Structural and Stratigraphic 3D Seismic Study of NahrUmr and Zubair Formations in Kifl oil field _ center of Iraq

This research is a reflection seismic study (structural and stratigraphic) of a 268.7 km2 area located in the central Iraq within the Karbala province (Kifl area). The study area was interpreted by using 3-D seismic data from Oil Exploration Company. Synthetic traces are prepared by using available data of the four wells (Kf-1), (Kf-2), (Kf-3) and (Kf-4), in order to define and piking the reflector on seismic section, These reflector are: (NahrUmr, Shuaiba, Zubair and Ratawi Formations) which are deposited during the lower cretaceous age. Faults were picked using instantaneous phase attribute of seismic section across 3D seismic volume of the studied reflectors. The study area affected by a major fault and minor normal faults, Two faults system has been observed in the study area; the major normal fault of (NW-SE) trending and minor normal faults of (NE-SW) trending, with a small displacement are influenced the studied reflectors. The time slices were studied across 3D seismic volume of the studied reflector, they proved the presence the structural anticline at lower cretaceous reflection level. Time, velocity and depth maps are prepared depending on the structural interpretation of the picked reflectors, the structural interpretation of these reflectors shows a structural anticline extending in NW-SE trend and plunges to the south east, and the general dip towards the east. Using seismic attribute techniques including (instantaneous frequency, RMS amplitude maps and reflection strength section), these attributes showed decreasing in frequency, amplitude and strength values. These reflect rocks of low velocity and indicate the presence of hydrocarbon accumulation area. The study of seismic facies of the picked reflectors distinction parallel seismic configuration. The results shows the Zubair and NahrUmrfacies are clastic depositional system deposited on delta platform, Zubair represents delta platform facies consisting of shallow- water, high-energy marine (delta sandstone, channel-fill sandstones).Pinch out are picked and interpreted by using cosine instantaneous phase attributes, these phenomena can be regarded as Pinch out stratigraphical traps. It's the main factor to explain the difference in thickness of the oil column between well Kf-4 and well Kf-1. Mound and Flat spot phenomenon has been observed within Zubair reflector by using the seismic composite attributes (Band bass filter on an instantaneousphase attributes, as mound stratigraphic traps and flat spot which is represent of Direct Hydrocarbon Indicators (DHI) that refers to the presence of hydrocarbons. Where the use of this techniques has helped to identify the (DHI) for hydrocarbon accumulation and have not been previously identified.Finally 3D seismic model for Kifl field show the extension of structural anticline and its plunge and the distribution of hydrocarbons accumulations in the Kifl field.