Date of Award

5-2017

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Physics

First Advisor

Nacir M. Tit

Second Advisor

Noureddine Amrane

Third Advisor

Attaelmanan Gaffar

Abstract

Well logging technique is used to determine the physical and chemical properties of borehole formation, by using neutron porosity oil well logging tools. The present study simplifies logging tool design in order to reduce the time spent on obtaining well logging. We have combined both carbon/oxygen (C/O) tool and thermal neutron porosity tool. This has been done by adding boron lining on the detectors in C/O tool, where the boron lining acts as a thermal neutron porosity tool while maintaining C/O functions simultaneously. The Monte Carlo N-Particle (MCNP) Transport Code, which was originally developed in Los Alamos National Laboratory, is used to investigate the combined tool response. The combined tool is employed to detect the effect of porosity. The effects of several factors, such as (i) the source-to-detector spacing, (ii) borehole salinity, (iii) capture cross section, (iv) boron lining thickness, (v) formation salinity, (vi) borehole salinity, (vii) temperature, and (viii) the casing on the detection sensitivity are investigated. The results show that the number of detected gamma rays is proportional to the porosity. Furthermore, a sensitivity measure (i.e., the sensitivity ratio) is defined and used to characterize the detectors sensitivity to the porosity. The effects of various factors on the sensitivity are studied and the response function is found to be very sensitive to the porosity especially in the domain of low values of it. The temperature factor was only examined to assess its effect on the nucleus speed. However, the results of our simulations showed that the temperature has very little minor effect. Evidently, the tool is sensitive to the porosity while maintaining all the functions of the C/O tool, which suggests that the boron lining can efficiently serve as a replacement of the porosity tool.

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