Neutron Reference Measurements to Petroleum Industry

Transcrição

1 LABORATÓRIO NACIONAL DE METROLOGIA DAS RADIAÇÕES IONIZANTES IRD- Instituto de Radioproteção e Dosimetria Neutron Reference Measurements to Petroleum Industry Karla C. de Souza Patrão, Evaldo S. da Fonseca, Walsan W. Pereira, Mauricio C. de Almeida and Luciane de R. Souza karla@ird.gov.br 1

2 Neutron Reference Measurements to Petroleum Industry In the evaluation of the reservatories of the field, porosity is one of the key measurements for quantify oil and gas reserves. The measurement of porosity by neutrons, employs a neutron source to measure the rate of hydrogen in a reservoir, which is directly related to its porosity.. 2

3 Neutron survey meter Instrument used to measure the quantity ambient dose equivalent in areas with individuals occupationally exposed to neutron fields. 3

4 Calibration It used a neutron source 241Am-Be (, n) standardized by a primary standard system Manganese Sulphate Bath at LN (according ISO 8529). Lab. low Scatering (LN) 4

5 Calibrations performed at LN

6 Neutron survey meters registered in LN 66% Oil & Gas others 6

7 What is the best frequency for the neutron area monitors calibration? 7

8 Currently in Brasil CNEN NN 3.01 Diretrizes Básicas de Radioproteção (2005) Calibration periodicaly CNEN NN 6.04 Funcionamento de Serviços de Radiografia Industrial (1989) annual calibration for gamma area monitors 8

9 Currently in Brasil NBR ISO/IEC General requirements for the competence of testing and calibration laboratories (2005) the laboratory customers should define the frequency of calibration. 9

10 Goal Check the calibration interval adopted for the neutron area monitors used in oil and gas industry. 10

11 Methodology Data on the calibration of area monitors from the oil and gas industries in the period 2006 to Data analysis using the method Schumacher 11

12 Number of Area Monitors Used in Oil and Gas Industry in Brazil ( ) Registered calibrations calibrations 32 2 calibrations 34 1 calibration 81

13 Percentage of bad monitor sent to calibration 20 37% 12% % 14% 7%

14 Schumacher Method Based on the last three calibrations compared to the current calibration to determine if the calibration range used can be maintained or should be reduced or increased.

15 Results CALIBRATED THREE TIMES MAXIMUM REDUCTION 58% REDUCTION 10,5% REMAINS 26,3 % INCREASES 5,3 % 15

16 Conclusion The results indicate reduction of the period performed by users of the neutron area monitors. The study should be thorough, considering other factors such as the origin of the instruments. The laboratory must improve its relationship with its customers. 16

17 Development of a portable system to test for neutron area monitors Goal Designing and Building a portable measurement system for verification of the operating conditions of area monitors for neutrons. 17

18 Features This device must be used by the users of area monitors. Allows a study of the stability of the monitors which helps in defining the range of instruments calibration.

19 Methodology LABORATÓRIO NACIONAL DE METROLOGIA DAS RADIAÇÕES IONIZANTES first step Definition of geometry and materials of the system; Simulation with the MCNP5; Experimental measurements to validate the simulation. second step Construction and Approval System.

20 Initial Conditions LABORATÓRIO NACIONAL DE METROLOGIA DAS RADIAÇÕES IONIZANTES Material: high density polyethylene. The dimensions were defined considering its portability and its use with the display area for neutrons Ludlum 12-4, to be the most used in the brazilian market. The neutron source used in the system is 241 Am-Be (, n), with 14.6 GBq. 20

21 Initial conditions LABORATÓRIO NACIONAL DE METROLOGIA DAS RADIAÇÕES IONIZANTES Rates of ambient dose equivalent: Were determined for each system over the rates of 50 μsv/h and 500 μsv/h. These points correspond to 50% of full scale, considering the two scales of interest in radiation protection (0-100 μsv/h and μsv/h). 21

22 First stage Simulation Geometry

23 Second step Construction and approval of portable The portable system was built by mechanical engineering sector of the IRD. They performed several measurements with different models of area monitors for neutrons, seeking the approval of the system. 24

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26 Second stage LABORATÓRIO NACIONAL DE METROLOGIA DAS RADIAÇÕES IONIZANTES

27 Results LABORATÓRIO NACIONAL DE METROLOGIA DAS RADIAÇÕES IONIZANTES Ludlum 12-4 Serial Number 12 cm H*(10) ( Sv/h) 2 cm H*(10) ( Sv/h) ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± 12.9 Média: 52.1 ± ± 37.7

28 Results Survey Meter Distance 12.0 cm from source H*(10) (msv/h) Distance 2.0 cm from source H*(10) (msv/h) Prescila Ludlum ± ± Prescila Ludlum ± ± Thermo Eberline FHT ± ± Thermo Eberline FHT ± ± 9.2 Eberline APS ± ± 24.1 Eberline E ± ± 11.3

29 Conclusion The system proved to be a suitable tool for checking the operating conditions of the area monitors, providing performance monitoring tools between these calibrations. This device should also be used to assist in determining the range of calibration of instruments, taking into account the intensity of use and the desired accuracy. The developed system is easy and inexpensive construction and can be purchased by users of area monitors for neutrons.