Formation density calculation method based on pulse neutron logging

A technology of pulsed neutron and formation density, applied in the field of well logging, can solve the problems of difficulty in keeping the output constant, affecting the calculation of density, and the influence of calculation accuracy, so as to achieve the effect of eliminating errors, accurate results, and reducing interference of measurement results.

Active Publication Date: 2019-11-19
BC P INC CHINA NAT PETROLEUM CORP +1
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Problems solved by technology

Therefore, the introduction of the capture gamma count has a certain negative impact on the calculation accuracy
[0009] 2) It is difficult to keep the output of pulsed neutron sources constant. If neutron counting is directly introduced into the algorithm, this fluctuation will have a great impact on neutron counting, which in turn will affect the calculation of density

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  • Formation density calculation method based on pulse neutron logging
  • Formation density calculation method based on pulse neutron logging
  • Formation density calculation method based on pulse neutron logging

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Embodiment Construction

[0043] The present invention is described in further detail below in conjunction with accompanying drawing:

[0044] Such as figure 1 As shown, the method for calculating formation density based on pulsed neutron logging of the present invention is calculated based on the data obtained by pulsed neutron logging tools, and the present embodiment uses figure 1 The described logging tool with a controllable neutron source will be described in detail as an example.

[0045] figure 1 The pulse neutron logging tool shown includes a neutron source, a shielding body 2, a thermal neutron detector 3, an epithermal neutron detector 4, and a near-gamma detector 5 arranged in sequence from bottom to top and far gamma detector6. In this embodiment, the shielding body 2 is a cylindrical tungsten-nickel alloy with a length of not less than 12 cm. The thermal neutron detectors 3 all use He-3 tube counters. The manufactured cadmium sheet is wrapped on the outside of the He-3 tube counter. B...

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Abstract

The invention discloses a formation density calculation method based on pulse neutron logging. The formation density calculation method based on pulse neutron logging comprises the following steps that first, the number of epithermal neutrons, the number of thermal neutrons, a near-source distance inelastic scattering gamma quantity and a distant-source distance inelastic scattering gamma quantityare obtained by measurement through a pulse neutron logging method; and second, the formation density is calculated according to data obtained in the first step, wherein Rine is the distant-source distance inelastic scattering gamma quantity, Nepi is the near-source distance inelastic scattering gamma quantity, Nepi is the number of epithermal neutrons, Nth is the number of thermal neutrons, Rhois the calculated formation density, and a, b and c are calibration factors. By adoption of the formation density calculation method based on pulse neutron logging, the precision of a formation density result calculated based on pulse neutron logging is improved.

Description

technical field [0001] The invention belongs to the technical field of logging, and relates to a method for calculating formation density based on pulse neutron logging. Background technique [0002] Density logging is a very important part of logging, and its measured value can be combined with other logging data to obtain formation porosity, lithology and other information. Traditional density logging uses Cs-137 as the gamma source, and the instrument usually adopts a dual-source design, that is, two detectors near and far are set to record the Compton scattering of gamma rays in the formation, so as to obtain formation information. [0003] With the development of pulsed neutron logging, major oil logging companies are studying the corresponding density logging methods. However, unlike traditional gamma-gamma logging, pulsed neutron logging uses secondary gamma sources, which are distributed in a certain space, and their intensity and spatial distribution are affected b...

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Application Information

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IPC IPC(8): E21B47/11E21B47/00E21B49/00G06Q50/02
CPCE21B47/00E21B49/00G06Q50/02
Inventor 岳爱忠陈涛王树声何彪何绪新罗翔樊云峰伍莹
Owner BC P INC CHINA NAT PETROLEUM CORP
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