Abstract: A system includes a dispensing device having a material chamber to store an oilfield material and to fluidly couple to a wellhead, a plurality of flow control devices to control a flow of the oilfield material via the material chamber, a plurality of sensors to measure one or more properties related to the dispensing device, and a control system communicatively coupled to the dispensing device. The control system opens a first flow control device to fill the material chamber with the oilfield material, monitors a condition associated with the material chamber based on the properties measured via the plurality of sensors, opens a second flow control device to provide a high pressure fluid into the material chamber when the condition is present, and open a third flow control device, where the third flow control device fluidly couples the material chamber to the wellhead.

Abstract: A method includes developing a lab-scale representative correlation between wettability index and tracer test return curve data for core samples, obtaining tracer test return curve data for rock at a well of interest, and determining a wettability index of the rock in situ using the representative correlation and the tracer test return curve data for the well. A method includes obtaining core samples of a rock representative of a formation of interest, determining a wettability index of each of the core samples, performing a tracer test on each of the core samples and obtaining tracer return curve data for each of the core samples, building a correlation between the wettability index and the tracer return curve data of the core samples, running a single-well tracer test at a well, obtaining tracer return curve data for the well, and determining a wettability index for the rock of the well.

Abstract: A method for identifying cuttings volume may comprise taking one or more inlet measurements of a drilling fluid at an inlet meter before the drilling fluid is circulated into a wellbore, taking one or more outlet measurements of a drilling fluid at an outlet meter after the drilling fluid is returned from the wellbore with cuttings, subtracting the one or more inlet measurements from the one or more outlet measurements and adding hole fill to determine mass of the cuttings, identifying a density of the cuttings, and converting the mass of the cuttings to the volume of the cuttings using the density of the cuttings. A system may comprise an inlet meter, an outlet meter, a pump for circulating a drilling fluid and one or more cuttings through the inlet meter and the outlet meter, and an information handling system.

Abstract: A flow monitoring system can have a plurality of sensors located at monitoring locations along a tubing string inserted into an injector well of a secondary recovery operation. The sensors are configured to monitor a measurable property of fluids flowing in a bore of the tubing string or in an annulus formed between the tubing string and injector bore to determine the presence of said injected fluids at each sensor. At least two fluids having different values of the measurable property are injected into the injector well in an alternating manner and at a known injection rate. The flow rates of the fluids out of various injection zones of the injection well can be calculated using the arrival times and the known injection flow rates of the fluids, cross-sectional area of the fluid conduit(s) through which the fluids travel, and distances between the sensors or between surface and the sensors.

Abstract: Downhole display systems and methods. A display of one or more portions of a well log of a well during drilling may be displayed together with a display of one or more portions of one or more reference well logs, which may be presented as projected onto one or more planes, respectively. The logs may be segmented and correlated, with the segments or correlated portions displayed in different colors. A user may manipulate the display of the logs or log segments to assist in correlating them. The user may also manipulate the display so that the view provided of the wellbore and the projected logs changes in any one or all of three dimensions. In addition, the user may manipulate the display by navigating along the length of the borehole to view the projected logs at any point along the well path.

Abstract: A method, a system, tools for use by the system, and an interpretation method for injecting and detecting tracers and conducting flow characterizing of a petroleum well are provided. The method describes monitoring of travel time and slip velocity between two/three different phases (oil/water and possibly gas) in the well. The travel time and slip velocity are determined using an injection tool for injection of an over pressurized injection, thus simultaneous injection to all phases, of the partitioning tracers each of which would follow certain phase. The tracers are detected by a tracer detector downstream the injector. The slip velocity is obtained from the difference of travel time of two tracers which partition to two different phases.

Abstract: A flowmeter profiling system for measuring a flow profile of water in a subsurface environment includes a tracer injection system positioned at least partially within the subsurface environment. The tracer injection system includes an injection tube that contains a tracer material, and an injection port that is coupled to the injection tube near a bottom of the injection tube. Additionally, the injection port is configured to inject the tracer material substantially horizontally into the subsurface environment. The injection port can include a plurality of exit holes such that the tracer material is injected substantially horizontally into the subsurface environment through each of the plurality of exit holes.

Abstract: Capsules with a cement additive covered by a polymeric outer shell are added to wellbore cement. The additive is released from the shells by osmosis or shell ruptures. Capillary forces draw the additive into micro-annuli or cracks present in the cement, where the additive seals the micro-annuli and cracks to define a self-sealing material. The empty shells remain in the cement and act as an additive that modifies cement elasticity. The capsules are formed by combining immiscible liquids, where one of the liquids contains a signaling substance, and each of the liquids contains a reagent. When combined, the liquids segregate into a dispersed phase and a continuous phase, with the dispersed phase having the signaling agent. The reagents react at interfaces between dispersed and continuous phases and form polymer layers encapsulating the signaling agent to form the capsules. Adjusting relative concentrations of the reagents varies membrane strength and permeability.

Abstract: This application discloses a method and an apparatus for the measurement of gases in hydraulic fracking sites, comprising a gas sensor, a computer, and a correction factor wherein the correction factor is applied to the observed gas reading to generate a more accurate reading of the gas level at the site.

Abstract: A method for detecting a malfunction during a drilling operation is carried out by making use of a drill bit, the method including the following: a) the comparison of a first magnitude (E) representative of the mechanical specific energy (MSE), with a first threshold value (Emax); b) when the first magnitude is greater than the first threshold value, the comparison of the ratio (E/S) between the first magnitude and a second magnitude (S) representative of the drilling force with a second threshold value ((E/S)max); c) the detection of a malfunction in the drilling operation when the ratio (E/S) between the first magnitude (E) and the second magnitude (S) is greater than the second threshold value ((E/S)max). The method provides the ability to ensure more precise detection of a malfunction during drilling operations.

Abstract: A logging device and method for locating a watered zone in a horizontal well with high watercut problem by isotope labeling is provided. The method successively includes the following operations: a. solidifying an isotope used in an isotope releasing device into a water-soluble carrier; b. connecting the isotope releasing device with a tubing and setting them to a horizontal segment of the well; c. dissolving the water-soluble carriers in the water at the bottom of the well to release the isotope, wherein the releasing rate is proportional to the flow rate of the water; d. starting a lift-up pump and beginning a production logging; and e. continuously performing ?-ray energy-spectrum analysis on produced water on the ground, so as to locate the watered zone of the horizontal well by the detected species and characteristic content of the isotope, thereby reduces operation risk, saves platform occupying time and logging cost.

Abstract: A method and system of monitoring for scale compounds that include scale co-contributors of cations and anions. A scale compound can be monitored by measuring gamma ray counts of scale contributors using a spectral gamma ray detector. A scale compound can be identified by identifying an increase in scale co-contributors over time from the gamma ray counts.

Abstract: A tracer composite comprises a tracer disposed in a metal-based carrier which comprises: a cellular nanomatrix and a metal matrix disposed in the cellular nanomatrix, wherein the tracer is detectable at a range of from about 1 ppt to about 1,000 ppm.

Abstract: A method and system is described for estimating flow rates of fluids from each of separate influx zones in a multilayered reservoir to a production flow (Q) in a well (Wr) in the reservoir, the well having at least two separate influx zones from the multilayer reservoir of known positions along the well, the well being provided with distinct tracer sources with distinct tracer materials of known positions in each of the at least two separate influx zones. Each influx zone is provided with a delay path for a tracer leakout stream flow from that influx zone. The method includes providing a global production flow change for the production flow in the well, establishing tracer concentrations in the production flow of the distinct tracer materials as a function of time, and estimating the production rates from each of the separate influx zones in the reservoir.

Abstract: A fluid monitoring apparatus includes a housing and a tracer sensor attached to an exterior of the housing. The housing has at least one flow passage for a fluid sample and a port for the tracer sensor to monitor the fluid sample in the housing. In one example, the monitoring apparatus may include a plurality of tracer sensors attached to the housing, wherein the tracer sensors are interchangeably attached to the housing. In one embodiment, the monitoring apparatus may be attached to a first well for detecting the presence of a tracer in the first well, wherein the tracer is supplied from a second well.

Abstract: Systems and methods for measuring neutron-induced activation gamma-rays in a subterranean formation are provided. In one example, a downhole tool for measuring neutron-induced activation gamma-rays may include a neutron source and a gamma-ray detector. The neutron source may emit neutrons according to a pulsing scheme that includes a delay between two pulses. The delay may be sufficient to allow substantially all neutron capture events due to the emitted neutrons to cease. The gamma-ray detector may be configured to detect activation gamma-rays produced when elements activated by the emitted neutrons decay to a non-radioactive state.

Abstract: The present disclosure relates to apparatus and methods for evaluating an earth formation though a drillstring during tripping of the drillstring, particularly locating an area of circulation loss in a wellbore. The apparatus may include a neutron source and at least one radiation detector, which may be disposed on a logging instrument, configured to be dropped or pumped into a drillstring at the end of drilling. The logging instrument may be configured to make measurements through a homogenous portion of the drillstring while the drillstring is being tripped. The apparatus may include a memory and processor for logging data for later retrieval. The method may include adding a radiation absorbing substance to drilling fluid in the wellbore; exposing the earth formation to neutron radiation; and making a plurality of measurement indicative of radiation measurements of sigma or distinct energy peaks along the wellbore.

Abstract: Apparatus and systems may operate to enable positron emission imaging with a unitary chamber body having an open end that defines a hollow interior portion shaped to completely contain a flexible sleeve that is used to cover a core sample when the sleeve is seated within the hollow interior portion. An end cap may be formed to engage the open end of the chamber body, which is configured to attenuate gamma rays approximately eight times less than stainless steel, while supporting a pressure differential of at least 3 MPa between the chamber inlet and the outlet when fluid carrying a radioactive tag to generate the gamma rays flows through the hollow interior portion and the core sample via the inlet and the outlet. Additional apparatus, systems, and methods are disclosed.

Abstract: A method is disclosed for determining radiation attenuation as a result of an object in a positron emission tomography scanner. In at least one embodiment, a phantom object is arranged in the positron emission tomography scanner during the method. First raw radiation data of the phantom object is acquired while the object is not arranged in the positron emission tomography scanner. A first image of the phantom object is calculated from the first raw radiation data. The object then is arranged in the positron emission tomography scanner (2) and preliminary radiation attenuation of the object is identified. Second raw radiation data of the phantom object is acquired while the object is arranged in the positron emission tomography scanner. A second image of the phantom object is calculated from the second raw radiation data taking into account the preliminary radiation attenuation. The radiation attenuation is determined on the basis of the first image and the second image.

Abstract: Methods and related systems are described for the detection of nuclear radiation. The system can include a scintillator material that intrinsically generates radiation and a photodetection system coupled to the scintillator material and adapted to generate electrical signals based on light emitted from the scintillator material. A processing system adapted and programmed to receive the electrical signals, to generate a count rate reference value based at least in part on electrical signals generated in response to the light emitted from the scintillator material due to the intrinsically generated radiation.

Abstract: Methods and related systems are described for the detection of nuclear radiation. The system can include a tool body adapted to be deployed in a wellbore and a scintillator material that intrinsically generates radiation. The scintillator material is mounted within the tool body. A photodetection system is coupled to the scintillator material, and mounted within the tool body. Features in a spectrum associated with a scintillation material's intrinsic radioactive decay are used for the determination of one or more parameter's of the response function of the radiation detector system.

Abstract: This invention relates to a process utilizing natural carbon-13 isotope for identification of early breakthrough of injection water in oil wells. All natural water sources are labeled by unique ratios of carbon isotopes (13C/12C). Following the requirements of the invention, the carbon isotope ratio for oil bearing formation water and for local aquifer water which is to be injected in to the oil reservoir rock is determined. The carbon isotope ratio of the produced water from the selected oil wells is then monitored periodically. When the carbon isotope ratio of the produced (oil well) water shows deviation from the formation water value and tends towards injection water value, then the early breakthrough phenomenon of injection water is identified. Thus the contrast in natural carbon isotope ratios of injection water, formation water and produced water from selected oil wells serve as tracer in the identification of “Early Breakthrough” phenomenon of injection water and its movement.

Abstract: A method for quantifying the uptake of at least one radiotracer in a body region of a patient of interest to a positron emission tomography measurement is disclosed. In at least one embodiment of the method, the uptake of the radiotracer in the body region of the patient of interest to the positron emission tomography measurement is quantified taking into account at least one permeability information item relating to the permeability of at least one blood vessel of the patient, in particular in the body region of interest.

Abstract: Disclosed herein is a method comprising disposing in a formation fracture, a proppant and/or a fracturing fluid that comprises a radiation susceptible material that comprises indium and/or vanadium; irradiating the radiation susceptible material with neutrons; measuring gamma-radiation emitted from the radiation susceptible material in a single pass; wherein the single pass does not involve measuring of background radiation from previous or subsequent logging passes; and determining formation fracture height from the measured gamma-radiation.

Abstract: Methods and apparatus to control the additives to a chemical composition for use in the oil field services industry. Specifically, a method and apparatus to determine fluid parameters for a fluid, including introducing an inert tracer in a component; forming a fluid comprising the component; observing the concentration of the tracer in the fluid; calculating the concentration of the component in the fluid; and introducing the fluid into a subterranean formation. An apparatus and method to control fluid parameters of interest for an oilfield formulation fluid such as chemical composition including introducing an inert tracer in a component; forming a fluid comprising the component; observing the concentration of the tracer in the fluid; calculating the concentration of the component in the fluid; adjusting a flow rate when forming the fluid in response to the calculating; and introducing the fluid into a subterranean formation.

Abstract: Systems, devices, and methods for filling containers with radioactive materials are described. In certain embodiments, the systems comprise a shielding material that substantially defines a chamber and, preferably, substantially blocks radioactivity, a conduit extending through the shielding material into the chamber, and a securing unit that is disposed in the chamber proximal to the conduit and is adapted to receive a container through the conduit.

Abstract: A gravel pack evaluation tool comprised of a low energy radiation source and multiple directionally-collimated radiation detectors to analyze small, azimuthal segments of a gravel pack. Methods of use are also provided. Collimators and radiation shielding used in conjunction with multiple detector arrays allow an azimuthal segmented view of a gravel pack, particularly at certain defined depths into a gravel pack. Radioactive tracers may be used in conjunction with these tools to produce enhanced images of gravel packs and formations.

Abstract: A method of determining the distance, from a reference point, of a tracer emitting radiation comprising a first component emitted at a first known energy level and a second component emitted at a second known energy level, the intensity of a penetrating portion of the first component that penetrates a substance between the tracer and the reference point and the intensity of a penetrating portion of the second component of the radiation that penetrates the substance being a function of the rate of gamma radiation emission of the tracer as well as of the distance of the tracer from the reference point, the method comprising: a) measuring the intensity of the first penetrating portion and the intensity of the second penetrating portion; b) determining the ratio of the intensity of the first penetrating portion to the intensity of the second penetrating portion; and c) determining the distance of the tracer from the reference point.

Abstract: The invention relates to methods and apparatus for determining a downhole parameter in an underbalanced drilling environment which include: selectively activating a first fluid flowing from the formation through a wellbore while under balanced drilled; detecting the activated first fluid; and determining a depth at which said fluid enters the wellbore.

Abstract: In methods according to the invention, subsurface formations below the surface of the earth are detected by introducing a condensable material in vapor form into the subsurface formation, measuring radiation of the condensable material, increasing the concentration of the condensable material through condensation, measuring radiation of the condensable material of increased concentration, and comparing the radiation of the condensable material of increased concentration to the radiation of the condensable material in vapor form to identity the presence of the condensable material.

Abstract: A stable isotopic identification comprising a mathematical array of concentrations of isotopes found in a product, said mathematical array being presented in a machine readable form and comparable to analytical results whereby the product can be distinguished from other similar products, said machine readable form also being indexed through stored product information. The stored product information may be displayed when desired. By the stable isotopic identification of the invention, a product may be securely traced through manufacturing of a product, marketing of a product and the use of a product.

Abstract: The present invention relates to an in-vessel or down-hole optical imaging sensor or system for operating in structures which may contain media with different spectral transmission characteristics. The imaging sensor of the present invention selectively emits and/or detects two or more independently controllable wavelengths or wavebands. The imaging sensor comprises an illuminator for emitting radiation of a specified wavelength or waveband through a medium to a target, at least one detector for detecting the radiation deflected by said target and at least one amplifier for providing non-linear amplification of the detector output.

Abstract: The present invention relates to an imaging sensor, particularly for use in oil-filled passages such as wells or pipelines, or for passages containing other similar viscous fluids. There is provided a downhole imaging system which operates in a wavelength region outside the visible band, preferably in the infrared region, to permit penetration of the surrounding fluid medium, e.g., oil. Positioning the optical part of the imaging sensor in a chamber whose walls are transparent to the radiation reduces the path length of the radiation in the oil. The chamber is filled with a material highly transmissive of the radiation.

Abstract: A method for calculating the position and quantity of scale downhole, while avoiding the need to run a before log is provided. The method includes assessing the gamma ray spectra of both scale and tracers in a single logging pass. A matrix of multipliers for both borehole and formation radium is included in the data used to evaluate the gamma ray log. The radium in the formation is distinguished from radium near the borehole (scale) using the deflection of the relative distance curve and the resulting calculations of gamma ray energy attributable to scale are used to correct the measured gamma ray emissions attributed to the tracers. The method allows several tracers to be monitored with a single logging pass, even in a hole that has been previously produced and has been contaminated with radioactive scale.

Abstract: A tracer solution suitable for use in measuring flow velocities in a borehole, includes: a) a gadolinium salt of a carboxylic acid of general formula ##STR1## where R is an alkyl of not less than four carbon atoms, typically C4 or C5 alkyl, and R.sub.1 and R.sub.2 are hydrogen or an alkyl group, typically hydrogen, methyl or ethyl; b) a free branched-chain carboxylic acid such as an excess of the acid used to form the Gd salt; and c) a non-polar solvent such as hexane or heptane. The Gd content of the solution should be not less than about 50 g/l and is best when it is as high as possible, for example greater than 100 g/l, and the viscosity should be less than 20 cP.

Abstract: Radioactive particles are provided for use in tracing the flow path in or near a well of fluids injected into the well. The particles include an element which can be made radioactive by bombardment with neutrons and a material to encapsulate the element. The encapsulant is preferably an organic polymer having a high softening temperature. The particles may be injected into a well in treating fluids and their location may be later determined by gamma ray logging of the well.

Abstract: The present invention generally pertains to apparatus and a method for continuously injecting a tracer in a borehole to thereby enable continuously measuring the flow of effluents in the borehole, i.e. either in an injection well or production well, of an oil, gas or geothermal field. The apparatus and method comprises positioning capillary tubing within the borehole, the tubing having a flowpath extending continuously from the surface to a desired depth, the capillary tubing having at least one sensor suspended in the borehole at the desired depth, injecting a tracer element into the tube from a pressurized source at the surface, releasing the tracer element at the desired depth and detecting the presence of the tracer.

Abstract: A tracer solution suitable for use in measuring flow velocities in a borehole, includes: a) a gadolinium salt of a carboxylic acid of general formula ##STR1## where R is an alkyl of not less than four carbon atoms, typically C4 or C5 alkyl, and R.sub.1 and R.sub.2 are hydrogen or an alkyl group, typically hydrogen, methyl or ethyl; b) a free branched-chain carboxylic acid such as an excess of the acid used to form the Gd salt; and c) a non-polar solvent such as hexane or heptane. The Gd content of the solution should be not less than about 50 g/l and is best when it is as high as possible, for example greater than 100 g/l, and the viscosity should be less than 20 cP.

Abstract: A method for real-time monitoring of fracture extension during a fracturing treatment of a producing subterranean formation. A radioactive tracer injector is coupled to and spaced from a gamma ray detector by a distance approximately equal to a distance from a point of injection during fracturing to a boundary between the desired interval to be fractured and an adjacent formation which it is desired not to fracture. A programmed central processing unit positioned at a surface location receives spectral signals generated by the gamma ray detector during the fracturing treatment and generates a fracture penetration signal and a fracture injection pump control signal that stops a fracture injection pump whenever the fracture extension signal indicates the presence of radioactive tracer material within the producing subterranean formation at the depth location of the gamma ray detector.

Abstract: The location in a wellbore of the top of a quantity of fill material which is sufficient to restrict flow in a tubing/casing annulus at a location deep in a well is determined by dropping a radioactive source through the annulus so that it falls to the top of the fill material. The depth of the thus deposited radioactive source is detected by radiation measurements, and the measured depth infers the location of the top of the fill material.

Abstract: A method of measuring flow velocities in flowing fluids includes injecting into the flow a non-radioactive tracer having a neutron capture cross section higher than that of the flowing fluids, for example a gadolinium compound, and measuring the neutron capture cross section in the fluid downstream of the injection point to detect the passage of the tracer and hence determine the time of flight. By making the tracer miscible with only one phase (typically the continuous phase) of a multi-phase fluid, it is possible to measure the flow velocity of that phase. The neutron capture cross section can be measured by irradiating with neutrons from a pulsed neutron generator and measuring capture .gamma. rays with a scintillation detector.

Abstract: A method of monitoring formation fractures in real-time is performed in which a fluid containing a radio-active tracer element is pumped at a high pressure down a wellbore into a formation. As the fluid creates fractures and moves through the formation gamma-rays are emitted from the radio-active tracer element in the fluid. Detector means placed at predetermined locations in the wellbore continuously detect these gamma-rays. Gamma-rays emitted from wellbore fracture fluids are distinguished from formation gamma-rays and the detected formation gamma-rays are counted. As the fracture fluid approaches the height or vertical depth of these detecter means, the gamma-ray count increases. Once the gamma-ray count reaches a predetermined level, the fracture will have reached a desired location in the formation and pumping of the fracture fluid will stop.

Abstract: A method for evaluating the penetration of downhole materials such as proppant, casing annulus fill, or packed gravel by radioactively tagging the material, conducting well logging with gamma ray spectroscopy equipment to generate data signals, and applying an improved low-noise processing routine to the data signals to determine the material's penetration diameter. After hydraulic fracturing, gravel packing, or cementing operations are performed on a cased well, the well is logged using gamma ray spectroscopy techniques. In an exemplary embodiment, the resultant data signals are divided into channels, sent uphole, consolidated into depth intervals, and summed into specified energy windows. The spectra are processed by a weighted least squares technique to represent the spectra as borehole and formation component signals.

Abstract: In a method of logging a well in a subterranean formation which formation has been fractured by injecting proppant tagged with at least one radioactive material into the formation through the well, the improvement comprising: utilizing a spectral gamma-ray tool in performing the logging. By analyzing one or more selected ratios of counting rates at certain energy areas of the spectrum one can determine the vertical height of the fracturing in the formation.

Abstract: A method for determining at least one dynamic flow characteristic of a multiphase flow circulating in a pipe, said flow being composed of an aqueous phase and a hydrocarbon (oil) phase. Oxygen atoms in the aqueous phase are activated by irradiation with neutrons at a chosen first location in the pipe. The concentration of activated oxygen at a chosen second location in the pipe is measured with a detector as a function of time t, so as to obtain at least one signal S(t). Then a relationship is fitted to the signal S(t) so as to derive the values of the velocity U of the aqueous phase. The slip velocity v.sub.s of a dispersed phase relative to the velocity of a continuous phase is also advantageously determined. From the values of velocities U and v.sub.s and from the volume fraction y.sub.1 of the continuous phase in the pipe (obtained by an ancillary measurement), the volumetric flow rates of the phases are determined.

Abstract: A natural gamma tag marking materials for sub or permanent markers used in gamma logging operations, such natural gamma materials having a gamma count of between 200 and 1000 counts per second. The instant invention further discloses a typical Sub, for insertion in a drilling operation, utilizing natural gamma element compounds which are considered to be non-hazardous and effective as tag markers when used in wireline logging operations.

Abstract: A method of analysis of rock samples taken from the bore of a well being drilled or from the Earth's surface and performed upon the apatite grains contained within the samples. The apatite grains are separated from the surrounding rock, polished to expose internal surfaces, and etched with acid to reveal the presence and characteristics of fission tracks within the apatite to determine the geological characteristics of the apatite. The grains containing the apatite are viewed under an optical microscope or other imaging apparatus and apatite crystals or crystal fragments which contain etched fission tracks are selected for analysis. If selected for analysis, measurements may be taken to determine the size and shape of the etched pits intersecting the apatite grain surface. The measurements are taken using a digitizing apparatus interconnected to a computer and containing a point light source superimposed upon the apatite grains viewed through the microscope.

Abstract: A method of measuring or detecting an unknown distribution and content of solid material in a flow of liquid and gas is achieved without any calibration. One or several activated probes or specimens emitting radiation are used. The radiation is measured by a detector on the outside of the flow pipe. Each probe emits radiation only to one detector. The probes are mounted apart both lengthwise and across the pipe section. The probes are mounted at an angle .alpha. to the fluid flow, 20.degree.<.alpha.60.degree.. Without any signal analyses, the probes will register whether the fluid flow contains solid material if the thickness of the probes is reduced 0.1 %. The particle content is calculated with a 0.25% thickness reduction. The amount of the particles impinging the probes can be calculated.

Abstract: There is provided radioactive particles having a ceramic matrix and an element which can be bombarded with neutrons to produce a gamma ray-emitting isotope. The particles are manufactured by mixing the ceramic components and the element, forming particles, sintering the particles, and the particles are subsequently made radioactive by bombardment with neutrons. Particles injected into wells or flow apparatus are traced by adding the radioactive particles and detecting the radioactive particles with gamma ray-sensitive instruments. Particles containing different elements are detected by spectral analysis of gamma rays.

Abstract: A potassium salt which is soluble either in water or in an oil-based drilling mud is forced via filtrate invasion into permeable subsurface formation zones adjacent a well borehole via an over-balanced drilling mud or completion system. Well logging is then performed in an interval of interest in the formations using natural gamma ray spectrometry. Gamma radiation at an energy of 1.46 MeV from the naturally occurring radioactive potassium isotope .sup.40 K is detected. Gamma radiation levels of the isotope .sup.40 K above normal background readings indicate the presence of permeable formations.