Mumbai Offshore Basin

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The Mumbai Basin, also known as the Bombay Basin covers an area of over 116,000 km2 and is considered as the offshore extension of Cambay Basin. Exploration started in the 1960 but the first oil discovery was until early 1974. The age of the basin ranges from late Cretaceous to Holocene with thick sedimentary filing. The Mumbai offshore is a pericratonic rift basin situated on the western continental margin of India. The Basin has Five major formations Mukta, Daman, Ratnagiri, Panna, and S1 Pay. The Mumbai offshore basin is home to an abundant amount of fossil fuels like petroleum gases and oil. [1].

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Geological History

Mumbai Offshore Basin is in the western continental margin of India mostly covered by the ocean. It formed due to the extensional tectonic plates drifting during the Indian plate from Madagascar in the early Jurassic and later Cretaceous. It is characterized by longitude extension faults giving rise to a series of horst and garden aspects. Multiple events occurred like marine regression and transgression that development of extensive carbonate over most of the basin like the Ratnagiri and the Herra-Bassein basin. [3].

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Production History

The Mumbai Offshore Basin contributes 55% domestic crude oil and 70% of gas production for India each year. The crude oil that is produced in this basin is of very good quality as compared to crude produced in the middle east. Mumbai crude has more than 60% paraffinic content and the middle east runs between 25%-30% paraffin. Oil and natural gas corporation limited has made India’s small sector of oil and gas and made a huge difference. ONGC is on a quest to decline global crude prices by taking significant investments decision by reserving production trends offshore. And venturing into deeper water plays to secure energy. India plans to produce more natural gas in the future to increase recovery technology and be less dependent on oil. Other petroleum companies in the Mumbai offshore basin like Indian Oil, and Prize Petroleum Company are promising nonpublic companies that do not produce as much as the ONGCL but understand the industry and is producing from the Ratnagiri and the Herra-bassein. [5].

Petroleum Geology

Source Rocks

The Ratnagiri, Panna-Bassein, and the Herra have continued to contribute benefits of hydrocarbon to the basin. The Finer clastics entering the Surat Depression through Narmada systems have been getting partially dispersed southward and entering these two prominent lows that appear at the depression extending south. However, the discovery of the Neelam, field with the basin indicates hydrocarbon possibilities with the Mumbai basin provides better reservoir facies and proper entrapment conditions. [6].The excellent source rocks of restricted marine to lagoonal deposits within the Panna Formation in the Central graben and adjoining area are the principal source of hydrocarbon accumulation in the basin. In the Mahim graben, a 400-m-thick sequence in the Panna Formation contains very good/excellent oil-prone effective source-rock facies, which account for the commercial petroleum reservoirs within Bassein, and Heera formations in the east of Panna and Bassein fields

Traps and Seals

Trap rocks are formed by an anticline structure with a concave roof caused by a deformation of a reservoir and have an impermeable cap rock. A seal consists of rocks that form a barrier or cap above and around the reservoir rock-forming into a trap that fluids cannot migrate beyond the reservoir. [7]. Mumbai Offshore basin has endowed with a wide variety of entrapment situations ranging from small to large. Trap from structural closure from four ways, fault closures with effective sealing, strati-structural like Paleogene wedging against rising flanks of mud mounds. Also, from carbonate build-up over time, unconformity-controlled traps and carbonate wedging. Is what turned carbohydrates into crude oil over a long period and under the perfect conditions. [8].

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Future Potential

The Future Potential of the Mumbai offshore involves exploration in deep water in the shelf margin, along with more gas recovery for India. The application of new technology, and the utilization of infrastructure, will mean that the Mumbai offshore basin will still contribute volumes to India's energy mix. Moving forward for oil but based on the present trends, gas dependences will begin to transition to the east coast. Lower Eocene-Paleocene sediments have very good source-rock characteristics and good hydrocarbon generation potential throughout the basin, but the quality and quantity of the organic matter deteriorated towards the peripheral area from the basinal lows. The organic matter is dominated by input from terrigenous higher land plants. However, two potential source sequences are identified in the lower EocenePaleocene sediments. Specific biomarkers, particularly the relative contribution from resinous plants, flowering plants, carbon isotopic composition, and marine organic matter diagnostic biomarkers.













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  11. [“The Mumbai Basin's Geological History, Future Potential, and Importance for India.” IHS Markit, 14 Jan. 2021,].
  12. [“Mumbai Offshore Basin.” Mumbai Offshore Basin | NDR (National Data Repository)-Directorate General of Hydrocarbons(DGH) | Ministry of Petroleum and Natural Gas, Government of India,].
  13. [Nair, Nisha, and Dhananjai K. Pandey. “Cenozoic Sedimentation in the Mumbai Offshore Basin: Implications for Tectonic Evolution of the Western Continental Margin of India.” Journal of Asian Earth Sciences, Pergamon, 26 Nov. 2017,].
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  19. [Eocene. Eocene - an overview | ScienceDirect Topics. (n.d.). Retrieved December 17, 2021, from Retrieved December 16, 2021, from]