--> Hydrocarbon Migration Model in a Salt Controlled Domain: A Study in the MexilhãO Field Area, Bender, Andre A.; Mio, Eduardo D., #90100 (2009)

Datapages, Inc.Print this page

Hydrocarbon Migration Model in a Salt Controlled Domain: A Study in the MexilhãO Field Area

Bender, Andre A.1
 Mio, Eduardo D.1

1HRT & Petroleum, Rio de Janeiro, Brazil.

Mexilhão Field is located in the Santos Basin, 137 km distant from the coast, at 400-500 m water depth. According to the ANP, Mexilhão holds gas and condensate in the sandstones of Santonian age. The trap that characterizes Mexilhão Field is difficult to represent in basin simulators. It is a mixture of structural and stratigraphic type, bounded along its western side by a normal fault. The geological context of the gas field is of salt weld domain in front of prograding Cretaceous sandstones leaning against a major landward-dipping normal fault (Cabo Frio Fault). It is a conspicuous geological feature that subsided strongly to accommodate several kilometers of sedimentary rocks. This thick wedge of sedimentary rocks is at the border of salt diapir zone, but probably the major drainage area extends down to the Salt wall zone (deep water) where the main petroleum generated is liquid. Geological observation and salt restoration indicate that the main salt activity took place from 100 to 72 Ma. The present day maturation of the Coquinas SR is at the wet gas zone, whereas the Barremian SR is in the wet and dry gas generation zones. However, to the east of the Mexilhão Field, below the salt wall domain, both source rocks are in the oil generation window. The maturity results are consistent with fluid composition of the field (~92% methane). The objective of this work is to provide insights about the petroleum systems of an intensively controlled salt domain by using petroleum basin modeling. The kinematics of the salt evolution is complex and has strong implications for the temperature and fluid flow histories of the area. The salt restoration is a challenge and the complexities of the geology can be tricky to be reasonably represented in basin simulators, even with advanced 3D simulators as PetroMod. In order to explore the possible migration pathways in the area, timing of the main petroleum pulses and composition of the accumulations, several simulations runs were carried out taking into account uncertainties characteristics of heat flow, salt restoration, rock properties, secondary cracking and source rock parameters (richness, distribution and thickness). An Important aspect of this work is that high amounts of vertical migration of hydrocarbons from pre-salt (as far as deep water areas) are responsible for charging the Mexilhão Field, surprisingly late, from 27 Ma to present day.

AAPG Search and Discover Article #90100©2009 AAPG International Conference and Exhibition 15-18 November 2009, Rio de Janeiro, Brazil