Organic-matter-rich Zones Determination in the Aghajari and Pazanan Oilfields by Using Geochemical and Petrophysical Data

Document Type : Research Paper

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Abstract

Based on the geochemical and petrophysical data, an exact depth of possible source rocks of Pabdeh and Kazhdumi formations in the Aghajari and Pazanan oilfields was separated and the formation spread (thickness) and organic material variations for each well was examined. Pabdeh formation can be divided into three units based on TOC amount, namely the upper and the lower units A and C with less than 1% TOC and the middle unit with higher than 1% TOC (unit). A and C units are mainly lime stony and the shale is more spread in B unit. Zone B is the main source rock zone and A and C are identified as sub-zones. Observing the rich unit (B) in Pabdeh formation and according to its quality having more than 2% organic matter, it is identified as a rich zone. The thickness of B is more than the two other units in all the wells. The average of organic matter in Pabdeh formation is 1 to 3 percent. Some of these wells are located on Paleo height, in which geothermal gradient increases the transition of organic matter to oil and decreases an average amount of organic matter. This phenomenon is impressed by adjacent fault zones or Paleo height boundaries. Pz#23 has high organic matte richness due to the location out of the Paleo height limit, but in Pz#17, due to location in the high thermal portion of Paleo height, high thermal conditions have caused a decrease in organic matter content immediately and low organic matter remained; but, it still has rich zones. For an accurate and comprehensive examination of organic matter enrichment in Pabdeh and Kazhdumi formations in these wells, an exact position of sampling and amount of organic matter are characterized with software and their adaptation rate with enriched zone is determined by using Rock Eval pyrolysis.

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References

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Journal of Petroleum Research
Volume 24, Issue 80 - Serial Number 80
March and April 2015
Pages 63-74

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