Title: Geophysical neutron logging-tool NNTE for measurements of porosity and rock matrix Sa - numerical simulations A. Drabina1), T. Zorski2) 1) INSTITUTE OF NUCLEAR PHYSICS Polish Academy of Sciences Krak
1Geophysical neutron logging-tool NNTE for
measurementsof porosity and rock matrix Sa -
numerical simulationsA. Drabina1), T.
Zorski2)1) INSTITUTE OF NUCLEAR PHYSICS
Polish Academy of SciencesKraków, Poland2)
AGH UNIVERSITY OF SCIENCE AND TECHNOLOGYFaculty
of Geology, Geophysics and Environmental
ProtectionKraków, Poland
2Well logging
3NNTE logging-tool
- The prototype logging-tool
- made by Polish geophysical prospecting company
- is designed to measure in the borehole
- 2 parameters of a geological formation
- - neutron porosity and
- - thermal neutron absorption cross-section, Sa
4NNTE logging-tool
5NNTE logging-tool Principles of the measurement
interpretation
- neutron porosity evaluation from the readings
of the NEAR epithermal detector, the NEAR thermal
detector or from the ratio of the NEAR-to-FAR
epithermal detector readings - rock matrix Sa evaluation from the difference
between the neutron porosity obtained from the
NEAR thermal detector and the neutron porosity
obtained from the NEAR epithermal detector
6Calibration of the NNTE tool
- Experimental calibration
- Basic calibration at the calibration facility in
Zielona Góra (Poland), property of the GEOFIZYKA
KRAKÓW Sp. z o.o. - 21 rock models which represent 3 lithologies
(limestone, sandstone and dolomite) - 2 borehole diameters (220 mm, 145 mm)
- 3 NaCl concentrations in the borehole fluid
- 4 Sa of the rock matrix
7Experimental calibration
Calibration facility in Zielona Góra (Poland),
property of the GEOFIZYKA KRAKÓW Sp. z o. o.
Rock models
General view
8Calibration of the NNTE tool
- Numerical calibration
- Extension of the calibration onto a wider range
of such parameters as - the rock matrix Sa and
- the borehole diameter
9Numerical calibration
Monte Carlo codes used for numerical
calculations MCNP4C and MCNP5 with ENDF/B-V and
ENDF/B-VI neutron libraries
- Steps of numerical calibration
- Modelling of the experimental geometry
10Modelling of the experimental geometry
11Numerical calibration
Monte Carlo codes used for numerical
calculations MCNP4C and MCNP5 with ENDF/B-V and
ENDF/B-VI neutron libraries
- Steps of numerical calibration
- Modelling of the experimental geometry
- Correlation between the calculation and
experimental results (calculations for the rock
models of the calibration facility in Zielona
Góra)
12Correlation between the calculation and
experimental results
13Numerical calibration
Monte Carlo codes used for numerical
calculations MCNP4C and MCNP5 with ENDF/B-V and
ENDF/B-VI neutron libraries
- Steps of numerical calibration
- Modelling of the experimental geometry
- Correlation between the calculation and
experimental results (benchmark calculations for
the rock models of the calibration facility in
Zielona Góra) - Creation of the standard calibration curves for a
given standard lithology (here Miocene standard)
- calculations for theoretical rock models
representing the lithology standard with porosity
varying from 0 to 100
14MCNP calculationThe standard calibration curves
Miocene standard
15Numerical calibration
Monte Carlo codes used for numerical
calculations MCNP4C and MCNP5 with ENDF/B-V and
ENDF/B-VI neutron libraries
- Steps of numerical calibration
- Modelling of the experimental geometry
- Correlation between the calculation and
experimental results (benchmark calculations for
the rock models of the calibration facility in
Zielona Góra) - Creation of the standard calibration curves for a
given standard lithology (here Miocene standard)
- calculations for theoretical rock models
representing the lithology standard with porosity
varying from 0 to 100 - Creation of nomograms for determining the rock
matrix Sa - calculations for theoretical rock
models representing the lithology standard with
the varying rock matrix Sa and porosity from 0 to
100
16Nomogram for the rock matrix Sa evaluation upon
the difference between porosity derived from the
NEAR thermal and epithermal detectors
17Prospects for the future
- Depth of investigation of the NNTE logging-tool
- observation of behavior of the detector signal
while increasing diameter of the rock model
18(No Transcript)
19The end