EVALUATION OF IRAQI COASTS USING LITTORAL AND MARINE BIVALVE SHELLS

The geochemical analysis of both of Crassostrea cucullata and Chione californensis shells and hydrochemical analyses of water are carried out to study the environmental evaluation in the Iraqi coasts. Shells and water are collected during low tide period (March to August 2011), from seven different stations (Fadakia, Rass AlBishah, Khor Abdullah, Khor Shytianah, Hacham Island, Khor AlZubair and Shatt AlBasrah). The hydrochemical analyses reflect two zones of water salinity, Fadakia and Shatt AlBasrah of brackish water with TDS range (15148 – 18130 ppm), and the other marine coastal sites of saline water with TDS range (34123 – 45220 ppm). XRD of shells of Chione californensis reveals that they have two layers, an inner layer constitutes of aragonite and outer layer constitutes of calcite, while the shells of Crassostrea cucullata have only calcite layer. Water salinity increasing associate with increase of major chemical constituents of oyster shells. Mg/Ca and Sr/Ca values in the coastal line Crassostrea cucullata shells are higher than Fadakia and Shatt AlBasrah shells that may be due to increment of salinity in the coastal line compared with Fadakia and Shatt AlBasrah areas. Zn, Cu, Pb, Sr, and Cr metals in Khor Shytianah Crassostrea cucullata are higher than the other areas may attribute to higher contamination in this area. The chemical constituents of CaO%, MgO, Sr/Ca and Mg/Ca in Khor Shytianah and Hacham Island Chione californensis shells are higher than Khor Abdullan shells, this result may be indicator to higher salinity of sea water in Khor Shytianah and Hacham Island compare with the sea water of Khor Abdullah. Heavy metals (Co, Ni, Rb, Sr, Zn, Ba, Cr, Th, Mo, and Pb) in Khor Shytianah Chione californensis shells were more than the other shells may be due to high range of contamination of sea water by this metal

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

WELL LOGGING AND ELECTROFACIES OF ZUBAIR FORMATION FOR UPPER SANDSTONE MEMBER IN ZUBAIR OIL FIELD, SOUTHERN IRAQ

The Lower Cretaceous Zubair reservoir is a main producing horizon in the Zubair oil Field, southern Iraq. The reservoir consists of a number of isolated vertical major sandstone units. Sedimentary characteristics can be determined using the well log data as one of the most fundamental methods for reservoir characterization in the oil and gas industry. The reading of high gamma-ray response indicates the presence of shale which contains clay minerals, K-feldspar, and organic material that emits natural gamma radiation. The clean sandstones emit less radiation so it has a lower gamma-ray count analysis. Five of electrofacies were identified in the upper sandstone member of Zubair formation in Zubair oil field, in more details H layer divided into three sub-units. Zubair formation delta deposited through sea regression followed by sea progression because shelf facies overlies other delta facies as shown H layer between K and C units both were shale rocks. Porosity and permeability of the upper sandstone member of Zubair Formation were identified in twenty oil-wells. The relationship between the porosity and permeability after correction with data obtained from the core analysis data showed an improvement to the north part of the field precisely in Hammar-Shuaiba domes. On the other hand the grain sizes varied from coarse to medium; medium to fine in Hammar dome while fine to medium fine to very fine with clay influence led to a decrease the porosity and permeability thus reduced oil production