Tectonics of Jacobabad‒Khairpur High and Its Impact on Petroleum Fields of the Region, Southern Indus Basin, Pakistan: A Case Study
NNW‒SSE-trending Jacobabad‒Khairpur High (JKH) is a part of Sukkur rift zone in the Lower Indus Basin (Pakistan), and it evolved during Jurassic rifting when Indian Plate separated from Australian‒Antarctic Plate. At that time, fractures developed due to the upwelling of magma which resulted in the...
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| Published in: | Geotectonics Vol. 57; no. 3; pp. 346 - 358 |
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| Main Authors: | , , , , , , , |
| Format: | Journal Article |
| Language: | English |
| Published: |
Moscow
Pleiades Publishing
01-06-2023
Springer Nature B.V |
| Subjects: | |
| Online Access: | Get full text |
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| Summary: | NNW‒SSE-trending Jacobabad‒Khairpur High (JKH) is a part of Sukkur rift zone in the Lower Indus Basin (Pakistan), and it evolved during Jurassic rifting when Indian Plate separated from Australian‒Antarctic Plate. At that time, fractures developed due to the upwelling of magma which resulted in the development of detached blocks which dropped relatively to the other ones. Jacobabad‒Khairpur High represents one of those blocks which maintained its original position. This study works out the causes of failure of exploration wells drilled at and in the vicinity of Jacobabad‒Khairpur High (JKH), and comprehends the tectonics, structural trends, and subsurface geology of the region to delineate role of JKH in distribution of source, reservoir and seal rocks for future prospects. This work is based on construction of stratigraphic cross-sections along and across Jacobabad‒Khairpur High, isopach and depth maps to delineate paleo- and present shapes of JKH and its impacts on the petroleum system of the region. This study indicates that Jacobabad‒Khairpur High developed in three stages from Jurassic to Early Eocene. Initially, JKH developed after the deposition of Middle Jurassic Chiltan Limestone and remained uplifted. This interpretation is supported by the absence of main source rocks ‒ Cretaceous Sembar Formation, of the basin on the northern and southern crest of the Jacobabad‒Khairpur High and absence of entire Cretaceous succession on the northern part of the JKH indicating subaerial conditions. Moreover, Cretaceous reservoir rocks—Lower Goru Sand, is also absent in the northern portion of the Jacobabad‒Khairpur High as Paleocene Dunghan Formation is directly overlying the Chiltan Limestone. Furthermore, due to absence of marl and shale of Upper Cretaceous Goru Formation (seal rocks) proper seals are absent in the area. It resulted in the dry holes like Kandra-01, Khairpur-01, Khairpur-02 and Jhatpat-01. However, rocks of petroleum system were deposited all around Jacobabad‒Khairpur High. At the same time, presence of Cretaceous source (Sembar Formation), reservoir (Lower Goru Sand) and seal (Goru Shale) rocks around Jacobabad‒Khairpur High resulted in many discoveries of oil and gas in the Middle and Lower Indus Basin. The Jacobabad‒Khairpur High submerged again during Paleocene when the Indian Plate passed over Kerguelen Hot Spot and became a part of the carbonate shelf to deposit Dunghan Formation over Chiltan Limestone in the northern part of the high. Finally, the Jacobabad‒Khairpur High again reactivated and uplifted to the present position, after the deposition of early Eocene Ghazij Formation when Indian Plate collided with Eurasian Plate. |
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| ISSN: | 0016-8521 1556-1976 |
| DOI: | 10.1134/S001685212303007X |