An overview of Neoproterozoic reservoirs in Pakistan

Abstract

Over time, Neoproterozoic rocks in Pakistan have intermittently attracted the interest of oil and gas exploration companies. However, despite these rocks having been penetrated by nearly 40 wells and being exposed in various parts of Pakistan, no serious efforts have yet been made to investigate their reservoir potential. Neoproterozoic rocks are exposed along the outer periphery of the Salt Range and Nagar Parker in Pakistan and in Rajasthan (India). Surface and subsurface data suggest a good correlation between outcrops in Rajasthan and wells in the Punjab Platform. However, the Neoproterozoic of the Punjab Platform seems to be somewhat different from that in Potwar, suggesting the existence of a kind of barrier or palaeo-high, separating the two basins. Proterozoic stromatolite found in a number of Himalayan sequences seems to be correlatable with similar facies encountered in other parts of the world, such as in the Abalog-1 and Yarba-1 wells in the Toudeni Basin in Mauritania and Mali, respectively. Glacial Pokhran boulder beds (representing snowball Earth) in the Hazara Basin, and reportedly in Pokran and Lawan across the border in India, also correlate with similar Neoproterozoic facies found in other parts of the world. Neoproterozoic offers a complete petroleum system. Regional data demand that the Neoproterozoic reservoir potential be re-evaluated, and a proper understanding of basinal configuration may play a vital role in future exploration success in this region.

Evaluation of Neoproterozoic Source Rock Potential in SE Pakistan and Adjacent Bikaner- Nagaur Basin India Based on Integrated Geochemical, Geological, and Geophysical Data

“…The movement of the tectonic plates is responsible for the Precambrian rocks' deformation and causes several subsided and uplifted blocks. This tectonic subsidence, resulting in the BK-N Basin development, which can be tied in with Kirana-Tosham Basin 9 . The local Highs that existed in the study area are inferred from Early Infracambrian times that frame the basin con guration more complicated.…”

“…Similar geochemistry of heavy oil has been reported from carbonate-evaporite facies of the Huqf Group (Infracambrian), located at more than 2000 km to the SW, along the eastern ank of southern Oman 2,6,10,12 . At the scale of the regional geology, these Infracambrian rocks were once within or near the western edge of Gondwanaland that was marked by a subsiding rift system, present-day outcropping to the west of the Aravalli ranges in the BK-N Basin and extending toward the north and northwest Pakistan 1,2,9 . The exposures of the Aravalli Range in the northwestern Indian Shield allowed the development of sedimentary basins along its anks (Fig.…”

“…The Infracambrian SR Formation is exposed in the northeastern part of Pakistan (Potwar Plateau) 9,10 .…”

“…The Infracambrian play in SE Pakistan has been previously explored to study the distribution and modelling of the source and reservoir rocks. Many deep wells targeting to penetrate Infracambrian rock were drilled on paleo-highs but did not encounter Infracambrian strata 6,9 . All wells were drilled to the uppermost column of the oil window and allowed minor in-situ heavy oil shows within the source rock beds.…”

“…In the BK-N Basin, the biomarker study from the Baghewala-1 well reveals that mature hydrocarbons have been generated from a deeper buried source rock 2 . Several authors reported that the same quantities of petroleum could be generated from the Infracambrian source rock of Salt Range (SR) Formation in southeastern (SE) Pakistan, where Infracambrian source rock beds are much deeper and thicker than that in the BK-N Basin 2,6,9 .…”