Patent Description:
Radiation detectors are well known in the drilling industry and are often incorporated into drilling tools for oil wells and into the tools used to log the geologic formations along the length of the borehole. At least some known radiation detectors typically include a light detecting and quantifying device, such as a photo-multiplier tube, and a scintillation element, such as a crystal or suitably compounded element. The scintillation element typically functions by capturing radiation from the formation and converting that energy into light. The radiation may be ambient radiation emitted by radioactive materials in the formation, or radiation emitted in response to bombardment of the formation by radiation sources within the tool or equipment in which the detectors are operating.

Light generated within a scintillation element, as a result of intercepting radiation, is transmitted through an optical window into the photo-multiplier tube. The light impulses are transformed into electrical impulses that are transmitted via a data stream to an instrumentation system. Optical coupling elements are typically used between the scintillation element and the light-detecting element in order to facilitate increasing the light transmission, and may be used to provide isolation between the scintillation element and the light-detecting element.

Measurement while drilling (MWD) operations or logging while drilling (LWD) operations utilize radiation detectors to help guide the drills and/or to help evaluate the formation, concurrent with the drilling operation, thereby subjecting the radiation detector to increased vibration and shock, while at temperatures up to <NUM> degrees Celsius, or higher. Other drilling applications that subject the radiation detectors to extreme environments include environmental evaluations, geologic surveys, and construction projects. In the above-noted instances, a highly ruggedized radiation detector is desired so that the radiation detector will not fail and will not produce noise as a result of the vibration and shock.

With some known radiation detectors, environmental effects during drilling, such as the presence of fluids, solids, or gas, prevent contact between the radiation detector and the surface to be measured (e.g. cuttings, mud, hydrocarbons, etc.). This can cause insufficient and/or inaccurate data to be received by the radiation detector. Moreover, due to the vibration and shock described above, the elements of typical radiation detectors, such as a scintillation crystal or a photo-multiplier tube, can be damaged or produce increased noise due to vibrations. Furthermore, the increased temperatures of the drilling environment may decrease the useful life of many known radiation detectors. <CIT> discloses devices and methods for a rugged semiconductor radiation detector. In particular it relates to a semiconductor radiation detector device for a downhole device, the detector including a printed circuit board. <CIT> discloses an apparatus and a method for imaging tissue or an inanimate object using a probe that has an integrated solid-state semiconductor detector and complete readout electronics circuitry.

In one aspect, there is disclosed a radiation detector as claimed in claim <NUM>. In another aspect, there is disclosed a method of detecting gamma rays in a borehole according to claim <NUM>.

Here and throughout the specification and claims, range limitations may be combined and/or interchanged; such ranges are identified and include all the sub-ranges contained therein unless context or language indicates otherwise.

As used herein, the terms "processor" and "computer" and related terms, e.g., "processing device" and "computing device", are not limited to just those integrated circuits referred to in the art as a computer, but broadly refers to a microcontroller, a microcomputer, a programmable logic controller (PLC), an application specific integrated circuit, and other programmable circuits, and these terms are used interchangeably herein. In the embodiments described herein, memory may include, but is not limited to, a computer-readable medium, such as a random access memory (RAM), and a computer-readable non-volatile medium, such as flash memory. Alternatively, a floppy disk, a compact disc - read only memory (CD-ROM), a magneto-optical disk (MOD), and/or a digital versatile disc (DVD) may also be used. Also, in the embodiments described herein, additional input channels may be, but are not limited to, computer peripherals associated with an operator interface such as a mouse and a keyboard. Alternatively, other computer peripherals may also be used that may include, for example, but not be limited to, a scanner. Furthermore, in the exemplary embodiment, additional output channels may include, but not be limited to, an operator interface monitor.

As used herein, the term "non-transitory computer-readable media" is intended to be representative of any tangible computer-based device implemented in any method or technology for short-term and long-term storage of information, such as, computer-readable instructions, data structures, program modules and sub-modules, or other data in any device. Therefore, the methods described herein may be encoded as executable instructions embodied in a tangible, non-transitory, computer readable medium, including, without limitation, a storage device and/or a memory device. Such instructions, when executed by a processor, cause the processor to perform at least a portion of the methods described herein. Moreover, as used herein, the term "non-transitory computer-readable media" includes all tangible, computer-readable media, including, without limitation, non-transitory computer storage devices, including, without limitation, volatile and nonvolatile media, and removable and non-removable media such as a firmware, physical and virtual storage, CD-ROMs, DVDs, and any other digital source such as a network or the Internet, as well as yet to be developed digital means, with the sole exception being a transitory, propagating signal.

Embodiments of the present disclosure provide high temperature direct conversion radiation detectors positioned in a borehole for downhole geological formation evaluation (e.g., natural gamma-ray, density, spectral, spectroscopy, and/or at bit radiation detection), well integrity, and production logging applications. In particular, the embodiments described herein facilitate forming a flexible high-temperature direct conversion gamma ray detector that is compact and can be eccentered and pushed against the surface of a downhole tool, at-bit, to measure gamma rays from the geological formation. As such, the embodiments described herein facilitate closer to the formation measurements, facilitating the corrections for environmental effects such as mud weight or borehole size. A plurality of gamma ray detectors formed using a dense gamma ray detector material, such as CMT crystals (e.g., Cadmium Magnesium Telluride (CdMgTe), Cadmium Manganese Telluride (CdMnTe), or a combination of Cadmium Magnesium Manganese Telluride (CdMgMnTe)), are coupled to flexible circuit board and enclosed in a flexible housing. The detector facilitates at-bit positioning, increased operating life (e.g., greater than about <NUM> hours), reduced fabrication costs, and increased ruggedness. In addition, including a flexible array of high temperature direct conversion gamma ray detectors facilitates higher resolution capability compared to current downhole scintillation detectors, for example, enhanced vertical and azimuthal resolution.

<FIG> is an exemplary drilling system <NUM>, including a flexible radiation detector <NUM> for detecting the presence, for example, of naturally occurring gamma ray sources. In the exemplary embodiment, a borehole <NUM> includes an upper section <NUM> having a casing <NUM> fitted therein and a lower section <NUM>. Lower section <NUM> has a drill string <NUM> extending from a drill rig <NUM> and configured for drilling lower section <NUM> using a drilling assembly <NUM>. Drill string <NUM> includes one or tubular members <NUM> that is attached to drilling assembly <NUM> at its lower end. In the exemplary embodiment, tubular members <NUM> include, for example, drill pipe sections coupled together. In some embodiments, tubular members <NUM> include any type of tubular member that enables drilling system <NUM> to function as described herein, such, for example, coiled tubing. In the exemplary embodiment, a drill bit <NUM> is coupled to a bottom end of drilling assembly <NUM> for cutting lower section <NUM>, and more particularly, the geological formation making up lower section <NUM>, to drill borehole <NUM> of a selected diameter. In some embodiments, drilling assembly <NUM> includes additional components (not shown), such as, for example, and without limitation, stabilizers, centralizers, steering units, and any other devices that facilitate operating and/or steering drilling assembly <NUM>.

In the exemplary embodiment, drill string <NUM> is shown lowered into the borehole <NUM> from drill rig <NUM> located at the surface <NUM>. While drill rig <NUM> is shown herein as a land-based drill rig, it is contemplated that drill rig <NUM> can be any type of drill rig that enables drilling system <NUM> to function as described herein, for example, and without limitation an offshore drill rig used for drilling boreholes under a body of water.

In the exemplary embodiment, a turntable or rotary table <NUM> located on drill rig <NUM> at surface <NUM> is coupled to drill string <NUM> to facilitate rotating drill string <NUM>. This facilitates rotating drilling assembly <NUM> and thus drill bit <NUM> to drill borehole <NUM>. In some embodiments, a drill motor (not shown) is included in drilling assembly <NUM> to rotate drill bit <NUM>. In the exemplary embodiment, as rotary table <NUM> turns drill bit <NUM>, a drilling pump <NUM> pumps a drilling fluid <NUM> received from a fluid source <NUM> downward through drill string <NUM>, as generally indicated by the arrow shown in <FIG>. Drilling fluid <NUM> is typically referred to as "mud" or "drilling mud. " Drilling fluid <NUM> is used, in part, to cool and/or lubricate drill bit <NUM> and drill string <NUM> during drilling operations. Drilling fluid <NUM> exits drill string <NUM> through drill bit <NUM> and facilitates carrying away debris and cuttings from the bottom of a borehole <NUM>. In particular, drilling fluid <NUM> exits drill bit <NUM> and mixes with the drill cuttings, debris, and other fluids present in the geological formation making up lower section <NUM> of borehole <NUM>. This mixture is typically referred to as a drilling mud <NUM> and flows back to surface <NUM> through a space <NUM> defined between drill string <NUM> and the geological formation making up lower section <NUM>, as generally indicated by the arrows shown in <FIG>. In some embodiments, drilling mud <NUM> is filtered and returned to fluid source <NUM>.

In the exemplary embodiment, drilling string <NUM> includes detector <NUM> and is typically referred to as a logging while drilling (LWD) tool and collects a variety of data relating to geological formation evaluation of the geological formation making up lower section <NUM> of borehole <NUM>. In a wireline tool string (not shown in <FIG>), a similar tool monitors fluids for production logging, or inspects casing and cement for well integrity applications. For example, and without limitation, detector <NUM> in drilling string <NUM> is configured to measure the physical properties of the geological formation making up lower section <NUM> of borehole <NUM>, such as density, porosity, resistivity, lithology, and so forth. In some embodiments, detector <NUM> in drilling string <NUM> may also include components that enable it to function as a measurement while drilling (MWD) tool and may measure certain drilling parameters, such as the temperature, pressure, orientation of drill string <NUM>, and so forth. In the exemplary embodiment, detector <NUM> is a ruggedized direct conversion radiation detector configured to detect radiation (e.g., neutrons, gamma rays, x-rays, and so forth). For example, the collected data includes counts and/or detected energies of radiation that enter detector <NUM> from the geological formation making up lower section <NUM> of borehole <NUM>. It should be noted that, although detector <NUM> is described by way of example in a logging-while-drilling (LWD) configuration, any other suitable means of data conveyance may be employed (e.g., wireline, slickline, coiled tubing, and so forth).

A drilling tool in drilling string <NUM>, including detector <NUM>, is configured to collect the data and store and/or process the data in detector <NUM> electronic board during drilling operations. In alternative embodiments, the collected data is sent to a computing device <NUM> located at surface <NUM> for storage and/or processing. The data may be transmitted to computing device <NUM>, for example, and without limitation, by electrical signals through the geological formation making up lower section <NUM> of borehole <NUM> or via mud pulse telemetry using drilling mud <NUM>. In the exemplary embodiment, the data is retrieved directly from detector <NUM> upon return to surface <NUM> and extraction from borehole <NUM>.

<FIG> is a block diagram of an exemplary embodiment of detector <NUM> suitable for use with drilling system <NUM> (shown in <FIG>). <FIG> is a schematic sectional view of an exemplary detector element <NUM> for use in detector <NUM> (shown in <FIG>). In the exemplary embodiment, detector <NUM> includes a plurality of detector elements <NUM> arranged in a rectangular array, which facilitates enhanced and/or increased vertical and azimuthal resolution as compared to typical scintillation detectors. Alternatively, the plurality of detector elements <NUM> can be arranged in any configuration that enables detector <NUM> to function as described herein. In the exemplary embodiment, each of detector elements <NUM> operate in direct-conversion (or semiconductor) mode at elevated temperatures, such as, for example up to <NUM> degrees Celsius. This is advantageous in downhole applications where the operating temperatures can be up to <NUM> degrees Celsius, or higher.

The plurality of detector elements <NUM> of detector <NUM> are enclosed in a flexible housing <NUM>, which is described further herein. The plurality of detector elements <NUM> are coupled to a voltage source <NUM> as shown in <FIG>. In the exemplary embodiment, detector <NUM> includes a processor <NUM> and a memory device <NUM> coupled to processor <NUM>. Processor <NUM> is coupled in communication to voltage source <NUM> and may include one or more processing units, such as, without limitation, a multi-core configuration. While voltage source <NUM>, processor <NUM>, memory device <NUM>, and communication interface <NUM> are shown in <FIG> as blocks separate from housing <NUM>, it is noted that this is for illustration only. Each of voltage source <NUM>, processor <NUM>, memory device <NUM>, and communication interface <NUM> can be integrated and/or coupled to housing <NUM> to form an integral detector <NUM>.

In the exemplary embodiment, processor <NUM> may include any type of processor that enables detector <NUM> to function as described herein. In some embodiments, executable instructions are stored in memory device <NUM>. Processor <NUM> is configurable to perform one or more executable instructions described herein by programming processor <NUM>. For example, processor <NUM> may be programmed by encoding an operation as one or more executable instructions and providing the executable instructions in memory device <NUM>. In the exemplary embodiment, memory device <NUM> is one or more devices that enable storage and retrieval of information such as, without limitation, executable instructions and/or data received from the plurality of detector elements <NUM>. Memory device <NUM> may include one or more tangible, non-transitory, computer readable media, such as, without limitation, random access memory (RAM), dynamic RAM, static RAM, a solid-state disk, a hard disk, read-only memory (ROM), erasable programmable ROM, electrically erasable programmable ROM, or non-volatile RAM memory. The above memory types are exemplary only, and are thus not limiting as to the types of memory usable for storage of a computer program.

In the exemplary embodiment, a communication interface <NUM> is coupled to processor <NUM> and is configured to be coupled in communication with one or more other devices, such as, without limitation, computing device <NUM>, and to perform input and output operations with respect to such devices while performing as an input/output channel. For example, communication interface <NUM> may include, without limitation, a wired network adapter, a wireless network adapter, a mobile telecommunications adapter, a serial communication adapter, or a parallel communication adapter. Communication interface <NUM> may receive a data signal from or transmit a data signal to one or more remote devices. Communication interface <NUM> is capable of providing information suitable for use with the methods described herein, such as, without limitation, providing information to computing device <NUM> and/or processor <NUM>. Accordingly, as described, communication interface <NUM> may be referred to as an output device. Similarly, communication interface <NUM> is capable of receiving information suitable for use with the methods described herein and may be referred to as an input device.

As shown in <FIG>, detector element <NUM> includes a gamma ray detector material semiconductor <NUM> formed from a radiation responsive semiconductor material, which in various embodiments is a direct conversion material, for example, and without limitation, CMT crystals (e.g., Cadmium Magnesium Telluride (CdMgTe) or Cadmium Manganese Telluride (CdMnTe)). It is noted that as used herein, a direct conversion material generally includes any detector material that directly converts (in a single conversion step) photons or other high frequency gamma ray energy to electrical signals or charges instead of in a multi-step process such as when using a scintillator (e.g., NaI(Tl) (thallium-doped sodium iodide)) and a photo-conversion device (e.g., a photo-diode). In the exemplary embodiment, CMT semiconductor <NUM> is a direct conversion material (DCM) that has good stopping power and energy gaps suitable for operation at temperatures, for example up to <NUM> degrees Celsius. CMT semiconductor <NUM> has an increased density compared to typical scintillation detector, which allows for a compact detector. For example, in one embodiment, CMT semiconductor <NUM> has a density of about <NUM> grams per cubic centimeter (g/cm<NUM>) and a die size of about <NUM> millimeters (mm) x <NUM> x <NUM>. Whereas in a typical scintillation detector, the NaI(Tl) scintillator has a density of about <NUM>/cm<NUM> and also requires use of a separate photo-conversion device, such as a photo-diode or a photomultiplier tube.

In the exemplary embodiment, detector element <NUM> includes an anode <NUM> and a cathode <NUM> operatively coupled to or otherwise formed on a respective side (e.g., an abode surface or a cathode surface, respectively) of CMT semiconductor <NUM>. In some embodiments, detector element <NUM>, including CMT semiconductor <NUM>, anode <NUM>, and cathode <NUM>, is formed as a pixelated structure having a plurality of pixels defined, for example, by photolithography or by cutting or dicing of the contact metal to form a plurality of pixel anode electrodes. Detector element <NUM> also includes a cathode <NUM> operatively coupled to or otherwise formed on an opposite surface or side (e.g., a cathode surface) of CMT semiconductor <NUM> from anode <NUM>.

In operation, ionizing radiation <NUM> is measured by the number of charge carriers set free in CMT semiconductor <NUM>. Ionizing radiation <NUM> emitted by a source <NUM> produces free electrons-hole pairs <NUM> proportional to the energy of the incident radiation. When an electric field is applied between the anode <NUM> and cathode <NUM>, electrons and holes travel to anode <NUM> and cathode <NUM>, resulting in a pulse that can be measured in an outer circuit (not shown in <FIG>). It should be noted that in some embodiments the current pulse signals are integrated over a predetermined time period, then measured and digitized.

<FIG> is a sectional view of an exemplary embodiment of detector <NUM> oriented in a convex orientation. As used herein, a convex orientation refers to detector <NUM> oriented such that detector elements <NUM> are on the outside of an arc defined by flexible circuit <NUM>, as shown in <FIG>. Flexible circuit <NUM> includes a printed circuit board, and is referred to as a flexible circuit board. In the exemplary embodiment, each of detector elements <NUM> are coupled to flexible circuit board <NUM> via a plurality of connections (not shown), which include, for example, a solder bump array formed along a surface of flexible circuit board <NUM>. The plurality of detector elements <NUM> are coupled to flexible circuit board <NUM>, for example, in a tiled manner and define one or more gap widths <NUM> between adjacent detector elements <NUM>. The term "flexible circuit board" includes a circuit board having a flexible base material that allows a repeated bending motion, and in particular a flexible circuit film that may be curved from a plane, e.g., nonplanar. Gap width <NUM> is selected to enable detector <NUM> to flex or bend in a curved shape having, for example, a determined minimum radius in a concave and/or convex orientation. In some embodiments, detector elements <NUM> are coupled to flexible circuit board <NUM> without gap width <NUM> defined therebetween. In such a configuration, detector <NUM> may be flat and/or flexed in a convex orientation only. In the exemplary embodiment, flexible circuit board <NUM> is formed as a flex circuit, and includes, for example, electronic circuit and/or electronic devices formed on a suitable flexible conductive substrate material.

In the exemplary embodiment, detector <NUM> includes voltage source <NUM>, processor <NUM>, memory device <NUM>, and communication interface <NUM> coupled to flexible circuit board <NUM>, for example, on a peripheral edge of flexible circuit board <NUM> via a plurality of connections (not shown), which include, for example, solder bumps formed along the surface of flexible circuit board <NUM>. For example, voltage source <NUM>, processor <NUM>, memory device <NUM>, and communication interface <NUM> are coupled to flexible circuit board <NUM> in a location outside of the array of detector elements <NUM>. As such, detector <NUM> has a generally continuous detector portion defined by the array of detector elements <NUM>. As described herein, detector elements <NUM> may be placed in any arrangement that enables detector <NUM> to function as described herein.

In the exemplary embodiment, flexible circuit board <NUM> includes a flexible back-shield <NUM> coupled to a side of flexible circuit board <NUM> opposite detector elements <NUM>. Back-shield <NUM> is formed from a material that prevents gamma rays, i.e., the photons, such as photon <NUM>, from passing through the material and traveling directly to the array of detector elements <NUM> from, for example, a mud channel <NUM> extending through drill string <NUM> (shown in <FIG>), and in particularly, tool housing <NUM>. As such, flexible back-shield <NUM> shields the detector elements <NUM> to facilitate reducing the effect from photon scattering in mud channel <NUM>. In the exemplary embodiment, flexible back-shield <NUM> may include carbide or steel sheet material, a gamma radiation shielding composite film, and/or any other suitable flexible material that enables back-shield <NUM> to function as described herein. In some embodiments, flexible back-shield <NUM> may include one or more stress relief grooves (not shown) to facilitate increasing flexibility and allowing flexible back-shield <NUM> to flex with detector <NUM>.

In the exemplary embodiment, a flexible chassis <NUM> is coupled to a peripheral frame portion <NUM> and configured to enclose flexible circuit board <NUM> and the array of detector elements <NUM> therein, forming flexible housing <NUM>. In some embodiments, flexible chassis <NUM> and peripheral frame portion <NUM> may be integrally formed and formed from a material having a thickness that renders housing <NUM> flexible. For example, the material may be a composite material, such as polyetheretherketone (PEEK), and/or any other flexible material that enables detector <NUM> to function as described herein. It is noted that flexible chassis <NUM> and/or frame portion <NUM> is selected from a material that is flexible, suitable for use in temperatures up to about <NUM> degrees Celsius, and has a density that allows passage of gamma rays to detector elements <NUM>. In one embodiment, flexible chassis <NUM> is an epoxy material (or PEEK) coupled to flexible circuit board <NUM> and the plurality of detector elements <NUM>. As shown in <FIG>, flexible chassis <NUM> and peripheral frame portion <NUM> encloses flexible circuit board <NUM> and the array of detector elements <NUM> on all sides to provide sealed housing <NUM>.

In operation, detector <NUM> is eccentered within tool housing <NUM> and may be coupled to an outer wall <NUM> of tool housing <NUM> for detecting radiation from the geological formation making up lower section <NUM> of borehole <NUM> (shown in <FIG>). Detector <NUM> is positioned such that the plurality of detector elements <NUM> are located at a gamma ray window <NUM> (fabricated from a low density material) formed in tool housing <NUM>. As compared to typical scintillation detectors, detector <NUM> provides a reduced detector size having a flexible configuration to enable fit into locations typical scintillation detectors cannot fit. The flexibility and reduced size of detector <NUM> enables detector <NUM> to be placed near or at drill bit <NUM> (shown in <FIG>) during drilling operations. This facilitates at-bit logging/measuring of gamma rays during drilling of borehole <NUM> (shown in <FIG>). In addition, detector <NUM> uses direct conversion detector elements <NUM>, which are less susceptible to the vibration and shock experienced proximate drill bit <NUM> during drilling of borehole <NUM>. As such, detector <NUM> has an increased operating life, for example, greater than about <NUM> hours, and reduced manufacturing cost as compared to typical scintillation detectors (e.g., typical scintillation detectors have an operating life of about <NUM> hours). In addition, detector <NUM> is operable in an increased temperature environment, where other direct conversion detectors fail. For example, detector <NUM> is operable in temperatures up to <NUM> degrees Celsius.

<FIG> is an exemplary logging system <NUM>, including a flexible detector element <NUM>. In the exemplary embodiment, flexible detector element <NUM> is substantially similar to detector <NUM> (shown in <FIG>). Logging system <NUM> includes a logging tool <NUM> disposed in a borehole <NUM>. Borehole <NUM> extends through a geological formation <NUM>. Logging tool <NUM> includes a housing <NUM> that is suspended within borehole <NUM> on a wireline <NUM> that routes through a wellhead assembly <NUM> on surface <NUM>. In some embodiments, logging tool <NUM> may also be deployed in drilling operations. In addition, in some embodiments, logging tool <NUM> also includes a gamma ray source <NUM> that emits gamma rays into geological formation <NUM>. In the exemplary embodiment, flexible detector element <NUM> senses gamma rays emitted by geological formation <NUM> and/or reflections of gamma rays emitted by gamma ray source <NUM>. In response, flexible detector element <NUM> produces an analog electrical signal that corresponds to the sensed energy. The analog data received from flexible detector element <NUM> is sampled and converted to digital signals using any suitable analog to digital conversion process.

In the exemplary embodiment, logging tool <NUM> includes a voltage source <NUM>, which is coupled to and configured to provide a voltage to flexible detector element <NUM>. The analog data received from flexible detector element <NUM> is transmitted to a computing device <NUM> via wireline <NUM>. Computing device <NUM> includes a processor <NUM> and a memory <NUM> coupled to processor <NUM>. Processor <NUM> is coupled in communication to voltage source <NUM> and may include one or more processing units, such as, without limitation, a multi-core configuration.

In the exemplary embodiment, processor <NUM> may include any type of processor that enables flexible detector element <NUM> to function as described herein. In some embodiments, executable instructions are stored in memory <NUM>. Processor <NUM> is configurable to perform one or more executable instructions described herein by programming processor <NUM>. For example, processor <NUM> may be programmed by encoding an operation as one or more executable instructions and providing the executable instructions in memory <NUM>. In the exemplary embodiment, memory <NUM> is one or more devices that enable storage and retrieval of information such as, without limitation, executable instructions and/or data received from flexible detector element <NUM>. Memory <NUM> may include one or more tangible, non-transitory, computer readable media, such as, without limitation, random access memory (RAM), dynamic RAM, static RAM, a solid-state disk, a hard disk, read-only memory (ROM), erasable programmable ROM, electrically erasable programmable ROM, or non-volatile RAM memory. The above memory types are exemplary only, and are thus not limiting as to the types of memory usable for storage of a computer program.

In some embodiments, computing device <NUM> includes a presentation interface <NUM> coupled to processor <NUM>. Presentation interface <NUM> presents information, such as, without limitation, data that represents counts and/or detected energies of radiation that enter flexible detector element <NUM> from geological formation <NUM>, to a user <NUM>. In one embodiment, presentation interface <NUM> includes a display adapter (not shown) coupled to a display device (not shown), such as, without limitation, a cathode ray tube (CRT), a liquid crystal display (LCD), an organic LED (OLED) display, or an "electronic ink" display. In some embodiments, presentation interface <NUM> includes one or more display devices. In addition, or alternatively, presentation interface <NUM> includes an audio output device (not shown), for example, without limitation, an audio adapter or a speaker (not shown).

In some embodiments, computing device <NUM> includes a user input interface <NUM>. In the exemplary embodiment, user input interface <NUM> is coupled to processor <NUM> and receives input from user <NUM>. User input interface <NUM> may include, for example, without limitation, a keyboard, a pointing device, a mouse, a stylus, a touch sensitive panel, such as, without limitation, a touch pad or a touch screen, and/or an audio input interface, such as, without limitation, a microphone. A single component, such as a touch screen, may function as both a display device of presentation interface <NUM> and user input interface <NUM>.

Presentation interface <NUM> is capable of providing information suitable for use with the methods described herein, such as, without limitation, providing information to user <NUM>. Accordingly, as described, presentation interface <NUM> may be referred to as an output device. Similarly, presentation interface <NUM> is capable of receiving information suitable for use with the methods described herein and may be referred to as an input device.

Embodiments of the flexible detectors described herein provide for high-temperature direct conversion downhole detectors. The flexible detectors are compact and flexible, enabling the detectors to be eccentered and coupled to the outer wall of the downhole tool. In addition, the compactness of the disclosed detectors enable positioning and use at-bit, that is, they are compact and ruggedized enough to be located proximate the drill bit of the downhole tool. This facilitates at-bit logging/measuring of gamma rays during drilling of the borehole. The detectors include an array of individual detectors that are fabricated from semiconductor direct conversion materials, such as a CMT material to enable use at elevated temperatures (e.g., up to about <NUM> degrees Celsius), such as those experienced downhole. Semiconductor direct conversion materials are less susceptible to the vibration and shock experienced proximate the drill bit during drilling operations. As such, the disclosed flexible detectors have increased operating life and reduced manufacturing costs.

Exemplary embodiments of methods and systems are not limited to the specific embodiments described herein, but rather, components of systems and steps of the methods may be utilized independently and separately from other components and steps described herein. For example, the methods may also be used to manufacture other measuring devices, and are not limited to practice with only the tools and methods as described herein. Rather, the exemplary embodiment can be implemented and utilized in connection with many other applications, equipment, and systems that may benefit from the advantages described herein.

Although specific features of various embodiments of the disclosure may be shown in some drawings and not in others, this is for convenience only. In accordance with the principles of the disclosure, any feature of a drawing may be referenced and claimed in combination with any feature of any other drawing.

Claim 1:
A radiation detector (<NUM>) useable in a downhole tool configured to be positioned in a borehole (<NUM>), said radiation detector comprising:
a flexible printed circuit board (<NUM>);
at least one detector element (<NUM>) coupled to said printed circuit board, said at least one detector element comprising:
a semiconductor direct conversion material (<NUM>) for directly converting gamma rays into electrical signals, said semiconductor direct conversion material comprising a cathode surface and an anode surface;
a cathode (<NUM>) operatively connected to the cathode surface; and
an anode (<NUM>) operatively coupled to the anode surface; and
a voltage source (<NUM>) coupled to said printed circuit board and configured to provide a voltage to said at least one detector element; and
a flexible housing (<NUM>) enclosing said flexible printed circuit board (<NUM>) and said at least one detector element (<NUM>), said flexible housing (<NUM>) comprising a peripheral frame portion (<NUM>) and a flexible chassis (<NUM>) coupled to said peripheral frame portion (<NUM>).