Schlumberger Technology Corporation

Other

Saudi Arabian Oil Company

Services Petroliers Schlumberger

Schlumberger Holdings Limited

Prad Research and Development Limited

James A Grau

Bradley Albert Roscoe

Jeffrey Miles

Markus Berheide

Peter D Wraight

Kenneth Edward Stephenson

Christian Stoller

Zilu Zhou

Michael M Herron

Susan L Herron

Russel C Hertzog

Robert Allen Badry

Shouxiang Mark Ma

Tong Zhou

Matthieu Simon

Harold Pfutzner

David Rose

Darwin V Ellis

Raghu Ramamoorthy

Jeffrey S Schweitzer

Paul Ryan Craddock

Hubert D Scott

John Paul Horkowitz

Ronald E Plasek

Gilles Mathieu

Fabien Haranger

William A Loomis

Nicholas B Nigrelli

Brad Roscoe

ZhanGuo Shi

Kent Lang

Roland Banas

Jerome A Truax

Laurent Mosse

Richard Radtke

Edward Clayton

Systems and method presented herein enable the estimation of porosity using neutron-induced gamma ray spectroscopy. For example, the systems and methods presented herein include receiving, via a control and data acquisition system, data relating to energy spectra of gamma rays captured by one or more gamma ray detectors of a neutron-induced gamma ray spectroscopy logging tool. The method also includes deriving, via the control and data acquisition system, one or more spectral yields relating to one or more elemental components from the data relating to the energy spectra of the gamma rays. The method further includes estimating, via the control and data acquisition system, a measurement of porosity based on the one or more spectral yields relating to the one or more elemental components.

Porosity measurements from nuclear spectroscopy

An earth formation traversed by a borehole is investigated. A borehole tool having a neutron source and a photon detector is located in the borehole and used to obtain photon scatter information in or about the borehole. A chemical element located in a region in or about the borehole is quantified by using the photon scatter information and at least two different spectral standards for that element.

Measuring spectral contributions of elements in regions in and about a borehole using a borehole spectroscopy tool

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.

Combining inelastic and capture gamma ray spectroscopy for determining formation elemental

Methods and systems are described for using pulsed neutron ?-ray spectroscopy to measure formation water salinity from within a borehole. Through generating a cross-plot of database values of ratios of spectroscopically determined yields of hydrogen (H) and chlorine (Cl) from two detectors, deriving apparent salinities therefrom, formation and borehole water salinities can be determined.

Method for measuring formation water salinity from within a borehole

Methods and related systems are described for gamma-ray detection. A gamma-ray detector is made depending on its properties and how those properties are affected by the data analysis. Desirable properties for a downhole detector include; high temperature operation, reliable/robust packaging, good resolution, high countrate capability, high density, high Z, low radioactive background, low neutron cross-section, high light output, single decay time, efficiency, linearity, size availability, etc. Since no single detector has the optimum of all these properties, a downhole tool design preferably picks the best combination of these in existing detectors, which will optimize the performance of the measurement in the required environment and live with the remaining non-optimum properties. A preferable detector choice is one where the required measurement precision (logging speed) is obtained for all of the required inelastic elements and/or minimization of unwanted background signals that complicate the data analysis.

Gamma-ray detectors for downhole applications

The accurate determination of formation hydrocarbon or water saturation is a useful step in the petrophysical evaluation of petroleum reservoirs. This disclosure presents a new method for estimating hydrocarbon saturation directly from a porosity log and a total organic carbon (TOC) log. The method is enabled by the recent development of a geochemical spectroscopy logging tool that combines inelastic and capture gamma ray measurements to provide a robust and accurate TOC log. The method differs from the prior approach of using carbon-to-oxygen ratios that is most often applied in cased hole evaluation. The main advantages of this method are that it does not use knowledge of formation water resistivity, it does not rely on a resistivity model, it does not use an extensive calibration database, and it is largely independent of clay or other lithology effects. Here, the principles of the method and the main challenges are described, and calculations that explore uncertainties in the saturation estimates arising from uncertainties in the log inputs are presented. The statistical uncertainty in the estimate of hydrocarbon saturation is as good as 10 saturation units (s.u.) in conventional reservoirs with porosities of 15 porosity units (p.u.) or greater. The method has been applied to the determination of hydrocarbon saturation in a variety of formations, including bitumen-filled dolomite, heavy oil sand, and shaly-sands with both open hole and cased hole wells. The method works equally well in formations drilled and logged with either oil- and water-based mud. The saturation estimates have been benchmarked against a combination of conventional and new logging approaches (e.g., resistivity, magnetic resonance and dielectric logs) and core measurements, with generally excellent agreement among independent determinations. Hydrocarbon saturations can be determined accurately using the method in a number of formation types where conventional methods and models for estimating fluid saturation commonly fail, such as freshwater and unknown water salinity in formations under enhanced oil recovery. The case studies included herein demonstrate that a TOC log derived from geochemical spectroscopy logs can be used to obtain reliable estimates of hydrocarbon saturation in a wide range of environmental conditions and formations.

Hydrocarbon saturation from total organic carbon logs derived from inelastic and capture nuclear spectroscopy

A method for analyzing a formation includes entering into a computer a number of detected gamma rays resulting from imparting neutrons into the formation. The detected gamma rays are characterized by energy levels thereof. A number of detected gamma rays in each energy level comprises a measured spectrum. In the computer, a non-Gaussian filter is applied to a reference spectrum to match the measured spectrum in shape. The filtered reference spectrum and measured spectrum are used to determine a fractional volume of at least one component of the formation.

Method for filtering for interpretation of neutron induced gamma ray measurements

A method and system for analyzing constituent elements in bulk media wherein neutrons are emitted into the bulk media to produce inelastic neutron interaction in the bulk media, and a gamma-ray spectrum resulting from the inelastic neutron interaction in the bulk media is detected. A set of standard spectra are used as part of spectral analysis that processes the standard spectra and the derived gamma-ray spectrum to determine a number of yield coefficients for the constituent elements as part of the bulk media. The standard spectra or the spectral analysis is configured to account for at least one environmental condition that affects detected gamma-rays that result from the inelastic neutron interaction in the bulk media.

Neutron-induced gamma-ray spectroscopy that accounts for environmental dependence of inelastic gamma-ray emission spectra

A method for estimating at least one geological constituent may include obtaining a measured energy spectrum for the at least one geological constituent for a first borehole configuration, generating a calculated energy spectrum for the at least one geological constituent for the first borehole configuration, and generating a calculated energy spectrum for the at least one geological constituent for a second borehole configuration different than the first borehole configuration. The method may further include determining a relationship between the calculated energy spectra for the first and second borehole configurations, and generating an estimated energy spectrum for the at least one geological constituent for the second borehole configuration based upon the measured energy spectrum and the relationship between the calculated energy spectra for the first and second borehole configurations.

Geological constituent estimation using calculated spectra relationships

A borehole tool calibration method may include obtaining a measured energy spectrum for at least one geological constituent based upon a first borehole tool, generating a calculated energy spectrum for the at least one geological constituent for the first borehole tool, and generating a calculated energy spectrum for the at least one geological constituent for a second borehole tool different than the first borehole tool. The method may further include determining a relationship between the calculated energy spectra for the first and second borehole tools, and determining a calibration parameter for the second borehole tool based upon the measured energy spectrum and the relationship between the calculated energy spectra for the first and second borehole tools.

Borehole tool calibration method

A method for estimating an aspect of a formation using a nuclear spectroscopy tool includes placing a nuclear spectroscopy tool into a borehole and emitting neutrons such that some of the neutrons generate gamma rays from a formation adjacent the nuclear spectroscopy tool and some of the neutrons generate gamma rays from elements within the nuclear spectroscopy tool. An energy spectrum of gamma rays induced by the emitted neutrons can be detected. The energy spectrum includes a background having a plurality of measured spectral components. A background ratio between at least one spectral component of the background and another measured spectral component can be determined or estimated in accordance with environmental measurements. The detected gamma ray spectra can be analyzed using a combination of standard spectra and subtracting at least one spectral component of the background in accordance with the background ratio.

Environmental corrections in nuclear spectroscopy using variable element ratio

Composition-matched downhole tools and methods for using such tools are provided. One such method includes emitting neutrons using a neutron source in the downhole tool to generate formation gamma rays in a surrounding formation. At the same time, however, some of the neutrons may interact with different parts of the downhole tool to form tool gamma rays. The gamma ray spectra of at least some of the formation gamma rays and the tool gamma rays may be detected using a gamma ray detector. The tool gamma rays from the different parts of the tool may have a substantially similar spectral shape. As such, a processor may be used to analyze the spectra of the tool gamma rays using a single tool background standard, thereby simplifying the analysis and improving the precision of the results.

Composition-matched inelastic or capture spectroscopy tool

The present invention provides systems and methods capable of improving the efficiency and effectiveness of leaching operations. In one embodiment, the present invention may utilize a coiled tubing directional drilling system capable of treating interior portions of the heap/formation. In one embodiment, the present invention may utilize a system and method capable of capturing real time temperature and resistivity data pertaining to pregnant solution characteristics in the heap/formation. In one embodiment, the present invention may utilize one or more wire line deployed X-Ray Fluorescence (XRF) spectrometers capable of quantitatively measuring concentrations of desired metals in the heap/formation during leaching operations. In one embodiment, the present invention utilizes multiple passes of elemental capture spectroscopy logs acquired at regular time intervals to monitor metal concentrations during leaching operations. In one embodiment, the present invention provides one or more subsurface barriers capable of optimizing leaching operations.

Mining systems and methods

A method of analyzing a geologic formation having a borehole therein may include operating at least one tool within the borehole to collect respective borehole dimensions at different depths in the borehole, and collect respective total values for a given element at the different depths in the borehole. Each total value may be based upon both a value for an adjacent portion of the geologic formation and a value for material within the borehole. The method may also include determining each value of the given element in the adjacent portion of the geologic formation based upon the total value and the corresponding borehole dimensions.

Method of determining an element value

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Marshfield, MA, United States of America

James A Grau