Hydrocarbon Generative Potential of Cretaceous and Jurassic Deposits in the Ahmedpur East Oilfield Subsurface, Punjab Platform, Pakistan

Abstract

Cretaceous and Jurassic deposits in the sub-surface of Ahmedpur East Oilfield, Punjab Platform, Pakistan, have been geochemically analysed. Source rock potential of three formations namely Mughal Kot and Goru (Cretaceous) and Samana Suk (Jurassic) located in Middle Indus Basin have been investigated. The formations were investigated using total organic carbon and Rock-Eval pyrolysis analysis measurements. Analysis were performed on fourteen samples from wells, having TOC 0.57-1.65 wt.%, the S2 values of the sample shows poor to fair generative potential and lies between 0.25-2.59 mg HC/g rock, HI values are generally low 37-150 mg HC/g TOC and Tmax values ranges from 417-453 ° C. The analysis shows Mughal Kot and Samana Suk formations samples have entered maturity window zone, however Goru Formation samples lies in immature zones, shown by hydrogen index vs Tmax plot. The samples from Mughal Kot and Goru formations have kerogen type III with poor generative potential, however Samana Suk Formation have fair generative potential having kerogen type III indicated by S2 vs TOC plot, hence from the results some minor gas could be expected to have been generated by Samana Suk Formation. Targeting these formations as a source rock to expel hydrocarbons involves high risk and exploration of such reserves may not be beneficial in terms of economic value.

Integrated Interpretation of Eocene-Palaeocene Rocks in Potwar Basin, Pakistan: Implications for Petroleum Generation

“…Reservoir rock characteristics were determined using various logs, including density, neutron, gamma ray, resistivity, and spontaneous potential logs. The reservoir properties were qualitatively described based on criteria from Rider (1986) and Shah and Shah (2021). This study specifically utilized well logs from Well A to investigate the reservoir potential of the Nammal Formation.…”

“…Approximately 100mg of crushed samples were subjected to pyrolysis in a helium atmosphere, heated to 600°C. The pyrolysis process provided three crucial parameters: S1, representing the amount of whole free petroleum; S2, indicating the quantity of hydrocarbons generated during thermal cracking; and Tmax, the temperature at which the maximum hydrocarbon generation occurs Shah and Shah, 2021). The hydrogen index and production yield were also calculated as other significant factors.…”

“…According to various studies, the primary source of hydrocarbons in the Potwar Basin is the Patala Formation. These researchers include , Fazeelat et al (2010), Fazeelat et al (2009), , Shah and Shah (2021), , and Yasin et al (2021). The sediments from two wells of the Fimkassar oilfield, which are of the Eocene and Palaeocene ages, have been studied (Fig.…”

“…This is the unique aspect of this research work. Previous studies by researchers such as Ihasn et al ( 2022), Nazir et al (2014), Shah et al (2021), Fazeelat et al (2010), Shah (2017), Nazir et al (2015Nazir et al ( ), H et al (2021, and Masood et al (2017) focused on different formations and used various techniques to evaluate them, including modelling the structure with faults for salt diapirs and studying specific formations like Sakesar, Tobra, and Khewra. However, there is a lack of information regarding the interpretation of all three formations' source and reservoir rock properties, which makes this study necessary and crucial.…”

“…This research will Table 1. Qualitative description of reservoirs porosity set by Rider's (1986) and Shah et al (2021).…”