WIRELINE LOGGING RESPONSE AND TRUE CORE ANALYSIS OF THE UPPER SHALE MEMBER OF ZUBAIR FORMATION, RUMAILA OILFIELD, SOUTHERN IRAQ
Sedimentary rocks can be defined from others not only by their lithology, structures, fossil content, geometry and sedimentary but furthermore by their general response to the wireline logs. This study involves the determination of the properties of Upper Shale Member of Zubair Formation (Lower Cretaceous) in Rumaila oilfield by using several log interpretation software through wireline logging response of lithology. Many wells were chosen in Rumaila oilfield to know the lithology of Upper Shale Member, in addition to calculating permeability for Rumaila oilfield by using eight wells through Rumaila cross-section. The Gamma Ray log responses of clean sand range between 30 – 40 API, while it decreased in the case of silt and clay cemented sand grain. Sandstones are dominated in the south of Rumaila, this could increase the porosity and permeability of the rocks. While clay and shale are dominated in the north of Rumaila. Log responses don’t give a true representation for formation lithology if comparison with true core lithology by using grain size analysis.