Precision Energy Services, Inc.

Computalog USA Inc.

Other

Donald E Tiller

Robert D Wilson

Richard C Odom

Apparatus and methods for measuring radiation in a borehole environment using a YAlO:Ce (YAP) scintillation crystal. Borehole instruments are disclosed which employ a gamma ray detector comprising a YAP scintillator coupled to a light sensing means such as a photomultiplier tube. One instrument embodiment combines a YAP scintillation detector and a source of pulsed neutrons. Borehole environs are irradiated with neutrons, and induced gamma radiation is measured using a YAP scintillation detector. Response of the detector is used to determine characteristics of the borehole environs. Mechanical and physical properties of YAP are utilized to obtain improved measurements. The relatively short light decay constant of YAP minimized pulse pile-up in the detector when measurements require that the detector be operated during a neutron pulse.

Method and apparatus for measuring radiation in a borehole

A borehole logging system for determining bulk density, porosity and formation gas/liquid fluid saturation of formation penetrated by a borehole. Measures of fast neutron radiation and inelastic scatter gamma radiation, induced by a pulsed neutron source, are combined with an iterative numerical solution of a two-group diffusion model to obtain the formation parameters of interest. Double-valued ambiguities in prior art measurements are removed by using the iterative solution of the inverted two-group diffusion model. The system requires two gamma ray detectors at different axial spacings from the source, and a single neutron detector axially spaced between the two gamma ray detectors. The system can be embodied as a wireline system or as a logging-while-drilling system.

Apparatus and method for determining density, porosity and fluid saturation of formations penetrated by a borehole

An improved fast neutron detector fabricated with alternating layers of hydrogenous, optically transparent, non scintillating material and scintillating material. Fast neutrons interact with the hydrogenous material generating recoil protons. The recoil protons enter the scintillating material resulting in scintillations. The detector is optically coupled to a photomultiplier tube which generates electrical pulses proportional in amplitude to the intensity of the scintillations, and therefore are an indication of the energy of the fast neutrons impinging upon the detector. Alternating layers of materials are dimensioned to optimize total efficiency of the detector, or to optimize the spectroscopy efficiency of the detector. The scintillating material is preferably ZnS, and the hydrogenous material is preferably plastic. The detector is ideally suited for well logging applications and fast neutron monitor applications.

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Fort Worth, TX, United States of America

Donald E Tiller