of a 5 mm length by a 5 mm width by a 0.5 mm height. The wide band gap solid state detector may operate in a routine environment of temperatures approximately equal to and above one of 150 Celsius or 200 Celsius or more. The wide band gap detector is compatible for applications in one of a microelectromechanical system (MEMS), a nanoelectromechanical system (NEMS), a micromachine related device, a nano-tips based detector or a Field-emitting array based gas detector.
According to some other aspects of the disclosed subject matter, a nano-tips based gas radiation detector, or field-emission gas tube may also operate in a routine environment of temperatures stated above or more. With a dimension of a few mm length by a few mm width and by a 0.5 mm height it can be also compatible for applications in one of a microelectromechanical system (MEMS), a nanoelectromechanical system (NEMS), or a micromachine related device. Comparing with a solid-state detector, the nano-tips based gas detector, due to the induced avalanches from the ionization, may have advantages of outputting read-out pulses with large amplitudes and detecting lower energy betas passing through the fluidic device.
According to some other aspects of the disclosed subject matter, the at least one electronic device such as a processor can be in communication with the one or more detector for receiving a pulsed signal from the one or more detector, the at least one electronic device processes the received pulsed signals to provide the capability to determine the one or more property including density of the fluid. The determined density measurement of the fluid may be from the group consisting of one of a gaseous fluid density measurement, an emulsion fluid density measurement, a non-Newtonian fluid density measurement, a supercritical fluid density measurement or a multiphase fluid density measurement. The device is in communication with a processor and a mass density measuring device that measures a mass density of the fluid, the processor is capable of determining a fluidic hydrogen index from data received from the device and the mass density measuring device. The device can be in communication with a processor and a fluidic hydrogen index measuring device that measures a fluidic hydrogen index, the processor is capable of determining a fluidic mass density from data received from the device and the fluidic hydrogen index measuring device.
According to some other aspects of the disclosed subject matter, the pressure housing can be of a material from the group consisting of a stainless steel or one or more other materials and stainless steel. The pressure housing may include a source space with a source retainer that is in communication with the first source window to secure the one or more radiation source. The pressure housing may include a detector space, detector shield and a detector cap that is in communication with the first detector window to secure the one or more detector. The detector space may further include an elastomeric device. It is possible the one or more detector is structured and arranged to be integral with the pressure housing. The pressure housing may be capable of withstanding pressures up to 30,000 psi or more and temperatures to 200 Celsius or more. The device can be designed to operate at pressures of one of 10 k psi or more, 15 k psi or more or 20 k psi or more. Further, the device may be designed to operate at temperatures of one of more than −150 Celsius, more than −50 Celsius, at least 50 Celsius, at least 100 Celsius or at least 150 Celsius. It is noted the device can be designed to operate at pressures within the flow device of one of at least 5 kpsi, at least 10 k psi or at least 20 kpsi.
According to some other aspects of the disclosed subject matter, the device may further comprise deploying the pressure housing, the radiation, the detector and the first source window and first detector window downhole and wherein the fluid measurements are made downhole. Further, the one or more window and flow device are made of a material having an approximate density of at least one combination of a glass and a peek material or a combination of the glass, the peek material and another material. It is noted that a thickness of the first source window, a wall of the flow device and the first detector window can be approximately equal. It is possible that a thickness of the first source window, a wall of the flow device approximate the first source window, the first detector window and a wall of the flow device approximate the first detector window may also be approximately equal. Further, a first distance from the first source window to the wall of the flow device approximate the first source window can be approximately equal to a second distance from the first detector window to the wall of the flow device approximate the first detector window. Further still, the first source window and the first detector window of the one or more window can have a thickness capable of allowing transmission of particles from the one or more particle source within the pressure housing to the one or more detector, to allow for the particles to be detected by the one or more detector. It is possible the one or more detector is from the group consisting of one of a solid state detector, a radiation detector, a scintillator detector, a gas detector, a solid state charged beta particle detector, a beta particle ionization detector, a wide band gap solid state detector such as a diamond detector or an another radiation detecting device.
According to some other aspects of the disclosed subject matter, the flow device can be from the group consisting of a tube, a flowline, a channel, a pipe and a microfluidic channel that is integral with the pressure housing. Further, the flow device can have one of a thickness or a diameter ranging from approximately equal to or less than 0.5 mm to approximately. It is noted the flow device can have one of two or more thicknesses such as a first and a second thickness or two or more diameters such as a first and a second diameter. Further still, the one or more beta sources can have two or more beta sources and the one or more beta detector has two or more beta detectors. It is possible a first beta source and a first beta detector can be arranged to measure the mixed fluid and a second beta source and a second beta detector are arranged to measure a gas. It is noted the device may further comprise of: (a) a first beta source of the two or beta sources is located approximate the first diameter of the flow device and the first source window, and a first beta detector of the two or more beta detectors is located approximate the first diameter of the flow device and the first detector window; and (b) a second beta source of the two or beta sources is located approximate the second diameter of the flow device and a second source window, and a second beta detector of the two or more beta detectors is located approximate the second diameter of the flow device and a second detector window. Further, the at least one electronic device can be in communication with the first detector and the second detector for receiving a first pulsed signal from the first detector and a second pulsed signal from the second detector, so that the at least one electronic device processes the received first and second pulsed signals to provide the capability to determine the one or more property including density of the fluid. Further still, the device can be deployed downhole and the one or more radiation source mounted within the pressure housing generates particles into the fluid within one of a downhole environment, a reservoir or in a borehole.
According to another embodiment of the disclosed subject matter, an apparatus for measuring one or more property of a fluid including density in a subterranean environment. The apparatus comprises: a pressure housing to be deployed within the subterranean formation having one or more window formed in the pressure housing capable of operating in routine pressures of at least 15 kpsi; a flow channel arranged in the pressure housing for the fluid to flow through the flow channel; one or more particle source mounted within the pressure housing approximate a first source window of the one or more window is configured to generate particles into the fluid within an energy range up to 3 MeV; and one or more detector mounted within the pressure housing approximate a first detector window of the one or more window, the first detector window located between the one or more detector and the flow channel.
According to some other aspects of the disclosed subject matter, the fluid may be from the group consisting of a liquid, a liquid mixed with a solid, a gas or some combination thereof, and the fluid is one of flowing or not flowing through the flow channel while determining the one or more property of the fluid that includes density. The one or more particle source can be from the group consisting of a beta particle source, a strontium source such as a strontium 90 source or a positron source. The one or more detector may be from, but not limited to, the group consisting of one of a solid state detector, a radiation detector, a scintillator detector, a gas detector, a solid state charged beta particle detector, a beta particle ionization detector, a wide band gap solid state detector such as a diamond detector or an another radiation detecting device Further, at least one electronic device such as a processor can be in communication with the one or more detector for receiving a pulsed signal from the one or more detector, the at least one electronic device processes the received pulsed signals to provide the capability to determine the one or more property including density of the fluid. Further still, the flow channel can have one of a thickness or a diameter ranging from approximately equal to or less than 0.5 mm to approximately. It is possible the first source window and the first detector window of the one or more window can have a thickness capable of allowing transmission of particles from the one or more particle source within the pressure housing to the one or more detector, to allow for the particles to be detected by the one or more detector. It is note that a portion of the pressure housing approximate the first detector window can have a thickness sufficient to substantially attenuate the transmission of particles so that a linear resolution of the one or more particle detector is increased.
According to some embodiments, a system for measuring one or more property of a fluid including density in a reservoir environment. The system comprising: a pressure housing to be deployed within the reservoir formation has one or more window formed in the pressure housing; a flow channel arranged in the pressure housing for the fluid to flow through the flow channel; one or more beta particle source mounted within the pressure housing approximate a first source window of the one or more window is configured to generate beta particles up to a energy of 3 MeV into the fluid; and one or more detector mounted within the pressure housing approximate a first detector window of the one or more window, the first detector window located between the one or more detector and the flow channel.
According to some other aspects of the disclosed subject matter, the one or more beta particle source can be a strontium source such as a strontium 90 source.
According to some embodiments, a method for measuring one or more property of a fluid including density in a subterranean environment. The method comprising: deploying a pressure housing within the subterranean formation configured to operate at temperatures of at least 150 Celsius, the pressure housing includes one or more window formed in the pressure housing; arranging a flow channel in the pressure housing for the fluid to flow through the flow channel; mounting one or more beta particle source within the pressure housing approximate a first source window of the one or more window configured to generate particles into the fluid; and mounting one or more wide band gap solid state detector such as a diamond detector within the pressure housing approximate a first detector window of the one or more window, the first detector window located between the one or more radiation detector and the flow channel.
According to some other aspects of the disclosed subject matter, the wide band gap solid state detector can include one of a band gap of approximately 5.45 eV, a approximate density of 3.51 g/cm3 or a approximate dimension of 5 mm height by 5 mm length by 0.5 mm width or some combination thereof.
According to some embodiments, a method for measuring one or more property of a fluid including density in a downhole environment. The method comprising: deploying a pressure housing within the subterranean formation having routine environment temperate of equal to or more than 140 Celsius, the pressure housing includes one or more window and a flow channel formed in the pressure housing, wherein the fluid channel is arranged for the fluid to flow through the flow channel; mounting one or more beta particle source within the pressure housing approximate a first source window of the one or more window that is configured to generate beta particles into the fluid; and mounting one or more solid state charged beta particle detector within the pressure housing approximate a first detector window of the one or more window, the first detector window located between the one or more solid state charged beta particle detector and the flow channel.
According to some other aspects of the disclosed subject matter, the one or more solid state charged beta particle detector can be one of a beta particle ionization detector or a wide band gap solid state detector such as a diamond detector. Further, the wide band gap solid state detector can include one of a band gap of approximately 5.45 eV, a approximate density of 3.51 g/cm3 or a approximate dimension of 5 mm height by 5 mm length by 0.5 mm width.
According to some other aspects of the disclosed subject matter, the fluidic channel or flowline can be geometrically wide or flat [the flow channel cross-section for example can be a few cm×a few mm] so that the flowing volume can be maintained high while the beta particle pass length is kept around a few mm. In such a geometrical arrangement, multiple Sr90 sources and multiple detectors can be implemented across the “flat” flowing channel, resulting a high counting or measurement speed.
Further features and advantages will become more readily apparent from the following detailed description when taken in conjunction with the accompanying drawings.
The present disclosure is further described in the detailed description which follows, in reference to the noted plurality of drawings by way of non-limiting examples of exemplary embodiments, in which like reference numerals represent similar parts throughout the several views of the drawings, and wherein:
The following description provides exemplary embodiments only, and is not intended to limit the scope, applicability, or configuration of the disclosure. Rather, the following description of the exemplary embodiments will provide those skilled in the art with an enabling description for implementing one or more exemplary embodiments. It is understood that various changes may be made in the function and arrangement of elements without departing from the spirit and scope of the subject matter disclosed in the application as set forth in the appended claims.
Specific details are given in the following description to provide a thorough understanding of the embodiments. However, it will be understood by one of ordinary skill in the art that the embodiments may be practiced without these specific details. For example, systems, processes, and other elements in the subject matter disclosed in the application may be shown as components in block diagram form in order not to obscure the embodiments in unnecessary detail. In other instances, well-known processes, structures, and techniques may be shown without unnecessary detail in order to avoid obscuring the embodiments. Further, like reference numbers and designations in the various drawings indicated like elements.
Also, it is noted that individual embodiments may be described as a process which is depicted as a flowchart, a flow diagram, a data flow diagram, a structure diagram, or a block diagram. Although a flowchart may describe the operations as a sequential process, many of the operations can be performed in parallel or concurrently. In addition, the order of the operations may be re-arranged. A process may be terminated when its operations are completed, but could have additional steps not discussed or included in a figure. Furthermore, not all operations in any particularly described process may occur in all embodiments. A process may correspond to a method, a function, a procedure, a subroutine, a subprogram, etc. When a process corresponds to a function, its termination corresponds to a return of the function to the calling function or the main function.
Furthermore, embodiments of the subject matter disclosed in the application may be implemented, at least in part, either manually or automatically. Manual or automatic implementations may be executed, or at least assisted, through the use of machines, hardware, software, firmware, middleware, microcode, hardware description languages, or any combination thereof. When implemented in software, firmware, middleware or microcode, the program code or code segments to perform the necessary tasks may be stored in a machine readable medium. A processor(s) may perform the necessary tasks.
According to an embodiment, a device for measuring one or more property of a fluid including density. The device comprising: a pressure housing having one or more window formed in the pressure housing. The device includes a flow device arranged in the pressure housing for the fluid to flow through the flow device, and one or more radiation source mounted within the pressure housing approximate a first source window of the one or more window that is configured to generate particles into the fluid. Finally, the device has one or more detector supported by the pressure housing and positioned approximate a first detector window of the one or more window, the first detector window located between the one or more detector and the flow device. It is possible the one or more detector can be from the group consisting of one of a solid state detector, a radiation detector, a scintillator detector, a gas detector, a solid state charged beta particle detector, a beta particle ionization detector, a wide band gap solid state detector such as a diamond detector or an another radiation detecting device.
Further, according to some embodiments, the devices, methods and related systems described for measuring one or more property of a fluid including density, includes a pressure housing having one or more window formed in the pressure housing, and a flow device arranged in the pressure housing for the fluid to flow through the flow device. Further, a radiation source mounted within the pressure housing approximate a first source window of the one or more window and configured to generate particles into the fluid. Also, a detector supported by the pressure housing and positioned approximate a first detector window of the one or more window, the first detector window located between the detector and the flow device. The detector can be a solid state charged beta particle detector such as a diamond detector, and the radiation source can be a beta particle source such as a strontium 90 source.
The subject matter of the application includes, by non-limiting example, the technique for downhole fluid density measurement that involves no direct contact of the sensor with the fluid to be measured. In particular, using a detector to measure the density-dependent attenuation of beta particles. The density measured is a volumetric average of the fluid density situated between a source and the detector and as such is less dependent upon surface contamination (i.e. scale buildup or the like), a common problem for density measurements in the challenging subterranean environment, i.e., downhole.
It is contemplated that at least two implementations for such a measurement may include a macroscopic implementation and a microscopic implementation. The macroscopic implementation may have applications in conventional oilfield application tools where the beta path length through a flowline is about approximately a few millimetres. An example of microscopic implementation is a density measurement downstream of a microfluidic separator through a microfluidic channel of a diameter of approximately 0.5 mm or less.
Where m is the electron mass, e the electron charge, and v the electron velocity. N and Z are the number density and atomic number of the absorbing material atoms. B represents the Bethe formula for the collisional losses of fast electrons, and is related to electron velocity or energy and the averaging excitation and ionization potential of the absorber, which is rather a constant for many common elements, compounds and different materials for fast electrons. Thus, for electrons with a given energy (mono-energetic) they can travel a certain distance in a given absorbing material. This distance is called the electron “range” and is reversely correlated to the electron number density in the material as shown by the NZ product in Eq. 1. The attenuation of beta particles emitted by a radioisotope source, because of the continuous distribution in their energy, differs significantly from the simple picture for mono-energetic electrons. The low energy betas are rapidly absorbed by a small thickness of the absorber material, so that the initial slope on the attenuation curve is greater. For the majority of beta spectra, the curve will have a near-exponential shape and is therefore nearly linear on the semilog plot. An “absorption co-efficient” μ is sometimes defined by:
where I0 is the counting rate without absorber, I counting rate with absorber, and t absorber thickness. The co-efficient μ is directly proportional to the beta energy losses in the absorber material and convoluted by the continuous energy distribution of the beta particles emitted from a source with fixed-endpoint energy. Hence the coefficient μ is directly related to the material density of the absorber. And the attenuation measurements can be used to extract the material density of the absorber.
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A high energy allows the beta particles to penetrate through 1-10 mm of liquid, for example. As beta particles travel through material they interact with shell electrons of atoms or molecules and produce ionization events, each time losing on the order of tens of electron volts of energy.
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Some additional advantages of the diamond detector, by non-limiting example, include: 1) its small size, for example, a 5×5×0.5 mm detector, which is ideal for applications where there is little space (i.e., in a logging while drilling applications, especially for small borehole sizes), and that it is compatible for applications in microelectromechanical system (MEMS), nanoelectromechanical system (NEMS) and micromachine related devices; 2) the detector is mechanically strong; chemically stable even at high temperatures; resistance to radiation damages; excellent linearity and provides stability when used as a radiation detector, which makes it ideal for high-radiation and hostile environments applications; 3) the detector is easy to use, it needs approximate 200-500 V/cm bias; has a fast charge collection (˜10 ns); has a good energy resolution for stopping alphas and betas (˜4%); and has a large signal comparable to silicon detectors; along with a very low leakage current (<pA).
It is noted that one of the alternatives to diamond detectors is to use a Silicon Carbide detector instead of a diamond detector, giving the fact that SiC does have a relative large band gap as shown in Table 1 above.
Some other additional advantages of diamond detectors relevant to the claimed subject matter of the application include the ability to make accurate measurements under subterranean environment conditions, such as downhole environment conditions. For example, at least one advantage over that of the known resonating sensors is its ability to make accurate measurements of properties of fluid, such as density, when measuring fluids under special fluid conditions. Special fluid conditions, as noted above include gaseous fluids, emulsions, non-Newtonian fluids, supercritical fluids or multiphase Fluids.
A special fluid condition such as a gaseous fluid presents problems for known resonating sensors when trying to measure fluid properties of a fluid, such as density. For example, trying to get an accurate density measurement of any low density fluid such as dry methane or condensates with low carbon number is difficult for any technique, especially for a well-known resonating sensor. After the initial cleaning of a flow line of the resonating sensor, as well as any immersed sensor, it is almost assured that it will be coated with mud. While one can remove particulates and mud with a miscible fluid; for example, oil directly from the formation, it is difficult to remove such residues with a gas stream. The analogy that is typically made, is that one cannot wash oily hands with just a blast of air. Rather, one needs a fluid that is miscible and can dissolve away the coated particulates and solids. A residual thin layer of mud will dramatically reduce the accuracy of the measurement. On the other hand, the claimed subject matter of the application overcomes the above problems and is able to make accurate measurements of properties of fluid, such as density by making a volumetric measurement through a fluid flow line which results in being less sensitive to such contamination.
Another example of a special fluid condition such as emulsions presents problems for the known resonator sensor when making density measurements. Oil/water emulsions are common in wells throughout the world. They may be resulted from water breakthrough during a sampling job or from the shearing action of drilling when using water-based mud. The measurement of emulsions with a known resonating sensor is particularly challenging due to wetting effects; typically one fluid prefers to wet the sensor tip, providing a biased measurement. On the other hand, the claimed subject matter of the application overcomes the above problems and is able to make accurate measurements of properties of fluid, such as density by making a volumetric measurement that is largely insensitive to wetting.
Another example of special fluid conditions may include non-Newtonian fluids which also present a significant challenge for resonating sensors. The shear rate of a resonating sensor immersed in fluid is maximum at its surface and decreases with distance, dictating that the shear rate is non-uniform throughout the interrogation volume. If the shear rate is non-uniform, then for a non-Newtonian fluid the shear stress will be non-uniform as well, producing a viscosity measurement that is certainly not representative of the zero shear rate viscosity. A preponderance of fluids experienced downhole appears to be shear-thinning, and measurements with a resonating sensor typically read low. A low accuracy measurement of the fluid viscosity with a resonating sensor that simultaneously measures fluid density often invalidates the interpretation and leads to incorrect density measurements. Again, a density measurement that did not involve resonance such as described in claimed subject matter of the applicant does not have this problem.
Another example of special fluid conditions may include supercritical fluids or multiphase fluids which also present significant challenges for resonating sensors. Supercritical fluid can be any substance at a temperature and pressure above its thermodynamic critical point. It can diffuse through solids like a gas, and dissolve materials like a liquid. There is no surface tension in a supercritical fluid as there is no liquid/gas phase boundary. Additionally, all supercritical fluids are completely miscible with each other. In general terms, supercritical fluids have properties between those of a gas and a liquid. However, close to the critical point, small changes in pressure or temperature result in large changes in density and viscosity, allowing many properties to be altered. Thus, this presents enormous challenges for resonating sensors. Further, carbon dioxide is usually in supercritical form under most downhole conditions.
Since resonating sensors measure fluid properties in a local volume or a small surface area, multiphase fluids such as a liquid with gas bulbs will present another challenge. On the other hand, a nuclear volumetric measurement described here is insensitive to the apparent forms of fluids regardless whether they are in supercritical forms or multiphase.
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Z/A=(1+ωH)/2. Eq. 3
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ρc=Z*N/N0=Z/A*ρm Eq. 4
where N/N0 is the number density of the material with N0 the Avogadro's number.
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As noted above, it is contemplated that at least two implementations for such a measurement may include a macroscopic implementation as discussed above and a microscopic implementation. The microscopic implementation is a density measurement downstream of a microfluidic separator through a microfluidic channel of a diameter of approximately 0.5 mm or less.
Whereas many alterations and modifications of the present disclosure will no doubt become apparent to a person of ordinary skill in the art after having read the foregoing description, it is to be understood that the particular embodiments shown and described by way of illustration are in no way intended to be considered limiting. Further, the disclosure has been described with reference to particular preferred embodiments, but variations within the spirit and scope of the disclosure will occur to those skilled in the art. It is noted that the foregoing examples have been provided merely for the purpose of explanation and are in no way to be construed as limiting of the present disclosure. While the present disclosure has been described with reference to exemplary embodiments, it is understood that the words, which have been used herein, are words of description and illustration, rather than words of limitation. Changes may be made, within the purview of the appended claims, as presently stated and as amended, without departing from the scope and spirit of the present disclosure in its aspects. Although the present disclosure has been described herein with reference to particular means, materials and embodiments, the present disclosure is not intended to be limited to the particulars disclosed herein; rather, the present disclosure extends to all functionally equivalent structures, methods and uses, such as are within the scope of the appended claims.
