Geochemistry and Sequence Stratigraphy of Pabdeh Formation In Mansuri Oilfield

Authors

1 Associate Professor, Department of Geology, Petroleum Geology and Geochemistry Research Centre (PGGRC), Shahid Chamran University.

2 Master science, Department of Geology, Shahid Chamran University.

3 Director of Exploration Department, National Iranian Oil Company.

4 Geology Section, National Iranian South Oil Company.

Abstract

In this study the hydrocarbon potential Evaluation of Pabdeh Formation as probable source rock using sequence stratigraphy framework in Mansuri oilfield is the main goal. To achieve this, sequence stratigraphy in Pabdeh Formation was performed using GR log of studied wells fed in Cyclolog 3.2 software. Also contemporaneous sedimentary units in this formation have been identified. For sequence stratigraphy accomplishment and evaluating of hydrocarbon potential Pabdeh Formation, geochemical data were used. This study shows three depositional system tracts of class two in Pabdeh Formation. In Late Paleocene to Middle Eocene the first regressive system tract has been deposited. The second system tract has been formed more or less in Late Eocene as a transgressive one. Finally the top section of this formation comprises a regressive system tract with Early Oligocene age. This investigation showed that Pabdeh Formation is heterogeneous in view of hydrocarbon potential. So this formation divided into three divisions. Sea level and hydrocarbon potential changes are showing a good relation. In middle zone (Late Eocene), while seal level rises, TOC values increase to about 5%. In this zone of Pabdeh Formation organic matter is mainly Type II Kerogen and has potential to generate oil. On the other hand the lower and upper zones being deposited in low sea level situation have TOC values as low as 0.5- 2% and Kerogen is Type III. These zones have gas generation potential. Identification of sequence stratigraphy boundaries helps interpreting the distribution of Pabdeh Formation even in the wells that have no geochemical data as; 28, 20, 15, 25, 14, 16, 21, 27, 31 wells. Finally it was revealed that the middle portion of Pabdeh Formation has higher hydrocarbon potential in the whole Mansuri oilfield. 
 

Keywords


امینی.ع.، 1388، مبانی چینه نگاری سکانسی، انتشارات دانشگاه تهران.
سراج.م.، 1384، تحلیل ساختاری مقدماتی میادین نفتی مناطق نفتخیز جنوب (محدوده فروافتادگی دزفول شمالی)، بایگانی شرکت ملی مناطق نفتخیز جنوب، گزارش شماره پ-5613.
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