Abstract: Apparatus for wellbore logging and method of use are provided for measurement of the annular materials interposed between the logging tool and formation and the apparent formation bulk density in open-hole, cased-hole or other conduit. The logging tool can be centralized in the borehole. Non-collimated gamma radiation is emitted into the surrounding media and the amount of radiation which returns to the tool is measured by multiple omni-directional detectors spaced a pre-set distances from the source to provide multiple radial depths of investigation. The annular thickness and density of materials interposed between the logging tool and the formation may be determined from the detector responses and be used to derive the apparent formation bulk density.

Abstract: Inverting nuclear log data for a geological formation surrounding a borehole involves acquiring nuclear log data for a borehole portion using a moveable nuclear logging tool and acquiring additional log data for the borehole portion using another logging device with superior resolution. Boundaries between adjacent zones are identified that exhibit an attribute of the geological formation to a detectably contrasting degree. From pre-acquired data describing one or more characteristics of the nuclear logging tool, a modelled log of the attributes is generated over the borehole portion, and a zone response is calculated from the pre-acquired data for each zone by using the boundaries to define an initial measure of the depth of each zone and ascribing a value of the attribute in dependence on the depth of each zone.

Abstract: Systems, methods, and devices for quantatively identifying gas zones irrespective of porosity or lithology using nuclear downhole tools are provided. In particular, because some formation materials such as shales can confound some conventional measurements, a gas detection measurement may be obtained that can be used to qualitatively identify gas zones. The as detection measurement may be based at least partly on a relationship between inelastic gamma rays, neutron capture gamma rays, and experimental or modeled formation data, such that the gas detection measurement qualitatively indicates a gas zone when a gas zone is present in a formation irrespective of a lithology or a porosity of the formation.

Abstract: Pulse sequences are applied to a fluid in an earth formation with an external static magnetic field and NMR spin echo signals are obtained. The received NMR signals are affected by internal field gradients due to a contrast in magnetic susceptibility between the grains of the formation matrix and the fluid in the pore space. Processing of the data gives the relaxation time and diffusivity of the fluid.

Abstract: A performance assessment system for deep geologic repository for radioactive waste disposal is introduced to integrate a number of independent sub-system to perform the repository assessments in a systematic way under computer-based environment. Basically, the sub-system includes the input data file preparation sub-system for near-field/far-field multiple running, the near-field/far-field multiple running sub-system and the uncertainty and sensitivity analysis sub-system. With the system, the assessment for the deep geologic repository for radioactive waste disposal in many aspects can be achieved more completely and precisely.

Abstract: A system and method of characterizing a property of an earth formation penetrated by a borehole are described. The method includes conveying a carrier through the borehole. The method also includes performing an NMR measurement with an NMR tool disposed at the carrier and obtaining NMR data, compressing the NMR data to generate compressed NMR data, and telemetering the compressed NMR data to a surface processor for processing. The method further includes decompressing the compressed NMR data directly to T1 or T2 domain distribution data, and determining the property of the earth formation based on the T1 or T2 domain distribution data.

Abstract: The present disclosure is intended to overcome the problem of hydrogen contamination of the density signal. The approach is to compute the neutron capture portion of the total gamma ray counts and subtract it from the total counts resulting in a pure inelastic gamma ray measurement.

Abstract: Formation fluid salinity is an important parameter in water saturation and formation porosity measurements. Systems and methods are disclosed herein to provide accurate water saturation and/or formation porosity measurements in the presence of unknown or highly variable salinity levels. Some logging tool assembly embodiments include a resistivity tool and an augmented neutron porosity tool. The neutron porosity tool is augmented with a gamma ray detector configured to measure the rate at which hydrogen nuclei capture neutrons from a neutron source. A processing system coupled to the logging tool assembly provides a salt compensated formation porosity log and/or a water saturation log. The logging tool assembly can also include a density logging tool and a natural gamma ray logging tool to provide a salt independent triple-combo log.

Abstract: A method of passive surveying comprises generating one or more detected signals by passively detecting a signal generated within a subsurface earth formation due to a seismoelectric response or an electroseismic response in at least one porous subsurface earth formation containing at least one fluid, and processing the one or more detected signals to determine at least one property of the subsurface earth formation.

Abstract: The present disclosure relates to borehole logging methods and apparatuses for estimating a parameter of interest of an earth formation using logging data acquired in a borehole penetrating the earth formation. The method may include estimating the at least one parameter of interest using a statistical analysis of logging data acquired by at least one sensor, wherein the statistical analysis is applied over interval plurality of intervals within the logging data. The logging data may include one or more of: gamma ray data and spontaneous potential data. The method may include acquiring logging data with the at least one sensor. The method may also include estimating a confidence level for the at least one estimated parameter. The apparatus may include at least one sensor configured to generate logging data information about an earth formation; and at least one processor configured perform at least some of the steps of the method.

Abstract: A method of passive surveying comprises generating one or more detected signals by passively detecting a signal generated within a subsurface earth formation due to a seismoelectric response or an electroseismic response in at least one porous subsurface earth formation containing at least one fluid, and processing the one or more detected signals to determine at least one property of the subsurface earth formation.

Abstract: A hydrocarbon exploration method is disclosed for generating anisotropic resistivity models of a subsurface reservoir from seismic and well data using a rock physics model. In one embodiment, the method comprises: selecting wells within a region of interest (101); obtaining a plurality of rock properties (102) and adjusting selected rock parameters (103) in the calibration of the rock physics model at the well locations; inverting porosity and shale content from seismic data (107); propagating the calibrated rock physics model to the region of interest (109) and calculating effective resistivity for the entire region of interest (109). The inventive method also provides for analyzing the uncertainty associated with the prediction of the resistivity volume.

Abstract: A method for determining weight fractions of a plurality of elements in a subsurface formation penetrated by a wellbore includes determining weight fractions of a first plurality of elements using measurements of capture gamma rays made in the wellbore. The capture gamma rays result from bombardment of the formations with high energy neutrons. A weight fraction of a second plurality of elements is determined using measurements of inelastic gamma rays made in the wellbore resulting from bombardment of the formations with high energy neutrons. The weight fraction for the second plurality is determined by setting a transformation factor for those elements common to both the first and second plurality to result in a statistically equivalent weight fraction for the common elements as determined, for the first plurality of elements. Weight fractions of elements in the second plurality not common to the first plurality of elements is determined using the set transformation factor.

Abstract: Percolation theory is applied to establish a connection between magnetization decay of nuclear magnetic resonance (NMR) measurements and residual carbon dioxide saturation (Scr). As a result, estimations of Scr are obtained through use of an NMR tool in a formation and appropriate processing. Data may be displayed as a log.

Abstract: Methods and related systems are described for analyzing electromagnetic survey data. Electromagnetic survey data of a subterranean formation is obtained using at least a downhole transceiver deployed in a borehole and a transceiver positioned on the surface or in another borehole. The electromagnetic survey data includes an incident wave component and a scattered wave component. The incident and scattered components are correlated so as to generate an image of the subterranean formation indicating spatial locations of one or more features, for example, electrical properties such as resistivity variations, in the formation. The image is based at least in part on one or more interference patterns of the incident and scattered wave components. The correlation preferably includes generating a simulation of the incident wave component propagated into the formation, and convolving the simulated propagated incident wave component with the scattered wave component.

Abstract: A system for determining at least one of a lithology of a formation traversed by a borehole and an operational condition of a component of a drill string disposed in the borehole is disclosed. The system includes a drill string with a high speed wired pipe telemetry system for transmitting downhole measurements made by a sensor to a computer processing system in real time. The computer processing system is external to the drill string and includes a model that models operation of the drill string and/or a formation that is being drilled. The model receives the downhole measurements and surface measurements of a drilling parameter and provides as output detection of the lithology of the formation and/or the operational condition of the component.

Abstract: Determining elemental content of an earth formation. At least some of the illustrative embodiments are methods including: irradiating a portion of a formation that surrounds a borehole; counting gammas to obtain a spectrum of counted gammas; finding a solution to a system of equations based on the spectrum of counted gammas, which system of equations has a plurality of solutions, the solution being indicative of a plurality of weight percentages for a respective plurality of elements within the formation; determining whether the solution meets a predetermined constraint; repeating the finding and determining until a solution is found that is determined to meet the predetermined constraint; and producing an indication of the elemental content of the formation using the solution that meets the predetermined constraint.

Abstract: Apparatus, systems, and methods may operate to receive radiated energy as scattered energy after the radiated energy interacts with a geologic formation, wherein the scattered energy is received at a sub-surface multi-channel sensor array that operates to transform the scattered energy into received signals, and wherein the radiated energy is provided by a sub-surface source of elastic energy; and to identify discontinuous features in the geologic formation by interferometric comparison of the received signals as elastic signals and/or electromagnetic signals among some sensors in the sensor array, or by time-reversal propagation of the received signals as elastic and/or electromagnetic signals in a numeric model of a volume of the geologic formation. Additional apparatus, systems, and methods are disclosed.

Abstract: Apparatus for in-situ wellbore measurements, said apparatus comprising one or more sensors arranged outside a wellbore, one or more actuators associated with the sensors, an electromagnetic transceiver situated inside a non-magnetic portion of wellbore conduit and mounted on an electric-line logging cable, a downhole interface unit also located on the electric-line cable for controlling communication to the apparatus. Also a method of in-situ wellbore measurements using said apparatus.

Abstract: Formation density measurements in the presence of invasion of drilling fluids. At least some of the illustrative embodiments are methods including: irradiating a formation with gammas from a source of gammas, wherein drilling fluid has invaded the formation, and wherein Pe of the drilling fluid that has invaded the formation is greater than Pe of the formation; determining a first value indicative of a parameter of the formation; determining a second value indicative of a parameter of the formation; determining a third value, the third value determined based on gammas in an energy range different than used in determining the first value; and calculating, using the first, second, and third values, information such as a standoff, a formation porosity, a formation density prior to invasion by the drilling fluid, and radial depth of invasion of the drilling fluid into the formation.

Abstract: A laboratory NMR methodology (and corresponding laboratory apparatus) defines a sample volume. The method stores downhole tool data corresponding to a hydrocarbon-bearing sample collected from a given subsurface formation. The downhole tool data includes parameters pertaining to magnetic fields used by a downhole tool during a suite of NMR measurements of the given subsurface formation. The sample is positioned in the sample volume of the laboratory apparatus, which applies a static magnetic field in the sample volume. Furthermore, the laboratory apparatus applies a suite of NMR measurements to the sample volume to thereby determine a property of the sample. The NMR measurements of the suite each include a pulse sequence of oscillating magnetic field in conjunction with a pulsed-mode gradient field. The pulsed-mode gradient field is based on the stored downhole tool data corresponding to the sample. A laboratory NMR methodology for optimizing downhole NMR measurements is also described.

Abstract: A method and a system are provided to characterize subterranean formations, which includes extracting drill cuttings from a drilling fluid, and grouping the drill cuttings into a group of cuttings based on a time of arrival of the drill cuttings at the Earth's surface, wherein these steps can be repeated at least once to provide a plurality of groups of drill cuttings that arrive sequentially at different recorded times that correspond to different downhole locations.

Abstract: A system and method for detecting hydrocarbon deposits includes a sensor that can measure radiation emanating from an earth surface within an area of interest and separate the measured radiation into component signals, each having a particular characteristic associated with the presence of hydrocarbon deposits. The system also includes a processor that can receive the component signals from the sensor, determine a difference between the component signals and a baseline radiation for the area of interest, and display data showing a likelihood of the presence of hydrocarbon deposits in locations within the area of interest based on the difference between the measured radiation and the baseline radiation. The processor may also generate maps of the area of interest.

Abstract: A method of passive surveying comprises generating one or more detected signals by passively detecting a signal generated within a subsurface earth formation due to a seismoelectric response or an electroseismic response in at least one porous subsurface earth formation containing at least one fluid, and processing the one or more detected signals to determine at least one property of the subsurface earth formation.

Abstract: Determining a value indicative of gas saturation of a formation. At least some of the illustrative embodiments are methods including obtaining an inelastic count rate and a capture count rate of a gamma detector for a particular borehole depth, calculating a ratio of an inelastic count rate to a capture count rate for the particular borehole depth, determining a value indicative of gas saturation based on the ratio of the inelastic count rate to the capture count rate for the particular borehole depth, repeating the obtaining, calculating and determining for a plurality of borehole depths, and producing a plot of the value indicative of gas saturation of the formation as a function of borehole depth.

Abstract: Example methods and apparatus to determine phase-change pressures are disclosed. A disclosed example method includes capturing a fluid in a chamber, pressurizing the fluid at a plurality of pressures, measuring a plurality of transmittances of a signal through the fluid at respective ones of the plurality of pressures, computing a first magnitude of a first subset of the plurality of transmittances, computing a second magnitude of a second subset of the plurality of transmittances, comparing the first and second magnitudes to determine a phase-change pressure for the fluid.

Abstract: The method for obtaining a fluid migration profile for a wellbore, including the steps of obtaining a static profile for a logged region of the wellbore, obtaining a dynamic profile for the logged region of the wellbore, digitally filtering the dynamic profile to remove frequency elements represented in the static profile, to provide a fluid migration profile, and storing the fluid migration profile on a computer-readable memory.

Abstract: A method for estimating a borehole independent porosity of a subterranean formation includes processing a neutron logging data point, preferably including average near and far detector neutron count rates with suitable input data to obtain the porosity estimate. The borehole independent formation porosity may be obtained without any compensation and without any reliance on the measurement or estimation of sensor standoff and/or borehole caliper.

Abstract: To evaluate an exact bone mineral density, when a reference bar region in an X-ray picture of a mandible and a reference bar disposed beside the mandible is selected, the mean value and deviation of the brightness of this region are displayed by means of letter groups. When an evaluation object region is selected, the brightness of this region is corrected according to the mean value and deviation of the brightness of the reference bar region and standard mean value and deviation, or, in other words, according to a fixed reference. The corrected brightness is displayed in the form of histogram. Furthermore, the mean value and deviation of the corrected brightness are determined, and they are displayed by means of letter groups. The bone mineral density is quantitatively evaluated from the histogram and the mean value and deviation of the corrected brightness.

Abstract: Apparatus, methods for forming the apparatus, and methods for operating the apparatus provide a value for a formation property or a borehole property from measurements obtained in a well. The value may be generated from determining a weighted average of the value for the formation property or the borehole property using both values corresponding to different azimuths and weights corresponding to different azimuths.

Abstract: A sensing apparatus (and corresponding method) for monitoring carbon dioxide dissolved in a liquid solution employs a crystal surrounded in part by a sample chamber such that, in use, the liquid solution is in direct contact with the crystal.

Abstract: A method for estimating a lithotype of an earth formation, the method includes: obtaining at least two different energy spectra of radiation received from the earth formation using the logging tool, each energy spectrum having at least one of a natural gamma-ray spectrum, a fast neutron-induced inelastic spectrum, and a thermal neutron induced capture spectrum; establishing at least one geochemically-based constraint related to elemental spectral yields to be determined; determining the elemental spectral yields from the at least two different energy spectra by decomposing the at least two different energy spectra over weighted sum of monoelemental standards wherein at least one weight is constrained by the at least one geochemically-based constraint and each weight represents a proportion of one monoelemental standard; converting the elemental spectral yields to elemental concentrations; and using a classifier to receive the elemental concentrations as input and to provide a lithotype as output.

Abstract: Acoustic monitoring is carried out using a fiber optic cable. Coherent Rayleigh noise generated by the transmission of a coherent beam of radiation through the fiber optic cable is detected, a phase of the coherent Rayleigh noise is measured and the measured phase is processed to identify an acoustic occurrence along the fiber optic cable. In certain aspects, an optical fiber serves as a distributed interferometer that may be used to monitor a conduit, wellbore or reservoir. The distributed interferometric monitoring provides for accurate detection of acoustic occurrences along the fiber optic cable and these acoustic occurrences may include fluid flow in a pipeline or wellbore, processes taking place in a wellbore or pipeline, fracturing, gravel packing, or production logging.

Abstract: A method for determining the water saturation of an underground formation traversed by a borehole, the method composing: determining a first parameter (?) that is representative of the critical exponent of the electrical conductivity of the formation: determining a second parameter (Wc or Sc or ?c) that is representative of the formation percolation threshold; measuring a first set of formation properties; and combining, said first set of formation properties, first and second parameters in order to determine the water saturation (Sw) of said underground formation.

Abstract: In a method of logging a geological formation, a neutron generator is pulsed to generate a series of neutron bursts that irradiate the formation. Mutually spaced radiation detectors are operated without counting or detecting individual pulses stimulated by a burst from the neutron generator. The detectors are located to detect neutrons that have traversed the formation and to generate respective current outputs indicative of the neutron detection at the respective detectors. The current outputs of the detectors are integrated to generate respective analog waveforms characteristic of the count rates at the detectors. Each of the analog waveforms is converted to digital form, and the respective digital waveforms are compared to establish a ratio of radiation detector count rates corresponding to the outputs of the respective radiation detectors. From the resulting ratio, a compensated measure of the neutron-based porosity of the formation is established.

Abstract: A device and method for measuring a fluid flow velocity and direction. The device includes: a modulator for modulating an incident signal from a fiber optical arrangement. The modulator includes an encoder resulting in a modulated signal having at least a first portion, a second portion and a third portion for each complete rotation of the encoder. The device further includes a processor for determining the fluid flow velocity and direction based on at least the first portion, the second portion and the third portion of the modulated signal. The method includes modulating an incident beam to have a first portion, a second portion and a third portion for each rotation of an encoder and processing the modulated signal to determine a fluid flow velocity and direction.

Abstract: The online measurement system of radioactive tracers in oil wells head, object of this invention, is characterized by the use of new technology to measure concentrations of tracer activity in real time, using a radiation detector NaI (TI), with features that make it possible to detect up to three different tracers and be able to operate in temperature conditions up to 150° C., which allows to be immersed in a container with fluid coming from the flow stream, achieving with this to increase the sensitivity of the measurements. This system of measurement in the head of production wells will allow having much more data of the tracer activity, avoiding having to transport the operational staff to production wells to carry out sampling test, with all the advantages that this represents.

Abstract: Systems, methods, and devices for inelastic gamma-ray logging are provided. In one embodiment, such a method includes emitting neutrons into a subterranean formation from a downhole tool to produce inelastic gamma-rays, detecting a portion of the inelastic gamma-rays that scatter back to the downhole tool to obtain an inelastic gamma-ray signal, and determining a property of the subterranean formation based at least in part on the inelastic gamma-ray signal. The inelastic gamma-ray signal may be substantially free of epithermal and thermal neutron capture background.

Abstract: Method and apparatus for transmitting a first data set from a tool to a receiver are provided. The method includes: obtaining a first plurality of measurements using the tool to form a first dataset; saving data from the first plurality of measurements that form the first dataset in non-volatile memory; transmitting first data-groups derived from the first dataset to the receiver, each of the first data-groups comprising different measurements of the formation; and storing in the non-volatile memory a storage position of a last transmitted first data-group. Upon restoration of a loss of communications that prevents transmission of all the first data-groups, determining the storage position of the last transmitted first data-group; and continuing the transmission of the first data-groups from the storage position of the first data-group last transmitted before the loss of communications.

Abstract: Methods for determining the locations/heights of fractures in a subterranean formation use a post-fracture log obtained with a compensated neutron or pulsed neutron logging tool. Utilizing predetermined relationships between tool count rates and associated near/far count rate ratios, the methods detect the presence of proppant containing high thermal neutron capture cross-section material, substantially eliminating proppant determination uncertainty resulting from changes in formation hydrogen index. In an interval of a well with given borehole and formation conditions, and not containing proppant, a relationship is developed between detector count rate and near/far ratio. This relationship is used to compute count rate from the ratio in intervals of the well possibly containing proppant and which have similar formation and borehole conditions.

Abstract: A apparatus for monitoring a downhole component is disclosed. The apparatus includes: an optical fiber sensor including a plurality of sensing locations distributed along a length of the optical fiber sensor; an interrogation assembly configured to transmit an electromagnetic interrogation signal into the optical fiber sensor and receive reflected signals from each of the plurality of sensing locations; and a processing unit configured to receive the reflected signals, select a measurement location along the optical fiber sensor, select a first reflected signal associated with a first sensing location in the optical fiber sensor, the first sensing location corresponding with the measurement location, select a second reflected signal associated with a second sensing location in the optical fiber sensor, estimate a phase difference between the first signal and the second signal, and estimate a parameter of the downhole component at the measurement location based on the phase difference.

Abstract: In general, in one aspect, the invention relates to a method for evaluating a volcanic reservoir formation having volcanic rock forming elements and a borehole penetrating the volcanic reservoir formation. The method includes controlling chlorine concentration in an environment of the borehole and a tool operation to enable neutron capture spectroscopy measurements of the volcanic rock forming elements, obtaining neutron capture spectroscopy data relating to the volcanic rock forming elements from borehole logging tools, determining a lithology of the volcanic reservoir formation based on at least the neutron capture spectroscopy data, and generating an evaluation of the volcanic reservoir formation based on at least the lithology.

Abstract: A method and system for processing three component seismic data includes determining a covariance data matrix from three component seismic data for each of a plurality of time periods to obtain eigenvectors and eigenvalues. One or more seismic attributes are calculated from the eigenvectors and eigenvalues for each of a plurality of time periods. A stability measure is determined from the calculated seismic attribute for each of the plurality of time periods and stored for display.

Abstract: Methods are provided for determining the locations and heights of fractures in a subterranean formation using a neutron-emitting logging tool. Utilizing predetermined relationships (1) between logging tool count rates and associated apparent formation hydrogen index values and (2) between logging tool count rate ratios and associated apparent formation hydrogen index values, the methods detect the presence and heights in the formation of proppant containing high thermal neutron capture cross section material in a manner substantially eliminating proppant determination uncertainty resulting from a prior change in formation hydrogen index values. A second, associated, method employing logging tool count rates and count rate ratios to determine the presence of proppant containing high thermal neutron capture cross section absorbers utilizes a crossplot of count rate versus ratio.

Abstract: A method of determining the density of an underground formation surrounding a borehole from measurement of gamma rays arising from irradiation of the formation by a nuclear source in a tool body located in the borehole, and measurement of gamma-ray flux in the tool body at two different detector spacings from the source, the method comprising determining a substantially straight-line relationship between gamma-ray flux measurements at each different spacing with respect to the density of the formation for a tool body with no standoff; determining a relationship defining the deviation with respect to tool standoff of the density determined from the measured gamma-ray flux measurements at the two different detector spacings from the density calculated from the straight line relationships; and for a given pair of gamma-ray flux measurements at the different detector spacings, determining the intersection of the relationship defining the deviation with the straight line relationship so as to indicate the density

Abstract: Percolation theory is applied to establish a connection between magnetization decay of nuclear magnetic resonance (NMR) measurements and residual carbon dioxide saturation (Scr). As a result, estimations of Scr are obtained through use of an NMR tool in a formation and appropriate processing. Data may be displayed as a log.

Abstract: Disclosed is a method for detecting a pair of opposing breakouts in a borehole penetrating an earth formation. The method includes: conveying a downhole tool configured to perform measurements of a property of the earth formation; producing an image of the earth formation from the measurements, the image comprising a plurality of sectors; dividing the sectors into radial segments, each segment corresponding to an opposite segment; rotating the segments at least one sector at a time until a specified angle is achieved; calculating an average value for the measurements associated with each segment for each rotation of the segments; stacking the average values for opposing segments to produce stack values; determining a maximum or minimum stack value; determining if the maximum or minimum stack value exceeds a threshold value; and detecting the first breakout and the second breakout if the maximum or minimum stack value exceeds the threshold value.

Abstract: A method for estimating a property of an earth formation, the method includes: conveying a carrier through a borehole penetrating the earth formation; performing a measurement of total organic carbon (TOC) within a region of investigation in the earth formation using a logging tool disposed at the carrier; and correlating the measured TOC to the property to estimate the property.

Abstract: An apparatus and method for determining a property of an earth formation using a radial basis function derived from a catalog of rock samples. Parameters of a Thomeer capillary pressure fitting curve are derived and used for analyzing rocks with unimodal or multimodal pore size distributions.

Abstract: The present disclosure relates to borehole logging methods and apparatuses for estimating formation properties using nuclear radiation, particularly an apparatus and method for estimating amounts of silicon and/or oxygen in the formation. The method may include using nuclear radiation information from at least one nuclear radiation detector to estimate at least one parameter of interest. The method may include separating a gross nuclear radiation count into separate nuclear radiation components. The method may also include reducing an error in the estimated formation properties due to speed variations of a nuclear radiation source that activates the silicon and oxygen in the formation. The apparatus may include at least one nuclear radiation detector. The apparatuses may include an information processing device to perform the methods.