Hydrocarbon probability of Middle Ordovician Hawaz Formation, Murzuq Basin, Southwestern Libya

摘要

The Middle Ordovician Hawaz clastic reservoir on the Murzuq Basin is a new exploration play of great importance in the NC186 concession. H-field is one of the new discoveries in this concession. The main target of this investigation is to detect and evaluate the hydrocarbon play of Hawaz Formation in H-field. Petrophysical characteristics and seismic interpretations of the Hawaz Formation in H oil field, Concession NC186 of Murzuq basin have been evaluated through the analysis of well-logging records of ten exploratory wells and 3D seismic sections distributed in H oil field. These data have been analyzed and interpreted through utilizing some analytical cross-plots. The lithosaturation analysis indicates that the Hawaz Formation is mainly oil-bearing with some water-bearing sand levels with thickness ranging from 550 ft in the northwestern part of this field and increasing to more than 640 ft. The average cutoff of H-field illustrated that the water saturation is 45 %, the porosity is 12 %, and the reservoir thickness is 190 m. This surface was picked at 840 ms (TWT) in the northwestern part of the study area and increased to 1060 ms (TWT) in the southeastern part of the study area. The Hawaz surface was located at depths ranges from 4360 ft in the H1-NC186 well in the northwestern part and increased to 4611 ft in the H3-NC186 well in the southeastern part of the H-field. The analytical formation evaluation reveals that the lithological facies consists mainly of sandstone and little shale. This sandstone is coarsening upward. The lateral distribution of the petrophysical parameters portrays that the Hawaz Formation is a good reservoir rock where H4 and H5 horizons are the main productive zones.