Abstract
F3 Sandston Member represent the main reservoir, in Wafa Field-NC169a, which located in southwest part of the Ghadames Basin. Wafa field was discovered in 1964 by drilled D1-52 well , Sirte Oil company drilled eight wells from 1991 to 1995 , with successfully tested hydrocarbons in the Middle Devonian sandstones (Aouinet Ouenine Formation- F3- member, it is represent the main reservoir in study area, geophysical and petrophysical analyses were carried out, and data from wells and 3D seismic data were used for create 3D geology model. The results shows that both thickness and lithology of the F3-Sand were latterly varies throughout the studied area, and the lithology were grading from sandstone in the northern part to shaly sandstone toward the southern part, which might be related to the sea level fluctuation at the time of deposition. F3-Sand was delineated and precisely mapped by using seismic attribute volume in conjunction with the seismic interpretation stack volume. 3D static model results show that F3-reservoir quality is variable throughout the studied area, the Lithology descripted as coarsening upward of sandstone where, the grain size profile possibly produced by seaward progradation representing a Barrier Island of sandstone that was possibly appeared in the manner of a barrier island which, was inferred as discontinuous large sandstone that absent towards the southwest of the study area, where the porosity reached up to 12% and permeability up to several hundred md, net pay thickness ranges from one foot to 101 feet, and average water saturation is 16 %. Our interpretations that the lithology mainly of sandstone with minor shale. This observation probably effected the Gas/Water contact of the F3 reservoir, which were not defined due to the facies changes.