Abstract A hydrocarbon exploration begins with the geological recognition of probable hydrocarbon accumulation areas, which are confirmed by seismic survey and, to ensure certainty, it is necessary to drill a well. On those exploration wells measurements are made down the hole for the formation evaluation. The evaluation of water, oil and gas saturations are attained by geological and petrophysical characteristics. To obtain such information it is necessary to use a combination of several sources, namely mud logging, coring, well logging and occasionally down the hole tests. Due to the high risks associated with drilling activities, such as safety problems and environmental impacts, it is extremely important to have a very well designed and established drilling program. Therefore, the activities monitoring and control and a good knowledge of what types of formations will be affected, and its principal characteristics, are priorities to take into consideration. Bearing in mind the sources for the formation evaluation, the present work aims to focus on wireline logs and the major challenge that is faced here which is data acquisition and petrophysical evaluation. The case study is a Niger Delta basin (Nigeria).