A New Pulsed Neutron Sonde for Derivation of Formation Lithology and
Mineralogy

Pemper, Richard; Sommer, Alan; Guo, Pingjun; Jacobi, David; Longo, J.M.; Bliven, Steve; Rodriguez, Eliseo; Mendez, Freddy; Han, Xiaogang

doi:10.2523/102770-ms

Cited by 7 publications

(11 citation statements)

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“…The inability to make a direct measurement of the TOC from the wellbore, and thus the reliance on empirical approaches, is one of the reasons why core analysis is used more readily for determining TOC and estimating the maturation of source rocks Montgomery et al, 2005). The benefit of making an in situ carbon measurement of the formation, using a geochemical logging sonde (Pemper et al, 2006), will be demonstrated with the discussion of the shale gas facies expert system. …”

Section: Lithofacies Effects On Empirical Methods Used For Shale Charmentioning

confidence: 99%

“…The algorithm is a rule-based expert system. The expert system uses geochemical data from a new geochemical logging sonde called the Formation Lithology Explorer (FLEX sm )and Spectra Log II (SLII sm ), which, used in tandem, measures and collects Si, Ca, Fe, S, Ti, Gd, Cl, Mg, Al, and C, and naturally occurring radioactive K, U, and Th data from the formation (Pemper et al, 2006). This chemical data is then used to determine the general lithology, then the specific lithology and finally the mineralogy and the TOC for each interval measured (Jacobi et al, 2007).…”

Section: The Shale-gas Facies Expert Systemmentioning

confidence: 99%

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Integrated Petrophysical Evaluation of Shale Gas Reservoirs

et al. 2008

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Gas shales are economically viable hydrocarbon prospects that have proven to be successful in North America. Unlike conventional hydrocarbon prospects, gas shales serve as the source, seal, and the reservoir rock. Generating commercial production from these unique lithofacies requires stimulation through extensive hydraulic fracturing. The absence of an accurate petrophysical model for these unconventional plays makes the prediction of economic productivity and fracturing success risky.This paper presents an integrated approach to petrophysical evaluation of shale gas reservoirs, specifically, the Barnett Shale from the Fort Worth basin is used as an example. The approach makes use of different formation evaluation data, including density, neutron, acoustic, nuclear magnetic resonance, and geochemical logging data. This combination of logging measurements is used to provide lithology, stratigraphy and mineralogy. It also differentiates source rock intervals, classifies depositional facies by their petrophysical and geomechanical properties, and quantifies total organic carbon. The analysis is also employed to locate optimal completion intervals, zones preferable for horizontal sections, and intervals of possible fracture propagation attenuation. Resistivity image analysis complements the approach with the identification of natural and drilling induced fractures. We compare results from three different wells to show the effectiveness of the method for shale gas characterization.The methodology presented provides a means to understand the geomechanical and petrophysical properties of the Barnett Shale. This knowledge can be used to design a selective completion strategy that has the potential to reduce fracturing expenses and optimize well productivity. Though developed specifically for the Barnett Shale, the underlying ideas are applicable to other thermogenic shale gas plays in North America.

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Section: Lithofacies Effects On Empirical Methods Used For Shale Charmentioning

confidence: 99%

Section: The Shale-gas Facies Expert Systemmentioning

confidence: 99%

Integrated Petrophysical Evaluation of Shale Gas Reservoirs

et al. 2008

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“…(Pemper et al 2006 and. These geochemical instruments investigate the inelastic, capture and natural gamma ray energy spectra to obtain elemental yields and weight fractions of various elements including Al, C, Ca, Fe, Gd, K, Mg, S, Si, Th, Ti and U. Lithology and mineralogy are then determined by an Expert System which uses the elemental weight fractions from the geochemical measurements as input.…”

Section: Shale Lithology and Mineralogy Loggingmentioning

confidence: 99%

State-of-the-art Openhole Shale Gas Logging

2012

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TX 75083-3836, U.S.A., fax 01-972-952-9435. AbstractFaced with increasing field maturity and production decline from conventional gas reservoirs, oil companies are shifting their focus and pursuing new alternatives; one of them being the development of shale and gas plays. To be economically viable, these low-permeability formations require fracture stimulation. Interval selection within shale reservoirs for hydraulic fracturing or horizontal laterals are based on several variables: sufficient organic matter or total organic carbon (TOC) and favorable hydraulic fracturing stimulation. The presence and extent of the natural fracture system can also influence the performance of a shale reservoir; therefore, natural fractures should be characterized within the shale formation not only from wireline or LWD borehole images logs but also from cross-dipole deep shear wave imaging which can illuminate fractures up to 60 ft away that do not intersect the well. To assess these aspects, a mineralogical, structural, and geomechanical characterization of the shale formation should be conducted. The mineralogical characterization and TOC quantifications mainly rely on a pulsed neutron spectroscopy and nuclear magnetic resonance (NMR) logs. The processing of capture and inelastic gamma ray spectra obtained from the pulsed neutron tool quantifies the formation's basic elemental composition, including silicon, calcium, aluminum, iron, sulfur, magnesium, and carbon. Geomechanical characterization is based on acoustic and density log responses. Variation in the reservoir mineralogy and TOC content affect the rock mechanics properties. Stress vs. strain curves can be derived from a micro-mechanical model of the rock which enable correlations between dynamic (obtained from acoustic logs) and static elastic properties (obtained from triaxial compression testing on core samples). Additionally, the azimuthal and transverse shear wave anisotropies are processed from cross-dipole acoustic logs to characterize the vertical and horizontal rock stiffness. This anisotropic characterization of the rock enables the evaluation of the fracture gradient and stress contrast between the target formation and the overlying and underlying formations. The paper focuses on the interaction between mineralogy, organic content and geomechanical analyses in shale gas reservoir evaluation.

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“…This technique was first applied in well logging 33 years ago (Goldman, 1978;Sherman, 1976) and continues to be practiced with contemporary tools (Pemper, et al, 2006). It is important to know how much material is required and to what extent the area near the detector must be shielded to obtain the maximum benefit.…”

Section: Thermal Neutron Shieldmentioning

confidence: 99%

“…In many instances, standard spectral responses for neutron-induced spectroscopy tools have been derived from a series of measurements made in formations whose chemical composition is believed to be well known, tanks of various liquids and, in some instances formations fabricated to emphasize the response of a given element (Hertzog, 1978;Pemper, 2006). Invariably, the process of deriving the standard spectra from laboratory measurements for neutron-induced gammaray spectroscopy tools involves subjective methods to isolate, or strip, elemental responses from those of other elements present in the measurement.…”

Section: Elemental Standard Spectramentioning

confidence: 99%

Field Test Results of a New Neutron-Induced Gamma-Ray Spectroscopy Geochemical Logging Tool

et al. 2009

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A new geochemical logging tool has been developed to provide measurements of elements important to the mineralogical analysis of rock formations and geochemical stratigraphy. The measurement system uses a chemical americium-beryllium neutron source to introduce moderate energy neutrons into the surrounding environment. These neutrons lose energy through scattering reactions and are eventually absorbed by materials in the borehole, the formation and the tool itself. The scattering and absorption reactions cause various elements among the atoms in the surrounding materials to emit gamma rays which have characteristic energies. Emitted gamma ray spectra are detected and recorded using a large bismuth germanate scintillation detector coupled to a high-efficiency photomultiplier and pulse-height analyzer.The recorded 256-channel spectra are analyzed to derive individual contributions, or elemental yields, arising from neutron capture reactions involving hydrogen, silicon, calcium, iron, sulfur, potassium, titanium, gadolinium, magnesium, aluminum and chlorine. The spectral analysis is performed with a constrained, weighted least-squares solver to ensure physically meaningful solutions are obtained for the elemental yields. Additional signals from inelastic neutron reactions with oxygen, carbon, silicon, calcium, and iron are treated separately in the spectral fitting process.The paper discusses several subjects including basic operation of the tool, derivation of characteristic elemental spectral responses, processing of the recorded spectra to obtain elemental yields and the conversion to elemental weight fractions for downstream formation mineralogy evaluations. Example logs from initial field tests are presented to demonstrate tool performance under various borehole conditions and lithologic environments including sandstone and carbonate reservoirs as well as organic shales.

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A New Pulsed Neutron Sonde for Derivation of Formation Lithology and Mineralogy

Cited by 7 publications

References 0 publications

Integrated Petrophysical Evaluation of Shale Gas Reservoirs

Integrated Petrophysical Evaluation of Shale Gas Reservoirs

State-of-the-art Openhole Shale Gas Logging

Field Test Results of a New Neutron-Induced Gamma-Ray Spectroscopy Geochemical Logging Tool

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