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Archive for the ‘Bahamas’ Category

Important scientific survey proposed for the US South Atlantic

Posted in Bahamas, Offshore Energy - General, tagged , , , , , , , on June 7, 2023| Leave a Comment »

Just as I was lamenting the absence of scientific surveying in the Atlantic, my former colleague Renee Orr brought this NOAA announcement to my attention. Researchers from the University of Texas Institute of Geophysics and Lamont-Doherty Earth Observatory, with funding from the National Science Foundation, propose to conduct seismic surveys in the Blake Plateau area of the South Atlantic (map below).

The proposed study would acquire two-dimensional (2-D) seismic reflection and seismic refraction data to examine the structure and evolution of the rifted margins of the southeastern United States, including the rift dynamics during the formation of the Carolina Trough and Blake Plateau.

The survey will lead to a better understanding of “the interaction between tectonic and magmatic processes that led to continental breakup and the onset of seafloor spreading in the central Atlantic Ocean 200 million years ago.” The investigators are particularly interested in the “stratigraphy of sediments that formed during and after rifting, the degree of crustal stretching at the continental margins, crustal faults that formed during extension of the margin, and the geometry of lava flows that were placed on the crust before the start of seafloor spreading.”

While not a primary purpose, the research should improve our understanding of the relationship between productive oil and gas fields offshore Africa and US analogs. Paul Post and his BOEM team estimated that the US Atlantic could contain >20 billion BOE (link to the latest report).

NOAA has conducted a detailed review of the proposal and made a “preliminary determination that the impacts resulting from this activity are not expected to adversely affect any of the species or stocks through effects on annual rates of recruitment or survival.”

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The Bahamas: More exploration coming?

Posted in Bahamas, drilling, tagged , on August 17, 2021| Leave a Comment »

Challenger Energy Graphic

The only 2021 Atlantic drilling activity offshore North America and south of Newfoundland was in Bahamian waters. Yesterday, Challenger Energy (formerly Bahamas Petroleum) provided an interesting update. Some highlights:

  1. The Perserverance I well was drilled approximately 20 miles from the Bahamas-Cuba maritime border, in water 518 meters deep. This was the first exploration drilling in The Bahamas since the mid-1980s, and the first test of any prospect located in deeper waters off the shallower water carbonate banks.
  2. There were no safety or environmental incidents.
  3. The well was plugged and secured in accordance with international and BSEE standards.
  4. Challenger advised the Government of The Bahamas of its intent to renew its exploration licences. 

Geologic summary:

Perseverance-1 reached total depth of 3,905 metres, having intersected five Albian, Upper Aptian, and Mid-Aptian horizons of interest. Post-drill analysis of the well has confirmed the geological risk elements for trap, seal and reservoir were present in the Lower Cretaceous carbonate play. Perseverance encountered high quality reservoirs in the targeted Lower Cretaceous carbonate closures, with thick sequences of evaporites providing effective seals. Depth and thicknesses of reservoir sections encountered were generally as prognosed pre-drill, and reservoir porosity was likewise generally in line with pre-drill expectations (in the range of 10% to 20%).

The presence of hydrocarbons was encountered at various horizons, indicated by elevated gas chromatography readings detected continually during drilling, generally increasing with depth and through the deeper Aptian reservoir column in particular. Oil was identified from high oil saturation values from logs in a number of reservoir sections, thus verifying the existence of a working Lower Cretaceous petroleum system and reservoir quality sequences in the Aptian.

Although hydrocarbons were present, these were not in commercial quantities, with the source quality and migration interpreted as being the primary reason for this non-commercial well outcome.

Petrophysical analysis of the well logs have confirmed high quality reservoirs down to the base of the well with no significant deterioration in porosity with depth, indicating the potential for high deliverability reservoirs in the underlying Jurassic formations.

In aggregate, the analysis of the data from Perseverance-1 drilling is broadly indicative of increased potential for oil in the underlying Jurassic interval (which was not penetrated by Perseverance-1). In particular, the relatively cool well temperatures place the postulated Jurassic source rock (producing in nearby Cuba and the US Gulf of Mexico) in the oil window, thus oil generative.

Challenger Energy, 8/16/2021

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