geophysical neutron loggingtool nnte for measurements of porosity

1、Geophysical neutron logging-tool NNTE for measurementsof porosity and rock matrix Sa - numerical simulationsA. Drabina1), T. Zorski2)1) INSTITUTE OF NUCLEAR PHYSICS Polish Academy of SciencesKrakw, Poland2) AGH UNIVERSITY OF SCIENCE AND TECHNOLOGYFaculty of Geology, Geophysics and Environmental Prot

2、ectionKrakw, PolandWell loggingNNTE logging-toolThe prototype logging-toolmade 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, SaNNTE logging-toolFAR epithermal

3、neutron detector (3He)NEARthermal neutron detector (3He)NEARepithermal neutrondetector (3He)Am-Be neutron sourceNaJ(Tl) natural gamma raydetectorNNTE logging-tool Principles of the measurement interpretationneutron porosity evaluation from the readings of the NEAR epithermal detector, the NEAR therm

4、al detector or from the ratio of the NEAR-to-FAR epithermal detector readingsrock 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 detectorCalibration of the NNTE toolExperimental

5、calibration Basic calibration at the calibration facility in Zielona Gra (Poland), property of the GEOFIZYKA KRAKW 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 fluid4 Sa of the r

6、ock matrixExperimental calibrationCalibration facility in Zielona Gra (Poland), property of the GEOFIZYKA KRAKW Sp. z o. o.General viewRock modelsCalibration of the NNTE toolNumerical calibrationExtension of the calibration onto a wider range of such parameters as the rock matrix Sa and the borehole

7、 diameterNumerical calibrationSteps of numerical calibration:Modelling of the experimental geometryMonte Carlo codes used for numerical calculations: MCNP4C and MCNP5 with ENDF/B-V and ENDF/B-VI neutron librariesModelling of the experimental geometryNNTE toolwaterrock modelconcreteNumerical calibrat

8、ionSteps of numerical calibration:Modelling of the experimental geometryCorrelation between the calculation and experimental results (calculations for the rock models of the calibration facility in Zielona Gra)Monte Carlo codes used for numerical calculations: MCNP4C and MCNP5 with ENDF/B-V and ENDF

9、/B-VI neutron librariesCorrelation between the calculation and experimental resultsNumerical calibrationSteps of numerical calibration:Modelling of the experimental geometryCorrelation between the calculation and experimental results (benchmark calculations for the rock models of the calibration fac

10、ility in Zielona Gra)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 % Monte Carlo codes used for numerical calculations: MCNP4C and

11、MCNP5 with ENDF/B-V and ENDF/B-VI neutron librariesMCNP calculationThe standard calibration curves: Miocene standardNumerical calibrationSteps of numerical calibration:Modelling of the experimental geometryCorrelation between the calculation and experimental results (benchmark calculations for the r

12、ock models of the calibration facility in Zielona Gra)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 det

13、ermining 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 %Monte Carlo codes used for numerical calculations: MCNP4C and MCNP5 with ENDF/B-V and ENDF/B-VI neutron librariesNomogram for the rock matrix Sa evaluation upon the difference between porosity derived from t