The present disclosure relates to a method for determining a remaining operating period of a detector unit for a radiometric, density- or fill-level measuring device. The detector unit includes a photomultiplier. In such method, the control voltage of the photomultiplier is registered over at least one predetermined time period, a time rate of change function is ascertained based on control voltage registered during the predetermined time period, and the remaining operating period until reaching a maximum control voltage is calculated by means of the time rate of change function and a current control voltage, which is present at the current operating time. The method of the present disclosure permits approximation of the remaining operating period of the detector unit and, thus, timely learning of when required maintenance measures, especially aging related replacement of the photomultiplier, must be performed.

The present disclosure relates to a method for determining a remaining operating period of a detector unit for a radiometric, density- or fill-level measuring device. The detector unit includes a photomultiplier. In such method, the control voltage of the photomultiplier is registered over at least one predetermined time period, a time rate of change function is ascertained based on control voltage registered during the predetermined time period, and the remaining operating period until reaching a maximum control voltage is calculated by means of the time rate of change function and a current control voltage, which is present at the current operating time. The method of the present disclosure permits approximation of the remaining operating period of the detector unit and, thus, timely learning of when required maintenance measures, especially aging related replacement of the photomultiplier, must be performed.

A variety of applications can include a gamma ray downhole logging system having a gamma ray detector, where temperature sensitivity of the gamma ray detector is accounted for in the operation of the logging system. Correction of sensitivity of the gamma ray detector can include using a measure of sensitivity drift derived from temperature binned gamma ray spectra from measurements by the gamma ray detector over a calibration period for a number of calibration periods. Additional apparatus, systems, and methods are disclosed.

A system for obtaining downhole azimuthal imaging information includes a pressure housing. The system also includes a source arranged within the pressure housing, the source including a directable electron beam. The system further includes an anode positioned proximate the source, within the pressure housing, the anode having a tapered face adapted to interact with the directable electron beam and direct an x-ray beam away from the anode. The system also includes a detector arranged proximate the anode, the anode being between the source and the detector, wherein the detector receives scattered x-rays, from the x-ray beam, the received scattered x-rays corresponding to imaging information to determine one or more properties of a wellbore.

A system for obtaining downhole azimuthal imaging information includes a pressure housing. The system also includes a source arranged within the pressure housing, the source including a directable electron beam. The system further includes an anode positioned proximate the source, within the pressure housing, the anode having a tapered face adapted to interact with the directable electron beam and direct an x-ray beam away from the anode. The system also includes a detector arranged proximate the anode, the anode being between the source and the detector, wherein the detector receives scattered x-rays, from the x-ray beam, the received scattered x-rays corresponding to imaging information to determine one or more properties of a wellbore.

An avalanche diode arrangement (10) comprises an avalanche diode (11) that is coupled to a first voltage terminal (16) and to a first node (13), an event detector (14) for detecting a trigger event of the avalanche diode (11) and being coupled to the first node (13), a quenching circuit (15) that is coupled to the first node (13), and a detection circuit (20) coupled to the first node (13). The detection circuit (20) is configured to provide a detection signal (SVC2) that depends on a value of a node voltage (SVA) at the first node (13).

A self-stabilizing scintillation detector system for the measurement of nuclear radiation, preferably gamma radiation, is provided, the system comprising a scintillation crystal, a photo detector, a photomultiplier (PMT) and one or two fast digital sampling analog to digital converters (ADC), where the scintillator is selected from a group of materials having a light decay time of at least 1 ns, and where the PMT is set to its highest possible gain. A first ADC for processing the single photo electron induced signals is connected to the PMT output, namely the anode output, this first ADC being set to operate with a very high sampling rate of at least 10 MHz, and a second ADC for processing the nuclear particle induced signals is connected to one of the PMT's dynodes with a significantly lower amplification.

A self-stabilizing scintillation detector system for the measurement of nuclear radiation, preferably gamma radiation, is provided, the system comprising a scintillation crystal, a photo detector, a photomultiplier (PMT) and one or two fast digital sampling analog to digital converters (ADC), where the scintillator is selected from a group of materials having a light decay time of at least 1 ns, and where the PMT is set to its highest possible gain. A first ADC for processing the single photo electron induced signals is connected to the PMT output, namely the anode output, this first ADC being set to operate with a very high sampling rate of at least 10 MHz, and a second ADC for processing the nuclear particle induced signals is connected to one of the PMT's dynodes with a significantly lower amplification.

For determining whether oil waste at a field testing site is exempt from selected naturally occurring radioactive material (NORM) waste regulations, a measurement apparatus including a detection module that determine radioactivity counts per minute for an oil waste sample is utilized. The measurement apparatus includes an analysis module that uses a first nonlinear transfer function to determine a mass for the oil waste based on a volume of solids determined via BS&W testing. The analysis module uses a second nonlinear transfer function to determine a maximum radioactivity level for the sample which is then normalized to picoCuries/g. The normalized maximum radioactivity level per gram is compared to a NORM exemption level for a selected region and communicated to entities at the field-testing site and optionally to other entities. A system and a method perform the functions of the measurement apparatus.

The current invention utilizes a downhole gamma ray counter having a processor and database to radially allocate gamma ray counts into buckets. Once a circumferential count is completed the buckets are utilized to form a pattern. The created pattern is then compared to various patterns within the database. Once a corresponding pattern is found within the database a value that is assigned to that pattern is transmitted to the surface. On the surface a surface processor compares the value to the values within the surface database finding the pattern assigned to that value. The surface processor and estimates the time of creation of the pattern downhole and uses the estimated time of creation and the pattern from the surface database to create an image of a portion of a wellbore.