A CASE FOR MESOZOIC HYDROCARBON ULTRA-DEEP EXPLORATION: BALTIMORE CANYON, U.S. OFFSHORE EAST COAST

Hydrocarbon exploration off the coast of New York and New Jersey, the Baltimore Canyon (BC) contained five wells with non-commercial quantities of gas condensates and dry gas. The most significant finds were within Kimmeridgian and Oxfordian Sandstone units in the prograding coastal plain and transitional marine deposits.

Of the 32 wells drilled no obvious source rocks were encountered. Reinterpretation of gas condensate from the Hudson River Canyon (BC), utilizing gas chromatography of hydrocarbon liquids and mass spectroscopy for diamondoids (HC-598 #1 Upper Jurassic at 4285 m, API gravity 36.6 degree and HC-642#2 early Cretaceous Albian at 2535 m, 48.4 API gravity degree) suggests a deeper Lower to Middle Jurassic source at a depth greater than 6 kms. The lithology of the source is a matter of discussion.

In the BCT geothermal gradients are low and vary from 1 to 1.45 degrees F / 100’. A thermal maturation profile (BasinMod 1D model) of the Shell 273-1 well indicates the Jurassic in early oil phase at 3800m and the main gas generation window at 5200 m. Early to Middle Jurassic sediments entered the main gas generation window during the Late Jurassic, from 5 to 6.5km of burial. North of the Shell 273-1, the Texaco 426-1 well contained a lower geothermal gradient and reflected a TAI of 3.00 at 4600m. Timing of hydrocarbon generation would be deeper and later in the Cretaceous.

Untested ultra-deep potential hydrocarbon resources are located in the BOEM play area 8, termed the BCT Structural Belt Jurassic-Cretaceous Interior Shelf. Significantly more risked recoverable reserves, due to 1) Two salt ridges penetrating Middle Jurassic age sediments identified in seismic records located to the north of the Schlee Dome, analogous to the ultra-deep salt related Norphlet Formation, offshore Gulf of Mexico and the onshore East Texas, Pearsall Field and 2) stratigraphic plays including below a 60 m thick and 7500 km square evaporitic feature in Early Jurassic rocks flanking the Schlee Dome.

Evaporites would provide mature source rocks and high pH fluidization for mesodiagenetic reservoir formation in carbonates (anhydrite dissolution and dolomitization and secondary porosity creation), and along with feldspar dissolution in sandstones.