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Abstract
Most oil and gas companies are now in their high activities to perform drilling for exploration and production to meet the world’s demand of oil and gas. More effective and efficient process of drilling exploration is becoming a priority. Formation evaluation of the wellbore to support the success of a drilling operation takes a great deal of attention. Technologies providing Logging While Drilling (LWD) services are expected to minimize time delay and change of formation due to time difference it takes if only conventional wireline logging tools are to be run. Neutron porosity and gamma-ray density as main core of LWD with nuclear sources using AmBe and Cs-137 is generally employed for formation evaluation to get the petrophysics properties for making up key decision regarding to the drilling process. Real time data provided by LWD with radioactive sources give a greater advantages as fresh data during the drilling process is occurring can be obtained. Although real time data does not necessarily have high quality, the sampled data sent uphole to the surface can be quite representative. The memory within the LWD tools offers both real-time and recorded mode data reading, the latter version presents a much higher quality of data, based of the number of sample saved within the memory itself, will usually be attached to the report sent to the client as a final result. The risks associating the radioactive materials applications in LWD must be anticipated by employing complete procedures based on health, safety and environmental concerns as regulated by the nuclear authorities. Uncertainties in the entire drilling process tend to create problems which in an undesired condition can result in a stuck tool with nuclear sources inside. For such matters, precautions must be attempted to avoid nuclear source abandonment in a well. If all efforts fail to retrieve the radioactive materials from the stuck tool and source abandonment becomes the only possible option, procedures based on nuclear regulation must be followed and nuclear authorities must be notified at once.