Geochemical Investigation and Mineral Matrix Effect on Probable Source Rock's Potentiality, Darquain Oilfield in the Abadan Plain
Subject Areas :بهرام علیزاده 1 , نسیم آزاد بخت 2 , سید حسین حسینی 3 , الهام ترهنده 4
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Keywords: Matrix Effect Source Rock Rock-Eval Analysis Transformation Ratio Darquain Oilfield. ,
Abstract :
Darquain anticline is located at 5 km northeast of city of Abadan. The axis trend of this oilfield is north through south. In this study, Kazhdumi, Gadvan, Garu and Sargelu Formations in Darquain Oilfield, in Abadan Plain, were analyzed by Rock-Eval 6 instrument. S2 vs. TOC plot revealed that kerogen type in this oilfield predominantly is of mixed of types II & III. Significant S2 Adsorption by matrix of Kazhdumi Formation in well numbers 1 and 2 (5.33-14.06 mg HC/gr rock) and Gadvan Formation in well numbers 2 and 3 (3.1-3.2 mg HC/gr rock) is due to low thermal maturity as well as low Gas-Oil Ratio factor. In Garu and Sargelu Formations amounts of adsorbed S2 by matrix are respectedly 0.82 and 0.84 mg HC/gr rock, that represent a medium thermal maturation and medium to high Gas-Oil Ratio factor. Quantity of TOClive in the Kazhdumi, Gadvan, Garu and Sargelu formations estimated to be in the range of 0.6-1.6, 0.2-1.9, 1.53 and 8.38 by weight percent respectively. This represents potential for the studied formations fair to excellent petroleum generation. Also the studied wells were modeled, by which the Ro of the source rocks were calculated according to their depth. Also transformation ratio of organic matter and the initial TOC is estimated. Transformation Ratio of Kerogen in studied formations ranges from 0.12 to 0.66. This is in accordance with estimated Easy Ro by PBM software (0.5-0.8). It can then be concluded that Kazhdumi Formation is in early oil window and already started to generate hydrocarbon. This is also verified by Tmax data. The Gas-Oil Ratio of Kazhdumi and Gadvan Formations is 0-1 indicating variable hydrocarbon generation. Also this factor for Garu and Sargelu is 0.58-1 indicates that they have more gas generation potential rather than oil generation potential. The inferences drawn from It can be inferenced from iso TOCoil and TOCgas maps led to the conclution that, in west and southwestern parts of the basin, the depth during deposition of mentioned formations was more in compare to other parts of Darquain.