The integration of well log analysis with subsurface mapping using 3-D seismic interpretation has been identified to be the key component for hydrocarbon exploration and evaluation of hydrocarbon reservoir potentials. Therefore, this research work was aimed at estimating reserves of hydrocarbon bearing sands in X-Field, Niger Delta with the specific objective of evaluating petrophysical parameters and predicting new prospects. Delineated sand units, A, B, and C are characterized by hydrocarbon saturations ranging from 74.3 % to 91 %. From these horizons three major faults were mapped for the purpose of carrying out 3-D subsurface structural interpretation. These were used in generating the time structure maps using the Petrel interpretational tool. The growth faults and the subtle small throw faults concentrated on the field, and occurring across an anticlinal structure can be significant in the creation of multiple reservoir traps and are therefore the ultimate targets in well positioning. The results show that the trapping mechanisms and the obtained Petrophysical parameters in this field are favourable for hydrocarbon accumulation. Hydrocarbon in-place was calculated from the obtained seismic and petrophysical parameters in order to unveil the potentials of the reservoirs. Hydrocarbon in-place for Sand A was estimated to be 98050473.93STB of oil.