Madbi-Biyadh/Qishn (!) petroleum system in the onshore Masila Basin of the Eastern Yemen

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• 作者：Mohammed Hail Hakimi^a ; ^b ; ^{ibnalhakimi@yahoo.com} ; Wan Hasiah Abdullah^a ; Mohamed Ragab Shalaby^c
• 关键词：Petroleum system ; Source rock ; Basin modeling ; Masila Basin ; Yemen
• 刊名：Marine and Petroleum Geology
• 出版年：2012
• 期刊代码：37_02648172
• 类别：pw
• 出版时间：August, 2012
• 卷：35
• 期：1
• 页码：116-127
• 文件大小：3722 K

摘要

The Masila Basin is one several onshore Mesozoic basins in Yemen. However, a full petroleum system, with its essential elements and processes, has not been assigned yet. In this study, one petroleum system in the Masila Basin was identified and named Madbi-Biyadh/Qishn (!) petroleum system. An extensive overview study showed that the main source and reservoir rocks in the Masila Basin are the Upper Jurassic Madbi shales and Lower Cretaceous Biyadh/Qishn sandstones, respectively; hence it appears that the most important effective petroleum system of the Masila Basin becomes the Madbi-Biyadh/Qishn (!) petroleum system. Organic-rich shales of the upper part of the Madbi Formation, deposited during the upper Jurassic, constitute the main source rock of the crude oils in the basin. These shales contain high total organic carbon content (TOC >2.0聽wt.%) and predominantly algal Type II with minor Type I kerogen. The Madbi shales are mature and, at the present time, are within the oil window with determined vitrinite reflectance values in the range of 0.53-0.91 Ro%. The Biyadh/Qishn sandstones are the main reservoir and were deposited in braided river channels, shoreface and shallow-marine environments, and consist of fine to coarse-grained, moderate to well sorted grains. Seal rocks are Cretaceous limestone and shales of the Qishn and Harshiyat Formations and Tertiary shales. Overburden rocks include the Cretaceous rocks and the Tertiary sediments deposited simultaneously with development of the traps during Oligocene-Middle Miocene time. Burial/thermal histories models demonstrate that hydrocarbon generation from the Madbi shales commenced in the Late Cretaceous and maximum rates of hydrocarbon expulsion occurred during the Early Tertiary. Geochemical oil-source rock correlation studies showed that regional distribution of the oil fields almost overlap with the previously constructed pod of active Madbi shales indicating that oil migrated from the active Madbi source rock to trapping sites via vertical migration pathways through faults as a result of Tertiary rifting during Oligocene-Middle Miocene time.