Petersen, Kenneth1, Gary H. Isaksen2
(1) ExxonMobil Upstream Research Company, Houston, TX
(2) ExxonMobil Exploration Co, Houston, TX
ABSTRACT: Integration of Advanced Technologies Unravel the Complex Nature of a Major Hydrocarbon System Offshore Mid-Norway
With an estimated 375 billion Sm3 (13.2 TCF) of recoverable sweet gas and 22 million
m3 (138 MOEB) of condensate, the recently discovered Ormen Lange field ranks as the second largest on the Norwegian Shelf. The field, located in 800-1000 meters of water offshore Mid-Norway, is currently in its development phase with production start up and gas deliveries to the UK and Europe planned for 2007.
One of the major enigmas of the Ormen Lange hydrocarbon system has been that the conventional late Jurassic source rocks expelled their main phase of oil and gas during the late Cretaceous This is significantly earlier than the Oligo-Miocene inversion which formed the trap within early Paleogene sheet sands. One model holds that the bulk of hydrocarbons are re-migrated from temporary entrapment deeper, unproven traps (the "hotel-theory"). An alternative model invokes a hitherto unproven effective Cretaceous source rock to resolve the trap and charge-timing dilemma. Both models are inherently unsatisfactory.
Integration of detailed geochemical and structural analyses with 3D basin modeling has resulted in an alternative charge model for Ormen Lange. Careful reconstructions of structural, thermal and pressure histories point to a long-distance migration route for hydrocarbons from the margin of the Møre Basin into the Ormen Lange trap. Sufficient trap-fill multiples from the conventional Jurassic source rocks are available post-trap formation in the corresponding drainage area. This new charge model is consistent with the geochemical properties of the discovered gas and liquids and the Jurassic source rock facies known to be present along the margin of the Møre Basin. This improved understanding of the Ormen Lange hydrocarbon system will impact the viability for continued exploration in the deepwater areas of the Norwegian Sea.
AAPG Search and Discovery Article #90026©2004 AAPG Annual Meeting, Dallas, Texas, April 18-21, 2004.